Article
Physics, Fluids & Plasmas
Q. Yu, S. Guenter
Summary: Numerical calculations have been conducted to study the nonlinear growth of the double tearing mode (DTM) in the reversed central magnetic shear configuration for medium-size tokamak plasma parameters. Three different regimes of the DTM growth have been identified: annular crash regime, core crash regime, and no crash regime.
Article
Astronomy & Astrophysics
Chen Shi, Anton Artemyev, Marco Velli, Anna Tenerani
Summary: The paper provides a detailed analysis of the stability of a multi-fluid current sheet configuration that mimics current sheets with transient ions in the magnetotail dynamics. It discusses the stabilizing effect of a finite Bz on current sheet stability, with counter-streaming ion flows and zero net flow being identified as the most stable configuration. The findings are important for understanding magnetotail dynamical models and spacecraft observations.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Physics, Multidisciplinary
Wu Sun, Jiaqi Wang, Lai Wei, Zhengxiong Wang, Dongjian Liu, Qiaolin He
Summary: This paper investigates the application of Galerkin spectral method for tearing mode instability in two-dimensional geometry. A resistive magnetohydrodynamic code is developed to discuss mode structures, resistivity scaling, convergence, and stability of tearing modes.
Article
Astronomy & Astrophysics
Emiliya Yordanova, Zoltan Voros, Luca Sorriso-Valvo, Andrew P. Dimmock, Emilia Kilpua
Summary: Research indicates that the formation of current sheets and vorticity in space plasmas is related to heating, and a new method can accurately identify them statistically through one-point proxies.
ASTROPHYSICAL JOURNAL
(2021)
Article
Nanoscience & Nanotechnology
Z. Li, X. Q. Wang, J. Huang, J. Shao, Y. Luo, Y. Xu, H. F. Liu, H. Liu
Summary: The effects of compressibility and guiding field on the Kelvin-Helmholtz instability in a double resonant surface system are numerically investigated. The study reveals a transition from double tearing modes to the Kelvin-Helmholtz instability depending on compressibility and guiding field with weak magnetic shear. These findings contribute to a better understanding of the properties of the Kelvin-Helmholtz instability in both space and laboratory plasmas.
Article
Physics, Fluids & Plasmas
X. L. Zhu, L. M. Yu, W. Chen, P. W. Shi, W. L. Ge, F. Wang, Q. B. Luan, H. E. Sun, Z. X. Wang
Summary: The resonant interaction between m/n = 2/1 tearing mode and m/n = 1/1 fishbone/sawtooth collapse has been observed in HL-2A experiments and understanding this phenomenon is crucial for future fusion reactors. In this study, a self-consistent nonlinear hybrid-kinetic simulation is conducted to analyze the transport, loss, and redistribution of energetic ions induced by the synergy between fishbone/sawtooth and tearing mode. The results show that this synergy enhances the loss rate of energetic ions due to the opening of an efficient loss channel connecting the plasma center and edge.
Article
Astronomy & Astrophysics
Jeffersson A. Agudelo Rueda, Daniel Verscharen, Robert T. Wicks, Christopher J. Owen, Georgios Nicolaou, Kai Germaschewski, Andrew P. Walsh, Ioannis Zouganelis, Santiago Vargas Dominguez
Summary: Energy dissipation in collisionless plasmas, particularly the energy transfer and transport associated with 3D small-scale magnetic reconnection events, is still not well understood. This study investigates the spatial energy transfer during a highly dynamic and asymmetric reconnection event in anisotropic and decaying Alfvenic turbulence. The findings suggest that electron bulk flow transports thermal energy density more efficiently than kinetic energy density, and the energy density transfer is dominated by plasma compression.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
W. Zhang, Z. W. Ma, H. W. Zhang, W. J. Chen, X. Wang
Summary: In this paper, we systematically investigate the nonlinear evolution of the resistive kink mode in the low resistivity plasma in Tokamak geometry. We find that the aspect ratio of the initial equilibrium can significantly influence the critical resistivity for plasmoid formation. Additionally, the critical resistivity for plasmoid formation decreases with increasing plasma viscosity in the moderately low resistivity regime. The geometry of Tokamaks also affects the critical resistivity for plasmoid formation.
