Journal of Plasma Physics最新文献

{"title":"Laser-machined two-stage nozzle optimised for laser wakefield acceleration","authors":"V. Tomkus, M. Mackevičiūtė, J. Dudutis, V. Girdauskas, M. Abedi-Varaki, P. Gečys, G. Račiukaitis","doi":"10.1017/s0022377824000059","DOIUrl":"https://doi.org/10.1017/s0022377824000059","url":null,"abstract":"In this paper, the modelling and manufacturing of a two-stage supersonic gas jet nozzle enabling the formation of adaptive plasma concentration profiles for injection and acceleration of electrons using few-cycle laser beams are presented. The stages are modelled using the rhoSimpleFoam algorithm of the OpenFOAM computational fluid dynamics software. The first 200–300 <jats:inline-formula> <jats:alternatives> <jats:tex-math>${rm mu}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000059_inline2A1.png\" /> </jats:alternatives> </jats:inline-formula>m diameter nozzle stage is dedicated to 1 % N<jats:sub>2</jats:sub> + He gas jet formation and electron injection. By varying the pressure between the first and second stages of the injectors, the electron injection location could be adjusted, and the maximum acceleration distance could be ensured. By changing the concentration of the nitrogen in the gas mixture, the charge of the accelerated electrons could be controlled. The second nozzle stage is designed for acceleration in fully ionised He or hydrogen gas and forms the optimal plasma concentration for bubble formation depending on the laser pulse energy, duration and focused beam diameter. In order to reduce the diameter of the plasma profile formed by the first nozzle and the concentration drop gap between the two nozzles, a one-side straight section was introduced in the first nozzle. The shock wave reflected from the straight section of the wall propagates parallel to the shock wave of the intersecting supersonic jets and ensures a minimal gap between the jets. The second-stage longitudinal plasma concentration profile could have an increasing gas density gradient to compensate for dephasing between the electron bunch and the plasma wave due to wave shortening with increasing plasma concentration.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"12 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761031","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}

{"title":"Role of the edge electric field in the resonant mode-particle interactions and the formation of transport barriers in toroidal plasmas","authors":"Giorgos Anastassiou, Panagiotis Zestanakis, Yiannis Antonenas, Eleonora Viezzer, Yannis Kominis","doi":"10.1017/s0022377824000047","DOIUrl":"https://doi.org/10.1017/s0022377824000047","url":null,"abstract":"The impact of an edge radial electric field on the particle orbits and the orbital spectrum in an axisymmetric toroidal magnetic equilibrium is investigated using a guiding centre canonical formalism. Poloidal and bounce/transit-averaged toroidal precession frequencies are calculated, highlighting the role of the radial electric field. The radial electric field is shown to drastically modify the resonance conditions between particles with certain kinetic characteristics and specific perturbative non-axisymmetric modes, and to enable the formation of transport barriers. The locations of the resonances and the transport barriers that determine the particle, energy and momentum transport are shown to be accurately pinpointed in the phase space by employing the calculated orbital frequencies.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"215 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768358","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}

{"title":"Hydrodynamic and kinetic representation of the microscopic classic dynamics at the transition on the macroscopic scale","authors":"Pavel A. Andreev","doi":"10.1017/s0022377823000818","DOIUrl":"https://doi.org/10.1017/s0022377823000818","url":null,"abstract":"An open problem of the derivation of the relativistic Vlasov equation for systems of charged particles moving with velocities up to the speed of light and creating the electromagnetic field in accordance with the full set of the Maxwell equations is considered. Moreover, the method of derivation is illustrated on the non-relativistic kinetic model. Independent derivation of the relativistic hydrodynamics is also demonstrated. The key role of these derivations of the hydrodynamic and kinetic equations includes the explicit operator of averaging on the physically infinitesimal volume suggested by L.S. Kuzmenkov.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"221 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139669900","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}

