As theoretical physicists...

We aim to understand the phenomenology of plasma in the laboratory and in the cosmos. We use mathematical models and computer simulations to explain how plasmas move, interact with magnetic fields and boundaries, and evolve on various scales.

Working with collaborators in the U.S. and around the world, we advance fundamental physics concepts that guide experiments and project applications, such as the development of magnetic fusion energy.

This website offers information about our group members, research activities, and publications. We invite you to browse it and to contact us with any questions.

News and Announcements

New Department of Astronomy and Astrophysics

UC San Diego is pleased to announce the formation of a new Department of Astronomy and Astrophysics within the School of Physical Sciences.

Prof. Diamond will serve as one of the 12 founding faculty members. This new department will leverage the University of California’s substantial existing investment in astronomical facilities to support students in reaching their full research and learning potential.

Research and instruction will cover a broad range of areas, from the evolution of the universe and the first stars to galaxy and planet formation and cosmology. The department will also play a key role in developing instrumentation for the Keck Observatory, Lick Observatory, the Thirty Meter Telescope, the Simons Observatory, and the Compton Spectrometer and Imager (COSI).

Learn more in the UC San Diego Today article, "Across the Universe: UC San Diego Announces New Astronomy and Astrophysics Department." Read the full campus annoucement to learn more.

International Center Fellowship

FAPPG graduate student Mingyun Cao was awarded a 2022-2023 Friends of the International Center Endowed Fellowship. The Center's fellowship supports UC San Diego graduate students in conducting research or study abroad activities that enhance their academic experience and foster friendship, understanding and cooperation in the international community. Congratulations, Mingyun!

Commencement Award

Congratulations to FAPPG undergraduate student Taurean Zhang, who won a 2022 Malmberg Award from UC San Diego's Department of Physics. The John Holmes Malmberg Prize is presented annually at commencement to a graduating physics student who is recognized for potential for a career in physics and a measure of experimental inquisitiveness. Brilliantly done, Taurean!

Teaching Honors

Congratulations to FAPPG Ph.D. student Fredy Ramirez, who was awarded a 2021-2022 UC San Diego Physics Department Distinguished Graduate Teaching Award.

This award recoginizes first- and second-year graduate students for outstanding performance as a teaching assistant. Many congratulations, Fredy!

Upcoming Seminars

October 15, 2024

Shigeru Inagaki

Kyoto University, Japan

"Observations of avalanche events in a helical-axis Heliotron plasma"

ABSTRACT: Plasma heat transport in a magnetic configuration with closed magnetic flux surfaces is anisotropic, and the heat transport properties in the direction across the flux surface (called the radial direction) are important for predicting the temperature of the plasma center. In anisotropic and inhomogeneous systems, Fourier's law does not hold, and heat does not diffuse like particles but propagates in waves, sometimes causing traffic jams [1]. Ballistic heat propagation with a long radial travel distance that occurs abruptly in magnetized plasmas is known as an avalanche. Such wave-like heat propagation is considered to be closely related to the nonlinearity, nonlocality, and multiple-valued nature of heat transport in magnetized plasma [2, 3]. Understanding the mechanisms of micro-processes of avalanche, i.e., avalanche formation by micro-turbulence (e.g. turbulence spreading), as well as macroscopic phenomenological understanding is strongly required. Here, we report observation and identification of avalanche event in the Heliotron J. Small temperature dips with long radial correlation were detected and the ballistic propagation property is determined by statistical analysis using transfer entropy. The presence of long-memory is indicated by a Hurst number greater than 0.5 and close to 1 [4].
The Heliotron J is a helical-axis heliotron, which has no axisymmetry unlike tokamak and has a quasi-isomagnetic configuration with mirror field components like the W7-X. The Heliotron J is also characterized by zero magnetic shear. No differences in avalanche properties, however, have been observed despite the differences in magnetic configuration between Heliotron J and tokamaks. Related to avalanches in the core, avalanche seeping into the scrape-off layer and turbulence spreading into the magnetic island have also been observed in Heliotron J [5]. Experimental observations of these avalanche events and associated turbulence characteristics will be summarized and discussed.

[1] Y. Kosuga, P. H. Diamond, O. D. Gurcan, Phys. Rev. Lett. 110 (2013) 105002.
[2] S. Inagaki, et. al., Nucl. Fusion 53 (2013) 113006.
[3] F. Kin, et. al., Sci. Rep. 13 (2023) 19748.
[4] F. Kin, et. al., Nucl. Fusion 64 (2024) 066023.
[5] A. Miyashita, et. al., Plasma Phys. Control. Fusion 66 (2024) 075008.

