Summary

PLASMA SCIENCE: ENABLING TECHNOLOGY, SUSTAINABILITY, SECURITY, AND EXPLORATION

Plasma science and engineering (PSE) is a technological and scientific success story. Advances in plasma science have enabled critical technologies and processes that benefit society, from materials processing and health care to forecasting space weather. That record of translating advances in fundamental science to technologies is continuing to address our nation’s most critical needs.

Plasmas, often called the fourth state of matter, are ionized gases and perhaps the most abundant form of matter, making up nearly 99.9 percent of the observable universe. Today, plasma dynamics informs our understanding of the most fundamental processes in the Sun and stars, planetary ionospheres and magnetospheres, interstellar space, and in accretion disks surrounding black holes. Many technologies defining modern society rely on the chemical activation of atoms and molecules that plasmas enable. Plasma-based technologies have enabled efficient lighting, new materials, welding, internal combustion and jet engines, medical implants, and water purification. Plasmas—which enable microelectronics fabrication through the etching and deposition of materials—have been indispensable to the information technology revolution. Translating basic research in plasma science and engineering has the potential to produce new society-altering technologies—clean energy and energy independence through controlled fusion; a new paradigm for chemical processing; compact particle accelerators for science, medicine, and industry; forecasting of extreme space weather events; agricultural and medical advances—all

while expanding our knowledge of extreme states of matter that govern astrophysical phenomena. From magnetic fields generated throughout the universe, to the earthly creation of states of matter that naturally exist only in the center of stars, to exploring whether life can exist on exoplanets—all are enabled by plasma science through theory, computations, observations, and experiments.

Plasma research is primarily funded as a science discipline by the Department of Energy (DOE), the National Science Foundation (NSF), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA). Several other agencies fund activities that are critical to plasma science by providing essential fundamental data required for plasma studies. However, the science and technologies enabled by plasmas are critical to almost all U.S. federal agencies and departments. The interdisciplinary impact of PSE cuts across many current and proposed federal initiatives. For example, advances in artificial intelligence, machine learning, and quantum-based computing are made possible by plasma materials processing of microelectronics devices. Initiatives in nanoscience and accelerators are partly enabled by plasma science. Similarly, exploration of the solar system is propelled by plasma-fueled electric propulsion. The National Nuclear Security Administration’s stockpile stewardship depends on high-energy-density (HED) plasmas, and space weather is a Sun-Earth plasma system.

The National Academies of Sciences, Engineering, and Medicine was tasked to assess progress and achievements in plasma science over the past decade and to identify major science challenges and opportunities for the next decade. This assessment evaluates plasma science’s contributions to the nation and how the discipline supports the U.S. economy and national security. This report also makes recommendations to ensure the health of the plasma science field, covering workforce development, the role of the United States in international collaborations, and the optimum deployment of resources to meet the science challenges. The report summarizes progress in the field since the Plasma Science: Advancing Knowledge in the National Interest¹ (“Plasma 2010 report”). Of special note is the emergence of laser-plasma interactions (LPIs) as a frontier field in advancing the fundamentals of plasma science, high field science, quantum physics, and translational research toward applications. This emergence was recognized in the scientific background to the 2018 Nobel Prize in Physics.

GRAND CHALLENGES OF PLASMA SCIENCE AND ENGINEERING

PSE transforms fundamental scientific research into powerful societal applications. This outstanding strength of PSE is captured in the following “PSE Grand

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¹ National Research Council, 2007, Plasma Science: Advancing Knowledge in the National Interest, The National Academies Press Washington, DC, https://doi.org/10.17226/11960.

