Article
Astronomy & Astrophysics
M. Sarfraz, R. A. Lopez, Shahzad Ahmed, P. H. Yoon
Summary: This paper explores the instabilities caused by electron temperature anisotropy in solar wind plasmas, finding that quasi-linear theory effectively captures the non-linear aspects of combined instability effects. However, a discrepancy with a previous PIC simulation result suggests further investigation is needed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Fluids & Plasmas
F. Cruz, T. Grismayer, L. O. Silva
Summary: This study explores the instability of a uniform, oscillatory plasma equilibrium sustained by a time-dependent current density through analytical and numerical analysis, revealing an infinite number of unstable kinetic modes as well as a kinetic mechanism for the decay of initial modes of infinite wavelength. The growth rate of the fastest growing unstable modes is found to scale with the largest Lorentz factor of the plasma distribution, hinting at a potential relevance in inductive electric field oscillations in pulsar magnetospheres.
Article
Physics, Fluids & Plasmas
M. Viktorov, I. Izotov, E. Kiseleva, A. Polyakov, S. Vybin, V. Skalyga
Summary: This study investigates kinetic instabilities in a dense plasma of a continuous electron cyclotron resonance (ECR) discharge in a mirror magnetic trap at the GISMO setup. Unstable regimes and corresponding plasma parameters are experimentally defined, where the excitation of electromagnetic emission is observed, accompanied by the precipitation of energetic electrons from the magnetic trap.
PHYSICS OF PLASMAS
(2023)
Article
Astronomy & Astrophysics
P. H. Yoon, M. Sarfraz, Z. Ali, C. S. Salem, J. Seough
Summary: This paper formulates a velocity moment-based quasi-linear theory to study the impacts of weakly unstable modes on the solar wind plasma. By characterizing the weakly unstable modes using an analytical formalism, an efficient numerical platform is provided for analyzing the development of these instabilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Geosciences, Multidisciplinary
Minna Palmroth, Tuija I. Pulkkinen, Urs Ganse, Yann Pfau-Kempf, Tuomas Koskela, Ivan Zaitsev, Markku Alho, Giulia Cozzani, Lucile Turc, Markus Battarbee, Maxime Dubart, Harriet George, Evgeniy Gordeev, Maxime Grandin, Konstantinos Horaites, Adnane Osmane, Konstantinos Papadakis, Jonas Suni, Vertti Tarvus, Hongyang Zhou, Rumi Nakamura
Summary: Rapid plasma eruptions release tremendous energy within Earth's magnetosphere, at the Sun and other planets. The exact mechanism leading to these eruptions, called plasmoids, has been a long-standing question in space physics. Two competing paradigms, magnetic reconnection and kinetic instabilities, have been proposed to explain the process.
Article
Physics, Fluids & Plasmas
L. Schiesko, A. Revel, T. Minea, E. Carbone
Summary: Using a particle-in-cell coupled to Monte-Carlo collisions model, researchers have discovered microscale instabilities in non-equilibrium plasmas that fulfill Penrose's instability criterion. These instabilities result from the spontaneous development of ion turbulence generated by charge exchange collisions, leading to modulations of the local electric field. The modulation of the electric field traps low energy electrons and transports them from the plasma volume to the sheath vicinity. A electrostatic tidal effect near the sheath then releases the trapped electrons as a monochromatic bunch, accelerating them back towards the source. This instability provides a theoretical explanation for the anomalous enrichment of low-energy electrons observed in similar conditions. The findings emphasize the need for a more comprehensive understanding of microscale instabilities in non-equilibrium low temperature plasmas.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2022)
Article
Physics, Fluids & Plasmas
Swadesh M. Mahajan, Felipe A. Asenjo
Summary: It is found that a subluminal electromagnetic plasma wave can undergo parametric amplification when it propagates in phase with a background subluminal gravitational wave in a dispersive medium. The dispersive characteristics of the two waves need to match properly and the response frequencies of the waves must lie within a definite and restrictive range. The combined dynamics is described by a Whitaker-Hill equation, which is the quintessential model for parametric instabilities. The exponential growth of the electromagnetic wave occurs at resonance, where the plasma wave grows at the expense of the background gravitational wave. Different physical scenarios where this phenomenon can occur are discussed.
