Physics of Plasmas最新文献_第2页

Symmetry and structure in the “Generalized Plasma Focus problem” 广义等离子体焦点问题 "中的对称性和结构

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-17 DOI: 10.1063/5.0225122

S. K. H. Auluck

{"title":"Symmetry and structure in the “Generalized Plasma Focus problem”","authors":"S. K. H. Auluck","doi":"10.1063/5.0225122","DOIUrl":"https://doi.org/10.1063/5.0225122","url":null,"abstract":"The “Generalized Plasma Focus problem” refers to a generic class of plasma propagation phenomena that share many features of a dense plasma focus device. Its recent theoretical development has been shown to predict some features of the pinch phase in PF-1000 and POSEIDON. The theory attempts to decompose the plasma propagation problem into two weakly interdependent subproblems. This is achieved by expressing every physical variable of an applicable continuum model of the plasma as the product of a scaling parameter, which contains device-related information and represents its numerical magnitude, and a scaled variable that is devoid of device-related information, is of order unity, and represents the spatiotemporal structure of that variable. The first subproblem seeks a traveling surface of revolution whose local normal velocity equals the scaling parameter for velocity and is aligned with the magnetic force density. Spatiotemporal distributions of all the scaled variables must move along with this reference surface by definition. This paper explores the resulting scaling theory and its symmetry properties. A new coordinate transformation results in a formula for the spatiotemporal distribution of the magnetic field of the curved and non-steady plasma sheath. New insights into the snowplow effect are obtained. A current sheath with a rear boundary exists only when the current is decreasing and only when the current carrying plasma is less dense than the fill gas. The current sheath thickness is the same for small and large devices. The geomagnetic flux compression problem has an exact solution.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Time-dependent probability density functions and information geometry in a stochastic prey–predator model of fusion plasmas 聚变等离子体随机捕食者-捕食者模型中与时间相关的概率密度函数和信息几何学

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-11 DOI: 10.1063/5.0193622

Patrick Fuller, Eun-jin Kim, Rainer Hollerbach, Bogdan Hnat

引用次数: 0

Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method 基于晶格玻尔兹曼法的可压缩等离子体非平衡效应建模

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-10 DOI: 10.1063/5.0211465

Haoyu Huang, Ke Jin, Kai Li, Xiaojing Zheng

{"title":"Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method","authors":"Haoyu Huang, Ke Jin, Kai Li, Xiaojing Zheng","doi":"10.1063/5.0211465","DOIUrl":"https://doi.org/10.1063/5.0211465","url":null,"abstract":"A magnetohydrodynamic lattice Boltzmann method (MHD-LBM) model for a 2D compressible plasma based on the finite volume scheme is established. The double distribution D2Q17 discrete velocities are used to simulate the fluid field. The hyperbolic Maxwell equations, which satisfy the elliptic constraints of Maxwell's equations and the constraint of charge conservation, are used to simulate the electromagnetic field. The flow field and electromagnetic field are coupled to simulate a compressible plasma through the electromagnetic force and magnetic induction equations. Four typical cases, the Taylor vortex flow, strong blast, Orszag–Tang vortex, and one-dimensional Riemann problems, are simulated to validate the MHD-LBM model for a compressible plasma. It is found that shock waves widely exist in a compressible plasma, and strong nonequilibrium effects exist around each shock wave. The quantitative simulation for the Brio–Wu problem demonstrates that this model can easily obtain the physical characteristics of nonequilibrium effects at sharp interfaces (shock waves and detonation waves). The magnetic fields can affect the magnitudes to which the system deviates from its equilibrium state. The viscosity can increase the magnitudes to which the system deviates from its equilibrium state. Compared with existing compressible MHD, these results for nonequilibrium effects can provide mesoscopic physical insights into the flow mechanism of a shock wave in a supersonic plasma.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

EFIT-Prime: Probabilistic and physics-constrained reduced-order neural network model for equilibrium reconstruction in DIII-D EFIT-Prime：用于 DIII-D 平衡重建的概率和物理约束降阶神经网络模型

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0213609

S. Madireddy, C. Akçay, S. E. Kruger, T. Bechtel Amara, X. Sun, J. McClenaghan, J. Koo, A. Samaddar, Y. Liu, P. Balaprakash, L. L. Lao

