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  • richardmitnick 9:20 pm on December 2, 2021 Permalink | Reply
    Tags: "Shaping up nicely-Adjusting the plasma edge can improve the performance of a star on Earth", , , , , PPPL NSTX-U Tokamak, Wendelstein 7-X fusion device at MPG Institute for Plasma Physics (IPP) in Greifswald (DE)   

    From DOE’s Princeton Plasma Physics Laboratory (US) : “Shaping up nicely-Adjusting the plasma edge can improve the performance of a star on Earth” 

    From DOE’s Princeton Plasma Physics Laboratory (US)

    at

    Princeton University

    Princeton University (US)

    Dec. 2, 2021
    Raphael Rosen

    1
    PPPL physicist Robert Lunsford with, clockwise from the top left, a schematic of the powder device, a computer rendering of the Wendelstein 7-X fusion facility, images of plasma within that facility, and pictures of the powder entering the plasma. Collage by Kiran Sudarsanan.

    Wendelstein 7-X fusion device at MPG Institute for Plasma Physics (IPP) in Greifswald (DE) 2011.

    While trying out a new device that injects powder to clean up the walls of the world’s largest stellarator, a twisty fusion device in Greifswald, Germany known as Wendelstein 7-X (W7-X), scientists were pleased to find that the bits of atoms confined by magnetic fields within the device got temporarily hotter after each injection. Researchers led by scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) in collaboration with The MPG Institute for Plasma Physics [MPG Institut für Plasmaphysik](DE) found that pulsed injections of boron carbide, an ingredient in sandpaper, increased the density and temperature of the ultrahot atom fragments, or plasma, leading to better fusion performance.

    Fusion, the power that drives the sun and stars, combines light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei, or ions — that makes up 99 percent of the visible universe. The reactions, which scientists around the world are seeking to reproduce on Earth to generate electricity, produce massive amounts of energy.

    Boron coatings are widely used to cover the interior of tokamaks, doughnut-shaped fusion devices that are operated around the world, along with stellarators, their twisting cousins [Wendelstein 7-X above].

    PPPL NSTX-U Tokamak.

    This coating prevents metals and other heavy elements from leaching from the walls into the plasma, making the fusion reactions less efficient. It also captures hydrogen that escapes from the main plasma, keeping it from returning into the plasma and cooling off the reactions.

    These coatings wear away over time, however, and many techniques used today to re-apply them only work when the high-energy fusion plasma device is turned off. While this is not a problem for today’s experiments, turning off future facilities will not be so easy because they will have to operate for weeks on end. “Finding a way to repair the coating on the walls while the fusion reaction is going on is an important part of our research,” said PPPL physicist Robert Lunsford, lead author of a paper reporting the results in Physics of Plasmas.

    At other fusion research facilities around the world, PPPL scientists have installed a three-foot-tall impurity powder dropper capable of distributing controlled amounts of powder directly onto the top of the plasma, like salt from a shaker. This technique was too difficult to install on W7-X in the available installation time, though it may be incorporated into the device in the future.

    “Instead, we had to strip out everything we could to shrink one of the powder droppers to the size of a loaf of bread so it would fit on a mechanical arm that reaches inside the plasma,” Lunsford said. “For a prototype, it worked very well.”

    What excited researchers was seeing the temperature go up after the injection. The Physics of Plasmas paper reported that the injected boron carbide appears to cool the edge of the plasma and increase the density gradient. “This means that the plasma edge gets denser faster as you move from the edge to the core,” Lunsford said. “This in turn reduces turbulence, the complex swirls that flush heat from the plasma.” Because of that reduced turbulence, the plasma retains more of its heat and makes the fusion reactions more efficient.

    “These results were very exciting,” said PPPL physicist Novimir Pablant, one of the paper’s coauthors. “There are only a few ways to get ions hot, so any new tool helps a great deal. Now we hope to use this technique to have more control over the plasma’s shape.”

    The researchers plan to conduct more experiments to confirm this finding. They also will work with W7-X scientists who have discovered other ways to change the plasma shape by techniques like launching hydrogen pellets at high speeds into the plasma core. These profile-shaping tools are an important step in advancing fusion research, the physicists say.

    Collaborators on this research included scientists from The MPG Institute for Plasma Physics [MPG Institut für Plasmaphysik](DE) and The Jülich Research Centre [Forschungszentrum Jülichs] (FZJ)(DE), The Center for Energy Research [Energiatudományi Kutatóközpont](HU), and The National Fusion Laboratory[Laboratorio Nacional de Fusión](ES). The research was supported by the DOE’s Office of Science (Fusion Energy Sciences) and the Euratom research and training programme.

    See the full article here .


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    PPPL campus

    Princeton Plasma Physics Laboratory (US) is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science.

    Princeton University

    Princeton University

    About Princeton: Overview

    Princeton University is a private Ivy League research university in Princeton, New Jersey(US). Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution. The institution moved to Newark in 1747, then to the current site nine years later. It was renamed Princeton University in 1896.

    Princeton provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences, and engineering. It offers professional degrees through the Princeton School of Public and International Affairs, the School of Engineering and Applied Science, the School of Architecture and the Bendheim Center for Finance. The university also manages the DOE’s Princeton Plasma Physics Laboratory. Princeton has the largest endowment per student in the United States.

    As of October 2020, 69 Nobel laureates, 15 Fields Medalists and 14 Turing Award laureates have been affiliated with Princeton University as alumni, faculty members or researchers. In addition, Princeton has been associated with 21 National Medal of Science winners, 5 Abel Prize winners, 5 National Humanities Medal recipients, 215 Rhodes Scholars, 139 Gates Cambridge Scholars and 137 Marshall Scholars. Two U.S. Presidents, twelve U.S. Supreme Court Justices (three of whom currently serve on the court) and numerous living billionaires and foreign heads of state are all counted among Princeton’s alumni body. Princeton has also graduated many prominent members of the U.S. Congress and the U.S. Cabinet, including eight Secretaries of State, three Secretaries of Defense and the current Chairman of the Joint Chiefs of Staff.