Article
Astronomy & Astrophysics
Zilu Zhou, Xiaojun Xu, Pingbing Zuo, Yi Wang, Qi Xu, Yudong Ye, Jing Wang, Ming Wang, Qing Chang, Xing Wang, Lei Luo
Summary: This study examines plasma heating at thin current sheets in the solar wind using data from the WIND spacecraft from 2004 to 2019. The results show significant plasma heating at current sheets in both slow and fast wind, with a more significant increase in proton temperature in the fast wind.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Physics, Multidisciplinary
Y. Yao, Zhihong Lin, J. Q. Dong, P. Shi, S. F. Liu, Jingchun Li
Summary: The investigation showed that increasing the separation of the rational surfaces enhances the growth rates of DTMs and leads to the decoupling of the DTM system into two single-tearing modes. Additionally, the presence of thermal ions destabilizes the DTM, and the toroidal effect has a mild destabilizing effect on the growth of DTMs.
Article
Physics, Fluids & Plasmas
M. Gobbin, M. Agostini, F. Auriemma, L. Carraro, R. Cavazzana, A. Fassina, P. Franz, L. Marrelli, B. Momo, R. Piovan, I Predebon, M. E. Puiatti, G. Spizzo, D. Terranova, M. Zuin
Summary: This paper investigates the collapse of electron temperature during reconnection events in high current reversed field pinch plasmas using high time resolution soft-x-ray diagnostics. The energy released during these events, similar to astrophysical plasmas, may be involved in ion heating. The authors further point out that these issues will be studied in RFX-mod2.
Article
Astronomy & Astrophysics
L. P. Chitta, H. Peter, S. Parenti, D. Berghmans, F. Auchere, S. K. Solanki, R. Aznar Cuadrado, U. Schuehle, L. Teriaca, S. Mandal, K. Barczynski, E. Buchlin, L. Harra, E. Kraaikamp, D. M. Long, L. Rodriguez, C. Schwanitz, P. J. Smith, C. Verbeeck, A. N. Zhukov, W. Liu, M. C. M. Cheung
Summary: By observing the untangling of small-scale coronal braids in different active regions, we found that this process is associated with impulsive heating of the gas in these braided loops. Moreover, our observations show signatures of spatially coherent and intermittent coronal heating during the relaxation of the magnetic braids.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Shiyong Zeng, Ping Zhu, Ruijie Zhou, Ming Xu
Summary: The successive formations of the 4/1, 3/1, and 2/1 magnetic islands as well as the subsequent braking of the 2/1 mode during a low-Z impurity penetration process in EAST experiments are accurately reproduced in our 3D resistive MHD simulations. The tearing mode growth is mainly driven by the enhanced parallel current perturbation induced by impurity radiation, while the damping of the 2/1 island rotation is primarily caused by the impurity accumulation influenced by high n modes.
Article
Geosciences, Multidisciplinary
Yongyuan Yi, Meng Zhou, Liangjin Song, Ye Pang, Xiaohua Deng
Summary: This study reveals the existence of electron-only magnetic reconnection during magnetic island coalescence, which is the early stage of the process. During this electron-only reconnection, ions are affected by the reconnection electric field although the ion bulk outflow is absent.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Xiaoyan Xie, Katharine K. K. Reeves
Summary: We investigated the heating effects of supra-arcade downflows (SADs) on the surrounding plasma in three selected flares. Previous studies found that the plasma around most SADs tends to heat up or stay the same temperature due to adiabatic and viscous heating. We extended this work to more flares and confirmed the presence of heating effects of SADs, with adiabatic heating dominating over viscous heating in each event.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
R. Fridstrom, S. Munaretto, L. Frassinetti, B. E. Chapman, P. R. Brunsell, J. S. Sarff
PHYSICS OF PLASMAS
(2016)
Article
Instruments & Instrumentation
C. Ruiz, S. T. A. Kumar, F. S. B. Anderson, D. T. Anderson
REVIEW OF SCIENTIFIC INSTRUMENTS
(2016)
Article
Physics, Fluids & Plasmas
S. T. A. Kumar, J. N. Talmadge, T. J. Dobbins, F. S. B. Anderson, K. M. Likin, D. T. Anderson
Article
Physics, Multidisciplinary
R. Fridstrom, B. E. Chapman, A. F. Almagri, L. Frassinetti, P. R. Brunsell, T. Nishizawa, J. S. Sarff
PHYSICAL REVIEW LETTERS
(2018)
Article
Physics, Fluids & Plasmas
S. T. A. Kumar, T. J. Dobbins, J. N. Talmadge, R. S. Wilcox, D. T. Anderson
PLASMA PHYSICS AND CONTROLLED FUSION
(2018)
Article
Physics, Fluids & Plasmas
T. J. Dobbins, S. T. A. Kumar, J. N. Talmadge, D. T. Anderson
Article
Physics, Fluids & Plasmas
S. Munaretto, B. E. Chapman, B. S. Cornille, A. M. DuBois, K. J. McCollam, C. R. Sovinec, A. F. Almagri, J. A. Goetz
Review
Physics, Fluids & Plasmas
L. Marrelli, P. Martin, M. E. Puiatti, J. S. Sarff, B. E. Chapman, J. R. Drake, D. F. Escande, S. Masamune
Summary: This paper reviews the research on the reversed field pinch (RFP) in the last three decades, highlighting substantial experimental and theoretical progress achieved. The experimental community in various countries has achieved impressive performance improvements through exploration of high current operation and active control of the current profile. The development of state-of-art active feedback control systems has been a crucial factor in the advancements obtained in the experiments.