Challenges”—high-level goals, presented without ranking, in which mastery of the complexities of plasma science benefits society:

• Understanding the behavior of plasmas under extreme conditions will enable predictive, efficient and controllable energy conversion by plasmas, addressing the challenges of sustainability, economic competitiveness, and national security, while expanding our knowledge of the most fundamental processes in the universe.
• Mastering the interactions of the world’s most powerful lasers and particle beams with plasmas will enable precision X-ray imaging for medical science, advances in national security, compact particle accelerators, advanced materials, and sustainable energy sources, while opening new regimes for high-energy and quantum physics.
• Developing fusion-generated electricity will tap the virtually unlimited fuel in seawater, to bring the benefits of energy independence and carbon-neutral power to the nation through economical, deployable, and sustainable fusion systems enabled by advances in experimental and computational plasma physics.
• Demonstrating that lasers and pulsed-power devices can produce inertially confined fusion ignition by creating plasma-based extreme states of matter to support stockpile stewardship, further the goal of sustainable energy, energy independence, and expand our knowledge of high energy density (HED) physics.
• Electrification of the chemical industry—that is, driving chemical processing by electrical means facilitated by plasmas—by controlling the flow of power through low-temperature plasmas (LTPs) will produce predictable chemical transformations in gases, solids, and liquids, on scales capable of economically establishing a future based on renewable and sustainable electricity, and address pandemic threats to our health through plasma sterilization of surfaces and tissue.
• Developing timely and actionable space-weather forecasting and nowcasting will enable us to mitigate the potentially damaging effects of extreme solar plasma storms on spacecraft, humans, power grids, and infrastructure.

REPORT RECOMMENDATIONS

The PSE community in the United States has seen many changes since the publication of the Plasma 2010² report, with landmark contributions to the science of plasmas, national security, space exploration, and economic competitiveness.

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² Ibid.

These advancements confirm the value and need for both discipline-centric fundamental research and interdisciplinary research that translates science to applications.

The interdisciplinary reach of PSE is a strength and testament of its value to the nation. However, the often highly mission-driven support of PSE also leads to fragmentation of the field, lack of an identifiable home agency, and a reduced ability to exploit interdisciplinary opportunities. While acknowledging that there are common scientific challenges that cross the field, this report is structured around the subfields of PSE to enable federal agencies to best receive the findings and recommendations most relevant to their missions. Nonetheless, the committee’s recommendations propose actions to mitigate fragmentation of the field, encourage a more cohesive discipline that embraces a diverse and inclusive community, enable greater plasma-related collaboration between programs and agencies, and support joint initiatives between plasma-focused agencies and those benefiting from plasma science and technology.

The following sections include the most high-level recommendations for this report. (These high-level recommendations, as well as more specific recommendations developed in the individual chapters, are collected in Appendix B.)

Stewardship and Advancement of Interdisciplinary Research

Fundamental research in PSE can and does rapidly translate to societally relevant technologies, the benefits of which cut across the missions of many federal agencies. The support for fundamental research in plasma science by several federal agencies, and particularly by the NSF/DOE Partnership in Basic Plasma Science and Engineering, is critical to addressing the grand challenges described above. While the underlying science has common intellectual threads, this inherently interdisciplinary community is organized into sometimes isolated subdisciplines. This isolation results in part from the diversity of applications that motivates the fundamental research and is reinforced by mission-driven support at the federal level that may not take full advantage of synergies between fundamental research in the subdisciplines and applications.

In many areas of PSE, such as plasma materials processing, application-focused research is the primary mission of a program that is different than that research funding fundamental plasma research. As a result, the interdisciplinary and multidisciplinary strengths of PSE are not being fully utilized, to the detriment of the fundamental plasma research and to the detriment of the intended applications. For example, there is enormous potential for PSE to contribute to one of society’s greatest challenges—sustainability—while also contributing to economic competitiveness. At NSF, this research would best be performed in the Engineering Directorate (ENG) while other areas of plasma science would find their homes in the Directorate for Mathematical and Physical Sciences and the Directorate for

Geosciences. Historical support for PSE in the ENG has been inconsistent, and particularly so since the Plasma 2010 report,³ in large part due to the changing priorities of individual ENG programs. This has made it difficult to develop long-term PSE strategies to address critically important challenges such as sustainability.