Article
Multidisciplinary Sciences
Yang Hwan Kim, Hyeon Kim, Seong Cheol Park, Yongjin Kwon, Kyunghoon Yeom, Wosik Cho, Taeyong Kwon, Hyeok Yun, Jae Hee Sung, Seong Ku Lee, Tran Trung Luu, Chang Hee Nam, Kyung Taec Kim
Summary: High-harmonic radiation can be continuously generated from a liquid plasma mirror, providing a possible way for the generation of intense attosecond pulses at a high-repetition rate. This research paves the way for the development of bright, stable, and high-repetition-rate attosecond light sources, benefiting the study of ultrafast laser-matter interactions.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Fluids & Plasmas
Ian E. Ochs, Vadim R. Munirov, Nathaniel J. Fisch
Summary: Advanced aneutronic fusion fuels, such as proton-Boron(11), require higher temperatures than conventional fuels. In mirror confinement systems, relativistic effects must be considered due to the escape of tail electrons. By matching higher temperatures with nonrelativistic solutions, accurate forms for confinement time and relativistic effects are obtained.
PHYSICS OF PLASMAS
(2023)
Article
Nanoscience & Nanotechnology
B. S. Bhaskar, H. Koivisto, O. Tarvainen, T. Thuillier, V. Toivanen
Summary: This study presents the experimental investigation of quasi-periodical kinetic instabilities in magnetically confined electron cyclotron resonance heated plasmas. The instabilities are characterized by fast sequences of periodic plasma losses with approximately 100 μs intervals between bursts, followed by quiescent periods of 1-10 ms before the next event. Increasing the plasma energy content, particularly the magnetic field strength, enhances the chaos of the instabilities in the time domain. Statistical analysis shows that the energy released in an instability event is dependent on the magnetic field strength and microwave power, but not on the neutral gas pressure. The correlation between the energy dissipated in an instability event and the recovery time of the periodic bursts is also observed.
Article
Multidisciplinary Sciences
H. Han, S. J. Park, C. Sung, J. Kang, Y. H. Lee, J. Chung, T. S. Hahm, B. Kim, J-K Park, J. G. Bak, M. S. Cha, G. J. Choi, M. J. Choi, J. Gwak, S. H. Hahn, J. Jang, K. C. Lee, J. H. Kim, S. K. Kim, W. C. Kim, J. Ko, W. H. Ko, C. Y. Lee, J. H. Lee, J. K. Lee, J. P. Lee, K. D. Lee, Y. S. Park, J. Seo, S. M. Yang, S. W. Yoon, Y-S Na
Summary: Nuclear fusion is a promising alternative energy source, but there are still many scientific challenges to harnessing fusion energy on a large scale. Researchers have achieved a plasma fusion regime at the Korea Superconducting Tokamak Advanced Research facility that meets most of the requirements for sustainable fusion. By stabilizing core plasma turbulence with abundant fast ions, they were able to generate plasma at a temperature of 100 million kelvin, lasting up to 20 seconds without instabilities or impurity accumulation. This regime, characterized by low plasma density and moderate input power, shows promise for reliable and disruption-free sustained operation, making it a potential path towards commercial fusion reactors.
Article
Physics, Fluids & Plasmas
C. P. S. Swanson, C. A. Galea, S. A. Cohen
Summary: This paper analyzes a new mechanism for the creation and confinement of energetic electrons in a mirror-configuration plasma. The mechanism utilizes end-localized coherent electrostatic oscillations to drive a Fermi-Ulam-type process, providing axial acceleration. The non-adiabatic nature of mu contributes to phase decorrelation and energy isotropization. The combination of these factors results in a Maxwellian-shaped electron energy distribution function, reducing loss-cone escape and overcoming the energy-limiting Chirikov criterion found in lower dimensional models. The theoretical predictions are compared with experimental data.
PHYSICS OF PLASMAS
(2022)
Article
Optics
Zhilun Zhang, Xianfeng Lin, Xu Zhang, Yonghui Luo, Shibiao Liao, Xiaoliang Wang, Gui Chen, Yingbin Xing, Haiqing Li, Jinggang Peng, Nengli Dai, Jun Zhou, Jinyan Li
Summary: In this study, a low-numerical aperture confined-doped long-tapered (LCT) Yb-doped fiber was proposed and fabricated. The LCT fiber showed excellent laser performance with high power stability and improved transverse mode instability thresholds compared to conventional fibers.
