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Slow magnetosonic wave absorption by pressure induced ionization–recombination dissipation 压力诱导电离复合耗散的慢磁声波吸收
arXiv: Plasma Physics Pub Date : 2020-05-15 DOI: 10.1063/5.0013983
T. Mishonov, A. Varonov
{"title":"Slow magnetosonic wave absorption by pressure induced ionization–recombination dissipation","authors":"T. Mishonov, A. Varonov","doi":"10.1063/5.0013983","DOIUrl":"https://doi.org/10.1063/5.0013983","url":null,"abstract":"A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure induced oscillations of the ionization degree is proposed. An explicit formula for the damping rate is quantitatively derived. Physical conditions where the new mechanism will dominate are briefly discussed. The ionization-recombination damping is frequency independent and has no hydrodynamic interpretation. Roughly speaking large area of partially ionized plasma are damper for basses of SMW while usual MHD mechanisms operate as a low pass filter. The derived damping rate is proportional to the square of the sine between the constant magnetic field and the wave-vector. Angular distribution of the spectral density of SMW and Alfven waves (AW) created by turbulent regions and passing through large regions of partially ionized plasma is qualitatively considered. The calculated damping rate is expressed by the electron impact cross section of the hydrogen atom and in short all details of the proposed damping mechanisms are well studied.","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":"76243937","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: 1
Terahertz emission from submicron solid targets irradiated by ultraintense femtosecond laser pulses 超强飞秒激光脉冲辐照亚微米固体目标的太赫兹发射
arXiv: Plasma Physics Pub Date : 2020-05-11 DOI: 10.1063/5.0013415
J. Déchard, X. Davoine, L. Gremillet, L. Bergé
{"title":"Terahertz emission from submicron solid targets irradiated by ultraintense femtosecond laser pulses","authors":"J. Déchard, X. Davoine, L. Gremillet, L. Bergé","doi":"10.1063/5.0013415","DOIUrl":"https://doi.org/10.1063/5.0013415","url":null,"abstract":"Using high-resolution, two-dimensional particle-in-cell simulations, we investigate numerically the mechanisms of terahertz (THz) emissions in submicron-thick carbon solid foils driven by ultraintense ($sim 10^{20},rm W,cm^{-2}$), ultrashort ($30,rm fs$) laser pulses at normal incidence. The considered range of target thicknesses extends down to the relativistic transparency regime that is known to optimize ion acceleration by femtosecond laser pulses. By disentangling the fields emitted by longitudinal and transverse currents, our analysis reveals that, within the first picosecond after the interaction, THz emission occurs in bursts as a result of coherent transition radiation by the recirculating hot electrons and antenna-type emission by the shielding electron currents traveling along the fast-expanding target surfaces.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79358419","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: 15
Fire-hose instability of inhomogeneous plasma flows with heat fluxes 带热通量的非均匀等离子体流的消防水带不稳定性
arXiv: Plasma Physics Pub Date : 2020-05-08 DOI: 10.1063/5.0013490
E. Uchava, A. Tevzadze, B. Shergelashvili, N. S. Dzhalilov, S. Poedts
{"title":"Fire-hose instability of inhomogeneous plasma flows with heat fluxes","authors":"E. Uchava, A. Tevzadze, B. Shergelashvili, N. S. Dzhalilov, S. Poedts","doi":"10.1063/5.0013490","DOIUrl":"https://doi.org/10.1063/5.0013490","url":null,"abstract":"We study the effects of heat flows and velocity shear on the parallel firehose instability in weakly collisional plasma flow. For this purpose we apply an anisotropic 16-moments MHD fluid closure model that takes into account the pressure and temperature anisotropy, as well as the effect of anisotropic heat flux. The linear stability analysis of the firehose modes is carried out in the incompressible limit, where the MHD flow is parallel to the background magnetic field, while the velocity is sheared in the direction transverse to the flow direction. It seems that an increase of the velocity shear parameter leads to higher growth rates of the firehose instability. The increase of the instability growth rate is most profound for perturbations with oblique wave-numbers $k_{perp}/k_{parallel} < 1$. The heat flux parameter introduces an asymmetry of the instability growth in the shear plane: perturbations with wave-vectors with a component in the direction of the velocity shear grow significantly stronger as compared to those with components in the opposite direction. We discuss the implications of the presented study on the observable features of the solar wind and possible measurements of local parameters of the solar wind based on the stability constraints set by the firehose instability.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86212571","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: 1
Constraining Alfvénic turbulence with helicity invariants 具有螺旋不变量的约束alvvac湍流