The challenges toward leveraging public-private partnerships for economic and national security benefits are large; however, the potential benefits outweigh these challenges. At the small-business end of the innovation chain, the resources and know-how required to make breakthroughs in translational research can fit poorly within traditional Small Business Innovation Research / Small Business Technology Transfer (SBIR/STTR) models. At the large-business end of the innovation chain, there are extreme pressures from international competition, in large part resulting from strong foreign government support for fundamental and translational research in key industries.

Recommendation: Federal agencies directly supporting plasma science and engineering (PSE) and those federal agencies benefiting (or potentially benefiting) from PSE should better coordinate their activities extending into offices and directorates within larger federal agencies.

Recommendation: Federal agencies and programs within federal agencies that are separately focused on fundamental plasma research, and those that are focused on science and technologies that utilize plasmas, should jointly coordinate and support initiatives with new funding opportunities.

Recommendation: The Engineering Directorate of NSF should, as a minimum, consistently list plasma science and engineering in descriptions of its relevant programs and consistently participate in the NSF/DOE plasma partnership.

Recommendation: More strategically, NSF should establish a plasma-focused program in the Engineering Directorate that would further engineering priorities across the board, including advanced agricultural systems, energy and environment, chemical transformation, advanced manufacturing, electronics, and quantum systems.

Recommendation: Federal agencies focused on plasma research, and DOE in particular, should develop new models that support the translation of fundamental research to industry. Programs that support vital industries depending on plasma science and engineering should be developed through relevant interagency collaborations.

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³ Ibid.

Education and Workforce Development

There are great opportunities for new university faculty in PSE to address sustainability, investigate laser-plasma-produced quantum effects, make space weather predictions, and explore exotic states of matter. However, the current trends in PSE demographics and hiring practices are eroding the ability of the field to meet these challenges and national priorities. A multidisciplinary approach has been at the heart of the success of the field of plasma science, while simultaneously working against its long-term vitality in academia. Plasma physics is a minority discipline in nearly every university department containing plasma-focused faculty, while many physics departments contain no plasma physics faculty. As a result, maintaining faculty expertise is becoming progressively more challenging. Many universities do not require or offer plasma physics classes for undergraduates in science and engineering. Plasma-specific educational and research programs that also provide opportunities to diverse and less advantaged populations are needed to ensure a critically populated PSE workforce. Increased emphasis on PSE undergraduate research and internships, particularly at principally undergraduate institutions (PUIs), will also improve awareness of this field among all undergraduates, and women and underrepresented students in particular. This approach will enable a fuller, more diverse pipeline and hence a more diverse discipline.

The demographics of the PSE workforce indicate that the next decade will likely see significant turnover, making it critical to take deliberate actions to renew the PSE workforce. Diversity, equity, and inclusion (DEI) broadens a discipline to the betterment of that discipline and to the betterment of the society the discipline serves. Regrettably, PSE is among the least diverse of the science, technology, engineering, and mathematics (STEM) fields. Rectifying this requires a diverse student pipeline and a commitment to welcome, support, and retain members of underrepresented groups. A professional workforce cannot reflect society if the student pipeline entering PSE is not diverse. The number and diversity of students entering the pipeline can be increased by increasing the numbers of undergraduate students exposed to PSE through research experiences. PSE research programs in PUIs could have a disproportionately large influence in both filling and diversifying the PSE pipeline.

Recommendation: Federal agencies—for example, DOE, NSF, NASA, and DoD—should structure funding programs to provide leadership opportunities to university researchers in plasma science and engineering areas and to directly stimulate the hiring of university faculty.

Recommendation: Federal agencies (e.g., DOE, NSF, NASA, DoD) should structure funding to support undergraduate and graduate educational, training, and research opportunities—including faculty—and encourage and enable access to plasmas physics for diverse populations.

