Research, teaching and outreach in Physics at UW–Madison
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Rogerio Jorge receives first grant as a professor
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Rogerio Jorge
Congrats to Prof. Rogerio Jorge who was awarded his first grant as a professor! The three-year, $500,000 National Science Foundation grant, titled “Moment Approach to Multiscale Plasmas,” will be used to fund a graduate student and postdoc on the project.
“Astrophysical plasmas appear in more than 90% of the universe — for example, on the surface of the sun or in the intergalactic medium — and there’s still a lot of things that we don’t understand about them,” Jorge says. “We need to study phenomena in astrophysical plasmas and try to replicate them numerically to better understand them.”
Jorge’s work will focus on the so-called collisionless regime of these plasmas, where particles travel for a long time before experiencing any collision. He says this regime is difficult to model, both experimentally and numerically.
“We’ve proposed a new method that has two parts. The first one is to try to simplify the equations using a reduced model, called a moment model,” Jorge says. “Second, it’s using machine learning to reduce it even more.”
Jorge and his team have the moment model theory ready to be applied. For the machine learning step, they will use JAX, an open-source machine learning framework developed by the DeepMind team at Google that many physicists are starting to use in their research.
Jorge plans to investigate one intriguing phenomenon in collisionless plasmas: how the acceleration of super-thermal particles occurs versus thermodynamic heating. This will help scientists understand how charged particles in a plasma become energized, a phenomenon applicable to both laboratory and astrophysical plasmas. He will also apply this new approach to the problem of magnetic reconnection in collisionless plasmas, a problem he says is difficult to model due to the topology changes that occur in short time scales.
“We need new models to try to handle these complex scenarios without spending months and months on a single simulation,” Jorge says.
NSF grants require investigators to address the broader impacts of their research, defined as “the potential to benefit society and contribute to the achievement of specific, desired societal outcomes.” Jorge plans to work with the department’s Wonders of Physics outreach program to create realistic movies that simulate these astrophysical plasma environments. For example, he hopes to show, in detail, what is happening with magnetic reconnection in auroras or around the surface of the sun, with both using the new code developed through his research.
For this research, Jorge is collaborating with experimentalists at UW-Madison’s WiPPL facilities, and computational plasma physicists at UCLA, MIT, and Princeton.
New Chair to continue department’s strengths, commit to diversity and inclusion
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Prof. Kevin Black
The department of physics is pleased to announce that Prof. Kevin Black has been named new department chair. His three-year term began July 1, 2024, succeeding Prof. Mark Eriksson. Black says he is looking to continue the department’s excellence in its mission of research, teaching, and outreach, and to continue developing an intentional commitment to diversity.
“Under Prof. Eriksson’s leadership, our department has attained near-record highs of faculty members as well as graduate and undergraduate students, which will lead to significant successes in our research program,” Black says. “Now, we need to continue to focus on making a commitment to diversity an active component of what we do as a department.”
Two pillars of the department’s mission have always been research and teaching, and Black wants to sustain successes in those areas. He begins his term with over a dozen faculty members who have joined the department in the previous three years, bringing the total number of professors to 56. These faculty members represent a range of seniority levels and a breadth of research fields. He also begins at a time when more students than ever are being taught in department courses.
“Research and education are the core values of a research university,” Black says. “We want to do excellent, cutting-edge research and we want to teach the next generation of scientists.”
Black’s focus on diversity and climate efforts represents a continuing effort from leadership before him. The need to add diversity as a pillar of the department’s mission became evident to him when he saw the list of department chairs who came before him, and he noted that he was the 33rd white male chair out of 35. He acknowledges the challenge that the broader field of physics faces, and specifically at UW–Madison: both lack adequate representation of students from marginalized groups.
“We need to improve diversity at all levels in this department,” Black says. “There’s no magic wand. It takes a concerted, sustained effort and we need to make it a priority going forward.”
Lastly, Black also believes that the department’s commitment to educational outreach is critical to fulfilling the Wisconsin Idea, the idea that education should influence people’s lives beyond the boundaries of the university. The department has a long-standing tradition of engaging in outreach, including over 100 years of running the Physics Museum and over four decades of running The Wonders of Physics outreach program.
“Physics outreach can inspire the next generation to think about the natural universe and think about how things work,” Black says. “In a world which is increasingly driven by soundbites and nonsense on the internet, it’s crucial to encourage and guide young students to think rationally about science and formulate questions and opinions.”
Black joined the faculty as a full professor in 2018 and works with the high energy experiment group on the Compact Muon Solenoid (CMS) experiment at CERN. He had previously been a professor at Boston University. Black earned a bachelor’s degree at Wesleyan University where he worked in an atomic physics lab. He has a doctorate in physics from Boston University, and much of his thesis work was completed on the Tevatron at Fermilab. He was then a postdoc and research scientist at Harvard University, where his work transitioned to the Large Hadron Collider at CERN.
