Fundamental Plasma Physics最新文献

{"title":"Exact spherical vortex-type equilibrium flows in fluids and plasmas","authors":"Jason M. Keller,&nbsp;Alexei F. Cheviakov","doi":"10.1016/j.fpp.2024.100063","DOIUrl":"10.1016/j.fpp.2024.100063","url":null,"abstract":"<div><p>The famous Hill’s solution describing a spherical vortex with nested toroidal pressure surfaces, bounded by a sphere, propelling itself in an ideal Eulerian fluid, is re-derived using Galilei symmetry and the Bragg–Hawthorne equations in spherical coordinates. The correspondence between equilibrium Euler equations of fluid dynamics and static magnetohydrodynamic equations is used to derive a generalized vortex type solution that corresponds to dynamic fluid equilibria and static plasma equilibria with a nonzero azimuthal vector field component, satisfying physical boundary conditions. Separation of variables in Bragg–Hawthorne equation in spherical coordinates is used to construct further new fluid and plasma equilibria with nested toroidal flux surfaces, featuring respectively boundary vorticity sheets and current sheets. Finally, the instability of the original Hill’s vortex with respect to certain radial perturbations of the spherical flux surface is proven analytically and illustrated numerically.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"11 ","pages":"Article 100063"},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000281/pdfft?md5=48286a2083b13c041ea1a8a771cfbc8e&pid=1-s2.0-S2772828524000281-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141281043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Star formation across cosmic time","authors":"Jonathan Freundlich","doi":"10.1016/j.fpp.2024.100059","DOIUrl":"10.1016/j.fpp.2024.100059","url":null,"abstract":"<div><p>The interstellar medium of galaxies is composed of multiple phases, including molecular, atomic, and ionized gas, as well as dust. Stars are formed within this medium from cold molecular gas clouds, which collapse due to their gravitational attraction. Throughout their life, stars emit strong radiation fields and stellar winds, and they can also explode as supernovae at the end of their life. These processes contribute to stirring the turbulent interstellar medium and regulate star formation by heating up, ionizing, and expelling part of the gas. However, star formation does not proceed uniformly throughout the history of the Universe and decrease by an order of magnitude in the last ten billion years. To understand this winding-down of star formation and assess possible variations in the efficiency of star formation, it is crucial to probe the molecular gas reservoirs from which stars are formed. In this article following my presentation at the 10th International Conference on Frontiers of Plasma Physics and Technology held in Kathmandu from 13–17 March 2023, I review some aspects of the multiphase interstellar medium and star formation, with an emphasis on the interplay between neutral and ionized phases, and present recent and ongoing observations of the molecular gas content in typical star-forming galaxies across cosmic time and in different environments. I also present some of our understanding of star-forming galaxies from theoretical models and simulations.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"11 ","pages":"Article 100059"},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000244/pdfft?md5=f61269f2a2c88f17fb56be04dcb9479c&pid=1-s2.0-S2772828524000244-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141143542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generations of spiral laser beam, spiral electron beam and longitudinal magnetic fields in hole-boring","authors":"K. Mima ,&nbsp;M. Matys ,&nbsp;Y. Sentoku ,&nbsp;H. Nagatomo ,&nbsp;N. Iwata ,&nbsp;T.M. Jeong ,&nbsp;S.V. Bulanov","doi":"10.1016/j.fpp.2024.100057","DOIUrl":"10.1016/j.fpp.2024.100057","url":null,"abstract":"<div><p>The hole-boring by intense laser is one of the key issues for fast ignition laser fusion, laser radiation pressure ion acceleration, generation of high energy radiations, and so on. In the hole-boring, laser pulse propagation and generation of relativistic electrons and magnetic fields are critical phenomena. When the laser intensity is higher than <span><math><mrow><msup><mrow><mn>10</mn></mrow><mn>20</mn></msup><mspace></mspace><mi>W</mi><mo>/</mo><mi>c</mi><msup><mrow><mi>m</mi></mrow><mn>2</mn></msup></mrow></math></span> and <span><math><msub><mi>a</mi><mn>0</mn></msub></math></span> is larger than 10, the self-generated quasi-static magnetic fields reaches Giga Gauss to play important roles in the electron dynamics and the laser propagation. We explore the hole-boring by a linearly and a circularly polarized laser-pulses with the 3 dimensional (3D) PIC simulations. It is found that strong longitudinal magnetic fields are generated in front of the hole-boring driven by a circular polarization laser. The circularly polarized laser is converted into spiral electromagnetic waves which include both radially polarized wave and azimuthally polarized wave in the hole. The radially polarized spiral wave generates a spiral electron beam which induces the longitudinal magnetic field. Those spiral structure-formations are essentially 3D-phenomena which are investigated in details in the first time. The spiral structure-formations may play important roles in fast ignition, radiation pressure ion acceleration, and so on.