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  • Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption
    J. Plasma Phys. (IF 2.238) Pub Date : 2021-01-22
    M. Hoppe; L. Hesslow; O. Embreus; L. Unnerfelt; G. Papp; I. Pusztai; T. Fülöp; O. Lexell; T. Lunt; E. Macusova; P. J. McCarthy; G. Pautasso; G. I. Pokol; G. Por; P. Svensson; the ASDEX Upgrade team; the EUROfusion MST1 team

    Synchrotron radiation images from runaway electrons (REs) in an ASDEX Upgrade discharge disrupted by argon injection are analysed using the synchrotron diagnostic tool Soft and coupled fluid-kinetic simulations. We show that the evolution of the runaway distribution is well described by an initial hot-tail seed population, which is accelerated to energies between 25–50 MeV during the current quench

    更新日期:2021-01-22
  • Analytical calculation of the orbital spectrum of the guiding centre motion in axisymmetric magnetic fields
    J. Plasma Phys. (IF 2.238) Pub Date : 2021-01-20
    Yannis Antonenas; Giorgos Anastassiou; Yannis Kominis

    Charged particle motion in axisymmetric toroidal magnetic fields is analysed within the context of the canonical Hamiltonian guiding centre theory. A canonical transformation to variables measuring the drift orbit deviation from a magnetic field line is introduced and an analytical transformation to action-angle variables is obtained, under a zero drift width approximation. The latter is used to provide

    更新日期:2021-01-20
  • Formation of transient high-β plasmas in a magnetized, weakly collisional regime
    J. Plasma Phys. (IF 2.238) Pub Date : 2021-01-20
    T. Byvank; D. A. Endrizzi; C. B. Forest; S. J. Langendorf; K. J. McCollam; S. C. Hsu

    We present experimental data providing evidence for the formation of transient (${\sim }20\ \mathrm {\mu }\textrm {s}$) plasmas that are simultaneously weakly magnetized (i.e. Hall magnetization parameter $\omega \tau > 1$) and dominated by thermal pressure (i.e. ratio of thermal-to-magnetic pressure $\beta > 1$). Particle collisional mean free paths are an appreciable fraction of the overall system

    更新日期:2021-01-20
  • Modelling effects of edge density fluctuations on electron-cyclotron current drive used for neoclassical tearing mode stabilization
    J. Plasma Phys. (IF 2.238) Pub Date : 2021-01-14
    C. Tsironis; P. Papagiannis; F. Bairaktaris; S. I. Valvis; K. Hizanidis

    In this work we study the undesired effects of electron density fluctuations (in the form of blob structures which may exist in the edge region of tokamak plasmas) to the electron-cyclotron wave propagation and current drive in connection to the efficiency of neoclassical tearing mode stabilization. Our model involves the evaluation of the driven current in the presence of density perturbations, by

    更新日期:2021-01-14
  • Plasma sheath and presheath development near a partially reflective surface
    J. Plasma Phys. (IF 2.238) Pub Date : 2021-01-13
    Boris N. Breizman; Dmitrii I. Kiramov

    This work addresses one-dimensional evolution of a collisionless plasma next to a solid surface that is immersed into the plasma instantaneously. In particular, we consider how the self-similar rarefaction wave (Allen & Andrews, J. Plasma Phys., vol. 4, 1970, pp. 187–194) establishes dynamically and how the electron reflection from the surface modifies the structure of the rarefaction wave and the

    更新日期:2021-01-13
  • An Alfvenic reconnecting plasmoid thruster
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-21
    Fatima Ebrahimi

    A new concept for the generation of thrust for space propulsion is introduced. Energetic thrust is generated in the form of plasmoids (confined plasma in closed magnetic loops) when magnetic helicity (linked magnetic field lines) is injected into an annular channel. Using a novel configuration of static electric and magnetic fields, the concept utilizes a current-sheet instability to spontaneously

    更新日期:2020-12-21
  • A new frontier in laboratory physics: magnetized electron–positron plasmas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-18
    M. R. Stoneking; T. Sunn Pedersen; P. Helander; H. Chen; U. Hergenhahn; E. V. Stenson; G. Fiksel; J. von der Linden; H. Saitoh; C. M. Surko; J. R. Danielson; C. Hugenschmidt; J. Horn-Stanja; A. Mishchenko; D. Kennedy; A. Deller; A. Card; S. Nißl; M. Singer; M. Singer; S. König; L. Willingale; J. Peebles; M. R. Edwards; K. Chin

    We describe here efforts to create and study magnetized electron–positron pair plasmas, the existence of which in astrophysical environments is well-established. Laboratory incarnations of such systems are becoming ever more possible due to novel approaches and techniques in plasma, beam and laser physics. Traditional magnetized plasmas studied to date, both in nature and in the laboratory, exhibit

    更新日期:2020-12-18
  • Slice collective dynamics, projected emittance deterioration and free electron laser performances detrimental effects
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-16
    G. Dattoli; S. Di Mitri; F. Nguyen; A. Petralia

