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  • richardmitnick 2:41 pm on June 21, 2018 Permalink | Reply
    Tags: , , Laser Technology, , ,   

    From Fermilab: “New laser technology shows success in particle accelerators” 

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    From Fermilab an enduring source of strength for the US contribution to scientific research world wide.

    June 21, 2018
    Sarah Lawhun

    1
    David Johnson, left, and Todd Johnson work on the recently installed laser notcher in the Fermilab accelerator complex. The laser notcher, the first application of its kind in an in-production particle accelerator, has helped boost particle beam production at the lab. Photo: Reidar Hahn

    Lasers — used in medicine, manufacturing and made wildly popular by science fiction — are finding a new use in particle physics.

    Fermilab scientists and engineers have developed a tool called a laser notcher, which takes advantage of the laser’s famously precise targeting abilities to do something unexpected: boost the number of particles that accelerators send to experiments. It’s cranked up the lab’s particle output considerably — by an incredible 15 percent — giving scientists more opportunities to study nature’s tiniest constituents.

    While lasers have been used during accelerator tests and diagnostics, this is the first application of its kind used in a fully operational accelerator.

    “For such a new design, the laser notcher has been remarkably reliable,” said Fermilab engineer Bill Pellico, who manages one of the laboratory’s major accelerator upgrade programs, called the Proton Improvement Plan. “It’s already shown it will provide a considerable increase in the number of particles we can produce.”

    The notcher increases particle production, counterintuitively, by removing particles from a particle beam.

    Bunching out

    The process of removing particles isn’t new. Typically, an accelerator generates a particle beam in bunches — compact packets that each contain hundreds of millions of particles. Imagine each bunch in a beam as a pearl on a strand. Bunches can be arranged in patterns according to the acceleration needs. Perhaps the needed pattern is a 80-bunch-long string followed by a three-bunch-long gap. Often, the best way to create the gap is to start with a regular, uninterrupted string of bunches and simply remove the unneeded ones.

    But it isn’t so simple. Traditionally, beam bunches are kicked out by a fast-acting magnet, called a magnetic kicker. It’s a messy business: Particles fly off, strike beamline walls and generally create a subatomic obstacle course for the beam. While it’s not impossible for the beam to pass through such a scene, it also isn’t smooth sailing.

    Accelerator experts refer to the messy phenomenon as beam loss, and it’s a measurable, predictable predicament. They accommodate it by holding back on the amount of beam they accelerate in the first place, setting a ceiling on the number of particles they pack into the beam.

    That ceiling is a limitation for Fermilab’s new and upcoming experiments, which require greater and greater numbers of particles than the accelerator complex could handle previously. So the lab’s accelerator specialists look for ways to raise the particle beam ceiling and meet the experimental needs for beam.

    The most straightforward way to do this is to eliminate the thing that’s keeping the ceiling low and stifling particle delivery — beam loss.

    Lasers against loss

    The new laser notcher works by directing powerful pulses of laser light at particle bunches, taking them out of commission. Both the position and precision of the notcher allow it to create gaps cleanly —delivering a one-two punch in curbing beam loss.

    First, the notcher is positioned early in the series of Fermilab’s accelerators, when the particle beam hasn’t yet achieved the close-to-light speeds it will attain by the time it exits the accelerator chain. (At this early stage, the beam lumbers along at 4 percent the speed of light, a mere 2.7 million miles per hour.) This far upstream, the beam loss resulting from ejecting bunches doesn’t have much of an impact.

    “We moved the process to a place where, when we lose particles, it really doesn’t matter,” said David Johnson, Fermilab engineering physicist who led the laser notcher project.

    Second, the laser notcher is, like a scalpel, surgical in its bunch removal. It ejects bunches precisely, individually, bunch by bunch. That enables scientists to create gaps of exactly the right lengths needed by later acceleration stages.

    For Fermilab’s accelerator chain, the winning formula is for the notcher to create a gap that is 80 nanoseconds (billionths of a second) long every 2,200 nanoseconds. It’s the perfect-length gap needed by one of Fermilab’s later-stage accelerators, called the Booster.

    A graceful exit

    The Fermilab Booster feeds beam to the next accelerator stages or directly to experiments.

    Prior to the laser notcher’s installation, a magnetic kicker would boot specified bunches as they entered the Booster, resulting in messy beam loss.

    With the laser notcher now on the scene, the Booster receives a beam that has prefab, well-defined gaps. These 80-nanosecond-long windows of opportunity mean that, as the beam leaves the Booster and heads toward its next stop, it can make a clean, no-fuss, no-loss exit.

    With Booster beam loss brought down to low levels, Fermilab accelerator operators can raise the ceiling on the numbers of particles they can pack into the beam. The results so far are promising: The notcher has already allowed beam power to increase by a whopping 15 percent.

    Thanks to this innovation and other upgrade improvements, the Booster accelerator is now operating at its highest efficiency ever and at record-setting beam power.

    “Although lasers have been used in proton accelerators in the past for diagnostics and tests, this is the first-of-its-kind application of lasers in an operational proton synchrotron, and it establishes a technological framework for using laser systems in a variety of other bunch-by-bunch applications, which would further advance the field of high-power proton accelerators,” said Sergei Nagaitsev, head of the Fermilab Office of Accelerator Science Programs.

    Plentiful protons and other particles

    The laser notcher, installed in January, is a key part of a larger program, the Proton Improvement Plan (PIP), to upgrade the lab’s chain of particle accelerators to produce powerful proton beams.

    As the name of the program implies, it starts with protons.

    Fermilab sends protons barreling through the lab’s accelerator complex, and they’re routed to various experiments. Along the way, some of them are transformed into other particles needed by experiments, for example into neutrinos—tiny, omnipresent particles that could hold the key to filling in gaps in our understanding the universe’s evolution. Fermilab experiments need boatloads of these particles to carry out its scientific program. Some of the protons are transformed into muons, which can provide scientists with hints about the nature of the vacuum.

    With more protons coming down the pipe, thanks to PIP and the laser notcher, the accelerator can generate more neutrinos, muons and other particles, feeding Fermilab’s muon experiments, Muon g-2 and Mu2e, and its neutrino experiments, including its largest operating neutrino experiment, NOvA, and its flagship, the Deep Underground Neutrino Experiment and Long-Baseline Neutrino Facility.

    “Considering all the upgrades and improvements to Fermilab accelerators as a beautiful cake with frosting, the increase in particle production we managed to achieve with the laser notcher is like the cherry on top of the cake,” Nagaitsev said.

    “It’s a seemingly small change with a significant impact,” Johnson said.

    As the Fermilab team moves forward, they’ll continue to put the notcher through its paces, investigating paths for improvement.

    With this innovation, Fermilab adds another notch in the belt of what lasers can do.

    See the full article here .


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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
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  • richardmitnick 1:40 pm on June 18, 2018 Permalink | Reply
    Tags: , Convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells, Laser Technology, ,   

    From Lawrence Berkeley National Lab: “Scientists Create Continuously Emitting Microlasers With Nanoparticle-Coated Beads” 

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    From Lawrence Berkeley National Lab

    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

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    At left, a tiny bead struck by a laser (at the yellowish spot shown at the top of the image) produces optical modes that circulate around the interior of the bead (pinkish ring). At right, a simulation of how the optical field inside a 5-micron (5 millionths of a meter) bead is distributed. (Credit: Angel Fernandez-Bravo/Berkeley Lab, Kaiyuan Yao)

    Researchers have found a way to convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells.

    These microlasers, which convert infrared light into light at higher frequencies, are among the smallest continuously emitting lasers of their kind ever reported and can constantly and stably emit light for hours at a time, even when submerged in biological fluids such as blood serum.

    The innovation, discovered by an international team of scientists at the U.S. Department of Energy’s Lawrence Berkeley Laboratory (Berkeley Lab), opens up the possibility for imaging or controlling biological activity with infrared light, and for the fabrication of light-based computer chips. Their findings are detailed in a report published online June 18 in Nature Nanotechnology.

    The unique properties of these lasers, which measure 5 microns (millionths of a meter) across, were discovered by accident as researchers were studying the potential for the polymer (plastic) beads, composed of a translucent substance known as a colloid, to be used in brain imaging.

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    A scanning electron micrograph image (left) of a 5-micron-diameter polystyrene bead that is coated with nanoparticles, and a transmission electron micrograph image (right) that shows a cross-section of a bead, with nanoparticles along its outer surface. The scale bar at left is 1 micron, and the scale bar at right is 20 nanometers. (Credit: Angel Fernandez-Bravo, Shaul Aloni/Berkeley Lab)

    Angel Fernandez-Bravo, a postdoctoral researcher at Berkeley Lab’s Molecular Foundry, who was the lead author of study, mixed the beads with sodium yttrium fluoride nanoparticles “doped,” or embedded, with thulium, an element belonging to a group of metals known as lanthanides. The Molecular Foundry is a nanoscience research center open to researchers from around the world.

    LBNL Molecular Foundry – No image credits found

    Emory Chan, a Staff Scientist at the Molecular Foundry, had in 2016 used computational models to predict that thulium-doped nanoparticles exposed to infrared laser light at a specific frequency could emit light at a higher frequency than this infrared light in a counterintuitive process known as “upconversion.”

    Also at that time, Elizabeth Levy, then a participant in the Lab’s Summer Undergraduate Laboratory Internship (SULI) program, noticed that beads coated with these “upconverting nanoparticles” emitted unexpectedly bright light at very specific wavelengths, or colors.

    “These spikes were clearly periodic and clearly reproducible,” said Emory Chan, who co-led the study along with Foundry Staff Scientists Jim Schuck (now at Columbia University) and Bruce Cohen.

