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  • richardmitnick 2:50 pm on November 5, 2014 Permalink | Reply
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    From SLAC: “Researchers Hit Milestone in Accelerating Particles with Plasma” 

    SLAC Lab

    November 5, 2014

    SLAC Demonstration Shows Technique is Powerful, Efficient Enough to Drive Future Particle Accelerators

    Scientists from the Department of Energy’s SLAC National Accelerator Laboratory and the University of California, Los Angeles have shown that a promising technique for accelerating electrons on waves of plasma is efficient enough to power a new generation of shorter, more economical accelerators. This could greatly expand their use in areas such as medicine, national security, industry and high-energy physics research.

    This achievement is a milestone in demonstrating the practicality of plasma wakefield acceleration, a technique in which electrons gain energy by essentially surfing on a wave of electrons within an ionized gas.

    Using SLAC’s Facility for Advanced Accelerator Experimental Tests (FACET), a DOE Office of Science User Facility, the researchers boosted bunches of electrons to energies 400 to 500 times higher than they could reach traveling the same distance in a conventional accelerator. Just as important, energy was transferred to the electrons much more efficiently than in previous experiments. This crucial combination of energy and efficiency had never been reached before. The results are described in a paper published today in the journal Nature.


    “Many of the practical aspects of an accelerator are determined by how quickly the particles can be accelerated,” said SLAC accelerator physicist Mike Litos, lead author of the paper. “To put these results in context, we have now shown that we could use this technique to accelerate an electron beam to the same energies achieved in the 2-mile-long SLAC linear accelerator in less than 20 feet.”

    Plasma wakefields have been of interest to accelerator physicists for 35 years as one of the more promising ways to drive the smaller, cheaper accelerators of the future. The UCLA and SLAC groups have been at the forefront of research on plasma wakefield acceleration for more than a decade. In a 2007 paper, researchers announced they’d accelerated electrons in the tail end of a long electron bunch from 42 billion electronvolts to 85 billion electronvolts, causing a great deal of excitement in the scientific community. However, fewer than 1 billion of the 18 billion electrons in the pulse actually gained energy and they had a wide spread of energies, making them unsuitable for experiments.

    In this experiment, researchers sent pairs of electron bunches containing 5 billion to 6 billion electrons each into a laser-generated column of plasma inside an oven of hot lithium gas. The first bunch in each pair was the drive bunch; it blasted all the free electrons away from the lithium atoms, leaving the positively charged lithium nuclei behind – a configuration known as the “blowout regime.” The blasted electrons then fell back in behind the second bunch of electrons, known as the trailing bunch, forming a “plasma wake” that propelled the trailing bunch to higher energy.

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

    An Efficient, Viable Technology

    Previous experiments had demonstrated multi-bunch acceleration, but the team at SLAC was the first to reach the high energies of the blowout regime, where maximum energy gains at maximum efficiencies can be found. Of equal importance, the accelerated electrons wound up with a relatively small energy spread.

    SLAC researchers Spencer Gessner, left, and Sebastien Corde monitor pairs of electron bunches sent into a plasma inside an oven of hot lithium gas at the Facility for Advanced Accelerator Experimental Tests (FACET). (SLAC National Accelerator Laboratory)

    SLAC researchers Michael Litos, left, and Sebastien Corde use a laser table at the Facility for Advanced Accelerator Experimental Tests (FACET) to create a plasma used for accelerating electrons to high energies in a very short distance. (SLAC National Accelerator Laboratory)

    This simulation depicts two electron bunches – containing 5 billion to 6 billion electrons each – that were accelerated by a laser-generated column of plasma inside an oven of hot lithium gas during experiments at SLAC. (SLAC National Accelerator Laboratory)

    “These results have an additional significance beyond a successful experiment,” said Mark Hogan, SLAC accelerator physicist and one of the principal investigators of the experiment. “Reaching the blowout regime with a two-bunch configuration has enabled us to increase the acceleration efficiency to a maximum of 50 percent – high enough to really show that plasma wakefield acceleration is a viable technology for future accelerators.”