arXiv: Plasma Physics Pub Date : 2020-05-07 DOI: 10.1093/mnras/staa1318
S. Mahajan, M. Lingam
{"title":"Constraining Alfvénic turbulence with helicity invariants","authors":"S. Mahajan, M. Lingam","doi":"10.1093/mnras/staa1318","DOIUrl":"https://doi.org/10.1093/mnras/staa1318","url":null,"abstract":"In this paper, we study the constraints imposed by the invariants (generalized helicities and energy) of extended magnetohydrodynamics on some global characteristics of turbulence. We show that the global turbulent kinetic and magnetic energies will approach equipartition only under certain circumstances that depend on the ratio of the generalized helicities. In systems with minimal thermal energy, we demonstrate that the three invariants collectively determine the characteristic length scale associated with Alfvenic turbulence.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86947686","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: 5
Space-filter techniques for quasi-neutral hybrid-kinetic models 准中性混合动力模型的空间过滤技术
arXiv: Plasma Physics Pub Date : 2020-05-06 DOI: 10.1063/5.0012924
S. Cerri, Enrico Camporeale
{"title":"Space-filter techniques for quasi-neutral hybrid-kinetic models","authors":"S. Cerri, Enrico Camporeale","doi":"10.1063/5.0012924","DOIUrl":"https://doi.org/10.1063/5.0012924","url":null,"abstract":"The space-filter approach has proved a fundamental tool in studying turbulence in neutral fluids, providing the ability to analyze scale-to-scale energy transfer in configuration space. It is well known that turbulence in plasma presents challenges different from neutral fluids, especially when the scale of interests include kinetic effects. The space-filter approach is still largely unexplored for kinetic plasma. Here we derive the space-filtered (or, equivalently \"coarse-grained\") equations in configuration space for a quasi-neutral hybrid-kinetic plasma model, in which ions are fully kinetic and electrons are a neutralizing fluid. Different models and closures for the electron fluid are considered, including finite electron-inertia effects and full electrons' pressure-tensor dynamics. Implications for the cascade of turbulent fluctuations in real space depending on different approximations are discussed.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76013493","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: 9
Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona 快速磁重联使托卡马克电流剖面变平，对日冕的影响
arXiv: Plasma Physics Pub Date : 2020-05-05 DOI: 10.1063/5.0014107
A. Boozer
{"title":"Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona","authors":"A. Boozer","doi":"10.1063/5.0014107","DOIUrl":"https://doi.org/10.1063/5.0014107","url":null,"abstract":"During tokamak disruptions the profile of the net parallel current is observed to flatten on a time scale that is so fast that it must be due to a fast magnetic reconnection. After a fast magnetic reconnection has broken magnetic surfaces, a single magnetic field line covers an entire volume and not just a magnetic surface. The current profile, given by $Kequivmu_0j_{||}/B$, relaxes to a constant within that volume by Alfven waves propagating along the chaotic magnetic field lines. The time scale for this relaxation determines the commonly observed disruption phenomena of a current spike and a sudden drop in the plasma internal inductance. An efficient method for studying this relaxation is derived, which allows a better understanding of the information encoded in the current spike and the associated sudden drop in the plasma internal inductance. Implications for coronal heating are also discussed.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87656953","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: 13
Self-absorption of synchrotron radiation in a laser-irradiated plasma 激光辐照等离子体中同步辐射的自吸收
arXiv: Plasma Physics Pub Date : 2020-05-01 DOI: 10.1063/5.0044766
T. Blackburn, A. Macleod, A. Ilderton, B. King, Suo Tang, Mattias Marklund
{"title":"Self-absorption of synchrotron radiation in a laser-irradiated plasma","authors":"T. Blackburn, A. Macleod, A. Ilderton, B. King, Suo Tang, Mattias Marklund","doi":"10.1063/5.0044766","DOIUrl":"https://doi.org/10.1063/5.0044766","url":null,"abstract":"Electrons at the surface of a plasma that is irradiated by a laser with intensity in excess of $10^{23}~mathrm{W}mathrm{cm}^{-2}$ are accelerated so strongly that they emit bursts of synchrotron radiation. Although the combination of high photon and electron density and electromagnetic field strength at the plasma surface makes particle-particle interactions possible, these interactions are usually neglected in simulations of the high-intensity regime. Here we demonstrate an implementation of two such processes: photon absorption and stimulated emission. We show that, for plasmas that are opaque to the laser light, photon absorption would cause complete depletion of the multi-keV region of the synchrotron photon spectrum, unless compensated by stimulated emission. Our results motivate further study of the density dependence of QED phenomena in strong electromagnetic fields.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85265506","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: 5