    The periodic spikes that Chan and Levy had observed are a light-based analog to so-called “whispering gallery” acoustics that can cause sound waves to bounce along the walls of a circular room so that even a whisper can be heard on the opposite side of the room. This whispering-gallery effect was observed in the dome of St. Paul’s Cathedral in London in the late 1800s, for example.

    In the latest study, Fernandez-Bravo and Schuck found that when an infrared laser excites the thulium-doped nanoparticles along the outer surface of the beads, the light emitted by the nanoparticles can bounce around the inner surface of the bead just like whispers bouncing along the walls of the cathedral.

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    A wide-field image showing the light emitted by microlasers in a self-assembled 2D array. (Credit: Angel Fernandez-Bravo)

    Light can make thousands of trips around the circumference of the microsphere in a fraction of a second, causing some frequencies of light to interact (or “interfere”) with themselves to produce brighter light while other frequencies cancel themselves out. This process explains the unusual spikes that Chan and Levy observed.

    When the intensity of light traveling around these beads reaches a certain threshold, the light can stimulate the emission of more light with the exact same color, and that light, in turn, can stimulate even more light. This amplification of light, the basis for all lasers, produces intense light at a very narrow range of wavelengths in the beads.

    Schuck had considered lanthanide-doped nanoparticles as potential candidates for microlasers, and he became convinced of this when Chan shared with him the periodic whispering-gallery data.

    Fernandez-Bravo found that when he exposed the beads to an infrared laser with enough power the beads turned into upconverting lasers, with higher frequencies than the original laser.

    He also found that beads could produce laser light at the lowest powers ever recorded for upconverting nanoparticle-based lasers.

    “The low thresholds allow these lasers to operate continuously for hours at much lower powers than previous lasers,” said Fernandez-Bravo.

    Other upconverting nanoparticle lasers operate only intermittently; they are only exposed to short, powerful pulses of light because longer exposure would damage them.

    “Most nanoparticle-based lasers heat up very quickly and die within minutes,” Schuck said. “Our lasers are always on, which allows us to adjust their signals for different applications.”

    In this case, researchers found that their microlasers performed stably after five hours of continuous use. “We can take the beads off the shelf months or years later, and they still lase,” Fernandez-Bravo said.

    Researchers are also exploring how to carefully tune the output light from the continuously emitting microlasers by simply changing the size and composition of the beads. And they have used a robotic system at the Molecular Foundry known as WANDA (Workstation for Automated Nanomaterial Discovery and Analysis) to combine different dopant elements and tune the nanoparticles’ performance.

    The researchers also noted that there are many potential applications for the microlasers, such as in controlling the activity of neurons or optical microchips, sensing chemicals, and detecting environmental and temperature changes.

    “At first these microlasers only worked in air, which was frustrating because we wanted to introduce them into living systems,” Cohen said. “But we found a simple trick of dipping them in blood serum, which coats the beads with proteins that allow them to lase in water. We’ve now seen that these beads can be trapped along with cells in laser beams and steered with the same lasers we use to excite them.”

    The latest study, and the new paths of study it has opened up, shows how fortuitous an unexpected result can be, he said. “We just happened to have the right nanoparticles and coating process to produce these lasers,” Schuck said.

    Researchers from UC Berkeley, the National Laboratory of Astana in Kazakhstan, the Polytechnic University of Milan, and Columbia University in New York also participated in this study. This work was supported by the DOE Office of Science, and by the Ministry of Education and Science of the Republic of Kazakhstan.

    See the full article here .


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  • richardmitnick 12:42 am on May 13, 2018 Permalink | Reply
    Tags: , , Laser Technology, , , X-rays from tabletop lasers allows scientists to peer through the ‘water window’   

    From Imperial College London: “X-rays from tabletop lasers allows scientists to peer through the ‘water window’” 

    Imperial College London
    From Imperial College London

    11 May 2018
    Hayley Dunning

    1

    Studying the fleeting actions of electrons in organic materials will now be much easier, thanks to a new method for generating fast X-rays.

    The technique means advanced measurements of fast reactions will now be possible in physics labs around the world, without having to wait to use expensive and scarce equipment. It could be used, for example, to study and improve light-harvesting technologies like solar panels and water splitters.

    When ‘soft’ X-rays, beyond the range of ultraviolet light, strike an object, they are strongly absorbed by some kinds of atoms and not others. In particular, water is transparent to these X-rays, but carbon absorbs them, making them useful for imaging organic and biological materials.

    However, a challenge has been to generate very fast soft X-rays. Creating pulses of X-rays that only last one thousandth of a millionth of a millionth of a second would allow researchers to image the extremely quick motions of electrons, crucial for determining how charge travels and reactions occur.

    Smallest and fastest reaction steps

    Fast soft X-rays have been created with large facilities, such as multi-billion dollar costing free-electron lasers, but now a research team from Imperial College London have generated fast and powerful fast soft X-ray pulses using standard laboratory lasers.

    The method, which can produce bright soft X-ray pulses that last hundreds of attoseconds (quintillionths of a second), is published today in Science Advances.

    With the new technique, researchers will be able to watch the movement of electrons on their natural timescale, giving them a dynamic picture of the smallest and fastest reaction steps.

    Senior author Professor Jon Marangos, from the Department of Physics at Imperial, said: “The strength of this technique is that it can be used by many physics labs around the world with lasers they already have installed.

    “This discovery will allow us to make measurements at extreme timescales for the first time. We are at the frontiers of what we can measure, seeing faster-than-ever processes important for science and technology.”

    Generating X-rays

    Generating X-rays in a lab requires exciting atoms until they release photons – particles of light. Normally, atoms in a long, dispersed cloud are excited in sequence so that they emit photons in ‘phase’, meaning they add up and create a stronger X-ray pulse. This is known as phase matching.

    But when trying to generate soft X-rays this way, effects in the cloud of atoms strongly defocus the laser, disrupting phase matching.

    Instead, the team discovered that they needed a thin, dense cloud of atoms and short laser pulses. With this setup, while the photons could not stay in phase over a long distance, they were still in phase over a shorter distance and for a short time. This led to unexpectedly efficient production of the short soft X-ray pulses.

    The team further measured and simulated the exact effects that cause high harmonic generation in this situation, and from this were able to predict the optimum laser conditions for creating a range of X-rays.

    Lead researcher Dr Allan Johnson, from the Department of Physics at Imperial, said: “We’ve managed to look inside what was before the relatively black-box of soft X-ray generation, and use that information to build an X-ray laser on a table that can compete with football-field spanning facilities. Knowledge is quite literally power in this game.”

    Improving solar technologies

    The team at Imperial plan to use the technique to study organic polymer materials, in particular those that harvest the Sun’s rays to produce energy or to split water. These materials are under intense study as they can provide cheaper renewable energy.

    However, many currently used materials are unstable or inefficient, due to the action of electrons that are excited by light. Closer study of the fast interactions of these electrons could provide valuable insights into methods for improving solar cells and catalysts.

    • ‘High-Flux Soft X-ray Harmonic Generation from Ionization-Shaped Few-Cycle Laser Pulses’ by Allan S. Johnson, Dane R. Austin, David A. Wood, Christian Brahms, Andrew Gregory, Konstantin B. Holzner, Sebastian Jarosch, Esben W. Larsen, Susan Parker, Christian S. Strüber, Peng Ye, John W. G. Tisch, and Jon P. Marangos is published in Science Advances.

    See the full article here .

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    Imperial College London is a science-based university with an international reputation for excellence in teaching and research. Consistently rated amongst the world’s best universities, Imperial is committed to developing the next generation of researchers, scientists and academics through collaboration across disciplines. Located in the heart of London, Imperial is a multidisciplinary space for education, research, translation and commercialisation, harnessing science and innovation to tackle global challenges.

     
  • richardmitnick 11:09 am on May 10, 2018 Permalink | Reply
    Tags: , , Laser Technology, , NIF From the ground up., ,   

    From The Atlantic Magazine: “The National Ignition Facility” 2014 Origins 

    Atlantic Magazine

    From The Atlantic Magazine

    Jan 9, 2014
    Alan Taylor

    At Lawrence Livermore National Laboratory, a federally funded research and development center about 50 miles east of San Francisco, scientists at the National Ignition Facility (NIF) are trying to achieve self-sustaining nuclear fusion — in other words, to create a miniature star on Earth.

    The core of the NIF is a house-sized spherical chamber aiming 192 massive lasers at a tiny target. One recent laser experiment focused nearly 2 megajoules (the energy consumed by 20,000 100-watt light bulbs in one second) of light energy onto a millimeter-sized sphere of deuterium and tritium in a 16-nanosecond pulse. The resulting energetic output, while far short of being a self-sustaining reaction, set a record for energy return, and has scientists hopeful as they fine-tune the targeting, material, and performance of the instruments. The facility itself bristles with machinery and instruments, impressing the producers of the movie Star Trek: Into Darkness, who used it as a film set for the warp core of the starship Enterprise.