    Self-amplified spontaneous emission (SASE) free electron laser (FEL) devices have disclosed an unexpected interplay between the laser intensity growth and regions of the electron bunch of the order of the coherence length. They are usually identified with the bunch slice and contribute to the laser dynamics with their own characteristics. The dynamical effects inducing geometrical and phase space misalignment

    更新日期:2020-12-18
  • Onset of fast magnetic reconnection and particle energization in laboratory and space plasmas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-01
    F. Pucci; M. Velli; C. Shi; K. A. P. Singh; A. Tenerani; F. Alladio; F. Ambrosino; P. Buratti; W. Fox; J. Jara-Almonte; H. Ji; M. Yamada; J. Yoo; S. Okamura; R. Ergun; S. Hoilijoki; S. Schwartz

    The onset of magnetic reconnection in space, astrophysical and laboratory plasmas is reviewed discussing results from theory, numerical simulations and observations. After a brief introduction on magnetic reconnection and approach to the question of onset, we first discuss recent theoretical models and numerical simulations, followed by observations of reconnection and its effects in space and astrophysical

    更新日期:2020-12-18
  • Anomalous diffusion across a tera-Gauss magnetic field in accreting neutron stars
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-06
    Russell M. Kulsrud; Rashid Sunyaev

    When mass falls on the polar regions of a neutron star in a binary X-ray source system, it tends to spread out over the entire surface. A long-standing question in research on this problem is: will the mass be anchored on the magnetic field lines and drag the field with it or is there a special mechanism that allows the mass to slip through the magnetic field lines, leading to much less distortion

    更新日期:2020-12-18
  • General formulas for adiabatic invariants in nearly periodic Hamiltonian systems
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-17
    J. W. Burby; J. Squire

    While it is well known that every nearly periodic Hamiltonian system possesses an adiabatic invariant, extant methods for computing terms in the adiabatic invariant series are inefficient. The most popular method involves the heavy intermediate calculation of a non-unique near-identity coordinate transformation, even though the adiabatic invariant itself is a uniquely defined scalar. A less well-known

    更新日期:2020-12-18
  • Stabilisation of short-wavelength instabilities by parallel-to-the-field shear in long-wavelength E × B flows
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-09
    M. R. Hardman; M. Barnes; C. M. Roach

    Magnetised plasma turbulence can have a multiscale character: instabilities driven by mean temperature gradients drive turbulence at the disparate scales of the ion and the electron gyroradii. Simulations of multiscale turbulence, using equations valid in the limit of infinite scale separation, reveal novel cross-scale interaction mechanisms in these plasmas. In the case that both long-wavelength

    更新日期:2020-12-18
  • Analytical studies of PROTO-SPHERA equilibria
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-26
    P. Buratti; B. Tirozzi; F. Alladio; P. Micozzi

    Analytical solutions of the Grad–Shafranov equilibrium equation in simply connected plasma configurations, comprised of toroidal magnetic surfaces and open surfaces connected to electrodes, are reviewed and generalised. The Grad–Shafranov equation is linearised introducing assumptions on plasma current and pressure, which preserve regularity of solutions on the symmetry axis, as required for a simply

    更新日期:2020-12-18
  • Optimized phasing conditions to avoid edge mode excitation by ICRH antennas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-03
    V. Maquet; A. Messiaen

    An ion cyclotron resonance heating (ICRH) antenna system must launch radio frequency (RF) power with a wavenumber spectrum which maximizes the coupling to the plasma. It should also ensure good absorption while minimizing the wave interaction with the plasma edge. Such interactions lead to impurity release, whose effect has been measured far from the antenna location (Klepper et al. 2013; Wukitch et

    更新日期:2020-12-18
  • Self-sustaining sound in collisionless, high-β plasma
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-09
    M. W. Kunz; J. Squire; A. A. Schekochihin; E. Quataert

    Using analytical theory and hybrid-kinetic numerical simulations, we demonstrate that, in a collisionless plasma, long-wavelength ion-acoustic waves (IAWs) with amplitudes $\delta n/n_0 \gtrsim 2/\beta$ (where $\beta \gg {1}$ is the ratio of thermal to magnetic pressure) generate sufficient pressure anisotropy to destabilize the plasma to firehose and mirror instabilities. These kinetic instabilities

    更新日期:2020-12-18
  • Chaos in positive ion–negative ion magnetized plasmas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-09
    Samiran Ghosh; Biplab Maity; Swarup Poria

    The dynamical behaviour of weakly nonlinear, low-frequency sound waves are investigated in a plasma composed of only positive and negative ions incorporating the effects of a weak external uniform magnetic field. In the plasma model the mass (temperature) of the positive ions is smaller (larger) than that of the negative ions. The dynamics of the nonlinear wave is shown to be governed by a novel nonlinear

    更新日期:2020-12-18
  • Simulations of ion–dust streaming instability in a highly collisional plasma
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-13
    K. Quest; M. Rosenberg; A. Levine

    The excitation of low frequency dust acoustic (or dust density) waves in a dusty plasma can be driven by the flow of ions relative to dust. We consider the nonlinear development of the ion–dust streaming instability in a highly collisional plasma, where the ion and dust collision frequencies are a significant fraction of their corresponding plasma frequencies. This collisional parameter regime may

    更新日期:2020-12-18
  • Spontaneous formation of coherent structures by an intense laser pulse interacting with overdense plasma
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-13
    Devshree Mandal; Ayushi Vashistha; Amita Das

    The formation and the dynamics of coherent magnetic field structures in the context of laser plasma interaction has attracted considerable attention. In the literature the formation of these structures has, however, mostly been reported in the wake of a laser pulse propagating in an underdense plasma medium (Bulanov et al., Phys. Rev. Lett., vol. 76, 1996, pp. 3562–3565; Nakamura & Mima Phys. Rev.