{"title":"A two-dimensional numerical study of ion-acoustic turbulence","authors":"Zhuo Liu, Ryan White, Manaure Francisquez, Lucio M. Milanese, Nuno F. Loureiro","doi":"10.1017/s0022377824000060","DOIUrl":"https://doi.org/10.1017/s0022377824000060","url":null,"abstract":"We investigate the linear and nonlinear evolution of the current-driven ion-acoustic instability in a collisionless plasma via two-dimensional (2-D) Vlasov–Poisson numerical simulations. We initialise the system in a stable state and gradually drive it towards instability with an imposed, weak external electric field, thus avoiding physically unrealisable super-critical initial conditions. A comprehensive analysis of the nonlinear evolution of ion-acoustic turbulence (IAT) is presented, including the detailed characteristics of the evolution of the particles’ distribution functions, (2-D) wave spectrum and the resulting anomalous resistivity. Our findings reveal the dominance of 2-D quasi-linear effects around saturation, with nonlinear effects, such as particle trapping and nonlinear frequency shifts, becoming pronounced during the later stages of the system's nonlinear evolution. Remarkably, the Kadomtsev–Petviashvili (KP) spectrum is observed immediately after the saturation of the instability. Another crucial and noteworthy result is that no steady saturated nonlinear state is ever reached: strong ion heating suppresses the instability, which implies that the anomalous resistivity associated with IAT is transient and short-lived, challenging earlier theoretical results. Towards the conclusion of the simulation, electron-acoustic waves are triggered by the formation of a double layer and strong modifications to the particle distribution induced by IAT.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"11 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139670024","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}

{"title":"Space–time structure of weak magnetohydrodynamic turbulence","authors":"Augustus A. Azelis, Jean C. Perez, Sofiane Bourouaine","doi":"10.1017/s0022377824000035","DOIUrl":"https://doi.org/10.1017/s0022377824000035","url":null,"abstract":"&lt;p&gt;The two-time energy spectrum of weak magnetohydrodynamic turbulence is found by applying a wave-turbulence closure to the cumulant hierarchy constructed from the dynamical equations. Solutions are facilitated via asymptotic expansions in terms of the small parameter &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$varepsilon$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S0022377824000035_inline1.png\"/&gt;&lt;/span&gt;&lt;/span&gt;, describing the ratio of time scales corresponding to Alfvénic propagation and nonlinear interactions between counter-propagating Alfvén waves. The strength of nonlinearity at a given spatial scale is further quantified by an integration over all possible delta-correlated modes compliant in a given set of three-wave interactions that are associated with energy flux through the said scale. The wave-turbulence closure for the two-time spectrum uncovers a secularity occurring on a time scale of order &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$varepsilon ^{-2}$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S0022377824000035_inline2.png\"/&gt;&lt;/span&gt;&lt;/span&gt;, and the asymptotic expansion for the spectrum is reordered in a manner comparable to the one-time case. It is shown that for the regime of stationary turbulence, the two-time energy spectrum exponentially decays on a lagged time scale &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$(varepsilon ^2 gamma _k^s)^{-1}$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S0022377824000035_inline3.png\"/&gt;&lt;/span&gt;&lt;/span&gt; in proportion to the strength of the associated three-wave interactions, characterized by nonlinear decorrelation frequency &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$gamma _k^s$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S0022377824000035_inline4.png\"/&gt;&lt;/span&gt;&lt;/span&gt;. The scaling of the form &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$k_{perp } v_0 chi _0$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S0022377824000035_inline5.png\"/&gt;&lt;/span&gt;&lt;/span&gt; exhibited by this frequency is reminiscent of random sweeping by the outer scale with characteristic fluctuation velocity &lt;span&gt;&lt;span&gt;&lt;span data-mathjax-type=\"texmath\"&gt;&lt;span&gt;$v_0$&lt;/span&gt;&lt;/span&gt;&lt;img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240131161305046-0563:S0022377824000035:S00223778240000","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"61 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139657327","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}