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"11 ","pages":"Article 100057"},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000220/pdfft?md5=4d94ee98bc25c609f44f2d9af7054687&pid=1-s2.0-S2772828524000220-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141143673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel instabilities in counter-streaming nonabelian fluids","authors":"Subramanya Bhat K.N. ,&nbsp;Amita Das ,&nbsp;V. Ravishankar ,&nbsp;Bhooshan Paradkar","doi":"10.1016/j.fpp.2024.100056","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100056","url":null,"abstract":"<div><p>The dynamics of strongly interacting particles are governed by Yang–Mills (Y–M) theory, which is a natural generalization of Maxwell Electrodynamics (ED). Its quantized version is known as quantum chromodynamics (QCD) (Gross and Wilczek, 1973; Politzer, 1973; ’t Hooft, 1972<span>[1]</span>, <span>[2]</span>, <span>[3]</span>) and has been very well studied. Classical Y–M theory is proving to be equally interesting because of the central role it plays in describing the physics of quark–gluon plasma (QGP) — which was prevalent in the early universe and is also produced in relativistic heavy ion collision experiments. This calls for a systematic study of classical Y–M theories. A good insight into classical Y–M dynamics would be best obtained by comparing and contrasting the Y–M results with their ED counterparts. In this article, a beginning has been made by considering streaming instabilities in Y–M fluids. We find that in addition to analogues of ED instabilities, novel nonabelian modes arise, reflecting the inherent nonabelian nature of the interaction. The new modes exhibit propagation/ growth, with growth rates that can be larger than what we find in ED. Interestingly, we also find a mode that propagates without getting affected by the medium.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"11 ","pages":"Article 100056"},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000219/pdfft?md5=43e6ee4af48becb964c4eb56a6cc21bb&pid=1-s2.0-S2772828524000219-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141095082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gyrofluid simulations of turbulence and reconnection in space plasmas","authors":"T. Passot ,&nbsp;S.S. Cerri ,&nbsp;C. Granier ,&nbsp;D. Laveder ,&nbsp;P.L. Sulem ,&nbsp;E. Tassi","doi":"10.1016/j.fpp.2024.100055","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100055","url":null,"abstract":"<div><p>A Hamiltonian two-field gyrofluid model is used to investigate the dynamics of an electron-ion collisionless plasma subject to a strong ambient magnetic field, within a spectral range extending from the magnetohydrodynamic (MHD) scales to the electron skin depth. This model isolates Alfvén, Kinetic Alfvén and Inertial Kinetic Alfvén waves that play a central role in space plasmas, and extends standard reduced fluid models to broader ranges of the plasma parameters. Recent numerical results are reviewed, including (i) the reconnection-mediated MHD turbulence developing from the collision of counter-propagating Alfvén wave packets, (ii) the specific features of the cascade dynamics in strongly imbalanced turbulence, including a possible link between the existence of a spectral transition range and the presence of co-propagating wave interactions at sub-ion scales, for which new simulations are reported, (iii) the influence of the ion-to-electron temperature ratio in two-dimensional collisionless magnetic reconnection. The role of electron finite Larmor radius corrections is pointed out and the extension of the present model to a four-field gyrofluid model is discussed. Such an extended model accurately describes electron finite Larmor radius effects at small or moderate values of the electron beta parameter, and also retains the coupling to slow magnetosonic waves.