The Competitive International Research Enterprise in Plasma Science and Engineering

The research enterprise in PSE has had broad impact over the past decade. However, this progress has also been made in an environment of tremendous international investments across the spectrum of PSE that challenge and may potentially usurp U.S. leadership. International investments in large fusion devices, powerful lasers, and research networks over the past decade have generally exceeded that made by the United States. Two examples are the European Union investment in the Extreme Light Infrastructure and the Wendelstein 7-X stellerator. Given these strong international investments, incremental progress in facilities in the United States is insufficient to maintain leadership. Computational plasma science and engineering (CPSE) has become essential across PSE for experiment and mission design and diagnosis, idea exploration, and prediction. For computations to continue to progress in PSE, the next generation of researchers needs to be better educated through the development of plasma-focused computational textbooks and courses, and through participation in funded computational research projects.

Recommendation: Federal agencies (e.g., DOE, NSF, NASA, DoD) should support a spectrum of facility scales that reflect the requirements for addressing a wide range of problems at the frontiers of plasma science and engineering.

Recommendation: Federal agencies whose core missions include plasma science and engineering (PSE)—for example, DOE, NSF, NASA, and DoD—should provide recurring and increased support for the continued development, upgrading, and operations of experimental facilities, and for fundamental and translational research in plasma science. A spectrum of facility scales should be supported, reflecting the requirements for addressing different problems at the frontiers of PSE.

Recommendation: Federal agencies should support research into the development of computational algorithms for plasma science and applications for the heterogeneous device computing platforms of today and upcoming

platforms (e.g., quantum computers), while also encouraging mechanisms to make advanced computational methods, physics-based algorithms, machine learning, and artificial intelligence broadly available.

Better Serving the Community

Following the recommendations of the Plasma 2010 report,⁴ the DOE Office of Fusion Energy Science (FES) broadened the scope of its programs to better serve the plasma science community. The title of the FES office does not now accurately reflect its broader mission and may actually hamper collaboration within DOE and with other federal agencies on nonfusion research.

Recommendation: Consistent with our recommendations to broaden the impact of plasma science, the DOE Office of Fusion Energy Science should be renamed to more accurately reflect its broader mission, and so maximize its ability to collaborate with other agencies and to garner nonfusion plasma support. A possible title is Office of Fusion Energy and Plasma Sciences.

ORGANIZATION OF THIS REPORT

In this report, outstanding contributions to scientific knowledge, economic vitality, and national security over the past decade in several fields of PSE are discussed. An initial overview chapter discusses the key findings and recommendations, while introducing a theme of fundamental research supporting translational research and the benefit of coordination and collaboration between federal agencies. The following six chapters each address a subfield of PSE. Each chapter presents exciting future research directions, the national benefits that will occur with the translation of scientific advances to applications, and develops individual chapter-level findings and recommendations. Although cross-cutting themes and challenges are discussed, particularly in Chapter 2, the committee elected to make vertical cuts through the discipline since this better maps onto the current support infrastructure of the federal agencies. If the recommendations of this report are adopted, the next plasma decadal study will be positioned to organize the report using horizontal disciplinary cuts. Synopses of the chapters follow.

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⁴ Ibid.

Chapter 2: The Foundations of Plasma Science

A recurrent theme of the report is linking basic plasma science research and translational research. The committee cannot over-emphasize the importance of maintaining strong support for research in fundamental and basic areas of the discipline—both for the intrinsic value of that research and in producing the necessary foundational knowledge that underlies all translational and applied research. Research in basic plasma science is essential to PSE, and there have been major advances in understanding the underlying, unifying principles that transcend plasma science: magnetic reconnection, waves and shocks, turbulence, particle acceleration, and self-organization. With the focus of basic plasma research being on understanding fundamental principles, the immediate applications are not always clear. However, this work provides the foundation for the entire field.