    1
    1. Inside the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, a service system lift allows technicians to access the target chamber interior for inspection and maintenance. The goal of the NIF is to initiate controlled nuclear fusion, in the hopes of creating a new source of energy for our growing world.
    Philip Saltonstall/Lawrence Livermore National Laboratory

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    2. During construction in the late 1990s – NIF’s “Grand Central Station” is its seven-story-tall Target Bay which houses the target chamber as well as the final optics assemblies, cryogenics systems, and diagnostic equipment. The chamber, a sphere ten meters (33 feet) in diameter, is covered with boron-injected concrete to absorb neutrons during NIF experiments. Lawrence Livermore National Laboratory

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    3. U.S. Secretary of Energy Bill Richardson, lower right, christens the 150-ton, 33-foot diameter aluminum laser target chamber at the National Ignition Facility in Lawrence Livermore National Laboratory in Livermore, California, on June 11, 1999. AP Photo/Ben Margot

    4
    4. The single largest piece of equipment at the NIF is its 130-ton target chamber. The design features 6 symmetric middle plates and 12 asymmetric outer plates, which were poured at the Ravenswood Aluminum Mill in Ravenswood, West Virginia. The plates were shipped to Creusot-Loire Industries in France, where they were heated and then shaped in a giant press. The formed plates were shipped from France to Precision Components Corp. in York, Pennsylvania, where they were trimmed and weld joints prepared. Assembly and welding activities at Lawrence Livermore National Laboratory (seen here) were performed in a temporary cylindrical steel enclosure looking much like an oil or water tank. Lawrence Livermore National Laboratory

    5
    5. In June 1999, after careful preparation, a rotating crane hoisted the target chamber and gently moved it to the Target Bay. Lawrence Livermore National Laboratory

    6
    6. After the target chamber was lowered into place, the seven-story walls and roof of the Target Bay were completed. Lawrence Livermore National Laboratory

    7
    7. The target chamber under construction. Holes in the target chamber provide access for the laser beams and viewing ports for NIF diagnostic equipment.
    Lawrence Livermore National Laboratory

    8
    8. Power Conditioning System – Peak power for the NIF electrical system exceeds one trillion watts, making it the highest-energy and highest-power pulsed electrical system of its kind. Lawrence Livermore National Laboratory

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    9. The fabrication of melted and rough-cut blanks of laser glass amplifier slabs needed for NIF construction (3,072 pieces) was completed in 2005. The amplifier slabs are neodymium-doped phosphate glass manufactured by Hoya Corporation, USA and SCHOTT North America, Inc. Lawrence Livermore National Laboratory

    10
    10. The target assembly for NIF’s first integrated ignition experiment is mounted in the cryogenic target positioning system, or cryoTARPOS. The two triangle-shaped arms form a shroud around the cold target to protect it until they open five seconds before a shot. Lawrence Livermore National Laboratory

    11
    11. A new “tentless” National Ignition Facility target showing the two-millimeter-diameter target capsule in the center of the hohlraum (a specially designed barrel-shaped housing for the target sphere). The tiny capsule is supported by the fill tube used to fill the capsule with fuel and a secondary stabilizing support tube at right. Both tubes are 30 microns in diameter. In previous targets, the capsule was supported by ultrathin plastic membranes known as tents; experiments indicated that the tents might be seeding hydrodynamic instabilities sufficient to interfere with the NIF implosions. Lawrence Livermore National Laboratory

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    12. A NIF target contains a polished capsule about two millimeters in diameter, filled with cryogenic (super-cooled) hydrogen fuel. Lawrence Livermore National Laboratory

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    13. NIF’s final optics inspection system, when extended into the target chamber from a diagnostic instrument manipulator, can produce images of all 192 laser final optics assemblies.
    Jacqueline McBride/Lawrence Livermore National Laboratory

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    14. The National Ignition Facility at Lawrence Livermore National Laboratory requires optics produced from large single crystals of potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP). Each crystal is sliced into 40-centimeter-square crystal plates. Traditionally DKDP has been produced by methods requiring approximately two years to grow a single crystal. With the development of rapid growth methods for KDP, the time required to grow a crystal has been reduced to just two months. NIF requires 192 optics produced from traditionally grown DKDP and 480 optics rapidly grown from KDP. Approximately 75 production crystals were grown totaling a weight of nearly 100 tons. Lawrence Livermore National Laboratory

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    15. This view from the bottom of the chamber shows the target positioner being inserted. Pulses from NIF’s high-powered lasers race toward the Target Bay at the speed of light. They arrive at the center of the target chamber within a few trillionths of a second of each other, aligned to the accuracy of the diameter of a human hair. Philip Saltonstall/Lawrence Livermore National Laboratory

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    16. Seen from above, each of NIF’s two identical laser bays has two clusters of 48 beamlines, one on either side of the utility spine running down the middle of the bay, eventually reaching the target chamber. Jacqueline McBride/Lawrence Livermore National Laboratory

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    17. Temperatures of 100 million degrees and pressures extreme enough to compress the target to densities up to 100 times the density of lead are created in the target chamber. Surrounding the target is diagnostic equipment capable of examining in minute detail the arrival of the laser beams and the reaction of the target to this sudden deposition of energy. Jacqueline McBride/Lawrence Livermore National Laboratory

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    18. The interior of the NIF target chamber. The service module carrying technicians can be seen on the left. The target positioner, which holds the target, is on the right.
    Lawrence Livermore National Laboratory

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    19. Lawrence Livermore National Laboratory technicians John Hollis (right) and Jim McElroy install a SIDE camera in the target bay of the National Ignition Facility (NIF). The camera was the last of NIF’s 6,206 various opto-mechanical and controls system modules to be installed. Jacqueline McBride/Lawrence Livermore National Laboratory

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    20. Director Edward Moses briefed California Governor Arnold Schwarzenegger at the NIF target chamber, on November 10, 2008. Jacqueline McBride/Lawrence Livermore National Laboratory

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    21. NIF’s millimeter-sized targets must be designed and fabricated to meet precise specifications for density, concentricity and surface smoothness for NIF experiments. LLNL scientists and engineers have developed a precision robotic assembly machine to manufacture the small and complex fusion ignition targets. Lawrence Livermore National Laboratory

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    22. California Governor Arnold Schwarzenegger examines a model of a target while touring the National Ignition Facility in Livermore, California, on November 10, 2008. AP Photo/Lea Suzuki, Pool

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    23. A tall view of the NIF target chamber. Jacqueline McBride/Lawrence Livermore National Laboratory

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    24. A new viewing window recently installed on the NIF Target Chamber allows members of the NIF team and visitors to see inside the chamber while it is vacuum-sealed for experiments. NIF Team members Bruno Van Wonterghem (left), Jim Nally (pointing) and Rod Saunders watch through the viewing window as the Final Optics Damage Inspection System is deployed.
    Lawrence Livermore National Laboratory

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  • richardmitnick 1:24 pm on May 2, 2018 Permalink | Reply
    Tags: ELI Beamlines facility, Laser Technology, ,   

    From Lawrence Livermore National Laboratory: “Lasers, photonics and powerful partnerships” 

    Lawrence Livermore National Laboratory

    April 30, 2018

    Stephen Wampler
    wampler1@llnl.gov
    925-423-3107

    1
    The commercialization of laser peening technology — similar to working a metal’s surface with a ballpeen hammer — has been one of the most successful transfers of Lawrence Livermore technology to industry. The laser peening technology, which was originally developed by Battelle in the 1970s and was first commercialized by LSP technologies in 1975, was upgraded by LLNL researchers working with Metal Improvement Co. Inc.

    The world’s most energetic laser sits in a secure, guarded federal laboratory, but its impact stretches far beyond the one-square-mile site of Lawrence Livermore National Laboratory (LLNL).


    National Ignition Facility at LLNL

    Since the outset, technologies developed or improved at the Laboratory have led to industry-defining partnerships and products that make millions of Americans’ lives better every day. Even if they’ve never heard of them.

    “Nearly all of us at this point have flown on an airplane with turbine blades that were laser peened with technology that Livermore commercialized years ago,” said Craig Siders, senior scientist and commercial technology development leader in NIF & Photon Science’s Advanced Photon Technologies program. Laser peening — using intense laser light to improve the quality of a material — had been invented in the 1970s, but had not achieved significant market penetration until LLNL introduced a new laser architecture that provided critical new functionality to the technology. Laser peening is commonplace now, thanks in part to Laboratory research that was spun off into the private sector.

    “It’s technology that’s absolutely in the hands of industry today, and the Lab is now out of the peening business, because it’s the right thing to do,” Siders added. “LLNL’s innovations in laser technology were a critical component in making peening a success story.”

    In 2003, former LLNL scientists Lloyd Hackel and Brent Dane, together with LLNL CRADA partner Metal Improvement Company (MIC), today part of Curtiss-Wright Corporation, brought the benefits of laser peening to the economy as a whole. The Laboratory’s commercialization process worked: Lawrence Livermore helped develop a cutting-edge technology until it was mature enough to stand on its own. Today, laser peening can exponentially extend the lifespan of an F-22 fighter jet’s airframe. MIC has treated jet engine fan blades on every Airbus A340 passenger plane and hundreds of Boeing 777s and 787s. It’s the third best royalty-producing technology in Lab history.

    And now, LLNL is offering the opportunity to license and commercialize an extension of laser-peening technology called high velocity laser accelerated deposition (HVLAD) for controlled laser-driven explosive bonding. HVLAD was selected by R&D Magazine as a winner of an R&D 100 Award in 2012.

    “We’re in the process of satisfying the primary goals of the Lab — pursuing national security, stockpile stewardship and fundamental science,” said David Dawes, a business development executive in LLNL’s Innovation and Partnerships Office (IPO). “All of these things can help generate spinoffs that are commercially important.”

    Dawes is a primary conduit between LLNL and industry. When scientists believe they have a breakthrough, they often come to Dawes for advice. Whether that conversation leads to a record of invention, a patent or a Collaborative Research and Development Agreement (CRADA), he’s instrumental in helping keep up with the laser and optics industry and matching research with opportunity. Many of NIF’s 40,000 brand new, specialized optical components represent commercialization opportunities, thanks to the new technologies developed to create them. As the Laboratory advances each dimension of laser and optics technology, companies can follow behind and adopt them as they become available.

    “All of these features involve leading-edge technologies that are important to the laser industry as a whole as they scale up their power levels,” Dawes says. “There’s marketable technologies there that we’re currently talking to a number of companies about licensing.” For other examples of current laser and optics technologies available for commercialization, see the IPO website.