Article
Mechanics
Claudio Cremaschini
Summary: Non-ideal fluids with pressure anisotropy effects are studied in the relativistic systems. The case of magnetized jet plasmas at equilibrium is considered, and a theoretical framework based on covariant statistical kinetic approach is implemented to calculate the system continuum fluid fields. The generation of temperature anisotropy is identified with magnetic moment conservation, and the non-isotropic pressure tensor is obtained by the analytical calculation of the fluid 4-flow and stress-energy tensor.
Article
Physics, Fluids & Plasmas
V. S. Mikhailenko, V. V. Mikhailenko, Hae June Lee
Summary: The study reveals that the spatial inhomogeneity of parametric IC turbulence and drift turbulence plays a crucial role in transporting a large part of FW power from pedestal plasma to the scrape-off layer and divertor along field lines.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Applied
V. Yu Goryainov, M. E. Viktorov, A. V. Vodop'yanov, A. V. Voronin
Summary: The investigation analyzed the structure of a plasma jet generated by a coaxial plasma accelerator, showing that the radiation intensity oscillates with characteristic frequencies for argon and deuterium. The behavior of the discharge in the accelerator revealed the initiation of a diffuse discharge at the base of the conical insert, eventually contracting and occurring between central and external electrodes. The results can be applied to gas ionization, material irradiation, and simulation of plasma flows interacting with magnetic fields in outer space.
Article
Physics, Fluids & Plasmas
Mikhail Viktorov, Alexander Chernyshov, Dmitry Chugunin, Mikhail Mogilevsky
Summary: Electromagnetic emissions above the electron gyrofrequency in mirror-confined electron cyclotron resonance plasma are reported and interpreted as the excitation of the fast extraordinary wave at the fundamental harmonic of the electron gyrofrequency, similar to Earth's auroral kilometric radiation. A method for studying the temporal characteristics of physical processes in the auroral electron acceleration region is proposed and applied to both satellite measurements and laboratory plasma emissions, revealing similarities in cyclotron instability development.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Instruments & Instrumentation
A. G. Shalashov, E. D. Gospodchikov, T. A. Khusainov, L. V. Lubyako, A. L. Solomakhin, M. E. Viktorov
Summary: This paper describes the hardware developed for the CTS diagnostic for the GDT magnetic trap, which is used in fusion research and reconstructs fast ion distributions driven by high-power neutral beam injection. The diagnostic uses a 400 kW/54.5 GHz gyrotron as a source of probe radiation and employs large-aperture quasi-optical mirror systems for beam formation and scattered microwave radiation collection.
JOURNAL OF INSTRUMENTATION
(2021)
Article
Physics, Fluids & Plasmas
A. G. Shalashov, E. D. Gospodchikov
Summary: The study investigates how ECR plasma heating at a frequency exceeding the minimum electron cyclotron frequency affects the heating effect. It is found that under certain conditions, it may result in the formation of 'butterfly-like' distribution functions of fast electrons.
PLASMA PHYSICS AND CONTROLLED FUSION
(2021)
Article
Physics, Fluids & Plasmas
E. D. Gospodchikov, T. A. Khusainov, A. G. Shalashov
Summary: A method is proposed for tomography of the distribution function of energetic ions using collective Thomson scattering diagnostic data. Measurements of scattering spectra from successive plasma cross sections corresponding to different magnetic-field strengths allow for the restoration of the ion distribution function in velocity space. The problem is reduced to an integral equation of the first kind, which can be solved analytically through various exact and approximate methods.
PLASMA PHYSICS REPORTS
(2021)
Article
Engineering, Electrical & Electronic
Vladimir V. Parshin, Evgeny A. Serov, Alexander V. Vodopyanov, Dmitry A. Mansfeld
Summary: A method for measuring dielectric parameters of powder materials, specifically the refractive index and tan delta values, has been developed based on a high quality Fabry-Perot resonator. Results of measuring metal oxide powders in a specific frequency and temperature range are presented, with the method aimed at understanding powder processes under radiation influence.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
L. Lubyako, A. G. Shalashov, A. F. Andriyanov, V. G. Bozhkov, E. D. Gospodchikov, D. S. Dorozhkina
Summary: The set of receiving equipment designed for experiments on the detection of Thomson collective scattering spectra of high-power millimeter-wave radiation in a large-scale open magnetic trap consists of two identical radiometers/spectrum analyzers. Each analyzer has an analysis band of 54.47 +/- 0.55 GHz and a sensitivity of no less than 0.080-0.025 eV, allowing for simultaneous measurements in two independent channels corresponding to different reception angles of the scattered radiation.
