Time：June 20-21, 2024

Location：Tsinghua University (on campus)

Chair：Peng Zhang (Michigan State University)

              Yangyang Fu (Tsinghua University)

Mark D. Johnston

Sandia National Laboratories

“Low temperature plasmas and discharges”

Prof. Mark Johnston is a Principal Member of Technical Staff at Sandia National Laboratories in Albuquerque, NM. He received his Bachelor of Science in Chemistry, summa cum laude, from Oakland University (1998) following six years in the US Navy as a nuclear power plant operator (1990-1996). He attended the University of Michigan, where he obtained his Master’s (2001) and PhD degrees (2004) in Nuclear Engineering and Radiological Sciences under the supervision of Dr. Ronald Gilgenbach. His research at Sandia involves plasma diagnostics and spectroscopy of low temperature plasmas in high energy density, pulsed-power environments. He was a principal investigator on the RITS-6 IVA accelerator, where he conducted research on electron beam diodes used as x-ray radiographic sources. He was a principal investigator on the Z-Machine, exploring plasma generation in the MITL power flow regions in support of the Next Generation Pulsed Power Facility (NGPPF), and now leads the design effort for the new Bremsstrahlung x-ray diode for the Combined Radiation Environments for Survivability Testing (CREST) project. He is a Research Professor in the Electrical and Computer Engineering Department at the University of New Mexico, where he teaches courses in low temperature plasmas, plasma diagnostics, and spectroscopy. He has authored or coauthored numerous papers and reports ranging from z-pinch wire physics to particle beam diodes to MITL plasma phenomena. He is a member of IEEE, NPSS, APS, ACS, and SPIE.

This minicourse talk is an overview of the fundamental physics of low temperature plasmas (LTPs). LTPs are partially ionized, atomic and molecular, non-equilibrium plasmas with electron temperatures within the range of ~1-10 eV that exhibit collisional and collective properties. These make up the majority of plasmas that we interact with here on Earth and in the laboratory. Being chemically reactive, they are used for etching, materials deposition, surface treatment/modification, biomedical, lighting, and aerospace applications, in addition to naturally occurring phenomena such as lightning, the ionosphere, and the aurora borealis.  This lecture will describe the physics involved in creating and sustaining these plasmas through electron-atom collisions, electron and ion transport, gas chemistries, and surface processes.  The generation of such plasmas in the laboratory is achieved through a variety of discharge processes, including DC, RF, Microwave, and Electron Cyclotron Resonance (ECR), which will be explained. The talk concludes by describing several current applications of LTPs, recent research, and future trends.

Yakov Krasik

Technion-Israel Institute of Technology

“Nanosecond timescale discharge in pressurized gas – physics and applications”

Prof. Yakov E. Krasik received his M.Sc. (1976) in physics from the Tomsk Polytechnic Institute, Russia and Ph.D. (1980) in physics from the Joint Institute for Nuclear Research, Russia. He held various academic positions at the Nuclear Research Institute, Tomsk (1980-1991) and at the Weizmann Institute of Science, Rehovot, Israel (1991-1996). Since 1997, he joined the Physics Department, Technion, Haifa, Israel, where he is currently Professor and Head of the Plasma Physics and Pulsed Power Laboratory and holds the Max Knoll Chair in Electronics and Opto-Electronics. He supervised 25 PhD students and 28 MSc students, published around 320 peer reviewed papers. He authored 27 patents in the field of pulsed power science. His H-index is 41 and citations number is around 6100. He is a Fellow of the American Physical Society, the IEEE Fellow and a member of the board of the Israel Plasma Society. He is the recipient of the 2020 IEEE Magne Kristiansen and 2023 IEEE Nuclear and Plasma Sciences PSAC awards for contributions to experimental nuclear and plasma science. His main research interests are in the fields of pulsed current-carrying plasmas, high-power microwaves and plasma diagnostics. Various applications of plasma physics are also within the scope of his interests.

Temporal and spatial evolution of a nanosecond timescale electrical discharge in pressurized gases under application of electric fields with amplitude >105 V/cm will be described and analyzed. Namely, it will be shown that such main phenomena as generation of run-away electrons, ionization front propagation and formation of a high conductivity plasma channel govern the dynamics of this type of the discharge. Different electrical, optical, spectroscopic and laser diagnostics, such as X-ray diagnostics, fast framing imaging of the plasma light emission, time- and space-resolved visible spectroscopy and Coherent Anti-Stokes Resonance Raman Scattering for the electric field evolution in the plasma were applied in this research. Application of the results obtained for high power microwave compressors, namely plasma interference switch and gas switches will be described as well.