    In particular, Dawes brings 35 years of experience in the industry (and some patents of his own) to bear on IPO’s work connecting research with companies. Maintaining long-standing relationships with industry and academic leaders, setting up visits to Livermore and monitoring trade and scientific journals are important tricks of Dawes’ trade. IPO screens every paper slated for journal publication in order to identify possibilities for future commercialization. Details on ongoing CRADAs and licensing are scarce, but the Laboratory’s track record speaks for itself.

    “The Lab has had a significant impact, historically, on the market,” said Siders. “There’s a lot of goodwill out there, built up with past success stories like peening.”

    Pushing the frontiers in lasers

    Anticipating the next generation of lasers is especially fertile ground for partnerships with LLNL’s NIF & Photon Science researchers. Scientists expect these lasers to be so powerful, current optics technologies won’t be able to withstand them.

    “When I was a professor, I called this the first law of directed energy,” said Siders. “Thou Shalt Destroy the Target Before You Destroy the Laser.”

    A current CRADA with Electro-Optics Technology (EOT) aims to address one of these. Known for their diode-like Faraday isolators — permitting light to pass in one direction only while preventing harmful backward propagation — EOT, among other industry leaders, got a call from Laboratory researchers with experience in high-power laser performance and component cooling looking for pushing the limits of isolator technologies. EOT was looking to advance applications of new materials, which fit perfectly into the needs for high-power isolators. Together, EOT and LLNL are close to producing a marketable product that will benefit the laser industry as a whole and prepare the Laboratory for advanced high-power laser systems.

    One such system is the new HAPLS pulsed-laser being installed in the European Union’s Extreme Light Infrastructure (ELI) Beamlines facility in the Czech Republic.

    The L3-HAPLS laser system, installed at the ELI Beamlines Research Center in Dolní Břežany, Czech Republic.

    HAPLS (the High-Repetition-Rate Advanced Petawatt Laser System designed, developed and delivered by LLNL) integrates a number of new, efficient, high-power laser and optical technologies that Siders believes will eventually lead to the lasers necessary for inertial fusion energy. It’s a powerful tool for its customer, ELI Beamlines, but it’s also a window for scientists into the future of high-power pulsed lasers and a possible fusion power plant.

    ELI Beamlines facility, Research Center in Dolní Břežany, Czech Republic

    2
    LLNL researchers partnered with Lasertel Inc. to develop the world’s highest peak power laser diode arrays, representing total peak power of 3.2 megawatts, to power the High-Repetition-Rate Advanced Petawatt Laser System. To drive the diode arrays, LLNL developed and patented a new type of pulsed-power system, which supplies the arrays with electrical power by drawing energy from the grid and converting it to extremely high-current, precisely-shaped electrical pulses. Photo by Damien Jemison/LLNL.

    “We’re actually looking to provide benefits back from investments that this nation and the Department of Energy have made over four or five decades of research into inertial confinement fusion and inertial fusion energy,” said Siders. While luck is always a component, he added that strategy and ongoing communication are key to maintaining fruitful partnerships.

    “By working with industry in that way, we can get products on the market that everyone can benefit from,” said Siders. “That helps move the nation’s laser technology capabilities forward. That’s a good news story.”

    In addition to the significant benefits Lawrence Livermore’s laser and optics research can provide to industry, commercialization can also have a tremendous impact on the scientists themselves.

    “I often tell folks here that there’s a future where they could walk into almost any lab in the world, point to something and say ‘hey, that’s my work,’” said Siders. “That’s immensely rewarding.”

    -Ben Kennedy

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  • richardmitnick 5:56 pm on April 25, 2018 Permalink | Reply
    Tags: Laser Technology, , , Ultrahigh-pressure laser experiments shed light on cores of ‘super-Earth’ exoplanets   

    From Princeton University: “Ultrahigh-pressure laser experiments shed light on cores of ‘super-Earth’ exoplanets” 

    Princeton University
    Princeton University

    April 25, 2018
    Liz Fuller-Wright

    Using high-powered laser beams, researchers have simulated conditions inside a planet three times as large as Earth.

    Scientists have identified more than 2,000 of these “super-Earths,” exoplanets that are larger than Earth but smaller than Neptune, the next-largest planet in our solar system. By studying how iron and silicon alloys respond to extraordinary pressures, scientists are gaining new insights into the nature of super-Earths and their cores.

    “We now have a technique that allows us to directly access the extreme pressures of the deep interiors of exoplanets and measure important properties,” said Thomas Duffy, a professor of geosciences at Princeton. “Previously, scientists were restricted to either theoretical calculations or long extrapolations of low-pressure data. The ability to perform direct experiments allows us to test theoretical results and provides a much higher degree of confidence in our models for how materials behave under these extreme conditions.”

    1
    Inside the target chamber at the University of Rochester’s Omega Facility, lasers compress iron-silicon samples to the ultrahigh pressures found in the cores of super-Earths.
    Photo courtesy of Laboratory for Laser Energetics

    U Rochester Laboratory for Laser Energetics

    The work, which resulted in the highest-pressure X-ray diffraction data ever recorded, was led by June Wicks when she was an associate research scholar at Princeton, working with Duffy and colleagues at Lawrence Livermore National Laboratory and the University of Rochester. Their results were published today in the journal Science Advances written by by June Wicks, Raymond Smith, Dayne Fratanduono, Federica Coppari, Richard Kraus, Matthew Newman, J. Ryan Rygg, Jon Eggert and Thomas Duffy.

    Because super-Earths have no direct analogues in our own solar system, scientists are eager to learn more about their possible structures and compositions, and thereby gain insights into the types of planetary architectures that may exist in our galaxy. But they face two key limitations: we have no direct measurements of our own planetary core from which to extrapolate, and interior pressures in super-Earths can reach more than 10 times the pressure at the center of the Earth, well beyond the range of conventional experimental techniques.

    The pressures achieved in this study, up to 1,314 gigapascals (GPa) are about three times higher than previous experiments, making them more directly useful for modeling the interior structure of large, rocky exoplanets, Duffy said.

    “Most high-pressure experiments use diamond anvil cells which rarely reach more than 300 GPa,” or 3 million times the pressure at the surface of the Earth, he said. Pressures in Earth’s core reach up to 360 GPa.

    “Our approach is newer, and many people in the community are not as familiar with it yet, but we have shown in this (and past) work that we can routinely reach pressures above 1,000 GPa or more (albeit only for a fraction of a second). Our ability to combine this very high pressure with X-ray diffraction to obtain structural information provides us with a very unique tool — there is no other facility in the world that can do this,” he said.

    The researchers compressed two samples for only a few billionths of a second, just long enough to probe the atomic structure using a pulse of bright X-rays. The resulting diffraction pattern provided information on the density and crystal structure of the iron-silicon alloys, revealing that the crystal structure changed with higher silicon content.

    “The method of simultaneous X-ray diffraction and shock experiments is still in its infancy, so it’s exciting to see a ‘real-world application’ for the Earth’s core and beyond,” said Kanani Lee, an associate professor of geology and geophysics at Yale University who was not involved in this research.

    This new technique constitutes a “very significant” contribution to the field of exoplanet research, said Diana Valencia, a pioneer in the field and an assistant professor of physics at the University of Toronto-Scarborough, who was not involved in this research. “This is a good study because we are not just extrapolating from low pressures and hoping for the best. This is actually giving us that ‘best,’ giving us that data, and it therefore constrains our models better.”

    Wicks and her colleagues directed a short but intense laser beam onto two iron samples: one alloyed with 7 weight-percent silicon, similar to the modeled composition of Earth’s core, and another with 15 weight-percent silicon, a composition that is possible in exoplanetary cores.

    A planet’s core exerts control over its magnetic field, thermal evolution and mass-radius relationship, Duffy said. “We know that the Earth’s core is iron alloyed with about 10 percent of a lighter element, and silicon is one of the best candidates for this light element both for Earth and extrasolar planets.”

    The researchers found that at ultrahigh pressures, the lower-silica alloy organized its crystal structure in a hexagonal close-packed structure, while the higher-silica alloy used body-centered cubic packing. That atomic difference has enormous implications, said Wicks, who is now an assistant professor at Johns Hopkins University.

    “Knowledge of the crystal structure is the most fundamental piece of information about the material making up the interior of a planet, as all other physical and chemical properties follow from the crystal structure,” she said.

    Wicks and her colleagues also measured the density of the iron-silicon alloys over a range of pressures. They found that at the highest pressures, the iron-silicon alloys reach 17 to 18 grams per cubic centimeter — about 2.5 times as dense as on the surface of Earth, and comparable to the density of gold or platinum at Earth’s surface. They also compared their results to similar studies done on pure iron and discovered that the silicon alloys are less dense than unalloyed iron, even under extreme pressures.

    “A pure iron core is not realistic,” said Duffy, “as the process of planetary formation will inevitably lead to the incorporation of significant amounts of lighter elements. Our study is the first to consider these more realistic core compositions.”

    The researchers calculated the density and pressure distribution inside super-Earths, taking into account the presence of silicon in the core for the first time. They found that incorporating silicon increases the modeled size of a planetary core but reduces its central pressure.

    Future research will investigate how other light elements, such as carbon or sulfur, affect the structure and density of iron at ultrahigh pressure conditions. The researchers also hope to measure other key physical properties of iron alloys, to further constrain models of exoplanets’ interiors.

    “For a geologist, the discovery of so many extrasolar planets has opened the door to a new field of exploration,” said Duffy. “We now realize that the varieties of planets that are out there go far beyond the limited examples in our own solar system, and there is a much broader field of pressure, temperature and composition space that must be explored. Understanding the interior structure and composition of these large, rocky bodies is necessary to probe fundamental questions such as the possible existence of plate tectonics, magnetic field generation, their thermal evolution and even whether they are potentially habitable.”