{"title":"EFIT-Prime: Probabilistic and physics-constrained reduced-order neural network model for equilibrium reconstruction in DIII-D","authors":"S. Madireddy, C. Akçay, S. E. Kruger, T. Bechtel Amara, X. Sun, J. McClenaghan, J. Koo, A. Samaddar, Y. Liu, P. Balaprakash, L. L. Lao","doi":"10.1063/5.0213609","DOIUrl":"https://doi.org/10.1063/5.0213609","url":null,"abstract":"We introduce EFIT-Prime, a novel machine learning surrogate model for EFIT (Equilibrium FIT) that integrates probabilistic and physics-informed methodologies to overcome typical limitations associated with deterministic and ad hoc neural network architectures. EFIT-Prime utilizes a neural architecture search-based deep ensemble for robust uncertainty quantification, providing scalable and efficient neural architectures that comprehensively quantify both data and model uncertainties. Physically informed by the Grad–Shafranov equation, EFIT-Prime applies a constraint on the current density Jtor and a smoothness constraint on the first derivative of the poloidal flux, ensuring physically plausible solutions. Furthermore, the spatial location of the diagnostics is explicitly incorporated in the inputs to account for their spatial correlation. Extensive evaluations demonstrate EFIT-Prime's accuracy and robustness across diverse scenarios, most notably showing good generalization on negative-triangularity discharges that were excluded from training. Timing studies indicate an ensemble inference time of 15 ms for predicting a new equilibrium, offering the possibility of plasma control in real-time, if the model is optimized for speed.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Theory of phase-space hydrodynamics of electron and ion holes in collisionless plasmas 无碰撞等离子体中电子和离子空穴的相空间流体力学理论

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0216144

Allen Lobo, Vinod Kumar Sayal

{"title":"Theory of phase-space hydrodynamics of electron and ion holes in collisionless plasmas","authors":"Allen Lobo, Vinod Kumar Sayal","doi":"10.1063/5.0216144","DOIUrl":"https://doi.org/10.1063/5.0216144","url":null,"abstract":"Phase-space holes are well-known Bernstein–Greene–Kruskal (B.G.K.) modes and are formed by particle-trapping in solitary potential waveforms. They exhibit orbital particle trajectories in the phase-space, due to which they are also referred to as phase-space vortices. In this article, we develop the theory of phase-space hydrodynamics for electron and ion phase-space in collisionless plasmas. The analogy between ordinary two-dimensional fluids and 1D−1V phase-space has been explored by introducing a momentum equation and a phase-space vorticity field, which enable the fluid-like analyses of the plasma phase-space. The developed kinetic-hydrodynamic equations are then employed to address the vortical nature of phase-space holes by exploring their fluid-analogous vortex-like characteristics, an identification technique of phase-space vortices, an exact derivation of the Schamel-df equations, and a measurable definition of the particle-trapping β parameter. This article introduces a new technique to the study of phase-space holes which focuses on the fluid-analogous vortical nature of the phase-space holes and prevents the need for an initial assumption of the trapped and free particle phase-space densities, thus presenting itself as a precursor to the Schamel-pseudopotential method.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sheet model description of spatiotemporal evolution of upper-hybrid oscillations in an inhomogeneous magnetic field 非均质磁场中上混合振荡时空演变的片状模型描述

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0220066

Nidhi Rathee, Someswar Dutta, R. Srinivasan, Sudip Sengupta

{"title":"Sheet model description of spatiotemporal evolution of upper-hybrid oscillations in an inhomogeneous magnetic field","authors":"Nidhi Rathee, Someswar Dutta, R. Srinivasan, Sudip Sengupta","doi":"10.1063/5.0220066","DOIUrl":"https://doi.org/10.1063/5.0220066","url":null,"abstract":"Spatiotemporal evolution of large amplitude upper-hybrid oscillations in a cold homogeneous plasma in the presence of an inhomogeneous magnetic field is studied analytically and numerically using the Dawson sheet model [J. Dawson, Phys. Fluids 5, 445–459 (1962)]. It is observed that the inhomogeneity in magnetic field, which causes the upper-hybrid frequency to acquire a spatial dependence, results in phase mixing and subsequent breaking of the upper-hybrid oscillations at arbitrarily low amplitudes. This result is in sharp contrast to the usual upper-hybrid oscillations in a homogeneous magnetic field, where the oscillations break within a fraction of a period when the amplitude exceeds a certain critical value [R. C. Davidson, Methods in Nonlinear Plasma Theory (Academic, New York, 1972)]. Our perturbative calculations show that the phase mixing (wave breaking) time scales inversely with the amplitude of magnetic field inhomogeneity (Δ) and amplitude of imposed density perturbation (δ) and scales directly with the ratio of magnetic field inhomogeneity scale length to imposed density perturbation scale length [(α/kL)−1] as ωpeτmix∼(1+β2)3/2kL/(β2δΔα), where β is the ratio of electron cyclotron frequency to electron plasma frequency. Further phase mixing time measured in simulations, performed using a 1–1/2 D code based on the Dawson sheet model [J. Dawson, Phys. Fluids 5, 445–459 (1962)], shows good agreement with the above-mentioned scaling. This result may be of relevance to plasma based particle acceleration experiments in the presence of a transverse inhomogeneous magnetic field.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Three-wave coupling observed between a shear Alfvén wave and a kink-unstable magnetic flux rope 在剪切阿尔弗波和不稳定磁通绳之间观测到的三波耦合