Article
Instruments & Instrumentation
S. Kobayashi, S. T. A. Kumar, F. S. B. Anderson, C. B. Deng, K. M. Likin, J. N. Talmadge, S. Ohshima, D. T. Anderson
Summary: This study demonstrates the feasibility of using BES diagnostic in the HSX stellarator to obtain the spatiotemporal structure of density fluctuation, by designing and optimizing viewing chords and estimating beam emission spectrum through simulation. Experimental results show that measuring beam emission in HSX plasmas using BES is feasible, with potential to improve system signal-to-noise ratio for higher frequency wave measurements.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Instruments & Instrumentation
J. F. Castillo, C. Clark, A. Bader, K. M. Likin, D. T. Anderson, B. Geiger, S. T. A. Kumar, C. Swee
Summary: The laser blow-off (LBO) system in the HSX stellarator enabled controlled injection of aluminum impurities into the plasma without significant disruption. Time-resolved emission measurements using a 20 channel AXUV photodiode detection system were performed to study the radial propagation and confinement of the injected impurities. The system has successfully achieved its design purpose and initial results indicate effective impurity transport investigations.
JOURNAL OF INSTRUMENTATION
(2021)
Article
Physics, Fluids & Plasmas
C. Swee, B. Geiger, R. Dux, S. T. A. Kumar, J. F. Castillo, A. Bader, M. Gerard
Summary: The transport of carbon impurities has been studied in the helically symmetric stellarator experiment (HSX) using active and passive charge exchange recombination spectroscopy (CHERS). Significant levels of impurity diffusion are observed, exceeding the neoclassical transport by about a factor of four in the core and more than 100 times towards the plasma edge, indicating a high level of anomalous transport.
PLASMA PHYSICS AND CONTROLLED FUSION
(2022)
Article
Physics, Fluids & Plasmas
Y. Yamamoto, S. Murakami, C. C. Chang, S. T. A. Kumar, J. N. Talmadge, K. M. Likin, D. T. Anderson
Summary: This study observes the spontaneous plasma flows in electron cyclotron heating plasmas and evaluates the parallel flow driven by ECH force. The obtained results show reasonable agreement with experiments, indicating that the radial electron current generated by ECH could drive the parallel flow.
Article
Physics, Fluids & Plasmas
B. S. Cornille, M. T. Beidler, S. Munaretto, B. E. Chapman, D. Del-Castillo-Negrete, N. C. Hurst, J. S. Sarff, C. R. Sovinec
Summary: This numerical study investigates the effects of resonant magnetic perturbations (RMPs) on the confinement of runaway electrons (REs) in tokamak discharges. The results show that a specific type of magnetic perturbation can achieve significant deconfinement of REs, while another type of perturbation cannot completely suppress REs. Magnetic reconnection influenced the trajectory of REs starting in the core region, as observed in the MHD simulations.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
N. C. Hurst, B. E. Chapman, A. F. Almagri, B. S. Cornille, S. Z. Kubala, K. J. McCollam, J. S. Sarff, C. R. Sovinec, J. K. Anderson, D. J. Den Hartog, C. B. Forest, M. D. Pandya, W. S. Solsrud
Summary: Steady-state tokamak plasmas with edge safety factor as low as 0.8 have been created, allowing for the study of self-organizing behavior in this regime. The results show a relaxation process leading to current profile broadening as the edge safety factor decreases.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
Yasuhiro Yamamoto, Sadayoshi Murakami, Ching-Chieh Chang, Santhosh T. A. Kumar, Joseph N. Talmadge, Konstantin Likin, David T. Anderson
PLASMA AND FUSION RESEARCH
(2019)