RADIOPHYSICS AND QUANTUM ELECTRONICS
(2021)
Article
Physics, Fluids & Plasmas
E. D. Gospodchikov, T. A. Khusainov, A. G. Shalashov
Summary: The electrodynamic reciprocity theorem is employed to study the scattering of finite-aperture microwave beams on density fluctuations in inhomogeneous magnetized plasma. The main result of this study is the representation of the spectral power density of scattered radiation detected by an antenna as a convolution of Wigner functions characterizing arbitrary spatially inhomogeneous distributions of the probe field and the field of the receiving antenna with the spectrum of the autocorrelation function of fluctuations of plasma density. The effects of wave field and medium inhomogeneity are analyzed in different limiting cases. The effective broadening of the scattering spectrum due to inhomogeneity in the planned experiment on collective scattering in the GDT setup is calculated as an example.
PLASMA PHYSICS REPORTS
(2022)
Article
Instruments & Instrumentation
V. A. Skalyga, I. V. Izotov, S. V. Golubev, S. V. Razin, A. V. Sidorov, M. E. Viktorov
Summary: The gasdynamic electron cyclotron resonance (ECR) ion source is a device that achieves ionization efficiency through high plasma density. It provides high-current and high-quality ion beams, making it suitable for applications such as high-current proton injectors. This paper discusses the physical aspects, diagnostic techniques, and future prospects of the gasdynamic ECR plasma.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Physics, Fluids & Plasmas
A. G. Shalashov, E. D. Gospodchikov, T. A. Khusainov, L. V. Lubyako, A. L. Solomakhin, D. V. Yakovlev
Summary: A fast-ion diagnostic method based on collective Thomson scattering of high-power gyrotron radiation has been developed at the gasdynamic trap facility in Budker Institute. This diagnostic aims to reconstruct the ion distributions over transverse and longitudinal velocities driven by strong neutral beam injection in the plasma core. The first experimental results show that the detected spectra, with an effective noise temperature of about 100 eV, are compatible with early theoretical predictions and can be interpreted as the expected scattering signal from fast ions.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
A. G. Shalashov, E. D. Gospodchikov, T. A. Khusainov, A. L. Solomakhin, D. Yakovlev, P. A. Bagryansky
Summary: In the experiments conducted at the GDT facility, two different scenarios of plasma discharges were realized by combining ECRH and NBI plasma heating. The first scenario showed a broad distribution of absorbed ECRH power and a stable plasma with improved energy confinement, while the second scenario exhibited a highly peaked electron temperature profile but was susceptible to low-frequency instabilities.
Article
Physics, Fluids & Plasmas
A. G. Shalashov, E. D. Gospodchikov
Summary: In this paper, the structure of radiation from the evanescent layer in inhomogeneous gyrotropic plasma is analyzed for an incident beam with a finite aperture. It is found that the reflected beam has wave distributions with a non-zero angular momentum due to reflection. The helicity of the reflected beam leads to unusual effects in the plasma electrodynamics.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
A. G. Shalashov, E. D. Gospodchikov, T. A. Khusainov
Summary: In this study, a quasi-optical wave code was combined with a simplified transport model to simulate the time evolution of electron temperature profile during ECR heating. By applying this hybrid code, the bifurcation of narrow and broad microwave heating regimes was successfully simulated and verified in experiments.
PLASMA PHYSICS REPORTS
(2022)
Article
Physics, Multidisciplinary
I. S. Abramov, E. D. Gospodchikov, A. G. Shalashov
Summary: The study demonstrates the possibility of efficiently emitting light in a wavelength range of 11.2 nm +/- 1% by sustaining a discharge in xenon using a subnanosecond terahertz radiation pulse from a modern free-electron laser. This method can achieve a high-intensity extreme ultraviolet radiation with an average power of 35 W, showing potential for applications in experiments using modern free-electron lasers.
JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
(2021)