Jón Tómas Guðmundsson

University of Iceland

“Physics and technology of magnetron sputtering discharges”

Prof. Jon Tomas Gudmundsson received the C.S. degree in electrical engineering and the M.S. degree in physics from the University of Iceland, Reykjavik, Iceland, in 1989 and 1991, respectively, and the Ph.D. degree in nuclear engineering from the University of California at Berkeley, Berkeley, CA, USA, in 1996. He joined the Science Institute, University of Iceland, in 1997, the Faculty of Electrical Engineering, University of Iceland, in 2001, and the University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai, China, in 2010. Since 2013, he has been a Professor of physics with the University of Iceland. Since 2015, he has also been an Affiliated Professor of space and plasma physics with the KTH Royal Institute of Technology, Stockholm, Sweden. His research interests include various low-pressure discharges, including capacitive discharges, inductively coupled discharges, magnetron sputtering discharges, and Hall thrusters, which he has explored both experimentally and with modeling work.

Physical vapor deposition (PVD) refers to the removal of atoms from a solid or a liquid by physical means, followed by deposition of those atoms on a nearby surface to form a thin film or coating. Magnetron sputtering deposition is the most widely used PVD technique for deposition of both metallic and compound thin films and is utilized in numerous industrial applications. Over the past few decades there has been a continuous development of the magnetron sputtering technology to improve target utilization, increase ionization of the sputtered species, increase deposition rates, and to minimize electrical instabilities such as arcs, as well as to reduce operating cost. The development from the direct current (dc) diode sputter tool to the magnetron sputtering discharge is discussed as well as the various magnetron sputtering discharge configurations. The magnetron sputtering discharge is either operated as a dc or radio frequency discharge, or it is driven by some other periodic waveforms depending on the application. This includes reactive magnetron sputtering which exhibits hysteresis and is often operated with an asymmetric bipolar mid-frequency pulsed waveform. Ionized physical vapor deposition was initially achieved by adding a secondary discharge between the cathode target and the substrate and later by applying high power pulses to the cathode target. The operating parameters, the discharge properties and the plasma parameters including particle densities, discharge current composition, electron and ion energy distributions, deposition rate, and ionized flux fraction will be discussed as well as the discharge maintenance, including the electron heating processes, the creation and role of secondary electrons and Ohmic heating. Furthermore, the role and appearance of instabilities in the discharge operation is discussed.

Xinpei Lu

Huazhong University of Science and Technology

“Atmospheric pressure plasmas and their applications in biomedical and nitrogen fixation”

Prof. Xinpei Lu has been actively engaged in research focusing on atmospheric pressure plasma and its applications. He has authored or co-authored over 200 journal papers, including 2 contributions to Physics Reports. He has achieved a H-index of 63, and since 2014, he has consistently received recognition as a highly cited scholar in China by Elsevier. Since 2019, he was honored by inclusion among the top 2% of the most-cited scientists globally by Stanford University. Additionally, Dr. Lu has authored or co-authored an English monograph and two Chinese monographs titled "Atmospheric Pressure Plasma Jets: I Physics Fundamentals" and "II Biomedical Applications." He holds 18 granted invention patents, with some of them having been transferred for a total value of 5 million RMB. Dr. Lu has also delivered more than 40 keynote and invited presentations at prestigious international conferences, including the International Conference on Plasma Science (ICOPS). In his capacity as a principal investigator, Dr. Lu has successfully secured funding of 7 projects from the National Natural Science Foundation of China, in addition to more than 30 other research projects.

The first section of this talk provides an introduction to cold plasma jets, including the rationale for studying them, the current state of research in this field, and an overview of the various inert gases and air-based plasma jets we have developed for practical applications. This section primarily explores the physical phenomena associated with cold plasma jets and their vacuum ultraviolet (VUV) radiation emissions. The second section delves into a novel approach to dielectric barrier discharge (DBD) known as non-equidistant DBD. In the third section, we present a spiral discharge concept that operates under magnet-free conditions. The fourth section addresses a fundamental scientific inquiry related to plasma medicine– the scientific definition of plasma dosage. The fifth section highlights a medical application of plasma, specifically its use in endodontic therapy during root canal treatment. The sixth section examines potential perforation effects that may arise from plasma treatment. Finally, in the seventh section, we present our research progress on the application of plasma in energy conversion, focusing on advances in plasma nitrogen fixation.