{"title":"Polarization effects in higher-order guiding-centre Lagrangian dynamics","authors":"Alain J. Brizard","doi":"10.1017/s0022377824000096","DOIUrl":"https://doi.org/10.1017/s0022377824000096","url":null,"abstract":"<p>The extended guiding-centre Lagrangian equations of motion are derived by the Lie-transform perturbation method under the assumption of time-dependent and inhomogeneous electric and magnetic fields that satisfy the standard guiding-centre space–time orderings. Polarization effects are introduced into the Lagrangian dynamics by the inclusion of the polarization drift velocity in the guiding-centre velocity and the appearance of finite-Larmor-radius corrections in the guiding-centre Hamiltonian and guiding-centre Poisson bracket.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"21 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139590509","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}

{"title":"Resonant excitation of terahertz surface magnetoplasmons by optical rectification over a rippled surface of n-type indium antimonide","authors":"Rohit Kumar Srivastav, A. Panwar","doi":"10.1017/s0022377823001459","DOIUrl":"https://doi.org/10.1017/s0022377823001459","url":null,"abstract":"<p>We analysed the excitation of a surface magnetoplasmon wave by the mode conversion of a p-polarized laser beam over a rippled semiconductor (n-type)-free space interface. The pump surface magnetoplasmon wave exerts a ponderomotive force on the free electrons in the semiconductor, imparting a linear oscillatory velocity at the laser modulation frequency to them. This linear oscillatory velocity couples with the modulated electron density to produce a current density, which develops a resonant surface magnetoplasmon wave in the terahertz region. The amplitude of the terahertz surface magnetoplasmon wave can be tuneable with an external magnetic field and the semiconductor's temperature.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"161 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139556076","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}

{"title":"The gap-size influence on the excitation of magnetorotational instability in cylindricTaylor–Couette flows","authors":"G. Rüdiger, M. Schultz","doi":"10.1017/s0022377823001356","DOIUrl":"https://doi.org/10.1017/s0022377823001356","url":null,"abstract":"The excitation conditions of the magnetorotational instability (MRI) are studied for axially unbounded Taylor–Couette (TC) flows of various gap widths between the cylinders. The cylinders are considered as made from both perfect-conducting or insulating material and the conducting fluid with a finite but small magnetic Prandtl number rotates with a quasi-Keplerian velocity profile. The solutions are optimized with respect to the wavenumber and the Reynolds number of the rotation of the inner cylinder. For the axisymmetric modes, we find the critical Lundquist number of the applied axial magnetic field: the lower, the wider the gap between the cylinders. A similar result is obtained for the induced cell structure: the wider the gap, the more spherical the cells are. The marginal rotation rate of the inner cylinder – for a fixed size of the outer cylinder – always possesses a minimum for not too wide and not too narrow gap widths. For perfect-conducting walls the minimum lies at &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$r_{{rm in}}simeq 0.4$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001356_inline1.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt;, where &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$r_{{rm in}}$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001356_inline2.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; is the ratio of the radii of the two rotating cylinders. The lowest magnetic field amplitudes to excite the instability are required for TC flows between perfect-conducting cylinders with gaps corresponding to &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$r_{{rm in}}simeq ~0.2$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001356_inline3.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt;. For even wider and also for very thin gaps the needed magnetic fields and rotation frequencies are shown to become rather huge. Also the non-axisymmetric modes with &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$|m|=1$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001356_inline4.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; have been considered. Their excitation generally requires stronger magnetic fields and higher magnetic Reynolds numbers in comparison with those for the axisymmetric modes. If TC experiments with too slow rotation for the applied magnetic fields yield unstable modes of any azimuthal symmetry, such as the currently reported Princeton experiment (Wang &lt;jats:italic&gt;et al.&lt;/jats:italic&gt;, &lt;jats:italic&gt;Phys. Rev. Lett.&lt;/jats:italic&gt;, vol. 129, 115001), then also other players, including axial boundary effects, than the MRI-typical linear combination of current-free fields","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"8 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139555653","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}