    The research was funded by the National Nuclear Security Administration through the National Laser Users’ Facility Program (contract nos. DE-NA0002154 and DE-NA0002720) and the Laboratory Directed Research and Development Program at Lawrence Livermore National Laboratory (project no. 15-ERD-012).

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    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

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  • richardmitnick 10:32 pm on April 20, 2018 Permalink | Reply
    Tags: , Laser Technology, , Second laser revolution   

    From Lawrence Berkeley National Lab: “Study Recommends Strong Role for National Labs in ‘Second Laser Revolution’” 

    Berkeley Logo

    Lawrence Berkeley National Lab

    April 20, 2018
    Glenn Roberts Jr.
    GERoberts@lbl.gov
    (510) 486-5582

    1
    A view of BELLA, the Berkeley Lab Laser Accelerator. (Credit: Roy Kaltschmidt/Berkeley Lab)

    A new study calls for the U.S. to step up its laser R&D efforts to better compete with major overseas efforts to build large, high-power laser systems, and notes progress and milestones at the Department of Energy’s Berkeley Lab Laser Accelerator (BELLA) Center and other sites.

    An investment in this so-called “second laser revolution” promises to open up a range of applications, from machining to medicine to particle acceleration, according to the December report by the National Academies of Sciences, Engineering, and Medicine, which offers independent analysis to government agencies and policymakers.

    The 280-page report, “Opportunities in Intense Ultrafast Lasers: Reaching for the Brightest Light,” recommends increased coordination and collaboration by government labs and agencies, universities, and industry to build up U.S. laser facilities and capabilities.

    It also recommends that the DOE lead the creation of a national strategy to develop and operate large-scale national laboratory-based laser projects, midscale projects that could potentially be hosted at universities, and a laser tech-transfer program connecting industry, academia, and national labs.

    2

    The committee that prepared the report visited Berkeley Lab and other Northern California national labs, including SLAC National Accelerator Laboratory and Lawrence Livermore National Laboratory. The committee also visited the Extreme Light Infrastructure Beamlines laser facility site that is underway in the Czech Republic, and the Laboratory for Laser Energetics of the University of Rochester in New York.

    At the DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab), BELLA scientists are working to develop laser-based acceleration techniques that could lead to more compact particle accelerators for high-energy physics and drivers for high-energy light sources; also, the report notes, “laser expertise and utilization” that had been concentrated at other laboratories “is now broadening with plans for utilization of lasers at (Berkeley Lab)” and elsewhere.

    BELLA has made progress in demonstrating the rapid acceleration of electrons using separate stages of laser-based acceleration by forming and heating plasmas in which a powerful wave is created for electrons to “surf” on.

    “There’s a lot of work that’s been done already, and Berkeley Lab has been a key developer for the vision of where things need to go,” said Wim Leemans, director of the BELLA Center and the Lab’s Accelerator Technology & Applied Physics Division.

    Berkeley Lab was home to a pioneering experiment in 2004 that showed laser plasma acceleration can produce relatively narrow energy spread beams – reported in the so-called “Dream Beam” issue of the journal Nature – and in 2006 used a similar laser-driven acceleration technique to accelerate electrons to a then-record energy of 1 billion electron volts, or GeV. That achievement was followed in 2014 by a 4.2 GeV beam, using the powerful new laser that is at the heart of the BELLA Center and will be key to its ongoing campaign for 10 GeV. In 1996, Berkeley Lab also logged the first demonstration of X-ray pulses lasting just quadrillionths of a second with a technique known as “inverse Compton scattering,” the report notes.

    K-BELLA: combining speed and power

    “What industry is seeing is the push toward higher-average-power lasers and ultrafast lasers, and it’s starting to impact machining and industrial applications,” Leemans said. “That’s really good news for us.” In laser lingo, average power relates to how much total power the laser puts out over time, counting the pulses and the “off time” between pulses, while the peak power is that of an individual pulse.

    A rapid-fire rate of high-power pulses gives a laser higher average power and can potentially be applied to a wider range of uses. The National Academies report recommends that U.S. scientific stakeholders should work to define the technical specifications in laser performance goals, such as targets for peak power, repetition rate, length of pulses, and the wavelength of laser light.

    In 2012 the BELLA Center’s laser set a record by delivering a petawatt (quadrillion watts) of power packed into pulses that measured 40 quadrillionths of a second in length and came at a rate of one per second.

    A new goal is to up this pulse rate to 1,000 per second, or a kilohertz, for a next-gen upgrade dubbed k-BELLA. Producing pulse rates of up to 10,000 or 100,000 per second could make this machine relevant for a new type of laser-based particle accelerator.

    There are lots of applications for a k-BELLA-style laser,” Leemans said. The vision is for k-BELLA to be a collaborative research facility that would be open to scientists from outside the Lab, he said, which also syncs with the recommendations in the report to foster a more cooperative environment for laser science and scientists. Forging and maintaining connections to other world-class laser centers is also key for the U.S. laser program, the report notes.

    Another upgrade that may be useful to the U.S. laser program is the addition of a second beamline at BELLA, Leemans said. A second beamline could enable exotic collisions between a beam of light and an electron beam, or between two beams of light.

    Laser-produced beams of light elements, and laser-produced low-energy electron beams, could also be pursued at BELLA to develop the biomedical basis for new types of medical treatments that better target cancers, for example. “We look forward to enhancing our own laser capabilities at Berkeley Lab while working with our partners to strengthen the nation’s laser R&D efforts,” said James Symons, associate laboratory director for physical sciences. “Higher average power lasers will be essential for all practical applications of laser plasma accelerators.”

    The National Academies report was sponsored by the U.S. Department of Energy’s Office of Science, the National Nuclear Security Administration, the Office of Naval Research, and the Air Force Office of Scientific Research.

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  • richardmitnick 11:48 am on April 17, 2018 Permalink | Reply
    Tags: , , Laser Technology, Marriage of a 20keV superconducting XFEL with a 100PW laser, , ,   

    From SPIE: “Marriage of a 20keV superconducting XFEL with a 100PW laser” 

    SPIE

    SPIE

    16 April 2018
    Toshiki Tajima, University of California, Irvine
    Ruxin Li, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences

    A new regime of science at exawatts and zeptoseconds.

    The Chinese national science and technology major infrastructure, Shanghai Coherent Light Facility (SCLF), organized an international review meeting for the Station of Extreme Light (SEL) in Shanghai on July 10, 2017.

    The Shanghai Institute of Applied Physics is building a Soft X-ray Free Electron Laser that is set to open to users in 2019. Credit Michael Banks

    The reviewing committee members included experts in strong-field laser physics, high-energy-density physics, and theoretical physics from Germany, USA, UK, France, Japan, Canada; and China chaired by R. Sauerbrey and N .Wang. The working group, led by Ruxin Li of the Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), has made a series of breakthroughs on high energy, high power, and high-repetition laser system development.

    Reflecting on this, the Review Committee Report1 stated: “The architecture of the laser system of the Optical Parametric Chirped Pulse Amplification (OPCPA) and its interaction with the XFEL are well thought out. The proposed 1023 W/cm2 peak laser power is feasible. The working group has made a series of breakthroughs on high-power laser technologies in the past decades. Their constant effort has resulted in valuable experience, outstanding engineering skills, and international recognition for the group. Their strong track record has laid a strong foundation, which will provide the basis for successful construction of the 100 PW laser system.”

    Based on this, the Committee applauded the work, stating: “The Station of Extreme Light at Shanghai Coherent Light Facility is dedicated to cutting-edge research in strong field science and applications. This includes, for example, astrophysics, nuclear physics, cosmology, and matter under extreme conditions. The combination of the hard XFEL and the world-leading 100PW laser in SEL will initiate exploration of effects such as vacuum birefringence, one of the most prominent strong-field QED effects, acceleration mechanisms leading to ultra-high energy cosmic rays, simulation of black hole physics, and generation of new forms of matter.”

    The developments proposed are based on solid research carried out at SIOM (and other scientific organizations). In particular, the research and development of the OPCPA laser amplifier at the highest power level at SIOM. Shown in Figure 1 is SIOM’s 10PW laser CPA device and the 10PW laser system. The 10PW laser system, Shanghai Superintense-Ultrafast Lasers Facility (SULF), is based on CPA technology and the diameter of the Ti-Sapphire used in the main amplifier is 235mm, which is the largest crystal for the laser manufactured by the scientists at SIOM.

    Based on these developments, SIOM has launched a 100PW laser system, Station for Extreme Light (SEL). This system has two significant salient features. First, the level of its power will be an order of magnitude beyond the planned highest-powered laser, Extreme Light Infrastructure (ELI). Secondly, its design is a combination of the 100PW laser as part of the system in the SCLF’s XFEL. This project received strong endorsement from the International Review Meeting that convened at SCLF of SIOM on July 10, 2017, and was approved by the Government of China. The overall funding level is approximately USD$1.3 Billion.

    Figure 1 10PW laser system in Shanghai pumped by CPA.

    II. Extreme field regime
    The parameters of SEL are well beyond what has so far been available. Table 1 shows typical principal physical parameters. The coherent x-ray energy from the SCLF ranges between 3 to 15 keV (hard x-rays) produced from the superconducting x-ray free electron laser (XFEL). The photon number per pulse of this XFEL is 1012. Its pulse focusability is 200nm with the energy resolution of 0.6eV. The x-ray’s intensity at focus is as high as 1021W/cm2.