Anthony B. Murphy

CSIRO

“Fundamentals and applications of thermal plasmas”

Dr. Anthony B. Murphy completed a PhD in physics at the University of Sydney in 1987 and a postdoctoral fellowship at Max Planck Institute for Plasma Physics in Munich before joining CSIRO (Australia’s leading government research organisation), where he is now a Chief Research Scientist. Most of his research has focused on the fundamentals and applications of thermal plasmas. Highlights include assisting with the development of the PLASCON (now known as Pyroplas®) process, which is used around the world for the destruction of ozone-depleting substances, greenhouse gases and hazardous organic compounds; developing the ArcWeld software for simulating arc welding and wire-arc additive manufacturing; and calculation of thermophysical properties, which have been adopted by over 60 research groups and companies in more than 25 countries. Dr Murphy has published 330 papers in refereed journals, with 12,500 citations and an h-index of 53 in the Web of Science. He has carried out research contracts with several Australian and international companies, including General Motors, CRRC, Boeing, SRL Plasma, LS Industrial Systems and Siemens. He has received several national and international awards. He is Editor-in-Chief of Plasma Chemistry and Plasma Processing, an Associate Editor of Journal of Manufacturing Processes, and an Editorial Board member of three other journals.

The presentation will begin with an overview of the many applications of thermal plasmas, demonstrating their relevance to a wide range of industries. I will then introduce the critical concept of local thermodynamic equilibrium (LTE) and its dependence on a high rate of collisions, followed by a discussion of the various approaches to generating and stabilising thermal plasmas. I will next consider the computational modelling of thermal plasmas, focusing on the simplest case of laminar subsonic flow in a single gas, before surveying the many possible complications. The discussion of modelling will be used to underline the necessity of calculating the thermophysical properties of thermal plasmas, which will lead into an introduction to the methods used. I will also briefly introduce the diagnostics of thermal plasmas, including emission spectroscopy and laser scattering. The talk will conclude with a more detailed consideration of one or two industrial applications. Audience members who listen carefully and answer questions will receive a small prize!

Chunqi Jiang

Old Dominion University

“Frontier applications of non-equilibrium atmospheric pressure plasma sources”

Prof. Chunqi Jiang is affiliated with both the Frank Reidy Research Center for Bioelectrics and the Department of Electrical and Computer Engineering at Old Dominion University (ODU). She received her PhD in Electrical Engineering from ODU and postdoctoral training in the pulsed power research group at University of Southern California (USC). She teaches Electromagnetics, Principles in Pulsed Power and Low-temperature Plasma Diagnostics courses at both graduate and undergraduate levels. Her recent research interests include fundamental studies of nanosecond pulsed plasma sources and their applications in industrial, environmental, and biomedical fields. Her research is funded by the US Air Force Office of Scientific Research, Department of Energy, and National Institutes of Health. She serves on the editorial board for Frontiers of Physics and High Voltage journals, as well as the Vice Chair for the IEEE NPSS Plasma Science and Applications committee.

Non-equilibrium atmospheric-pressure plasmas in forms of streamers, surface discharges and dielectric barrier discharges are spearheading frontier applications in energy, environment, agriculture, and medicine due to their promising features in energy efficiency, versatility, and economy. In addition to an introduction to the plasma sources, this minicourse provides examples include plasma-assisted ignition for combustion, plasma-aided nitration for agriculture, and controlled oxidation-reduction chemistry for medical applications such as cancer therapy and plasmid DNA delivery. Particular attention will be paid to nanosecond pulsed plasma sources and their recent applications in energy, environment, and medical fields. 

Xiaogang Wang

Harbin Institute of Technology

“Recent progresses in experimental space plasma physics”

Prof. Xiaogang Wang in Physics and Chief Scientist of Space Plasma Environment Research Facility (SPERF), Harbin Institute of Technology; PhD of Columbia University, Fellow of American Physical Society (APS); worked as Research Scientist at University of Iowa, Distinguished Professor at Dalian University of Technology, Professor and Director of the Institute of Plasma Physics and Fusion Studies at Peking University, as well as Chair of the Plasma Physics Division of the Chinese Physical Society, Associate Editor of Journal of Geophysical Physics - Space Physics.

A ground based experimental device for laboratory simulation of space environment, the Space Environment Simulation and Research Infrastructure (SESRI), is starting its operation phase currently at Harbin Institute of Technology (HIT) in China. It is the latest contribution to experimental space physics, with a well-designed set of coils and plasma sources, for laboratory simulation of geospace plasma physics processes. The facility consists a chamber of three sub-systems for magnetosphere plasma studies, Dipole Research Experiment (DREX), Asymmetric Reconnection Experiment (AREX), and Tail Reconnection Experiment (TREX). The DREX provides a laboratory platform for simulating radiation belt physics process, e.g., trapping, acceleration/loss, and transport of energetic charged particles in a dipole magnetic field relevant to the inner magnetosphere. The AREX provides a unique experimental platform to study 3D asymmetric reconnection dynamics relevant to the interaction between the interplanetary and magnetospheric plasmas. The TREX provides a research platform to understand the physics processes in magnetotail, e.g., the dipolarization front formation and propagation. An overview of the fundamental design of SPERF, and recent progresses in research of experimental space plasma physics researches will also be presented.