Daniel Den Hartog earns Progress Award from Laser Society of Japan
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Congrats to plasma scientist Daniel Den Hartog who is part of a team that was recently awarded a Progress Award from the Laser Society of Japan. This award is given to research that has shown a significant impact on the advancement of laser engineering.
The work was led by Ryo Yasuhara of the National Institute for Fusion Science in Japan. The team was recognized for “research on transient plasma electron and temperature distribution measurement by Thomson scattering method using a repetitive 20 kHz, 1.2 J, nanosecond laser.”
The Progress Award was one of a handful awarded recently by the Laser Society of Japan. For a full list, see LSJ’s awards site.
Separate research groups push fusion plasma performance to new levels
Two teams of scientists have announced a breakthrough in fusion energy research, demonstrating for the first time the ability to simultaneously achieve high plasma density and confinement in a tokamak reactor. Derived from a Russian acronym, a tokamak is a donut-shaped experimental device that uses magnetic fields to make use of the energy of nuclear…
Front row from left: Dorota Brzezińska (UW-Vice Chancellor for Research), John D. Wiley (former UW Chancellor), Pupa Gilbert (John D. Wiley Professor of Physics), Jennifer Mnookin (UW Chancellor) Back row from left: Lauren Bishop (professor of Social Work, Romnes winner), Charles Lee Isbell, Jr. (UW Provost), Susan Harness (Maria Stuchly Professor of Electrical Engineering), Russ Shafer-Landau (Elliott Sober Professor of Philosophy).
Physics professor Pupa Gilbert is one of eight UW–Madison faculty awarded WARF Named Professorships, which come with $100,000 and honor faculty who have made major contributions to the advancement of knowledge, primarily through their research endeavors, but also as a result of their teaching and service activities. Award recipients choose the names associated with their professorships.
Gilbert, the John D. Wiley professor of physics, joined the Department of Physics in 1999 as a full professor, following staff scientist positions in the Italian National Research Council (CNR) in Rome and the Swiss Institute of Technology in Lausanne (EPFL). Her research focuses on biomineralization, that is, on understanding the nanoscale formation mechanisms of natural biominerals, especially coral skeletons, but on a side she also studies sea urchin spines, mollusk shell nacre, tooth enamel, and inner ear cochleaer bone. She also strives to understand the evolution of biomineralization, and how biominerals interact with the environment in the past, present, and future. She is actively working to save coral reefs from climate change.
Her role in the profession has included being research director for the NSF-funded Synchrotron Radiation Center at UW–Madison, chair of the Division of Biological Physics (DBIO) of the American Physical Society, a Radcliffe Fellow at Harvard University, and establishing “the Cnidarians,” a group of tens of diverse undergraduate students at UW–Madison who produce great discoveries by doing massively parallel data processing. She teaches Physics in the Arts, a popular course for non-science majors on light, color, and sound. She was knighted by Italian President Carlo A. Ciampi in 2001.
“Prof. Pupa Gilbert is a luminary in the field of biomineralization, developing a fundamental understanding of these crucial processes that are shared by many diverse organisms,” says Kevin Black, chair of the UW–Madison department of physics. “Prof. Gilbert is a knight of the Italian Republic, and stalwart advocate for involving undergraduates, in particular those from underrepresented groups in her research. This award recognizes the many contributions to the academy in her long and productive interdisciplinary research program and is well deserved.”
For her named professorship, Gilbert chose John D. Wiley, the former UW–Madison Chancellor who earned his MS and PhD from this department. He was a member of the technical staff at Bell Laboratories, then a visiting scientist at Max Planck Institute for Semiconductor Physics. He joined the faculty at UW–Madison as professor of electrical and computer engineering in 1975, where he did groundbreaking research on semiconductors and metals, and earned major patents at WARF. Later, he became Chair of the Materials Science Program, Dean of the Graduate School, Provost, and then Chancellor (2001-2008), all at UW–Madison.
Wiley also started campus-wide initiatives such as cluster hiring and originated many campus building projects. He was the first Director of the Wisconsin Institute of Discovery, a position he held from 2008 until he retired in 2011.
Gilbert chose Wiley, whom she calls “a brilliant physicist,” for her named professorship for all the reasons listed above. She also credits him with bringing her to UW–Madison.
“When there was a cluster hire in biophotonics back in 1999, John Wiley wanted me to join the university and he had them include the word spectromicroscopy — the synchrotron method that I developed — into the search to encourage me to apply,” Gilbert says. “I really didn’t want to apply, I was on my way to CalTech, but of course I couldn’t say no to John.”