SERF 329, or join via Zoom (https://ucsd.zoom.us/j/92056518886; Meeting ID: 920 5651 8886)

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Newest Publications

Very Local Impact on the Spectrum of Cosmic-Ray Nuclei Below 100 TeV
Malkov, M.A., I.V. Moskalenko, P.H. Diamond and M. Cao
Advances in Space Research, in press; doi:10.1016/j.asr.2024.08.060

J-TEXT Achievements in Turbulence and Transport in Support of Future Device/Reactor
Chen, Zhipeng, Zhangsheng Huang, Min Jiang, Ting Long, Lu Wang, Weixin Guo, Zhoujun Yang, Hai Liu, Tao Lan, Kaijun Zhao, Yuhong Xu, Rui Ke, Youwen Sun, Hanhui Li, Wen He, Ge Zhuang, Yuejiang Shi, Wulyu Zhong, Yonghua Ding, Yunfeng Liang, Wenjing Tian, Xin Xu, Guodong Zhang, Malik Sadam Hussain and Patrick Diamond
Plasma Sci. Technol. 26, 114001, 2024; doi:10.1088/2058-6272/ad663b

Mesoscopic Transport in KSTAR Plasmas: Avalanches and the E × B Staircase
Choi, Minjun J., Jae-Min Kwon, Lei Qi, P.H. Diamond, T.S. Hahm, Hogun Jhang, Juhyung Kim, M. Leconte, Hyun-Seok Kim, Jisung Kang, Byoung-Ho Park, et al.
Plasma Phys. Contr. Fusion 66, 065013, 2024; doi:10.1088/1361-6587/ad4176

The Role of Shear Flow Collapse and Enhanced Turbulence Spreading in Edge Cooling Approaching the Density Limit
Long, Ting, P.H. Diamond, Rui Ke, Zhipeng Chen, Xin Xu, Wenjing Tian, Rongjie Hong, Mingyun Cao, Yanmin Liu, Min Xu, et al.
Nucl. Fusion 64, 066011, 2024; doi:10.1088/1741-4326/ad3e15 (Open Access)

On How Structures Convey Non-Diffusive Turbulence Spreading
Long, Ting, P.H. Diamond, Rui Ke, Zhipeng Chen, Mingyun Cao, Xin Xu, Min Xu, Rongjie Hong, Wenjing Tian, Jinbang Yuan, et al.
Nucl. Fusion 64, 064002, 2024; doi:10.1088/1741-4326/ad40c0 (Open Access)

Formation, propagation and conversion of transport barriers triggered by dynamical critical gradient in tokamak plasmas
Li, Xiaobo, Zhibin Guo and P.H. Diamond
Nucl. Fusion 64, 044001, 2024; doi:10.1088/1741-4326/ad2d39 (Open Access)

Potential Vorticity Conservation for Plasma Turbulence in an Inhomogeneous Magnetic Field: Theory and Implications
Hahm, T.S., P.H. Diamond, S.J. Park and Y.-S. Na
Phys. Plasmas 31, 032310, 2024; doi:10.1063/5.0189855

How Turbulence Spreading Improves Power Handling in Quiescent High Confinement Fusion Plasmas
Li, Zeyu, Xi Chen, Patrick H. Diamond, Xueqiao Xu, Xijie Qin, Huiqian Wang, Filippo Scotti, Rongjie Hong, Guanying Yu, Zheng Yan, Filipp Khabanov and George R. McKee
Comm. Phys. 7, 96, 2024; doi:10.1038/s42005-024-01590-0 (Open Access)

Turbulence Spreading Effects on the ELM Size and SOL Width
Li, Nami, X.Q. Xu, P.H. Diamond, Y.F. Wang, X. Lin, N. Yan, and G.S. Xu
J. Plasma Phys. 90(1), 905900117, 2024; doi:10.1017/S0022377824000199 (Open Access)

Nonlinear Elasticity and Short-Range Mechanical Coupling Govern the Rate and Symmetry of Mouth Opening in Hydra
Goel, Tapan, Ellen M. Adams, April L. Bialas, Cassidy M. Tran, Trevor Rowe, Sara Martin, Maia Chandler, Johanna Schubert, Patrick H. Diamond and Eva-Maria S. Collins
Proc. R. Soc. B. 291, 20232123, 2024; doi:10.1098/rspb.2023.2123

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