{"title":"On hydromagnetic wave interactions in collisionless, high-β plasmas","authors":"S. Majeski, M.W. Kunz","doi":"10.1017/s0022377823001435","DOIUrl":"https://doi.org/10.1017/s0022377823001435","url":null,"abstract":"<p>We describe the interaction of parallel-propagating Alfvén waves with ion-acoustic waves and other Alfvén waves, in magnetized, high-<span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240118175605382-0650:S0022377823001435:S0022377823001435_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$beta$</span></span></img></span></span> collisionless plasmas. This is accomplished through a combination of analytical theory and numerical fluid simulations of the Chew–Goldberger–Low (CGL) magnetohydrodynamic (MHD) equations closed by Landau-fluid heat fluxes. An asymptotic ordering is employed to simplify the CGL-MHD equations and derive solutions for the deformation of an Alfvén wave that results from its interaction with the pressure anisotropy generated either by an ion-acoustic wave or another, larger-amplitude Alfvén wave. The difference in time scales of acoustic and Alfvénic fluctuations at high-<span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240118175605382-0650:S0022377823001435:S0022377823001435_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$beta$</span></span></img></span></span> means that interactions that are local in wavenumber space yield little modification to either mode within the time it takes the acoustic wave to Landau damp away. Instead, order-unity changes in the amplitude of Alfvénic fluctuations can result after interacting with frequency-matched acoustic waves. Additionally, we show that the propagation speed of an Alfvén-wave packet in an otherwise homogeneous background is a function of its self-generated pressure anisotropy. This allows for the eventual interaction of separate co-propagating Alfvén-wave packets of differing amplitudes. The results of the CGL-MHD simulations agree well with these predictions, suggesting that theoretical models relying on the interaction of these modes should be reconsidered in certain astrophysical environments. Applications of these results to weak Alfvénic turbulence and to the interaction between the compressive and Alfvénic cascades in strong, collisionless turbulence are also discussed.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"29 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500907","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}

{"title":"Development of the ambipolar electric field in a compressed current sheet and the impact on magnetic reconnection","authors":"Ami M. DuBois, Chris Crabtree, Gurudas Ganguli","doi":"10.1017/s0022377823001447","DOIUrl":"https://doi.org/10.1017/s0022377823001447","url":null,"abstract":"<p>Satellite data analysis of a compressed gyro-scale current sheet prior to magnetic reconnection in the magnetotail shows that electrostatic lower hybrid waves localized to the region of a transverse ambipolar electric field at the centre of the current sheet are driven by <span><span><span data-mathjax-type=\"texmath\"><span>$boldsymbol{E} times boldsymbol{B}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240118174804757-0379:S0022377823001447:S0022377823001447_inline1.png\"/></span></span> velocity shear and result from compression. The presence and location of shear-driven waves around the centre of the current sheet, where the magnetic field reverses and the density gradient is minimal, is consistent with our model. This is notable because the free energy source is the curvature of the electron <span><span><span data-mathjax-type=\"texmath\"><span>$boldsymbol{E} times boldsymbol{B}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240118174804757-0379:S0022377823001447:S0022377823001447_inline2.png\"/></span></span> flow and not the density gradient. Laboratory experiments and particle-in-cell (PIC) simulations have shown that shear-driven lower hybrid fluctuations are capable of producing anomalous cross-field transport (viscosity) and resistivity, which can trigger magnetic reconnection. We estimate the terms in the generalized Ohm's Law directly from MMS data as the spacecraft cross a gyro-scale current sheet. Our analysis shows that the wave effects (resistivity, diffusion and viscosity) and pressure anisotropy effects are comparable. We also find that the quasi-static electric field gradient is correlated with a non-gyrotropic electron distribution function, which is consistent with our model. Furthermore, theoretical arguments suggest agyrotropy is an indicator of the possibility for magnetic reconnection to occur.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"51 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500628","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}