    Princeton University, founded as the College of New Jersey, was considered the successor of the “Log College” founded by the Reverend William Tennent at Neshaminy, PA in about 1726. New Light Presbyterians founded the College of New Jersey in 1746 in Elizabeth, New Jersey. Its purpose was to train ministers. The college was the educational and religious capital of Scottish Presbyterian America. Unlike Harvard University(US), which was originally “intensely English” with graduates taking the side of the crown during the American Revolution, Princeton was founded to meet the religious needs of the period and many of its graduates took the American side in the war. In 1754, trustees of the College of New Jersey suggested that, in recognition of Governor Jonathan Belcher’s interest, Princeton should be named as Belcher College. Belcher replied: “What a name that would be!” In 1756, the college moved its campus to Princeton, New Jersey. Its home in Princeton was Nassau Hall, named for the royal House of Orange-Nassau of William III of England.

    Following the untimely deaths of Princeton’s first five presidents, John Witherspoon became president in 1768 and remained in that post until his death in 1794. During his presidency, Witherspoon shifted the college’s focus from training ministers to preparing a new generation for secular leadership in the new American nation. To this end, he tightened academic standards and solicited investment in the college. Witherspoon’s presidency constituted a long period of stability for the college, interrupted by the American Revolution and particularly the Battle of Princeton, during which British soldiers briefly occupied Nassau Hall; American forces, led by George Washington, fired cannon on the building to rout them from it.

    In 1812, the eighth president of the College of New Jersey, Ashbel Green (1812–23), helped establish the Princeton Theological Seminary next door. The plan to extend the theological curriculum met with “enthusiastic approval on the part of the authorities at the College of New Jersey.” Today, Princeton University and Princeton Theological Seminary maintain separate institutions with ties that include services such as cross-registration and mutual library access.

    Before the construction of Stanhope Hall in 1803, Nassau Hall was the college’s sole building. The cornerstone of the building was laid on September 17, 1754. During the summer of 1783, the Continental Congress met in Nassau Hall, making Princeton the country’s capital for four months. Over the centuries and through two redesigns following major fires (1802 and 1855), Nassau Hall’s role shifted from an all-purpose building, comprising office, dormitory, library, and classroom space; to classroom space exclusively; to its present role as the administrative center of the University. The class of 1879 donated twin lion sculptures that flanked the entrance until 1911, when that same class replaced them with tigers. Nassau Hall’s bell rang after the hall’s construction; however, the fire of 1802 melted it. The bell was then recast and melted again in the fire of 1855.

    James McCosh became the college’s president in 1868 and lifted the institution out of a low period that had been brought about by the American Civil War. During his two decades of service, he overhauled the curriculum, oversaw an expansion of inquiry into the sciences, and supervised the addition of a number of buildings in the High Victorian Gothic style to the campus. McCosh Hall is named in his honor.

    In 1879, the first thesis for a Doctor of Philosophy (Ph.D.) was submitted by James F. Williamson, Class of 1877.

    In 1896, the college officially changed its name from the College of New Jersey to Princeton University to honor the town in which it resides. During this year, the college also underwent large expansion and officially became a university. In 1900, the Graduate School was established.

    In 1902, Woodrow Wilson, graduate of the Class of 1879, was elected the 13th president of the university. Under Wilson, Princeton introduced the preceptorial system in 1905, a then-unique concept in the United States that augmented the standard lecture method of teaching with a more personal form in which small groups of students, or precepts, could interact with a single instructor, or preceptor, in their field of interest.

    In 1906, the reservoir Carnegie Lake was created by Andrew Carnegie. A collection of historical photographs of the building of the lake is housed at the Seeley G. Mudd Manuscript Library on Princeton’s campus. On October 2, 1913, the Princeton University Graduate College was dedicated. In 1919 the School of Architecture was established. In 1933, Albert Einstein became a lifetime member of the Institute for Advanced Study with an office on the Princeton campus. While always independent of the university, the Institute for Advanced Study occupied offices in Jones Hall for 6 years, from its opening in 1933, until its own campus was finished and opened in 1939.

    Coeducation

    In 1969, Princeton University first admitted women as undergraduates. In 1887, the university actually maintained and staffed a sister college, Evelyn College for Women, in the town of Princeton on Evelyn and Nassau streets. It was closed after roughly a decade of operation. After abortive discussions with Sarah Lawrence College to relocate the women’s college to Princeton and merge it with the University in 1967, the administration decided to admit women and turned to the issue of transforming the school’s operations and facilities into a female-friendly campus. The administration had barely finished these plans in April 1969 when the admissions office began mailing out its acceptance letters. Its five-year coeducation plan provided $7.8 million for the development of new facilities that would eventually house and educate 650 women students at Princeton by 1974. Ultimately, 148 women, consisting of 100 freshmen and transfer students of other years, entered Princeton on September 6, 1969 amidst much media attention. Princeton enrolled its first female graduate student, Sabra Follett Meservey, as a PhD candidate in Turkish history in 1961. A handful of undergraduate women had studied at Princeton from 1963 on, spending their junior year there to study “critical languages” in which Princeton’s offerings surpassed those of their home institutions. They were considered regular students for their year on campus, but were not candidates for a Princeton degree.

    As a result of a 1979 lawsuit by Sally Frank, Princeton’s eating clubs were required to go coeducational in 1991, after Tiger Inn’s appeal to the U.S. Supreme Court was denied. In 1987, the university changed the gendered lyrics of “Old Nassau” to reflect the school’s co-educational student body. From 2009 to 2011, Princeton professor Nannerl O. Keohane chaired a committee on undergraduate women’s leadership at the university, appointed by President Shirley M. Tilghman.

    The main campus sits on about 500 acres (2.0 km^2) in Princeton. In 2011, the main campus was named by Travel+Leisure as one of the most beautiful in the United States. The James Forrestal Campus is split between nearby Plainsboro and South Brunswick. The University also owns some property in West Windsor Township. The campuses are situated about one hour from both New York City and Philadelphia.