    The parameters of the 100PW laser for optical photons are as follows: Its peak power is 100PW, while its focal intensity is as high as 1023W/cm2. (If we can managed to focus better than this, it could go toward 1025W/cm2). While this is a single shot performance, it could deliver the repetition rate of 1Hz of optical laser if the power is at 0.1 to 1PW.

    These parameters by themselves are exciting. However, their coexistence and marriage as a combined unit shows a remarkable capability for future scienctific exploration. The combination of a synchrotron light source and an intense laser was first suggested and conducted in 1990s. Toshiki Tajima suggested that Professor Mamoru Fujiwara at Osaka University make use of the high-energy (8GeV) electrons of the SPRing-8 combined with an intense laser to make extremely high-energy gamma photons, which he did in his lab.2 Since then, the combination of these accelerator-based synchrotron light sources (or even more advanced XFEL with intense lasers) have come a long way. The present SCLF’s marriage of these two will uncover a new regime of science and greatly impact various technologies and applications, such as nuclear photonics and nonlinear interferometry.

    4
    Table 1 shows the schematic layout of the SEL. The interaction of XFEL and the plasma chamber takes place in the experimental area. Figure 3 indicates the 100PW laser based on the OPCPA technology.

    4
    Figure 2: Schematic layout figure of SEL that couples the 100PW laser with the XFEL.

    5
    Figure 3: Details of the amplification stages of the 100PW laser based on OPCPA.

    The scheme of this marriage is seen in the concept of the SEL at which the coherent high-energy x-rays photons are shone in the configuration shown in Figure 2. This way we will be able to observe the interaction of the high-energy x-ray photons and most intense lasers and their developed matter interaction. This will greatly increase the experimental probe of intense laser-matter interaction. The XFEL beam will provide ultra-short MHz x-ray beam with energy range of 3-5keV and significantly large photon number of 1012. Specific x-ray energy of 12.914keV will be used for QED experiments with very low energy spread of 0.6eV. The x-ray beam will collide head-on with the 100PW laser pulse in the experimental chamber. The 100PW laser system contains four beams and each beam reaches the peak power of 25 PW.

    Figure 2 shows that the main laser system will occupy two floors and its power supply and control system are set at different floors. After the four-beam combination, the laser pulse will be sent to the experimental area on the bottom floor. There is a large-size vacuum chamber, where the 100PW laser pulse will be focused to 5μm and collide with the x-ray beam.

    Details of the 100PW laser system are shown in Figure 3. At the core is the OPCPA system. The 100PW laser pulse starts at high temporal laser source, where its temporal synchronization signal comes from the XFEL beam. This source will generate high-quality seed pulses, which will go into the PW level repetition-rate OPCPA front-end. The laser energy will reach 25J and its spectrum width will support 15fs at PW level OPCPA front-end.

    The main amplifier is based on OPCPA technology and it provides 99% energy gain of the whole laser system, which requires sufficient pump energy from a Nd Glass pump laser. The final optics assembly will compress the high-energy of 2500J 4ns laser pulse to 15fs. After the compression, the laser pulse will be sent into the experimental chamber with the peak intensity 1023 W/cm2. As shown in Figure 1, we developed and tested the performance of a high-intensity laser with CPA up to 10PW level.

    III. High Field Science
    The proposed SEL aims to achieve the ultimate in high field science [3],[4],[5]. Here, we describe a simple way to reach that goal.

    The radiation dominance regime (1023 W/cm2) as described in Ref. 2 may be accessible and experimentally explored for the first time in sufficient details with the help of the coherent X-ray probe. As discussed in Sec. 1, if one can focus a bit narrowly, we may be able to enter the so-called QED Quantum regime (~1024 W/cm2)[4],[5].

    The particle acceleration by laser will enter a new regime. The wakefield generation [6] becomes so nonlinear that it enters what is sometimes called the bow-wake regime [7]. This may be relevant to the astrophysical extreme high-energy cosmic ray genesis by AGN (active galactic nuclei) jets [8]. In this regime, the physics of wakefield acceleration and that of the radiation pressure acceleration begin to merge (1023W/cm2)[9],[10]. Thus, the laser pulse should be able to pick up ions as well as electrons to become accelerated. Soon or later, the energy of ions begins to exceed that of electrons and their acceleration should become as coherent as the electron acceleration in this regime. Such acceleration will allow ion accelerators to be smaller. (A broader scope at this regime and slightly higher intensity regime than just mentioned has been reviewed [9].)

    However, it could go much further than that, since the invention of a new compression technique called “thin film compression11.” With this technique, a laser may be compressed to even higher power and intensity such as EW and further by relativistic compression into the shortest possible pulses ever in zs12. We will thus see the continuous manifestation of the Intensity-Pulse Duration Theorem into the extension of EW and zs [13]. It will not only explore strong field QED physics [14],[15], but we will also see the emergence of new phenomena at play in a wider variety of fundamental physics, including: (1) possible search of the proposed “fifth force” [16],[17]; (2) dark matter search by four wave mixing [18]; (3) x-ray wakefield in solid state matter [19] and related x-ray and optical solid state plasmonics [20]; (4) possible testing of the energy dependence of gamma photon propagation speed in a vacuum to test the foundational assumption of the Theory of Special Theory of Relativity [21]; and (5) zeptosecond streaking of the QED process [22].

    Chen et al.[23] suggested the exploration of general relativity using the equivalence principle of acceleration-gravity to test the Hawking-Unruh process.

    IV. Gamma-ray diagnosis and the marriage of XFEL and HFS
    In the issues of high field science, we often enter into the physical processes in higher energies and shorter timescales, which may not be easily resolvable in optical diagnosis. Here, the powerful XFEL’s resolution in time and space come in [24]. X-rays can be also signatures in high intensity experiments such as laser-driven acceleration experiments [25]. A typical display of such interplay may be seen in the diagnostics of the physical processes in the problem of x-ray wakefield acceleration in solid-state matter. In this case, nanoscopic materials with a nanohole structure [20] need to be observed and controlled. The surface of the nanotubes may be exhibiting surface plasmons and polaritons in nanometer size and zs temporal dynamics, best diagnosed by the XFEL. This is but an example of the marriage of a 20keV superconducting XFEL and a 100PW laser. In addition this technology will enhance studies in photon-induced nuclear physics [26] and the treatment of nuclear materials [27] (including nuclear waste), nuclear pharmacology, nuclear biochemistry, and medicine [28],[29].

    Another example is to use gamma photons to mediate the vacuum nonlinearity caused by intense laser pulse to exploit zeptosecond streaking via the gamma photon mediation [22]. In this scheme the presence of intense laser pulse and x-ray photon play a crucial role. If this example elucidates a beginning of exploration of zeptosecond photometric and zeptosecond optics, it would be an achievement comparable of the opening of the femtosecond optics flowing by attosecond optics [30].

    One more example of exploring the proposition was recently made for the Fifth Force [17]. In the Hungarian nuclear experiment, a mysterious photon at the energy of 17MeV was observed. The paper [5] suggested this emission of gamma photon may be due to the unknown force (the Fifth Force). It may be helpful if we can inject a large amount of monoenergetic photons at this energy to see if the reversal of this process of photon emission (i.e. injection of photon) can explore this process more quantitatively. We can check of the fifth force (17MeV gamma)16,17,31 with the process and an outcome of the following, utilizing the energy specific laser induced gamma photon interaction: e + 17MeV gamma → e + X.

    Finally, there is a recent suggestion by Day and Fairbairn [32] that XFEL laser pulses at 3.5keV may be used to investigate the astrophysically observed x-ray excess by fluorescent dark matter. Such an avenue may open up with this device. Such an effort along with the astrophysical observations may become an important interdisciplinary development.

    In order to maximize the success of these implications, we recommend the formation of a broad international collaboration with the organizations and institutions that are engaging in related fields. Learning from these labs in their technologies, practice, and collaborative engagements should reduce risks and duplications and enhance learning and the scope of experience. Collaborations with a variety technology sectors are important both for the execution of experiments and their applications.

    The authors are grateful for close discussions with all the committee members (Naiyan Wang, Roland Sauerbrey, Pisin Chen, See Leang Chin, Thomas Edward Cowan, Thomas Heinzl, Yongfeng Lu, Gerard Mourou, Edmond Turcu, Hitoki Yoneda, Lu Yu) of SEL. The discussions with Profs. T. Tait, K. Abazajian, T. Ebisuzaki, and K. Homma were also very useful. Prof. X. M. Zhang helped with our manuscript.

    References:
    1. Report of the International Review Meeting for Station of Extreme Light (2017).

    2. G. A. Mourou, T. Tajima and S. V. Bulanov, Optics in the relativistic regime, Rev. Mod. Phys. 78, p. 309, 2006.

    3. T. Tajima, K. Mima and H. Baldis, Eds., High-Field Science, Kluwer Academic/Plenum Publishers, New York, NY, 2000.

    4. T. Tajima and G. Mourou, Zettawatt-exawatt lasers and their applications in ultrastrong-field physics, Phys. Rev. ST AB 5, p. 031301, 2002.

    5. G. Mourou and T. Tajima, Summary of the IZEST science and aspiration, Eur. Phys. J. ST 223, pp. 979-984, 2014.

    6. T. Tajima and J. M. Dawson, Laser electron accelerator, Phys. Rev. Lett. 43, p. 267, 1979.

    7. C. K. Lau, P. C. Yeh, O. Luk, J. McClenaghan, T. Ebisuzaki and T. Tajima, Ponderomotive acceleration by relativistic waves, Phys. Rev. ST AB 18, p. 024401, 2015; T. Tajima, Laser acceleration in novel media, Eur. Phys. J. ST 223, pp. 1037-1044, 2014.

    8. T. Ebisuzaki and T. Tajima, Astrophysical ZeV acceleration in the relativistic jet from an accreting supermassive blackhole, Astropart. Phys. 56, pp. 9-15, 2014.