Effects of collisions on the generation and suppression of temperature anisotropies and the Weibel instability 碰撞对温度各向异性的产生和抑制及维贝尔不稳定性的影响
arXiv: Plasma Physics Pub Date : 2020-04-28 DOI: 10.1103/PHYSREVRESEARCH.2.033233
K. Schoeffler, L. Silva
{"title":"Effects of collisions on the generation and suppression of temperature anisotropies and the Weibel instability","authors":"K. Schoeffler, L. Silva","doi":"10.1103/PHYSREVRESEARCH.2.033233","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.033233","url":null,"abstract":"The expansion of plasma with non-parallel temperature and density gradients, and the generation of magnetic field via the Biermann battery is modeled using particle-in-cell simulations that include collisional effects via Monte Carlo methods. A scaling of the degree of collisionality shows that an anisotropy can be produced, and drive the Weibel instability, for gradient scales shorter than the mean free path. For larger collision rates, the Biermann battery dominates as the cause of magnetic field generation. When the most energetic particles remain collisionless, the Nernst effect causes the Biermann field to be dragged with the heat flux, piled up, and enhanced.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81205618","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
The ion-acoustic instability of the inductively coupled plasma driven by the ponderomotive electron current formed in the skin layer 电感耦合等离子体在蒙皮层中形成的有源电子电流驱动下的离子声不稳定性
arXiv: Plasma Physics Pub Date : 2020-04-28 DOI: 10.1063/1.5144472
V. Mikhailenko, V. Mikhailenko, H. J. Lee
{"title":"The ion-acoustic instability of the inductively coupled plasma driven by the ponderomotive electron current formed in the skin layer","authors":"V. Mikhailenko, V. Mikhailenko, H. J. Lee","doi":"10.1063/1.5144472","DOIUrl":"https://doi.org/10.1063/1.5144472","url":null,"abstract":"The stability theory of the inductively coupled plasma (ICP) is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. The theory predicts the existence the instabilities of the ICP which are driven by the current formed in the skin layer by the accelerated electrons, which move relative ions under the action of the ponderomotive force.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86536746","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: 4
Dependence of the impurity transport on the dominant turbulent regime in ELM-y H-mode discharges on the DIII-D tokamak DIII-D托卡马克上ELM-y h模放电中杂质输运对主导湍流区的依赖
arXiv: Plasma Physics Pub Date : 2020-04-23 DOI: 10.1063/5.0010725
Tomáš Odstrčil, N. Howard, F. Sciortino, C. Chrystal, C. Holland, E. Hollmann, G. McKee, K. Thome, T. Wilks
{"title":"Dependence of the impurity transport on the dominant turbulent regime in ELM-y H-mode discharges on the DIII-D tokamak","authors":"Tomáš Odstrčil, N. Howard, F. Sciortino, C. Chrystal, C. Holland, E. Hollmann, G. McKee, K. Thome, T. Wilks","doi":"10.1063/5.0010725","DOIUrl":"https://doi.org/10.1063/5.0010725","url":null,"abstract":"Laser blow-off injections of aluminum and tungsten have been performed on the DIII-D tokamak to investigate the variation of impurity transport in a set of dedicated ion and electron heating scans with a fixed value of the external torque. The particle transport is quantified via the Bayesian inference method, which, constrained by a combination of a charge exchange recombination spectroscopy, soft X-ray measurements, and VUV spectroscopy provides a detailed uncertainty quantification of the transport coefficients. Contrasting discharge phases with a dominant electron and ion heating reveal a factor of 30 increase in midradius impurity diffusion and a 3-fold drop in the impurity confinement time when additional electron heating is applied. Further, the calculated stationary aluminum density profiles reverse from peaked in electron heated to hollow in the ion heated case, following a similar trend as electron and carbon density profiles. Comparable values of a core diffusion have been observed for W and Al ions, while differences in the propagation dynamics of these impurities are attributed to pedestal and edge transport. Modeling of the core transport with non-linear gyrokinetics code CGYRO [J. Candy and E. Belly J. Comput. Phys. 324,73 (2016)], significantly underpredicts the magnitude of the variation in Al transport. The experiment demonstrates a 3-times steeper increase of impurity diffusion with additional electron heat flux and 10-times lower diffusion in ion heated case than predicted by the modeling. However, the CGYRO model correctly predicts that the Al diffusion dramatically increases below the linear threshold for the transition from the ion temperature gradient (ITG) to trapped electron mode (TEM).","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90564819","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
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