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0217895

S. Vincena, S. K. P. Tripathi, W. Gekelman, P. Pribyl

{"title":"Three-wave coupling observed between a shear Alfvén wave and a kink-unstable magnetic flux rope","authors":"S. Vincena, S. K. P. Tripathi, W. Gekelman, P. Pribyl","doi":"10.1063/5.0217895","DOIUrl":"https://doi.org/10.1063/5.0217895","url":null,"abstract":"Results from a laboratory experiment are presented in which, for the first time, a shear Alfvén wave is launched using an antenna in a current-carrying plasma column that is tailored to be either stable or unstable to the kink oscillation. As the plasma is driven kink unstable, the frequency power spectrum of the Alfvén wave evolves from a single peak to a peak with multiple sidebands separated by integer multiples of the kink frequency. The main sidebands (one on either side of the launched wave peak in the power spectrum) are analyzed using azimuthal wavenumber matching, perpendicular and parallel wavenumber decomposition, and bispectral time series analysis. The dispersion relation and three-wave matching conditions are satisfied, given each sideband is a propagating Alfvén wave that results from the interaction of the pump Alfvén wave and the co-propagating component of a half-wavelength, standing kink mode. The interaction is shown to generate smaller perpendicular wavelength Alfvén waves that drive energy transport to scales that will approach the dissipation scale of k⊥ρs=1, with k⊥ being the perpendicular wavenumber and ρs being the ion gyroradius at the electron temperature.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Microtearing mode in electron temperature pedestal evolution and collapse of KSTAR H-mode plasmas KSTAR H 模等离子体电子温度基座演化和坍缩中的微撕裂模式

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-06 DOI: 10.1063/5.0210947

Jaehyun Lee, Minho Kim, Gunsu S. Yun, Minwoo Kim, Jae-Min Kwon, Juhyung Kim, Sumin Yi, Sehoon Ko, Yongkyoon In

引用次数: 0

Establishing criteria for the transition from kinetic to fluid modeling in hollow cathode analysis 在空心阴极分析中建立从动力学模型向流体模型过渡的标准

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0213313

W. Villafana, A. T. Powis, S. Sharma, I. D. Kaganovich, A. V. Khrabrov

引用次数: 0

An efficient Cherenkov oscillator with an independent injection channel for generating phase-controlled super-radiance pulses 具有独立注入通道的高效切伦科夫振荡器，用于产生相位控制的超辐照脉冲

IF 2.2 3区物理与天体物理

Physics of Plasmas Pub Date : 2024-09-05 DOI: 10.1063/5.0220916

Jiaoyin Wang, Renjie Cheng, Ping Wu, Renzhen Xiao, Yibing Cao, Haiyang Wang, Hao Li, Yihong Zhou, Biao Hu, Hao Zhou, Tingxu Chen, Kun Chen, Tianming Li

{"title":"An efficient Cherenkov oscillator with an independent injection channel for generating phase-controlled super-radiance pulses","authors":"Jiaoyin Wang, Renjie Cheng, Ping Wu, Renzhen Xiao, Yibing Cao, Haiyang Wang, Hao Li, Yihong Zhou, Biao Hu, Hao Zhou, Tingxu Chen, Kun Chen, Tianming Li","doi":"10.1063/5.0220916","DOIUrl":"https://doi.org/10.1063/5.0220916","url":null,"abstract":"An efficient Cherenkov oscillator with gigawatt phase-controlled super-radiance (SR) pulses is studied for the application of coherent summation systems. To obtain phase-controlled SR pulses, an ultra-short seed pulse is required to be injected into the interaction space from the direction of the collector, which substitutes the impact of the spontaneous emission from the front edge of the electron beam. It means that, for a conventional Cherenkov oscillator, the injection seed pulse and output gigawatt SR pulse need to share the same channel. Therefore, an additional quasi-optical reflection system is needed to separate these two signals. To optimize such a scheme, we introduce a front extractor near the reflector and an injection channel at the side of the collector, allowing the output and injection channels to be independent of each other. Particle-in-cell simulations reveal that as the diode voltage is 260 kV, the beam current is 3.5 kA, and the magnetic field is 0.42 T, a short SR pulse with peak power of 1.93 GW is obtained. The corresponding conversion factor (ratio of average output power and input DC power) is up to 2.12. When the seed pulse has a rise time of 0.3 ns and a width of 0.2 ns injection, the phase of the seed pulse and the initiated SR pulse are closely correlated with the accuracy of 0.17 rad as the power ratio is down to −25 dB. The advantages of high efficiency and phase control make the oscillator a promising device used for the miniaturization and practicability of coherent summation systems.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142221813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0