    9. T. Tajima, B. C. Barish, C. P. Barty, S. Bulanov, P. Chen, J. Feldhaus, et al., Science of extreme light infrastructure, AIP Conf. Proc. 1228, pp. 11-35, 2010.

    10. T. Esirkepov, M. Borghesi, S. V. Bulanov, G. Mourou and T. Tajima, Highly efficient relativistic-ion generation in the laser-piston regime, Phys. Rev. Lett. 92, p. 175003, 2004.

    11. G. Mourou, S. Mironov, E. Khazanov and A. Sergeev, Single cycle thin film compressor opening the door to Zeptosecond-Exawatt physics, Eur. Phys. J. ST 223, pp. 1181-1188, 2014.

    12. N. Naumova, J. Nees, I. Sokolov, and G. Mourou, Relativistic generation of isolated attosecond pulses in a λ3 focal volume, Phys. Rev. Lett. 92, p. 063902, 2004.

    13. G. Mourou and T. Tajima, More intense, shorter pulses, Science 331, pp. 41-42, 2011.

    14. M. Marklund and P. K. Shukla, Nonlinear collective effects in photon-photon and photon-plasma interactions, Rev. Mod. Phys. 78, p. 591, 2006.

    15. A. Di Piazza, C. Müller, K. Z. Hatsagortsyan and C. H. Keitel, Extremely high-intensity laser interactions with fundamental quantum systems, Rev. Mod. Phys. 84, p. 1177, 2012.

    16. A. J. Krasznahorkay, M. Csatlós, L. Csige, Z. Gácsi, J. Gulyás, M. Hunyadi, et al., Observation of anomalous internal pair creation in Be 8: a possible indication of a light, neutral boson, Phys. Rev. Lett. 116, p. 042501, 2016.

    17. J. L. Feng, B. Fornal, I. Galon, S. Gardner, J. Smolinsky, T. M. Tait and P. Tanedo, Protophobic fifth-force interpretation of the observed anomaly in Be-8 nuclear transitions, Phys. Rev. Lett. 117, p. 071803, 2016.

    18. K. Homma, D. Habs and T. Tajima, Probing the semi-macroscopic vacuum by higher-harmonic generation under focused intense laser fields, Appl. Phys. B 106, pp. 229-240, 2012.

    19. T. Tajima, Laser acceleration in novel media, Eur. Phys. J. ST 223, pp. 1037-1044, 2014.

    20. X. Zhang, T. Tajima, D. Farinella, Y. Shin, G. Mourou, J. Wheeler and B. Shen, Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes, Phys. Rev. AB 19, p. 101004, 2016.

    21. T. Tajima, M. Kando and M. Teshima, Feeling the texture of vacuum: laser acceleration toward PeV, Progr. Theor. Phys. 125, pp. 617-631, 2011.

    22. T. Tajima, G. Mourou and K. Nakajima, Laser acceleration, Riv. Nuovo Cim. 40, p. 1, 2017.

    23. P. Chen and G. Mourou, Accelerating plasma mirrors to investigate the black hole information loss paradox, Phys. Rev. Lett. 118, p. 045001, 2017.

    24. C. Pellegrini, A. Marinelli and S. Reiche, The physics of x-ray free-electron lasers, Rev. Mod. Phys. 88, p. 015006, 2016.

    25. S. Corde, K. T. Phuoc, G. Lambert, R. Fitour, V. Malka, A. Rousse and E. Lefebvre, Femtosecond x rays from laser-plasma accelerators, Rev. Mod. Phys. 85, p. 1, 2013.

    26. S. V. Bulanov, T. Z. Esirkepov, M. Kando, H. Kiriyama and K. Kondo, Relativistically strong electromagnetic radiation in a plasma, J. Exp. Theor. Phys. 122, pp. 426-433, 2016.

    27. S. Gales, IZEST meeting presentation, ELI-EP, French Embassy in Tokyo, 2013. https://gargantua.polytechnique.fr/siatel-web/linkto/mICYYYSI7yY6. Accessed 10 November 2017.

    28. D. Habs and U. Köster, Production of medical radioisotopes with high specific activity in photonuclear reactions with γ-beams of high intensity and large brilliance, Appl. Phys. B 103, pp. 501-519, 2011; Ö. Özdemir, Eds., Current Cancer Treatment – Novel Beyond Conventional Approaches, INTECH Open Access Publisher, 2011.

    29. A. Bracco and G. Köerner, Eds., Nuclear Physics for Medicine, Nuclear Physics European Collaboration Committee, 2014.

    30. F. Krausz and M. Ivanov, Attosecond physics, Rev. Mod. Phys. 81, p. 163, 2009.

    31. T. Tajima, T. Tait, and J. Feng, private comment, 2017.

    32. F. Day and M. Fairbairn, submitted to J. High Energy Phys., 2017.

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  • richardmitnick 10:31 am on April 13, 2018 Permalink | Reply
    Tags: Laser Technology, , NIF petawatt-class Advanced Radiographic Capability (ARC),   

    From LLNL: “A powerful new source of high-energy protons” 

    Lawrence Livermore National Laboratory

    April 12, 2018
    Breanna Bishop
    bishop33@llnl.gov
    925-423-9802

    1
    Illustration of a typical experiment on high-energy, or fast, proton acceleration from a laser-irradiated solid target. Credit: Andrea Macchi, et al., Rev. Mod. Phys., Vol. 85, No. 2, April–June 2013

    Nearly 20 years ago, researchers conducting experiments on Lawrence Livermore National Laboratory’s (LLNL) Nova Petawatt laser system — the world’s first quadrillion-watt laser — discovered that when the system’s intense short-pulse laser beams struck a thin foil target, an unexpected torrent of high-energy electrons and protons streamed off the back of the target.

    (LLNL) Nova Petawatt laser system

    Earlier this month, an international team of researchers used the Nova Petawatt’s successor, the National Ignition Facility’s (NIF) petawatt-class Advanced Radiographic Capability (ARC), to begin developing an experimental platform that promises to turn Nova’s surprise discovery into a powerful new source of protons to study the extreme conditions deep inside the planets and the stars, enhance targeted tumor therapy and advance the frontiers of high energy density (HED) science.

    LLNL National Ignition Facility’s (NIF) petawatt-class Advanced Radiographic Capability (ARC)

    In two NIF Discovery Science experiments, the researchers fired four ARC beamlets at a 33-micron-thick titanium foil, setting up a strong electrostatic sheath field called a Target Normal Sheath Accelerating (TNSA) field perpendicular to the target (normal is a geometric term for perpendicular). As the field blew away from the back of the target, it accelerated high-energy protons and ions from the contamination layer of proton-rich hydrocarbons and water coating the target’s surface, all moving rapidly in the same direction.

    “The results were as good as we had hoped for,” said LLNL physicist Tammy Ma, the campaign’s principal investigator. “It was definitely a win. ARC is not as intense as a lot of other short-pulse lasers, so some in the community were concerned that the intensities might not be sufficient to generate these beams. But (the result) was more protons than we expected with energies approaching 20 MeV (million electron volts) — definitely a source that will enable other applications and cool physics.”

    In the experiments, two of NIF’s 192 beamlines were split to form the four short-pulse ARC beamlets. The beamlets were fired simultaneously for 10 or one picoseconds (trillionths of a second), generating up to 200 terawatts (trillion watts) of power per beamlet. The total of about 700 terawatts in the second experiment was the highest peak power yet generated on NIF.

    ARC’s high peak power is made possible by a process called chirped-pulse amplification, in which a short, broadband pulse generated by an oscillator is stretched in time to reduce its peak intensity, then amplified at intensities below the damage threshold in the laser amplifiers, and finally compressed to a short pulse and highest peak power in large compressor vessels.

    The new Discovery Science platform, supported by LLNL’s Laboratory Directed Research and Development (LDRD) program, is designed to study the physics of particle-beam generation at previously unexplored ultra-high short-pulse laser energies and long pulse durations. Coupled to NIF’s 1.8 million joules of ultraviolet energy, the capability will enable myriad HED applications and allow the creation and study of extreme states of matter.

    3
    After amplification in the NIF laser, the ARC beamlets are compressed in the Target Bay and focused to Target Chamber Center.

    NIF is the world’s only facility capable of achieving conditions like those in the interiors of stars and giant planets. Using ARC short-pulse generated proton beams for ultrafast heating of matter to extreme states will enable opacity and equation-of-state measurements at unprecedented energy-density states.

    In addition, “protons deposit their energy very specifically,” noted LLNL postdoc Derek Mariscal, lead experimentalist for the project. “That’s why protons are promising for applications such as tumor therapy. You can send a beam of protons toward a tumor and get it to deposit all of its energy exactly where you want it to without damaging other areas of the body.

    “Likewise with a solid material,” he said. “(The proton beam) deposits its energy where you want it to very quickly, so you can heat up a material really fast before it has time to hydrodynamically expand — your material stays dense, and that’s the name of the game — high energy, high density.”

    Once the proton-acceleration platform has been demonstrated and understood, Mariscal said, the next step in the project will be to fire the ARC beams at a deuterated carbon (CD) foil to generate a beam of deuterons. “You could impact those onto a second foil, like lithium fluoride or beryllium, and then you get a beam of neutrons — a real, laser-like neutron source, only using two beams of NIF instead of all 192.”

    Along with managing the project, Ma serves as the LLNL liaison with the collaborating institutions: the University of California, San Diego, General Atomics, Oxford University, the SLAC National Accelerator Laboratory, Rutherford Appleton Laboratory, Los Alamos National Laboratory, the University of Alberta and Osaka University. Scott Wilks, who was a member of the team that discovered the TNSA process on the Nova Petawatt laser, is coordinating the theory and modeling effort.