    The first building on campus was Nassau Hall, completed in 1756 and situated on the northern edge of campus facing Nassau Street. The campus expanded steadily around Nassau Hall during the early and middle 19th century. The McCosh presidency (1868–88) saw the construction of a number of buildings in the High Victorian Gothic and Romanesque Revival styles; many of them are now gone, leaving the remaining few to appear out of place. At the end of the 19th century much of Princeton’s architecture was designed by the Cope and Stewardson firm (same architects who designed a large part of Washington University in St Louis (US) and University of Pennsylvania(US)) resulting in the Collegiate Gothic style for which it is known today. Implemented initially by William Appleton Potter and later enforced by the University’s supervising architect, Ralph Adams Cram, the Collegiate Gothic style remained the standard for all new building on the Princeton campus through 1960. A flurry of construction in the 1960s produced a number of new buildings on the south side of the main campus, many of which have been poorly received. Several prominent architects have contributed some more recent additions, including Frank Gehry (Lewis Library), I. M. Pei (Spelman Halls), Demetri Porphyrios (Whitman College, a Collegiate Gothic project), Robert Venturi and Denise Scott Brown (Frist Campus Center, among several others), and Rafael Viñoly (Carl Icahn Laboratory).

    A group of 20th-century sculptures scattered throughout the campus forms the Putnam Collection of Sculpture. It includes works by Alexander Calder (Five Disks: One Empty), Jacob Epstein (Albert Einstein), Henry Moore (Oval with Points), Isamu Noguchi (White Sun), and Pablo Picasso (Head of a Woman). Richard Serra’s The Hedgehog and The Fox is located between Peyton and Fine halls next to Princeton Stadium and the Lewis Library.

    At the southern edge of the campus is Carnegie Lake, an artificial lake named for Andrew Carnegie. Carnegie financed the lake’s construction in 1906 at the behest of a friend who was a Princeton alumnus. Carnegie hoped the opportunity to take up rowing would inspire Princeton students to forsake football, which he considered “not gentlemanly.” The Shea Rowing Center on the lake’s shore continues to serve as the headquarters for Princeton rowing.

    Cannon Green

    Buried in the ground at the center of the lawn south of Nassau Hall is the “Big Cannon,” which was left in Princeton by British troops as they fled following the Battle of Princeton. It remained in Princeton until the War of 1812, when it was taken to New Brunswick. In 1836 the cannon was returned to Princeton and placed at the eastern end of town. It was removed to the campus under cover of night by Princeton students in 1838 and buried in its current location in 1840.

    A second “Little Cannon” is buried in the lawn in front of nearby Whig Hall. This cannon, which may also have been captured in the Battle of Princeton, was stolen by students of Rutgers University in 1875. The theft ignited the Rutgers-Princeton Cannon War. A compromise between the presidents of Princeton and Rutgers ended the war and forced the return of the Little Cannon to Princeton. The protruding cannons are occasionally painted scarlet by Rutgers students who continue the traditional dispute.

    In years when the Princeton football team beats the teams of both Harvard University and Yale University in the same season, Princeton celebrates with a bonfire on Cannon Green. This occurred in 2012, ending a five-year drought. The next bonfire happened on November 24, 2013, and was broadcast live over the Internet.

    Landscape

    Princeton’s grounds were designed by Beatrix Farrand between 1912 and 1943. Her contributions were most recently recognized with the naming of a courtyard for her. Subsequent changes to the landscape were introduced by Quennell Rothschild & Partners in 2000. In 2005, Michael Van Valkenburgh was hired as the new consulting landscape architect for the campus. Lynden B. Miller was invited to work with him as Princeton’s consulting gardening architect, focusing on the 17 gardens that are distributed throughout the campus.

    Buildings

    Nassau Hall

    Nassau Hall is the oldest building on campus. Begun in 1754 and completed in 1756, it was the first seat of the New Jersey Legislature in 1776, was involved in the battle of Princeton in 1777, and was the seat of the Congress of the Confederation (and thus capitol of the United States) from June 30, 1783, to November 4, 1783. It now houses the office of the university president and other administrative offices, and remains the symbolic center of the campus. The front entrance is flanked by two bronze tigers, a gift of the Princeton Class of 1879. Commencement is held on the front lawn of Nassau Hall in good weather. In 1966, Nassau Hall was added to the National Register of Historic Places.

    Residential colleges

    Princeton has six undergraduate residential colleges, each housing approximately 500 freshmen, sophomores, some juniors and seniors, and a handful of junior and senior resident advisers. Each college consists of a set of dormitories, a dining hall, a variety of other amenities—such as study spaces, libraries, performance spaces, and darkrooms—and a collection of administrators and associated faculty. Two colleges, First College and Forbes College (formerly Woodrow Wilson College and Princeton Inn College, respectively), date to the 1970s; three others, Rockefeller, Mathey, and Butler Colleges, were created in 1983 following the Committee on Undergraduate Residential Life (CURL) report, which suggested the institution of residential colleges as a solution to an allegedly fragmented campus social life. The construction of Whitman College, the university’s sixth residential college, was completed in 2007.

    Rockefeller and Mathey are located in the northwest corner of the campus; Princeton brochures often feature their Collegiate Gothic architecture. Like most of Princeton’s Gothic buildings, they predate the residential college system and were fashioned into colleges from individual dormitories.

    First and Butler, located south of the center of the campus, were built in the 1960s. First served as an early experiment in the establishment of the residential college system. Butler, like Rockefeller and Mathey, consisted of a collection of ordinary dorms (called the “New New Quad”) before the addition of a dining hall made it a residential college. Widely disliked for their edgy modernist design, including “waffle ceilings,” the dormitories on the Butler Quad were demolished in 2007. Butler is now reopened as a four-year residential college, housing both under- and upperclassmen.

    Forbes is located on the site of the historic Princeton Inn, a gracious hotel overlooking the Princeton golf course. The Princeton Inn, originally constructed in 1924, played regular host to important symposia and gatherings of renowned scholars from both the university and the nearby Institute for Advanced Study for many years. Forbes currently houses nearly 500 undergraduates in its residential halls.

    In 2003, Princeton broke ground for a sixth college named Whitman College after its principal sponsor, Meg Whitman, who graduated from Princeton in 1977. The new dormitories were constructed in the Collegiate Gothic architectural style and were designed by architect Demetri Porphyrios. Construction finished in 2007, and Whitman College was inaugurated as Princeton’s sixth residential college that same year.