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"11 ","pages":"Article 100055"},"PeriodicalIF":0.0,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000207/pdfft?md5=032438d03b2ba4566b39a6340ff88931&pid=1-s2.0-S2772828524000207-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141084643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface modification of polymers by 50 Hz dielectric barrier discharge (DBD) plasma produced in air at 40 Torr","authors":"Deepak Prasad Subedi,&nbsp;Rajesh Prakash Guragain,&nbsp;Ujjwal Man Joshi","doi":"10.1016/j.fpp.2024.100058","DOIUrl":"10.1016/j.fpp.2024.100058","url":null,"abstract":"<div><p>This study deals with the surface modification of polymer films utilizing a custom designed cost- effective dielectric barrier discharge (DBD) plasma produced in air at reduced pressure. We comprehensively examine diverse aspects of surface modification, encompassing electrical discharge characterization, optical signal analysis, contact angle measurements, and surface morphology assessment. Our observations unveiled the presence of distinctive filamentary streamer-based micro-discharges during the DBD process, with a power consumption of approximately 5.64 W and an electron density of 3.4 × 10¹¹ cm⁻³. Optical emission spectroscopy identifies multiple emission peaks attributed to nitrogen emissions. Notably, plasma treatment substantially reduced the water contact angle and augmented surface energy on polypropylene (PP) and polyethylene terephthalate (PET) films. Surface morphology analysis illustrated an increase in surface roughness following plasma treatment. Intriguingly, the initial rapid alterations in wettability and surface morphology attained equilibrium after approximately 30 s of treatment. This study highlights atmospheric DBD plasma's effectiveness in customizing polymer surfaces, improving wettability and roughness, offering promising applications for enhanced adhesion and wetting.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"10 ","pages":"Article 100058"},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000232/pdfft?md5=812df3a553b453a87a7c8e3cdfd72b78&pid=1-s2.0-S2772828524000232-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141048877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A collision operator for describing dissipation in noncanonical phase space","authors":"Naoki Sato ,&nbsp;Philip J. Morrison","doi":"10.1016/j.fpp.2024.100054","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100054","url":null,"abstract":"<div><p>The phase space of a noncanonical Hamiltonian system is partially inaccessible due to dynamical constraints (Casimir invariants) arising from the kernel of the Poisson tensor. When an ensemble of noncanonical Hamiltonian systems is allowed to interact, dissipative processes eventually break the phase space constraints, resulting in a thermodynamic equilibrium described by a Maxwell–Boltzmann distribution. However, the time scale required to reach Maxwell–Boltzmann statistics is often much longer than the time scale over which a given system achieves a state of thermal equilibrium. Examples include diffusion in rigid mechanical systems, as well as collisionless relaxation in magnetized plasmas and stellar systems, where the interval between binary Coulomb or gravitational collisions can be longer than the time scale over which stable structures are self-organized. Here, we focus on self-organizing phenomena over spacetime scales such that particle interactions respect the noncanonical Hamiltonian structure, but yet act to create a state of thermodynamic equilibrium. We derive a collision operator for general noncanonical Hamiltonian systems, applicable to fast, localized interactions. This collision operator depends on the interaction exchanged by colliding particles and on the Poisson tensor encoding the noncanonical phase space structure, is consistent with entropy growth and conservation of particle number and energy, preserves the interior Casimir invariants, reduces to the Landau collision operator in the limit of grazing binary Coulomb collisions in canonical phase space, and exhibits a metriplectic structure. We further show how thermodynamic equilibria depart from Maxwell–Boltzmann statistics due to the noncanonical phase space structure, and how self-organization and collisionless relaxation in magnetized plasmas and stellar systems can be described through the derived collision operator.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"10 ","pages":"Article 100054"},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000190/pdfft?md5=dd0047a8bebbf536e73a46a63ba0ed47&pid=1-s2.0-S2772828524000190-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140951241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model expressions for refractive indices of electron waves in cold magnetoactive plasma of arbitrary density","authors":"D.R. Shklyar ,&nbsp;N.S. Artekha","doi":"10.1016/j.fpp.2024.100053","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100053","url":null,"abstract":"<div><p>Despite the undoubted importance of having fairly simple analytical expressions for the refractive indices of wave modes in a magnetoactive plasma, such expressions are known only in some particular cases. For electron waves with frequencies much higher than the lower hybrid resonance frequency, such an expression is known only for whistler waves in a dense plasma when the electron plasma frequency significantly exceeds the electron cyclotron frequency. In this Letter, we propose simple operational expressions for the refractive indices of all four electron modes in a magnetoactive plasma, namely, the fast magnetosonic, also called whistler mode, the slow extraordinary mode, the ordinary mode, and the fast extraordinary mode. The form of these expressions does not depend on the value of the ratio of plasma frequency to cyclotron frequency.