Computational Plasma Science and Engineering

Computation and theory are critical for prediction, diagnosis, and experimental design in PSE, which will only be enhanced by artificial intelligence (AI) and machine learning (ML). Computational science is essential to PSE, expanding our understanding of fundamental science and helping develop technologies. Thus, the continued impact of computational plasma science and engineering will depend on making state-of-the-art computations accessible to researchers who are not computational experts

Chapter 3: Laser-Plasma Interactions

Expanding plasma-based capabilities in high-intensity ultrafast lasers, with increasing energies, repetition rates, and control are opening new areas of high field plasma physics, including the investigation of quantum processes and the creation of matter from pure photon energy. Laser and particle-beam control of the most intense sustained electromagnetic fields in plasmas is opening new disciplines in plasma optics and particle acceleration. Plasma-driven electron and ion accelerators can achieve high particle energies in a smaller spatial region compared to conventional accelerators and are opening new regimes for high-energy particle physics colliders and high-performance compact X-ray sources. These new compact accelerators have important application to medicine, industry, and national security.

Chapter 4: Extreme States of Plasmas

Understanding the dynamics of plasmas in the high energy density (HED) regime addresses fundamental questions in astrophysics and space physics, material

science and quantum materials, nuclear physics, and atomic physics, and is essential to stockpile stewardship. Major new facilities have had a great impact on the HED field, helping it to flourish over the past decade. HED physics encompasses inertial confinement fusion (ICF), the pursuit of controlled fusion in the laboratory by compressing matter to densities found at the center of stars. We stand at the brink of achieving the milestone of fusion ignition, sharing science, similar challenges, and the potential for societal benefit with magnetic fusion energy. While existing HED facilities will produce further scientific advances over the next decade, planning for successor ICF and HED facilities, both laser- and pulsed-power driven, is beginning.

Chapter 5: Low-Temperature Plasmas

The chemically reactive nature of low-temperature plasmas (LTPs) has enabled society-wide transformations in our quality of life, ranging from materials synthesis and water purification, to enabling the IT revolution through plasma-enabled fabrication of microelectronics. LTPs are partially ionized plasmas that produce chemically reactive environments in gases, on surfaces, and in liquids. Over the past decade, LTPs have greatly advanced atomic-layer etching and deposition of materials, control of electromagnetic waves, space propulsion, human health care, and agriculture, and protecting the food chain. LTP technologies are propelling the electrification of the chemical industry—that is, driving chemical processing by electrical means facilitated by plasmas.

Chapter 6: Magnetic Confinement Fusion Energy

The societal benefit from magnetic confinement fusion energy (MFE) could be enormous, as fusion energy can provide a carbon-free source of electrical power from an essentially limitless source of fuel and enabling energy independence. Nuclear fusion, the process of fusing lighter elements to create heavier elements and release energy, powers stars. In the laboratory, strong magnetic fields can confine hot plasmas to produce star-like fusion—MFE. The past decade has brought MFE to the brink of creating the first burning plasma in the ITER project, scheduled to come online by 2026, and to produce a burning plasma in 2036. A 2019 National Academies study⁵ endorsed U.S. participation in ITER as an essential step toward realizing commercial fusion power in the United States and recommended using that knowledge to develop an economical compact fusion pilot power plant.

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⁵ National Academies of Sciences, Engineering, and Medicine, 2019, Final Report of the Committee on a Strategic Plan for U.S. Burning Plasma Research, The National Academies Press, Washington, DC, https://doi.org/10.17226/25331.

Chapter 7: Space and Astrophysical Plasmas

Space and astrophysical plasmas (SAPs) possess properties inaccessible to Earth-bound experiments, raising questions as varied as the origins of the universe and the habitability of exoplanets. Future Earth- and space-based observing platforms and space missions will address some of the most profound questions about the universe. The societal benefits of understanding SAPs extend from the practical to the inspirational. Notably, the past decade has brought us closer to understanding the origins and effects of space weather, enabling forecasting and nowcasting that will protect spacecraft, instruments, and humans in space, along with electrical power grids on Earth—all of which are essential to U.S. national security. Startling recent advances include detection of a possible neutron star merger through the simultaneous excitation of gravitational waves, gamma-ray bursts, X-ray and visible plasma emission, and the first images of a black hole—both extraordinarily exotic events that represent SAP research.