    The precursor of the present college system in America was originally proposed by university president Woodrow Wilson in the early 20th century. For over 800 years, however, the collegiate system had already existed in Britain at Cambridge and Oxford Universities. Wilson’s model was much closer to Yale University (US)’s present system, which features four-year colleges. Lacking the support of the trustees, the plan languished until 1968. That year, Wilson College was established to cap a series of alternatives to the eating clubs. Fierce debates raged before the present residential college system emerged. The plan was first attempted at Yale, but the administration was initially uninterested; an exasperated alumnus, Edward Harkness, finally paid to have the college system implemented at Harvard in the 1920s, leading to the oft-quoted aphorism that the college system is a Princeton idea that was executed at Harvard with funding from Yale.

    Princeton has one graduate residential college, known simply as the Graduate College, located beyond Forbes College at the outskirts of campus. The far-flung location of the GC was the spoil of a squabble between Woodrow Wilson and then-Graduate School Dean Andrew Fleming West. Wilson preferred a central location for the college; West wanted the graduate students as far as possible from the campus. Ultimately, West prevailed. The Graduate College is composed of a large Collegiate Gothic section crowned by Cleveland Tower, a local landmark that also houses a world-class carillon. The attached New Graduate College provides a modern contrast in architectural style.

    McCarter Theatre

    The Tony-award-winning McCarter Theatre was built by the Princeton Triangle Club, a student performance group, using club profits and a gift from Princeton University alumnus Thomas McCarter. Today, the Triangle Club performs its annual freshmen revue, fall show, and Reunions performances in McCarter. McCarter is also recognized as one of the leading regional theaters in the United States.

    Art Museum

    The Princeton University Art Museum was established in 1882 to give students direct, intimate, and sustained access to original works of art that complement and enrich instruction and research at the university. This continues to be a primary function, along with serving as a community resource and a destination for national and international visitors.

    Numbering over 92,000 objects, the collections range from ancient to contemporary art and concentrate geographically on the Mediterranean regions, Western Europe, China, the United States, and Latin America. There is a collection of Greek and Roman antiquities, including ceramics, marbles, bronzes, and Roman mosaics from faculty excavations in Antioch. Medieval Europe is represented by sculpture, metalwork, and stained glass. The collection of Western European paintings includes examples from the early Renaissance through the 19th century, with masterpieces by Monet, Cézanne, and Van Gogh, and features a growing collection of 20th-century and contemporary art, including iconic paintings such as Andy Warhol’s Blue Marilyn.

    One of the best features of the museums is its collection of Chinese art, with important holdings in bronzes, tomb figurines, painting, and calligraphy. Its collection of pre-Columbian art includes examples of Mayan art, and is commonly considered to be the most important collection of pre-Columbian art outside of Latin America. The museum has collections of old master prints and drawings and a comprehensive collection of over 27,000 original photographs. African art and Northwest Coast Indian art are also represented. The Museum also oversees the outdoor Putnam Collection of Sculpture.

    University Chapel

    The Princeton University Chapel is located on the north side of campus, near Nassau Street. It was built between 1924 and 1928, at a cost of $2.3 million [approximately $34.2 million in 2020 dollars]. Ralph Adams Cram, the University’s supervising architect, designed the chapel, which he viewed as the crown jewel for the Collegiate Gothic motif he had championed for the campus. At the time of its construction, it was the second largest university chapel in the world, after King’s College Chapel, Cambridge. It underwent a two-year, $10 million restoration campaign between 2000 and 2002.

    Measured on the exterior, the chapel is 277 feet (84 m) long, 76 feet (23 m) wide at its transepts, and 121 feet (37 m) high. The exterior is Pennsylvania sandstone, with Indiana limestone used for the trim. The interior is mostly limestone and Aquia Creek sandstone. The design evokes an English church of the Middle Ages. The extensive iconography, in stained glass, stonework, and wood carvings, has the common theme of connecting religion and scholarship.

    The Chapel seats almost 2,000. It hosts weekly ecumenical Christian services, daily Roman Catholic mass, and several annual special events.

    Murray-Dodge Hall

    Murray-Dodge Hall houses the Office of Religious Life (ORL), the Murray Dodge Theater, the Murray-Dodge Café, the Muslim Prayer Room and the Interfaith Prayer Room. The ORL houses the office of the Dean of Religious Life, Alison Boden, and a number of university chaplains, including the country’s first Hindu chaplain, Vineet Chander; and one of the country’s first Muslim chaplains, Sohaib Sultan.

    Sustainability

    Published in 2008, Princeton’s Sustainability Plan highlights three priority areas for the University’s Office of Sustainability: reduction of greenhouse gas emissions; conservation of resources; and research, education, and civic engagement. Princeton has committed to reducing its carbon dioxide emissions to 1990 levels by 2020: Energy without the purchase of offsets. The University published its first Sustainability Progress Report in November 2009. The University has adopted a green purchasing policy and recycling program that focuses on paper products, construction materials, lightbulbs, furniture, and electronics. Its dining halls have set a goal to purchase 75% sustainable food products by 2015. The student organization “Greening Princeton” seeks to encourage the University administration to adopt environmentally friendly policies on campus.

    Organization

    The Trustees of Princeton University, a 40-member board, is responsible for the overall direction of the University. It approves the operating and capital budgets, supervises the investment of the University’s endowment and oversees campus real estate and long-range physical planning. The trustees also exercise prior review and approval concerning changes in major policies, such as those in instructional programs and admission, as well as tuition and fees and the hiring of faculty members.

    With an endowment of $26.1 billion, Princeton University is among the wealthiest universities in the world. Ranked in 2010 as the third largest endowment in the United States, the university had the greatest per-student endowment in the world (over $2 million for undergraduates) in 2011. Such a significant endowment is sustained through the continued donations of its alumni and is maintained by investment advisers. Some of Princeton’s wealth is invested in its art museum, which features works by Claude Monet, Vincent van Gogh, Jackson Pollock, and Andy Warhol among other prominent artists.

    Academics

    Undergraduates fulfill general education requirements, choose among a wide variety of elective courses, and pursue departmental concentrations and interdisciplinary certificate programs. Required independent work is a hallmark of undergraduate education at Princeton. Students graduate with either the Bachelor of Arts (A.B.) or the Bachelor of Science in Engineering (B.S.E.).

    The graduate school offers advanced degrees spanning the humanities, social sciences, natural sciences, and engineering. Doctoral education is available in most disciplines. It emphasizes original and independent scholarship whereas master’s degree programs in architecture, engineering, finance, and public affairs and public policy prepare candidates for careers in public life and professional practice.