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"10 ","pages":"Article 100053"},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000189/pdfft?md5=cfce0ca354cae85e7af3b6727d940f9a&pid=1-s2.0-S2772828524000189-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140901363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasma wave propagation conditions analysis using the warm multi-fluid model","authors":"Huasheng Xie ,&nbsp;Haojie Ma ,&nbsp;Yukun Bai","doi":"10.1016/j.fpp.2024.100050","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100050","url":null,"abstract":"<div><p>Although an accurate description of wave propagation and absorption in plasmas requires complicated full-wave solutions or kinetic simulations, local dispersion analysis can still be helpful to capture the main physics of wave properties. Plasma wave propagation conditions or accessibility informs whether a wave can propagate to a region, which usually depends on the wave frequency, wave vector, the local plasma density, and magnetic field. We demonstrate a warm multi-fluid eigenvalue model and a matrix approach to rapidly calculate plasma wave accessibility diagrams, where thermal effects are also included via an isotropic pressure term. All cold plasma waves, from high-frequency electron cyclotron waves, intermediate-frequency lower hybrid waves, to low-frequency ion cyclotron waves, are presented. By comparing with the kinetic model, it is interesting to find that the warm multi-fluid model, though incapable of reproducing the Bernstein modes, can provide a quick way to determine whether thermal effects are important.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"10 ","pages":"Article 100050"},"PeriodicalIF":0.0,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000153/pdfft?md5=e7df8ca765e52eb87ab1b02c3084e6b4&pid=1-s2.0-S2772828524000153-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140807850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prospects of negative triangularity tokamak for advanced steady-state confinement of fusion plasmas in MHD stability consideration","authors":"Linjin Zheng,&nbsp;M.T. Kotschenreuther,&nbsp;F.L. Waelbroeck,&nbsp;M.E. Austin,&nbsp;W.L. Rowan,&nbsp;P. Valanju,&nbsp;X. Liu","doi":"10.1016/j.fpp.2024.100051","DOIUrl":"https://doi.org/10.1016/j.fpp.2024.100051","url":null,"abstract":"<div><p>The steady-state confinement, beta limit, and divertor heat load are among the most concerned issues for toroidal confinement of fusion plasmas. In this work, we show that the negative triangularity tokamak has promising prospects to address these issues. We first demonstrate that the negative triangularity tokamak generates the filed line rotation transform more effectively. This brings bright prospects for the advanced steady-state tokamak scenario. Given this, the MHD stability and equilibrium confinement of negative triangularity tokamak are investigated. We point out that the negative triangularity configuration with a broad pressure profile is indeed more unstable for low-<span><math><mi>n</mi></math></span> magnetohydrodynamic modes than the positive triangularity case so that the H-mode confinement can hardly be achieved in this configuration, where <span><math><mi>n</mi></math></span> is the toroidal mode number. Nevertheless, we found that the negative triangularity configuration with high bootstrap current fraction, high poloidal beta, and peaked pressure profiles can achieve higher normalized beta for low-<span><math><mi>n</mi></math></span> modes than the positive triangularity case. In a certain parameter domain, the normalized beta can reach about twice the extended Troyon limit, while the same computation indicates that the positive triangularity configuration is indeed constrained by the Troyon limit. This shows that the negative triangularity tokamaks are not only favorable for divertor design to avoid the edge localized modes but also can have promising prospects for advanced steady-state confinement of fusion plasmas in high beta.</p></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"10 ","pages":"Article 100051"},"PeriodicalIF":0.0,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772828524000165/pdfft?md5=7226485704d08552a46a853c6c20fd6c&pid=1-s2.0-S2772828524000165-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140821979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}