arXiv: Plasma Physics最新文献_第7页

Active Janus particles in a complex plasma 复杂等离子体中的活跃两面星粒子

arXiv: Plasma Physics Pub Date : 2020-06-25 DOI: 10.1103/physrevresearch.2.033226

V. Nosenko, F. Luoni, A. Kaouk, M. Rubin-Zuzic, H. Thomas

引用次数: 20

Laser-pulse and electron-bunch plasma wakefield accelerator 激光脉冲和电子束等离子体尾流场加速器

arXiv: Plasma Physics Pub Date : 2020-06-23 DOI: 10.1103/physrevaccelbeams.23.111304

Tianhong Wang, V. Khudik, G. Shvets

引用次数: 3

Identifying observable carrier-envelope phase effects in laser wakefield acceleration with near-single-cycle pulses 近单周期脉冲激光尾流场加速中可观测载波包络相位效应的识别

arXiv: Plasma Physics Pub Date : 2020-06-18 DOI: 10.1063/5.0037925

J. Huijts, I. Andriyash, L. Rovige, A. Vernier, J. Faure

{"title":"Identifying observable carrier-envelope phase effects in laser wakefield acceleration with near-single-cycle pulses","authors":"J. Huijts, I. Andriyash, L. Rovige, A. Vernier, J. Faure","doi":"10.1063/5.0037925","DOIUrl":"https://doi.org/10.1063/5.0037925","url":null,"abstract":"Driving laser wakefield acceleration with extremely short, near single-cycle laser pulses is crucial to the realisation of an electron source that can operate at kHz-repetition rate while relying on modest laser energy. It is also interesting from a fundamental point of view, as the ponderomotive approximation is no longer valid for such short pulses. Through particle-in-cell simulations, we show how the plasma response becomes asymmetric in the plane of laser polarization, and dependent on the carrier-envelope phase (CEP) of the laser pulse. For the case of self-injection, this in turn strongly affects the initial conditions of injected electrons, causing collective betatron oscillations of the electron beam. As a result, the beam pointing and electron energy spectrum become CEP-dependent. For injection in a density gradient these effects are reduced, as electron injection is mostly longitudinal and mainly determined by the density gradient. Our results highlight the importance of controlling the CEP in this regime for producing stable and reproducible relativistic electron beams. Mitigation of CEP effects can nevertheless be achieved using density gradient injection.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81170532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 18

Laser-driven collisionless shock acceleration of ions from near-critical plasmas 近临界等离子体中离子的激光驱动无碰撞冲击加速

arXiv: Plasma Physics Pub Date : 2020-06-12 DOI: 10.1063/1.5144446

S. Tochitsky, A. Pak, F. Fiuza, D. Haberberger, N. Lemos, A. Link, D. Froula, C. Joshi

引用次数: 7

Dust vortex flow analysis in weakly magnetized plasma 弱磁化等离子体中尘埃涡旋流动分析

arXiv: Plasma Physics Pub Date : 2020-06-03 DOI: 10.1063/5.0010850

Prince Kumar, D. Sharma

引用次数: 2

Anomalous edge plasma transport, neutrals, and divertor plasma detachment 异常边缘等离子体输运，中性，和转移器等离子体脱离