    The university has ties with the Institute for Advanced Study, Princeton Theological Seminary and the Westminster Choir College of Rider University(US).

    Undergraduate

    Undergraduate courses in the humanities are traditionally either seminars or lectures held 2 or 3 times a week with an additional discussion seminar that is called a “precept.” To graduate, all A.B. candidates must complete a senior thesis and, in most departments, one or two extensive pieces of independent research that are known as “junior papers.” Juniors in some departments, including architecture and the creative arts, complete independent projects that differ from written research papers. A.B. candidates must also fulfill a three or four semester foreign language requirement and distribution requirements (which include, for example, classes in ethics, literature and the arts, and historical analysis) with a total of 31 classes. B.S.E. candidates follow a parallel track with an emphasis on a rigorous science and math curriculum, a computer science requirement, and at least two semesters of independent research including an optional senior thesis. All B.S.E. students must complete at least 36 classes. A.B. candidates typically have more freedom in course selection than B.S.E. candidates because of the fewer number of required classes. Nonetheless, in the spirit of a liberal arts education, both enjoy a comparatively high degree of latitude in creating a self-structured curriculum.

    Undergraduates agree to adhere to an academic integrity policy called the Honor Code, established in 1893. Under the Honor Code, faculty do not proctor examinations; instead, the students proctor one another and must report any suspected violation to an Honor Committee made up of undergraduates. The Committee investigates reported violations and holds a hearing if it is warranted. An acquittal at such a hearing results in the destruction of all records of the hearing; a conviction results in the student’s suspension or expulsion. The signed pledge required by the Honor Code is so integral to students’ academic experience that the Princeton Triangle Club performs a song about it each fall. Out-of-class exercises fall under the jurisdiction of the Faculty-Student Committee on Discipline. Undergraduates are expected to sign a pledge on their written work affirming that they have not plagiarized the work.

    Graduate

    The Graduate School has about 2,600 students in 42 academic departments and programs in social sciences; engineering; natural sciences; and humanities. These departments include the Department of Psychology; Department of History; and Department of Economics.

    In 2017–2018, it received nearly 11,000 applications for admission and accepted around 1,000 applicants. The University also awarded 319 Ph.D. degrees and 170 final master’s degrees. Princeton has no medical school, law school, business school, or school of education. (A short-lived Princeton Law School folded in 1852.) It offers professional graduate degrees in architecture; engineering; finance and public policy- the last through the Princeton School of Public and International Affairs founded in 1930 as the School of Public and International Affairs and renamed in 1948 after university president (and U.S. president) Woodrow Wilson, and most recently renamed in 2020.

    Libraries

    The Princeton University Library system houses over eleven million holdings including seven million bound volumes. The main university library, Firestone Library, which houses almost four million volumes, is one of the largest university libraries in the world. Additionally, it is among the largest “open stack” libraries in existence. Its collections include the autographed manuscript of F. Scott Fitzgerald’s The Great Gatsby and George F. Kennan’s Long Telegram. In addition to Firestone library, specialized libraries exist for architecture, art and archaeology, East Asian studies, engineering, music, public and international affairs, public policy and university archives, and the sciences. In an effort to expand access, these libraries also subscribe to thousands of electronic resources.

    Institutes

    High Meadows Environmental Institute

    The High Meadows Environmental Institute is an “interdisciplinary center of environmental research, education, and outreach” at the university. The institute was started in 1994. About 90 faculty members at Princeton University are affiliated with it.

    The High Meadows Environmental Institute has the following research centers:

    Carbon Mitigation Initiative (CMI): This is a 15-year-long partnership between PEI and British Petroleum with the goal of finding solutions to problems related to climate change. The Stabilization Wedge Game has been created as part of this initiative.
    Center for BioComplexity (CBC)
    Cooperative Institute for Climate Science (CICS): This is a collaboration with the National Oceanographic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory.
    Energy Systems Analysis Group
    Grand Challenges

     
  • richardmitnick 11:35 am on November 26, 2021 Permalink | Reply
    Tags: "Korea's Cutting-Edge Fusion Reactor Just Broke Its Own Record For Containing Plasma", , , China's Experimental Advanced Superconducting Tokamak (EAST), Every test facility does things a little differently using variations on the technology to push the limits., , , KSTAR is one of a handful of test facilities attempting to iron the kinks out of a plasma-wrangling technology called a tokamak., PPPL NSTX-U Tokamak, , The trick with tokamaks is to fine-tune the current in such a way that it doesn't slip free of its magnetic confines.,   

    From Science Alert (US) : “Korea’s Cutting-Edge Fusion Reactor Just Broke Its Own Record For Containing Plasma” 

    ScienceAlert

    From Science Alert (US)

    26 NOVEMBER 2021
    MIKE MCRAE

    1
    The KSTAR Tokamak. Credit: KOREA INSTITUTE OF FUSION ENERGY (KR).

    Barely a year after the Korea Superconducting Tokamak Advanced Research (KSTAR project | KOREA INSTITUTE OF FUSION ENERGY [초전도 핵융합연구장치] (KR)) broke one record for fusion, it’s smashed it again, this time holding onto a churning whirlpool of 100 million degree plasma for a whole 30 seconds.

    Though it’s well short of the 101 seconds set by The Chinese Academy of Sciences [中国科学院](CN) earlier this year, it remains a significant milestone on the road to cleaner, near-limitless energy that could transform how we power our society.

    Here’s why it’s so important.

    Deep inside stars like our Sun, gravity and high temperatures give simple elements such as hydrogen the energy they need to overcome the repulsion of their nuclei and force them to squeeze into bigger atoms.

    The result of this nuclear fusion is heavier elements, a few stray neutrons, and a whole lot of heat.

    On Earth, scooping together a Sun’s worth of gravity isn’t possible. But we can achieve similar results by swapping the crunch of gravity for some extra punch in the form of heat. At some point we can even squeeze enough heat from the fusing atoms to keep the nuclear reaction going, with enough left over to siphon off for power.

    That’s the theory. But getting that insanely hot plasma to stay in place long enough to tap into its heat supply for a sustained, reliable source of energy requires some clever thinking.