In total, thirty-two University of Wisconsin–Madison faculty were awarded fellowships from the Office of the Vice Chancellor for Research for 2024-25, including eight WARF named professorships, 13 Romnes faculty fellowships, and 11 Kellett mid-career awards. The awardees span the four research divisions on campus: arts and humanities, physical sciences, social sciences and biological sciences.
“These awards recognize excellence in faculty research, academics, and outreach at various stages of their scholarly careers and provide an opportunity for continued development of their research programs,” says Cynthia Czajkowski, interim vice chancellor for research. “I look forward to seeing the results of their imaginative use of these funds.”
The awards are possible due to the research efforts of UW–Madison faculty and staff. Technology that arises from these efforts is licensed by the Wisconsin Alumni Research Foundation and the income from successful licenses is returned to the OVCR, where it’s used to fund research activities and awards throughout the divisions on campus.
Raheem Hashmani discusses microwaves in Everyday Health articles
This story was originally published by the Office of the Vice Chancellor for Research
Mark Eriksson, professor of physics, and Mikhail Feldman, professor of mathematics, have been named recipients of UW–Madison Steenbock Professorships.
“This professorship is among the most prestigious and important professorships for researchers at the UW–Madison,” says Cynthia Czajkowski, interim vice chancellor for research. “This recognition is accompanied by discretionary funds to provide recipients the freedom to explore innovative research directions and to explore new approaches to their research areas.”
In the early 1980s, Evelyn Steenbock initiated a program to endow a series of professorships in the natural sciences in honor of her late husband, Harry Steenbock, emeritus professor of biochemistry.
Harry Steenbock (1886-1967) developed an inexpensive method of enriching foods with Vitamin D. His discovery led to the eradication of rickets, the bone-deforming deficiency disease, throughout most of the world. He is also renowned for his discovery of the conversion of carotenes to vitamin A.
Steenbock assigned his patents for advances in human and animal nutrition to the Wisconsin Alumni Research Foundation (WARF), and accumulated royalties from Steenbock’s patents supplied about half the funds for the Steenbock Memorial Library construction on campus. Steenbock Memorial Library is a primary resource library for the students, faculty and research staff at the UW–Madison.
The Steenbock Professorship provides research funds to recipients annually for 10 years and honors those faculty who have made major contributions to the advancement of knowledge, primarily through their research endeavors at UW–Madison, but also as a result of their teaching and service activities.
Mark Eriksson
Eriksson, awarded the Steenbock Professorship in the Physical Sciences, was recently chair of the Department of Physics. He joined the UW–Madison physics faculty in 1999 and is a world-leading expert in the development of quantum information systems using solid-state quantum dot qubits.
As department chair, Eriksson promoted the Wisconsin Idea by supporting the department’s role in connecting with audiences all around the state of Wisconsin, including restarting The Wonders of Physics Traveling Show.
Eriksson received a bachelor’s degree in physics and mathematics from UW–Madison in 1992, received his PhD from Harvard University and was a postdoctoral member of technical staff at Bell Labs.
His research has focused on quantum computing, semiconductor quantum dots and nanoscience. He leads a team dedicated to developing spin qubits in gate-defined silicon quantum dots with the goal of enabling quantum computers, which manipulate information coherently, to be built using many of the materials and fabrication methods that are the foundation of modern, classical integrated circuits.
Eriksson is widely recognized for engaging collaborative partnerships with industry, government leaders and other university research institutions to tackle some of the greatest challenges in quantum information science and technology. Last year, the Eriksson group announced its partnership with Intel and HRL Laboratories as part of the LPS Qubit Collaboratory (LQC) national Quantum Information Science Research Center hosted at the Laboratory for Physical Sciences at the University of Maryland, College Park to collaborate on research in advanced computer technologies.
“I intend to use the award to explore new opportunities in silicon-based quantum computing, including new ideas for connecting qubits to each other across large distances, and the use of near-atomic-scale metamaterials to endow semiconductors with properties even better suited to quantum computing than those available today,” Eriksson says.
UW–Madison alum and theoretical physicist named WIPAC director
Dan Hooper, PhD, has been selected as the new director of the Wisconsin IceCube Particle Astrophysics Center (WIPAC). Hooper will begin his role at WIPAC on Sept. 9 and as director will report to the Vice Chancellor for Research. Hooper will have a joint faculty appointment with the Department of Physics. Hooper is a Senior […]
Madison Symmetric Torus operates stable plasma at ten times the Greenwald Limit
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If net-positive fusion energy is to ever be achieved, density is key: the more atomic nuclei crashing into each other the more efficient the reaction will be. Nearly 40 years ago, Martin Greenwald identified a density limit above which tokamak plasmas become unstable, and the so-called Greenwald limit has at best been exceeded by a factor of two in the ensuing decades.