arXiv: Plasma Physics Pub Date : 2020-05-27 DOI: 10.1088/1741-4326/aba9ec/meta

Yanzeng Zhang, S. Krasheninnikov, R. Masline, R. Smirnov

引用次数: 0

On quasi-parallel whistler waves in the solar wind 关于太阳风中的准平行哨声波

arXiv: Plasma Physics Pub Date : 2020-05-26 DOI: 10.1063/5.0003401

I. Vasko, I. Kuzichev, A. Artemyev, S. Bale, J. Bonnell, F. Mozer

{"title":"On quasi-parallel whistler waves in the solar wind","authors":"I. Vasko, I. Kuzichev, A. Artemyev, S. Bale, J. Bonnell, F. Mozer","doi":"10.1063/5.0003401","DOIUrl":"https://doi.org/10.1063/5.0003401","url":null,"abstract":"The recent simulations showed that the whistler heat flux instability, which presumably produces the most of quasi-parallel coherent whistler waves in the solar wind, is not efficient in regulating the electron heat conduction. In addition, recent spacecraft measurements indicated that some fraction of coherent whistler waves in the solar wind may propagate anti-parallel to the electron heat flux, being produced due to a perpendicular temperature anisotropy of suprathermal electrons. We present analysis of properties of parallel and anti-parallel whistler waves unstable at electron heat fluxes and temperature anisotropies of suprathermal electrons typical of the pristine solar wind. Assuming the electron population consisting of counter-streaming dense thermal core and tenuous suprathermal halo populations, we perform a linear stability analysis to demonstrate that anti-parallel whistler waves are expected to have smaller frequencies, wave numbers and growth rates compared to parallel whistler waves. The stability analysis is performed over a wide range of parameters of core and halo electron populations. Using the quasi-linear scaling relation we show that anti-parallel whistler waves saturate at amplitudes of one order of magnitude smaller than parallel whistler waves, which is at about $10^{-3};B_0$ in the pristine solar wind. The analysis shows that the presence of anti-parallel whistler waves in the pristine solar wind is more likely to be obscured by turbulent magnetic field fluctuations, because of lower frequencies and smaller amplitudes compared to parallel whistler waves. The presented results will be also valuable for numerical simulations of the electron heat flux regulation in the solar wind.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85289457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 17

Birefringence in thermally anisotropic relativistic plasmas and its impact on laser–plasma interactions 热各向异性相对论等离子体中的双折射及其对激光等离子体相互作用的影响

arXiv: Plasma Physics Pub Date : 2020-05-25 DOI: 10.1063/5.0008018

A. Arefiev, D. Stark, T. Toncian, M. Murakami

引用次数: 5

Feasibility of Net Energy Gain in Kinematic Nuclear Fusion Devices 动态核聚变装置净能量增益的可行性

arXiv: Plasma Physics Pub Date : 2020-05-23 DOI: 10.13140/RG.2.2.17302.37445

E. Tsiper

引用次数: 0

Adjoint methods for stellarator shape optimization and sensitivity analysis 仿星器形状优化及灵敏度分析的伴随方法

arXiv: Plasma Physics Pub Date : 2020-05-15 DOI: 10.13016/TNOZ-3MOV

E. Paul

{"title":"Adjoint methods for stellarator shape optimization and sensitivity analysis","authors":"E. Paul","doi":"10.13016/TNOZ-3MOV","DOIUrl":"https://doi.org/10.13016/TNOZ-3MOV","url":null,"abstract":"The design of a stellarator with acceptable confinement properties requires optimization of the magnetic field in the non-convex, high-dimensional spaces describing their geometry. Another major challenge facing the stellarator program is the sensitive dependence of confinement properties on electro-magnetic coil shapes, necessitating the construction of the coils under tight tolerances. In this Thesis, we address these challenges with the application of adjoint methods and shape sensitivity analysis. Adjoint methods enable the efficient computation of the gradient of a function that depends on the solution to a system of equations, such as linear or nonlinear PDEs. This enables gradient-based optimization in high-dimensional spaces and efficient sensitivity analysis. We present the first applications of adjoint methods for stellarator shape optimization. The first example we discuss is the optimization of coil shapes based on the generalization of a continuous current potential model. Understanding the sensitivity of coil metrics to perturbations of the winding surface allows us to understand features of configurations that enable simpler coils. We next consider solutions of the drift-kinetic equation. An adjoint drift-kinetic equation is derived based on the self-adjointness property of the Fokker-Planck collision operator, allowing us to compute the sensitivity of neoclassical quantities to perturbations of the magnetic field strength. Finally, we consider functions that depend on solutions of the MHD equilibrium equations. We generalize the self-adjointness property of the MHD force operator to include perturbations of the rotational transform and the currents outside the confinement region. This self-adjointness property is applied to develop an adjoint method for computing the derivatives of such functions with respect to perturbations of coil shapes or the plasma boundary.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79908476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3