    The KSTAR is just one of a handful of test facilities around the world attempting to iron the kinks out of a plasma-wrangling technology called a tokamak.

    ITER Tokamak in Saint-Paul-lès-Durance which is in southern France.

    PPPL NSTX-U Tokamak.

    Tokamaks are essentially large metal loops designed to contain clouds of hot, charged particles. Being charged, the moving cloud generates a strong magnetic field, allowing it to be pushed into place by a counter-field.

    The trick with tokamaks is to fine-tune the current in such a way that it doesn’t slip free of its magnetic confines. This is easier said than done, as heated pulses of plasma aren’t so much tornadoes of particles, as unstable, churning maelstroms of chaos.

    Try to contain a loop of jelly inside a ring of rubber bands to get a sense of the challenge.

    There are various other ways to achieve similar results. Stellerators, like Germany’s Wendelstein 7-X test-device, flip the script and use a highly complex, AI-designed tunnel of magnetic coils to keep its churning loop of plasma in place, for example.

    Wendelstein 7-X fusion device at MPG Institute for Plasma Physics (IPP) in Greifswald (DE) 2011.

    This promises a longer hang-time, but makes it a little harder to heat the plasma.

    Tokamaks, on the other hand, have been hitting bigger and bigger temperatures the past few years.

    China’s Experimental Advanced Superconducting Tokamak (EAST) reactor in Hefei became the first to hit a significant temperature landmark of 100 million degrees Celsius back in 2018, a temperature that’s still out of reach of stellerators (for now).

    China – Experimental Advanced Superconducting Tokamak (EAST) reactor

    This year, EAST heated plasma to 120 million degrees Celsius, holding it for more than a minute and a half.

    Those temperatures, however, were a measure of the energy shared among its electrons. Hot, no question, but getting the temperature of the much heavier ions to increase is also important. Not to mention harder.

    The KSTAR hit 100 million for its ion temperature last year, maintaining the pulse for 20 seconds.

    The fact it’s just hit 30 seconds – a little over 12 months later – is incredibly encouraging.

    Every test facility does things a little differently using variations on the technology to push the limits on anything from pulse duration to stability to electron or plasma temperature.

    While it’s tempting to see each record as a competition, it’s important to celebrate every milestone as one more lesson learned.

    Every achievement shows others ways to deal with the hurdles we still face in harnessing the Sun’s engine into a powerhouse on Earth.

    See the full article here .


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    Please help promote STEM in your local schools.


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  • richardmitnick 3:11 pm on August 30, 2021 Permalink | Reply
    Tags: "PPPL physicist helps confirm a major advance in stellarator performance for fusion energy", , , , , , , PPPL NSTX-U Tokamak, Wendelstein 7-X fusion device at MPG Institute for Plasma Physics (IPP) in Greifswald (DE) 2011.   

    From DOE’s Princeton Plasma Physics Laboratory (US) and : “PPPL physicist helps confirm a major advance in stellarator performance for fusion energy” 

    From DOE’s Princeton Plasma Physics Laboratory (US)

    and

    MPIPP bloc

    MPG Institute for Plasma Physics [MPG Institut für Plasmaphysik] (DE)

    August 30, 2021
    John Greenwald

    1
    PPPL physicist Novimir Pablant with computer simulation of W7-X magnetic coils and plasma. Photo of Pablant and collage by Elle Starkman/Office of Communications. Computer simulation courtesy of IPP.

    Stellarators, twisty magnetic devices that aim to harness on Earth the fusion energy that powers the sun and stars, have long played second fiddle to more widely used doughnut-shaped facilities known as tokamaks. The complex twisted stellarator magnets have been difficult to design and have previously allowed greater leakage of the superhigh heat from fusion reactions.

    Now scientists at the MPG Institute for Plasma Physics [MPG Institut für Plasmaphysik] (DE), working in collaboration with researchers that include the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), have shown that the Wendelstein 7-X (W7-X) device in Greifswald, Germany, the largest and most advanced stellarator in the world, is capable of confining heat that reaches temperatures twice as great as the core of the sun.

    Key indicator

    A diagnostic instrument called the XICS, chiefly designed, built and operated by PPPL physicist Novimir Pablant in collaboration with IPP physicist Andreas Langenberg, is a key indicator of a sharp reduction of a type of heat loss called “neoclassical transport” that has historically been greater in classical stellarators than in tokamaks. Causing the troublesome transport are frequent collisions that knock heated particles out of their orbits as they swirl around the magnetic field lines that confine them. Contributing to the transport are drifts in the particle orbits.

    A recent report on W7-X findings in Nature magazine confirms the success of the efforts of designers to shape the intricately twisted stellarator magnets to reduce neoclassical transport. First author of the paper was physicist Craig Beidler of the IPP Theory Division. “It’s really exciting news for fusion that this design has been successful,” said Pablant, a coauthor along with Langenberg of the paper. “It clearly shows that this kind of optimization can be done.”

    David Gates, head of the Advanced Projects Department at PPPL that oversees the laboratory’s stellarator work, was also highly enthused. “It’s been very exciting for us, at PPPL and all the other U.S. collaborating institutions, to be part of this really exciting experiment,” Gates said. “Novi’s work has been right at the center of this amazing experimental team’s effort. I am very grateful to our German colleagues for so graciously enabling our participation.”

    Carbon-free power

    The fusion that scientists seek to produce combines light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei, or ions, that makes up 99 percent of the visible universe — to generate massive amounts of energy. Producing controlled fusion on Earth would create a virtually inexhaustible supply of safe, clean, and carbon-free source of power to generate electricity for humanity and serve as a major contributor to the transition away from fossil fuels.

    Stellarators, first constructed in the 1950s under PPPL founder Lyman Spitzer, can operate in a steady state with little risk of the plasma disruptions that tokamaks face.

    However, their complexity and history of relatively poor heat confinement has held them back. A major goal of the optimized design of W7-X, which produced its first plasma in 2015, has been to demonstrate the appropriateness of an optimized stellarator as an eventual fusion power plant.

    Results obtained by the XICS demonstrate hot ion temperatures that could not have been achieved without a sharp reduction in neoclassical transport. These measurements were also made by the CXRS diagnostic built and operated by IPP, which were thought to be a little more accurate but could not be made in all conditions. The final temperature profiles in the Nature report were taken from CXRS and supported by measurements with XICS in similar plasmas.