In a new study published July 29 in Physical Review Letters, physicists at the University of Wisconsin–Madison produced a tokamak plasma that is stable at 10 times the Greenwald limit. The findings may have implications for tokamak fusion reactors, though the researchers caution that their plasma is not directly comparable to that in a fusion reactor.
The Madison Symmetric Torus (MST). credit: Noah Hurst
“Tokamak devices are considered a leading contender in the race to build a nuclear fusion reactor that generates power in the same way as the sun,” says Noah Hurst, a scientist with the Wisconsin Plasma Physics Laboratory (WiPPL) and lead author on the study. “Our discovery of this unusual ability to operate far above the Greenwald limit is important for boosting fusion power production and preventing machine damage.”
Tokamaks are toroidal devices, basically hollow metal donuts that churn ionized plasma through the tube by applying both a magnetic field and an electrical current. This shape has been shown to be particularly adept at confining the plasma, which is required to reach the high temperature and density needed for fusion. But the design can also lead to instabilities in the plasma: as its density increases, the plasma becomes more turbulent, causing the plasma to give up all its energy to the wall and cool off.
The device that the WiPPL team used in this new study is the Madison Symmetric Torus, or MST. For many years, MST has operated as one of the leading programs studying the reversed field pinch, a toroidal configuration closely related to the tokamak. MST was designed to anticipate operation as a tokamak, allowing direct comparison of the two toroidal configurations in the same device. Unlike other tokamaks, the metal donut that houses the MST plasmas is thick and highly conducting, allowing for more stable operation..
In 2018, MST scientists received National Science Foundation funding to build power supplies that are programmable, facilitating easier access to a range of toroidal plasma configurations, from tokamak to reversed field pinch. Hurst was hired in 2019 to study MST plasmas in tokamak mode with the new power supply.
“My job was to try to find ways to make the plasma go unstable,” Hurst says. “I tried, and I found that, well, in many cases, it doesn’t. It was surprising.”
WiPPL scientists were able to experimentally create a stable plasma 10x greater than the Greenwald limit (the dashed horizontal line).Hurst and colleagues looked into plasma density, trying to destabilize the plasma by puffing in more and more gas. They set the power supply to provide whatever voltage was needed to maintain a steady 50000 amps of current in each plasma (as plasma density increases, it becomes more resistive, and more voltage is needed to keep the current steady). They measured the achieved plasma density with interferometers viewing the plasma along 11 different lines of sight.
The Greenwald limit is just the ratio of the plasma density to the product of the plasma current and plasma size, a simple metric that allows comparison of different devices and operating conditions. Since the limit was defined, only a handful of devices have operated above it, and by at most a factor of two.
“Here, we were at a factor of ten,” Hurst says. “Future reactor-scale tokamaks will likely need to operate near or above the Greenwald limit, so if we can better understand what’s causing the density limit and understand the physics of how we got to ten times the limit, then maybe we have a shot at doing something about it.”
Though the researchers feel confident in their results, they are unexpected. The team is actively exploring explanations.
“The first thing we would ask is, what’s different about our machine relative to other machines?” Hurst says. “MST is very different because it was designed with a thicker wall than most tokamaks. Also, most tokamaks produce lower-resistance plasmas, so they don’t need these large voltages like we did in order to run.”
Noah Hurst
Hurst also emphasizes that these results are unlikely to be directly applicable to fusion reactors, such as ITER and others that are being built in the hopes of being the first net-positive energy production tokamaks. But he and the team are cautiously optimistic.
“Our results were obtained in a low magnetic field, low temperature plasma, which is not capable of fusion power production. Still, we were the first ones to be able to do this, and you have to start somewhere,” Hurst says. “We’re going to keep studying these plasmas, and we think that what we learn might help higher-performance fusion devices to operate at the higher densities they need to be successful.”
This study was supported by the U.S. Department of Energy (DE-SC0020245); by the Wisconsin Plasma Physics Laboratory, a research facility supported by the U.S. DOE Office of Fusion Energy Sciences under contract DE-SC0018266; and by a National Science Foundation Major Research Instrumentation grant (PHY 1828159).
UW-Madison one step closer to harnessing the power of the sun through fusion research
For the first time, a fusion device at the University of Wisconsin in Madison has generated plasma, inching one step closer toward using nuclear fusion as a source of carbon-free energy.
![a graph with time [ms] on the x axis and electron density) aka plasma density on the y axis. Several data lines, given in a rainbow of colors, all go up within the first few ms, hold steady for up to 40ms, and then drop down to 0. A dotted line, representing the Greenwald limit, is shown around 0.75 on the y axis; all but one of the data lines goes well above that dotted line, up to 10x the value of the Greenwald limit](https://www.physics.wisc.edu/wp-content/uploads/2024/07/nlim_summary.png)