    The plasma source used in the experiment was developed by a team of scientists led by Chandrashekhar Joshi, director of the Neptune Facility for Advanced Accelerator Research at UCLA. He is the UCLA principal investigator for this research, a faculty member with the UCLA Henry Samueli School of Engineering and Applied Science, and a long-time collaborator with the SLAC group.

    “It is gratifying to see that the UCLA-SLAC collaboration on plasma wakefield acceleration continues to solve seemingly intractable problems one by one through systematic experimental work,” Joshi said. “It is this kind of transformative research that attracts the best and the brightest students to this field, and it is imperative that they have facilities such as FACET to carry it out.”

    This animation explains how electrons can be efficiently accelerated to high energy using wakes created in a plasma

    There are more milestones ahead. Before plasma wakefield acceleration can be put to use, Hogan said, the trailing bunches must be shaped and spaced just right so all the electrons in a bunch receive exactly the same boost in energy, while maintaining the high overall quality of the electron beam.

    “We have our work cut out for us,” Hogan said. “But you don’t get many chances to conduct research that you know in advance has the potential to be immensely rewarding, both scientifically and practically.”

    Computer simulations used in the experiments were developed by Warren Mori’s group at UCLA. Additional contributors included researchers from SLAC, the University of Oslo in Norway, Tsinghua University in China and Max Planck Institute for Physics in Germany. The research was funded by the DOE Office of Science.

    See the full article here.

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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  • richardmitnick 7:35 pm on May 23, 2013 Permalink | Reply
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    From Symmetry: “FACET boosts plasma acceleration” 

    May 23, 2013
    Lori Ann White

    Upgrades to the Facility for Advanced Accelerator Experimental Tests—including a new 10-terawatt laser—will assist in R&D for new methods of particle acceleration.

    “Just over a year after opening its beam to researchers from around the world, the Facility for Advanced Accelerator Experimental Tests (FACET) at SLAC is shining a little brighter. With the addition of a new 10-terawatt laser and other equipment upgrades, one of the facility’s main goals—the development of a new method of particle acceleration that boosts particles’ energy on waves of plasma—looks especially promising.


    During the facility’s first run, which took place from April through early July of 2012, researchers sent electrons accelerated in the SLAC linear accelerator into a chamber of hot gas, turning it into a plasma. Some of those very same electrons then rode the resulting plasma wave to even higher energies. This accelerated the electrons with great efficiency—thousands of times more in the same distance than the technology used in today’s particle accelerators.

    But, as happens so often in basic research, FACET’s first run also revealed the need to make some modifications. Using the accelerated electron bunch to create its own plasma had issues—issues that make the laser a vital addition to the 2013 run, says SLAC Advanced Accelerator Research Department leader Mark Hogan, who is both an important part of FACET and, as one of the leaders of the plasma wakefield acceleration team, a hands-on experimenter himself.

    ‘Controlling the characteristics of both the electron bunches and the resulting plasma to where the process is efficient enough has turned out to be tough,’ Hogan says. ‘As it is, not enough of the electrons are being accelerated.’

    The team will now use the new laser to zap the chamber of hot gas, turning it into a plasma before any electrons enter. That laser-created plasma will be more consistent than the electron-created version, which means that when the electron bunches do enter they’ll cause a more controlled plasma wave.

    Selina Li, the SLAC accelerator physicist in charge of the project, says the laser is in good shape and should be operational this summer.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 9:59 am on July 16, 2012 Permalink | Reply
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    From SLAC Today: “FACET Promises to Improve Power, Efficiency of Particle Accelerators” 

    July 16, 2012
    Lori Ann White

    The Department of Energy’s newest user facility – a cutting-edge particle accelerator available to scientists from all over the world – is a radical new chapter in the history of the world’s longest, most powerful linear accelerator.


    For more than four decades, the two-mile-long linac at SLAC National Accelerator Laboratory fueled Nobel-winning particle-physics research. Now it’s been repurposed – one might even say reimagined – in ways that keep it at the forefront of discovery, and not just in particle physics.

    The final third of the linac now powers the Linac Coherent Light Source, the world’s first hard X-ray laser. Researchers from around the world use LCLS’s unique ability to take crisp pictures of atomic motion and changes in chemical bonds to drive applications in energy and environmental sciences, bioscience and materials engineering.