    “Extremely valuable”

    “Without the XICS we probably would not have discovered this [good confinement] regime,” said Robert Wolf, head of the W7-X heating and operation division and a co-author of the paper. “We needed a readily available ion temperature measurement and this was extremely valuable.”

    Researchers conducted a thought experiment to check the role that optimization played in the confinement results. The experiment found that in a non-optimized stellarator large neoclassical transport would have made the high temperatures recorded on W7-X for the given heating power impossible. “This showed that the optimized shape of W7-X reduced the neoclassical transport and was necessary for the performance seen in W7-X experiments,” Pablant said. “It was a way of showing how important the optimization was.”

    The results mark a step toward enabling stellarators based on the W7-X design to lead to a practical fusion reactor, he added. “But reducing neoclassical transport isn’t the only thing you have to do. There are a whole bunch of other goals that have to be shown, including running steady and reducing the turbulent transport.” Producing turbulent transport are ripples and eddies that run through the plasma as the second main source of heat loss.

    The W7-X will reopen in 2022 following a three-year upgrade to install a water-cooling system that will lengthen fusion experiments and an improved divertor that will exhaust high-performance heat. The upgrades will enable the next step in the investigation by W7-X researchers of the worthiness of optimized stellarators to become blueprints for power plants.

    Support for this work comes from the Euratom research and training programme and the DOE Office of Science.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    MPG Institute for Plasma Physics [MPG Institut für Plasmaphysik] (DE) is a physics institute for the investigation of plasma physics, with the aim of working towards fusion power. The institute also works on surface physics, also with focus on problems of fusion power.

    The IPP is an institute of the Max Planck Society, part of the European Atomic Energy Community, and an associated member of the Helmholtz Association.

    The IPP has two sites: Garching near Munich (founded 1960) and Greifswald (founded 1994), both in Germany.

    It owns several large devices, namely

    the experimental tokamak ASDEX Upgrade (in operation since 1991)

    ASDEX tokamak at MPG Institute for Plasma Physics.

    It also cooperates with the ITER and JET projects.

    MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V](DE) is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at MPG Institutes – and many of those articles are among the most-cited publications in the relevant field.

    What is the basis of this success? The scientific attractiveness of the MPG Society is based on its understanding of research: MPG institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The MPG Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

    The currently 83 MPG Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. MPG Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

    MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the MPG Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

    According to its primary goal, the MPG Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014) MPG institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

    The MPG Institutes focus on excellence in research. The MPG Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the MPG institutes fifth worldwide in terms of research published in Nature journals (after Harvard University (US), Massachusetts Institute of Technology (US), Stanford University (US) and the National Institutes of Health (US)). In terms of total research volume (unweighted by citations or impact), the MPG Society is only outranked by the Chinese Academy of Sciences [中国科学院] (CN), the Russian Academy of Sciences [Росси́йская акаде́мия нау́к](RU) and Harvard University. The Thomson Reuters-Science Watch website placed the Max Planck Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

    [The blog owner wishes to editorialize: I do not think all of this boasting is warranted when the combined forces of the MPG Society are being weighed against individual universities and institutions. It is not the combined forces of the cited schools and institutions, that could make some sense. No, it is each separate institution standing on its own.]

    The MPG Society and its predecessor Kaiser Wilhelm Society hosted several renowned scientists in their fields, including Otto Hahn, Werner Heisenberg, and Albert Einstein.

    History

    The organization was established in 1911 as the Kaiser Wilhelm Society, or Kaiser-Wilhelm-Gesellschaft (KWG), a non-governmental research organization named for the then German emperor. The KWG was one of the world’s leading research organizations; its board of directors included scientists like Walther Bothe, Peter Debye, Albert Einstein, and Fritz Haber. In 1946, Otto Hahn assumed the position of President of KWG, and in 1948, the society was renamed the MPG Society after its former President (1930–37) Max Planck, who died in 1947.

    The MPG Society has a world-leading reputation as a science and technology research organization. In 2006, the Times Higher Education Supplement rankings of non-university research institutions (based on international peer review by academics) placed the MPG Society as No.1 in the world for science research, and No.3 in technology research (behind AT&T Corporation and the DOE’s Argonne National Laboratory (US).

    The domain mpg.de attracted at least 1.7 million visitors annually by 2008 according to a Compete.com study.

    MPG Institutes and research groups

    The MPG Society consists of over 80 research institutes. In addition, the society funds a number of MPG Research Groups (MPRG) and International MPG Research Schools (IMPRS). The purpose of establishing independent research groups at various universities is to strengthen the required networking between universities and institutes of the MPG Society.

    The research units are primarily located across Europe with a few in South Korea and the U.S. In 2007, the Society established its first non-European centre, with an institute on the Jupiter campus of Florida Atlantic University (US) focusing on neuroscience.

    The MPG Institutes operate independently from, though in close cooperation with, the universities, and focus on innovative research which does not fit into the university structure due to their interdisciplinary or transdisciplinary nature or which require resources that cannot be met by the state universities.

    Internally, MPG Institutes are organized into research departments headed by directors such that each MPG institute has several directors, a position roughly comparable to anything from full professor to department head at a university. Other core members include Junior and Senior Research Fellows.

    In addition, there are several associated institutes:

    International Max Planck Research Schools
    Together with the Association of Universities and other Education Institutions in Germany, the MPG Society established numerous International Max Planck Research Schools (IMPRS) to promote junior scientists:

    Cologne Graduate School of Ageing Research, Cologne
    International Max Planck Research School for Intelligent Systems, at the MPG Institute for Intelligent Systems (DE) located in Tübingen and Stuttgart
    International Max Planck Research School on Adapting Behavior in a Fundamentally Uncertain World (Uncertainty School), at the Max Planck Institutes for Economics, for Human Development, and/or Research on Collective Goods
    International Max Planck Research School for Analysis, Design and Optimization in Chemical and Biochemical Process Engineering, Magdeburg
    International Max Planck Research School for Astronomy and Cosmic Physics, Heidelberg at the MPG for Astronomy
    International Max Planck Research School for Astrophysics, Garching at the MPG Institute for Astrophysics
    International Max Planck Research School for Complex Surfaces in Material Sciences, Berlin
    International Max Planck Research School for Computer Science, Saarbrücken
    International Max Planck Research School for Earth System Modeling, Hamburg
    International Max Planck Research School for Elementary Particle Physics, Munich, at the MPG Institute for Physics
    International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Marburg at the MPG Institute for Terrestrial Microbiology
    International Max Planck Research School for Evolutionary Biology, Plön at the Max Planck Institute for Evolutionary Biology
    International Max Planck Research School “From Molecules to Organisms”, Tübingen at the MPG Institute for Developmental Biology
    International Max Planck Research School for Global Biogeochemical Cycles, Jena at the Max Planck Institute for Biogeochemistry
    International Max Planck Research School on Gravitational Wave Astronomy, Hannover and Potsdam MPG Institute for Gravitational Physics
    International Max Planck Research School for Heart and Lung Research, Bad Nauheim at the MPG Institute for Heart and Lung Research
    International Max Planck Research School for Infectious Diseases and Immunity, Berlin at the Max Planck Institute for Infection Biology
    International Max Planck Research School for Language Sciences, Nijmegen
    International Max Planck Research School for Neurosciences, Göttingen
    International Max Planck Research School for Cognitive and Systems Neuroscience, Tübingen
    International Max Planck Research School for Marine Microbiology (MarMic), joint program of the MPG Institute for Marine Microbiology in Bremen, the University of Bremen [Universität Bremen](DE), the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, and the Jacobs University Bremen [Jacobs Universität Bremen] (DE)
    International Max Planck Research School for Maritime Affairs, Hamburg
    International Max Planck Research School for Molecular and Cellular Biology, Freiburg
    International Max Planck Research School for Molecular and Cellular Life Sciences, Munich
    International Max Planck Research School for Molecular Biology, Göttingen
    International Max Planck Research School for Molecular Cell Biology and Bioengineering, Dresden
    International Max Planck Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster (DE) and the MPG Institute for Molecular Biomedicine (DE)
    International Max Planck Research School on Multiscale Bio-Systems, Potsdam
    International Max Planck Research School for Organismal Biology, at the University of Konstanz [Universität Konstanz] (DE) and the MPG Institute for Ornithology (DE)
    International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion (DE)
    International Max Planck Research School for Science and Technology of Nano-Systems, Halle at MPG Institute of Microstructure Physics (DE)
    International Max Planck Research School for Solar System Science at the University of Göttingen – Georg-August-Universität Göttingen (DE) hosted by MPG Institute for Solar System Research [Max-Planck-Institut für Sonnensystemforschung] (DE)
    International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie] (DE) (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
    International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
    International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at MPG Institute for Iron Research [MPG Institut für Eisenforschung] (DE)
    International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg

     
  • richardmitnick 2:28 pm on November 3, 2020 Permalink | Reply
    Tags: "Building a star in a smaller jar", , Improved confinement is made possible by the so-called enhanced pedestal (EP) H-mode., Plasma in fusion technology, , PPPL NSTX-U Tokamak   

    From PPPL: “Building a star in a smaller jar” 


    From PPPL

    October 29, 2020
    Raphael Rosen

    1
    PPPL physicist Devon Battaglia with graphs illustrating fusion plasma in enhanced pedestal H-mode. Credit: Elle Starkman.

    PPPL NSTX-U Tokamak.

    Researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have gained a better understanding of a promising method for improving the confinement of superhot fusion plasma using magnetic fields. Improved plasma confinement could enable a fusion reactor called a spherical tokamak to be built smaller and less expensively, moving the world closer to reproducing on Earth the fusion energy that powers the sun and stars.

    The improved confinement is made possible by the so-called enhanced pedestal (EP) H-mode, a variety of the high performance, or H-mode, plasma state that has been observed for decades in tokamaks around the world. When a fusion plasma enters H-mode, it requires less heating to get to the superhot temperatures necessary for fusion reactions.

    The new understanding reveals some of the underlying mechanics of EP H-mode, a condition that researchers discovered more than a decade ago. Scientists led by physicists at PPPL have now found that the EP H-mode improves upon H-mode in spherical tokamaks by lowering the density of the plasma edge.

    The reduced density occurs in EP H-mode when small instabilities in the plasma edge eject relatively cold, low-energy particles. With fewer cold particles to bump into, the hotter particles in the plasma are less likely to leak out.

    “As the higher energy particles stay in the plasma in larger quantities, they increase the pressure in the plasma, feeding the instabilities that throw out colder particles and further lowering the edge density,” said PPPL physicist Devon Battaglia, lead author of a paper reporting the results in Physics of Plasmas. “Ultimately, the fortuitous interaction allows the plasma to stay hotter with the same heating and little change to the average plasma density.”

    Physicists want to understand the conditions under which EP H-mode occurs so they can recreate them in future fusion power plants. “If we could run the plasma with this characteristic in a steady-state fashion, it would provide an additional route to optimize the size and power gain of future fusion reactors,” said PPPL physicist Walter Guttenfelder, one of the researchers who contributed to the findings.

    Fusion reactors combine light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei — to generate large amounts of energy. Scientists use fusion reactors to develop the process that drives the sun and stars for a virtually inexhaustible supply of power to generate electricity.

    Physicists Rajesh Maingi and David Gates discovered EP H-mode in 2009 while using PPPL’s National Spherical Torus Experiment (NSTX), the predecessor of the National Spherical Torus Experiment-Upgrade (NSTX-U). “Their discovery was exciting because the confined plasma reorganized and did a better job of holding on to its heat without a big change in the amount of plasma,” said Battaglia.

    “It’s like adding better insulation to your house,” he said. “The more the plasma holds on to its heat, the smaller you can make the device, since you don’t need additional layers of plasma to insulate the hot core.” Moreover, he added, “by taking a leap in our understanding of how EP H-mode comes about, we can have more confidence in being able to predict if it’s going to happen. The next step is to use the new capabilities of NSTX-U to demonstrate that we can take advantage of this process in our designs for fusion reactors.”

    Collaborators have included researchers from PPPL and the University of Wisconsin-Madison. The research was supported by the DOE’s Office of Science.

    NSTX-U is a DOE Office of Science user facility.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition


    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science.

    About Princeton: Overview
    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    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.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

    Princeton Shield

     
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