    Other LLNL team members are Jackson Williams, Nuno Lemos, Hui Chen, Prav Patel, Bruce Remington, Andrew MacPhee, Andreas Kemp, Matt Mcmahon, Art Pak, Sasha Rubenchik, Max Tabak, Steve Hatchett (retired), Mark Sherlock, Andy Mackinnon, Anthony Link, Mark Hermann and Constantin Haefner.

    4
    Members of the ARC proton acceleration team outside the NIF Control Room: Front row, from left: Derek Mariscal (LLNL), Alessio Morace (Osaka University), Krish Bhutwala (UCSD), Tammy Ma (LLNL), Alex Savin (Oxford University), Chris McGuffey (UCSD), and Mingsheng Wei (GA). Back row: Graeme Scott (Rutherford Appleton Laboratory), Joohwan Kim (UCSD), Mark Sherlock (LLNL), Scott Wilks (LLNL), Andreas Kemp (LLNL), Nuno Lemos (LLNL), Sasha Rubenchik (LLNL), Jackson Williams (LLNL), Chandra Curry (University of Alberta), Constantin Haefner (LLNL) and Max Tabak (LLNL). Not pictured: Bruce Remington, Hui Chen, Prav Patel, Matthew Mcmahon, Andrew MacPhee, Andy Mackinnon, Mark Hermann and Steve Hatchett (LLNL); Farhat Beg, Pierre Forestier-Colleoni, and Brandon Edghill (UCSD); Peter Norreys (Oxford University); Yasuhiko Sentoku and Natsumi Iwata (Osaka University); Shaun Kerr (University of Alberta); Alex Zylstra (LANL); David Neely (RAL); and Mario Manuel (GA). Credit: Jason Laurea

    The proton acceleration shots were among a weeklong series of Discovery Science experiments on NIF. Four other campaigns studied planar direct-drive hydrodynamics, the iron melt curve for studying magnetospheres and exoplanets, high-pressure compressed carbon and laser-driven magnetic field generation. Principal investigators for those experiments were Alexis Casner from the University of Bordeaux, Russell Hemley from the George Washington University and the Capital/DOE Alliance Center, Justin Wark from Oxford University and Brad Pollock from LLNL.

    -Charlie Osolin

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  • richardmitnick 8:36 am on April 2, 2018 Permalink | Reply
    Tags: , How Far Can Laser Light Travel?, , Laser Technology,   

    From Inside Science: “How Far Can Laser Light Travel?” 

    Inside Science

    1
    Image credits: Abigail Malate, Staff Illustrator

    March 30, 2018
    Yuen Yiu

    Have you ever played with a pocket-sized laser, wondering how far its light would travel? Could you, a naughty student inside a classroom on Earth, annoy a poor substitute teacher on Mars by waggling your laser pointer at him?​

    T​he short answer: no. By the time the light finally reached Mars, the glint would be a million times dimmer than the faintest light visible to the human eye.

    But you don’t need to take our word for it. The math needed to calculate the answer is surprisingly simple.

    Partly inspired by a talk at a recent astronomy meeting that explored whether we could detect photons from potential exoplanet-dwelling aliens, Inside Science performed some of our own calculations to see if a hypothetical alien Galileo could observe photons coming from Earth.

    All we need is an equation for calculating how quickly a laser beam spreads out as it travels through space. From that we can use straightforward geometry to derive the diameter of the beam when it hits its target. Finally, we divide the power output of the laser by the area of the final lit spot and voila! — that’s how intense the laser is at the destination. While the way humans, or aliens, perceive the brightness of this light is much less straightforward, for the purpose of this exercise we treat brightness and light intensity as the same thing.

    ______________________________________________________________________________________
    The math:

    One only needs three rather simple equations for all the calculations done in this article. First, if we assume the laser is optimized so that its spreading angle is at its theoretical minimum, then we can calculate its beam divergence (in radians) using this equation.

    (The laser’s wavelength)/(π × The laser’s aperture)

    Then a little bit of geometry will give us the size of the final lit spot at the destination.

    π × (Beam divergence in radians × Distance)2

    Finally, the brightness at the destination is given by dividing the output power of the laser over the area of the spot.

    (The laser’s power)/(Size of the spot)

    If you didn’t make a mistake in your calculations and kept everything in radians, watts and meters, the final number should be in watts per square meter.

    The dimmest light visible to the naked eye in perfect darkness is around one ten-billionth of a watt per square meter. However, with the presence of urban light pollution, one usually can’t see stars much dimmer than the North Star, which has an intensity of around four-billionths of a watt per square meter. For comparison, the full moon is almost a million times brighter at one-thousandth of a watt per square meter. Finally, the midday sun is at a whopping 1,000 watts per square meter, about half a million times brighter than the moon.

    In this article, we will be using these numbers as references.
    ______________________________________________________________________________________

    Your pocket laser pointer

    The power for an average laser pointer is a measly 0.005 watts. However, because of the narrow path of the laser beam, if you pointed it directly at your eye from an arm’s length away, the little illuminated dot on your eyeball would be 30 times brighter than the midday sun. So, don’t do this at home, or anywhere.

    Still, the narrow beam will spread out over long distances. Around 100 meters away from a red laser pointer, its beam is about 100 times wider and looks as bright as a 100-watt light bulb from 3 feet away. Viewed from an airplane 40,000 feet in the air — assuming there’s no clouds or smog — the pointer would be as bright as a quarter moon. From the International Space Station, it would fade to roughly as bright as the brightest star in the night sky — Sirius.

    For Starman, the dummy driving the Tesla car that Elon Musk’s company Space X recently launched into space, your little red laser pointer would be too dim to notice. If you want to get his attention, you’ll need something brighter.

    The Navy’s missile-killer

    The U.S. Navy might have what we need. According to recent reports [Military Balance Blog], their current goal is to develop a laser that is both logistically practical and powerful enough to destroy incoming cruise missiles. A laser like that would need to put out about 500,000 watts of power — 100 million times more powerful than your pocket laser pointer. These lasers typically operate in the infrared spectrum, which is invisible to humans. But for the sake of this exercise we’ll assume that both Starman and the Martians can see in the infrared.

    Weapons-grade lasers also tend to have a much larger opening, or aperture, which counterintuitively causes the laser beam to spread out less, thus enhancing the beam’s ability to maintain its intensity over longer distances.

    Because of the larger aperture, if the missile-killer laser beam is aimed at the moon, the infrared spot it would make on the surface would only be about 1.5 miles across. For comparison, the incredibly dim red dot from your pocket laser pointer would be 8 miles wide once it reached the moon.

    If you could see in the infrared and stood on the moon underneath the military laser’s beam, it would appear roughly 30 times brighter than the full Earth. That’s quite bright, but not blindingly so. It’s still only one-thousandth the brightness of the midday sun on Earth.

    By the time the beam reached the Martians — if we assume the shortest possible distance between Earth and the red planet, which is about 34 million miles — the spotlight would be about 200 miles across. Its light should still be noticeable — about half as bright as the brightest star in the sky sans the sun — but not exactly attention grabbing.

    Looks like we need more power.

    The most powerful laser ever built

    Several scientific facilities around the world have huge lasers that operate at more than a thousand trillion watts. In other words, these lasers have as much power as a million trillion pocket laser pointers — that’s almost a billion laser pointers for every person on the planet!

    3
    One of the acceleration beams of the LFEX laser in Osaka. Credit: Osaka University


    National Ignition Facility at LLNL


    The National Ignition Facility has followed up on its March firing with yet-another record, flicking the switch on a pulse that topped 500 trillion watts and 1.85 megajoules of UV laser. Richard Chirgwin 16 Jul 2012

    If run continuously, these lasers would use up the entire world’s electricity supply in seconds. Luckily, the only reason these lasers can put out such intense power is that they concentrate the release over an extremely short period of time — usually less than a trillionth of a second. The extremely short laser pulse is then focused down to a point a few thousandths of a millimeter across, and can be 10 trillion trillion times brighter than the surface of our sun. It’s so powerful that scientists are using them to rip apart empty space itself in a quest to learn more about the fundamental laws of our universe.

    What if we just want to use this for fun and shoot it at space invaders? One major drawback is that these lasers usually produce ultraviolet light, which is mostly absorbed by the Earth’s atmosphere. If we don’t want to turn our air into plasma, we’d have to construct our building-sized super laser cannon in space instead.

    For the extremely brief time we could afford to fire the laser at Mars, it would cast UV light a thousand times more intense than the midday sun on Earth over an area 150 miles across. Let’s hope that the Martians have some SPF-1,000 sunblock handy.

    Sadly, as we know by now, there are no little green men on Mars, or most likely anywhere else in our solar system. However, there are thousands of discovered exoplanets — planets that orbit around stars outside our solar system — many of which have the possibility to contain life. What if we try to get their attention?

    Proxima Centauri, located roughly four light-years away, is the closest star to us and is orbited by several exoplanets. If we aimed our most powerful laser there, by the time the light reached it, it would appear brighter than the brightest star looks to us in a clear night sky. So, four years after we’ve fired our laser, if there’s any alien astronomer looking at the right spot in their night sky, they may notice a nanosecond flash of ultraviolet light and go, “What was that?”

    Yuen would like to thank Eric Korpela, an astronomer from the Berkeley SETI Research Center for the insightful conversation that led to this exercise. This article is partly inspired by a presentation by Barry Welsh, an astronomer from the University of California, Berkeley, during the 231st meeting of the American Astronomical Society, and also this blog post from What If?by Randall Munroe.

    See the full article here .

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    Inside Science is brought to you in part through the generous support of The American Physical Society and The Acoustical Society of America and a coalition of underwriters.

     
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