    And the remaining two-thirds of the accelerator have been claimed by FACET, the Facility for Advanced Accelerator Experimental Tests, which is revving up the 50-year-old equipment and packing the final section with state-of-the-art instruments. The result is a test bed for technology that promises to improve the power and efficiency of today’s particle accelerators and expand their roles in medicine, materials and biological science, high-energy physics and more.”

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 10:22 am on May 1, 2012 Permalink | Reply
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    From SLAC Today: “SLAC’s Newest Facility Kicks Off User Run” 

    May 1, 2012
    Lori Ann White

    “After months of installation and commissioning efforts, SLAC’s newest user facility welcomed its first two groups of experimenters on Friday. They came to use the tightly focused electron bunches delivered by FACET, the Facility for Advanced Accelerator Experimental Tests, for two very different purposes.

    SLAC graduate student Spencer Gessner aligns a mirror for FACET’s X-ray spectrometer. The instrument was just one of the many new instruments and pieces of equipment installed in the beam tunnel… (Photo by Brad Plummer)

    According to Spencer Gessner, a graduate student at SLAC and a member of the team, ‘One of the goals of this first run is to replicate and then extend some of the results achieved by E167,’ a plasma wakefield experiment that took place at SLAC’s Final Focus Test Beam before it shut down in 2007 to make room for the Linac Coherent Light Source. E167 raised the energy of a few electrons from 42 billion to 85 billion electronvolts over a distance of just 84 centimeters – a little less than a yard.

    In the second experiment, Ioan Tudosa of the Stanford Institute for Materials and Energy Science, a joint SLAC–Stanford institute, will also continue work previously done at SLAC, this time in magnetic switching. The magnetic switching technique, in which an electric field is used to make north and south poles swap places in a magnet, works more than 1000 times faster than current technology and could revolutionize data storage. Tudosa will expose magnetic samples to FACET’s powerful electron pulses.”

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science. i1

  • richardmitnick 5:18 pm on January 6, 2012 Permalink | Reply
    Tags: , , , SLAC FACET, ,   

    From SLAC Today: Good News For 2012 from the Director 

    SLAC Lab Director Persis Drell(Photo by Brad Plummer)

    This is the Director’s complete article. But visit SLAC News Center early and often for more news. You can even get SLAC News via email.

    January 6, 2012
    Persis Drell

    “Just before we closed for the holidays Congress passed a budget. That by itself is excellent news. Having a budget removes tremendous uncertainty for both our projects and operations, and we will not have the seesaw of drama that we had last spring with the long continuing resolution and threats of a government shutdown.

    However, it was not surprising, given the overall economic concerns of the country, that the FY12 budget for the DOE Office of Science didn’t increase a great deal over FY11. Overall, the Office of Science saw a 0.9 percent increase, with the Office of Basic Energy Sciences (which funds the Linac Coherent Light Source and Stanford Synchrotron Radiation Lightsource) increasing by 1 percent and High Energy Physics decreasing by 0.5 percent.

    Within that very constrained, essentially flat budget, SLAC did just fine. Our operations budgets for our facilities, LCLS and SSRL, will keep the machines running and support the new users coming on to LCLS as more experimental stations come on line. Perhaps most importantly, LCLS-II is going forward full steam, and we even got funding to get our new user support building, SUSB, which will replace Panofsky auditorium and the cafeteria, off to a good start.

    In Particle Physics and Astrophysics, the Large Synoptic Survey Telescope is continuing to move forward. In the Accelerator Directorate, FACET, the Facility for Advanced aCcelerator Experimental Tests, will operate for users during a planned three-month run this spring.

    The SLAC FY12 budget is a huge vote of confidence in the laboratory. In this tough year, our facilities are operating fully and our projects are going forward. This is a vote of confidence in our ability to deliver projects and a vote of confidence in the science we will be producing. We cannot fail to deliver in any aspect of our performance!

    Most importantly, the CD-2 baseline review for LCLS-II will be coming up this spring or early summer and this is a review we cannot stumble on. In times like these, there are many other worthy projects that are being deferred so that ours can go forward, and we have to deliver! It is a priority for the laboratory this year to have a successful CD-2 review for LCLS-II. I have great confidence that we can and we will!

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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