    更新日期:2020-12-18
  • Properties of toroidal magnetic fields in axial plasma flow on the PF-1000U plasma focus facility
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-16
    V. I. Krauz; K. N. Mitrofanov; M. Paduch; K. Tomaszewski; A. Szymaszek; E. Zielinska; V. I. Pariev; V. S. Beskin; Ya. N. Istomin

    This paper presents the results of studies of plasma flow parameters on the PF-1000U facility. A distinctive feature of this facility is the ability to create profiled initial gas distributions using gas puffs. In the experiments described, a combined system for filling the vacuum chamber with a working gas was used, in which an additional injection of various gases (deuterium, helium, neon and their

    更新日期:2020-12-18
  • Enhanced laser-driven proton acceleration with gas–foil targets
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-19
    Dan Levy; X. Davoine; A. Debayle; L. Gremillet; V. Malka

    We study numerically the mechanisms of proton acceleration in gas–foil targets driven by an ultraintense femtosecond laser pulse. The target consists of a near-critical-density hydrogen gas layer of a few tens of microns attached to a $2\ \mathrm {\mu }$ m-thick solid carbon foil with a contaminant thin proton layer at its back side. Two-dimensional particle-in-cell simulations show that, at optimal

    更新日期:2020-12-18
  • Self-magnetic insulation in plasma opening switches
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-01
    Sergey V. Loginov

    The paper analyses the penetration of a magnetic field into the plasma bridge of nanosecond and microsecond opening switches. For switches with a conduction time of ~100 ns, simple formulae are derived to estimate the magnetic field velocity in collisionless and collisional plasmas. It is shown that in both cases this velocity is determined by the magnetic field rise rate to plasma density ratio raised

    更新日期:2020-12-18
  • Dependence of fishbone cycle on energetic particle intensity in EAST low-magnetic-shear plasmas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-10
    Xiang Zhu; Long Zeng; Zhiyong Qiu; Baolong Hao; Wei Shen; Xiang Gu; Muquan Wu; Tian Tang; Jinping Qian; Haiqing Liu; Di Jiang; Liqing Xu; Jizong Zhang; Yong Liu; Qing Zang; Yinxian Jie; Xiang Gao; Xiaodong Lin

    The dependence of fishbone cycle on energetic particle intensity has been investigated in EAST low-magnetic-shear plasmas. It is observed that the fishbone mode growth rate, saturation amplitude as well as fishbone cycle frequency clearly increase with increasing neutral beam injection (NBI) power. Moreover, enhanced electron density and temperature perturbations as well as energetic particle loss

    更新日期:2020-12-18
  • Stability and evolution of electromagnetic solitons in relativistic degenerate laser plasmas
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-10
    Sima Roy; A. P. Misra

    The dynamical behaviours of electromagnetic (EM) solitons formed due to nonlinear interaction of linearly polarized intense laser light and relativistic degenerate plasmas are studied. In the slow-motion approximation of relativistic dynamics, the evolution of weakly nonlinear EM envelope is described by the generalized nonlinear Schrödinger (GNLS) equation with local and nonlocal nonlinearities. Using

    更新日期:2020-12-18
  • Propagation of shear Alfvén waves in a two-ion plasma and application as a diagnostic for the ion density ratio
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-12-15
    J. Robertson; T. A. Carter; S. Vincena

    In this paper, we propose an efficient diagnostic technique for determining spatially resolved measurements of the ion density ratio in a magnetized two-ion species plasma. Shear Alfvén waves were injected into a mixed helium–neon plasma using a magnetic loop antenna, for frequencies spanning the ion cyclotron regime. Two distinct propagation bands are observed, bounded by $\omega < \varOmega _\textrm

    更新日期:2020-12-18
  • Hybrid simulation of NBI fast-ion losses due to the Alfvén eigenmode bursts in the Large Helical Device and the comparison with the fast-ion loss detector measurements
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-11-03
    R. Seki; Y. Todo; Y. Suzuki; K. Ogawa; M. Isobe; D. A. Spong; M. Osakabe

    The multiphase simulations are conducted with the kinetic-magnetohydrodynamics hybrid code MEGA to investigate the spatial and the velocity distributions of lost fast ions due to the Alfvén eigenmode (AE) bursts in the Large Helical Device plasmas. It is found that fast ions are lost along the divertor region with helical symmetry both before and during the AE burst except for the promptly lost particles

    更新日期:2020-11-03
  • Kinetic entropy-based measures of distribution function non-Maxwellianity: theory and simulations
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-21
    Haoming Liang; M. Hasan Barbhuiya; P. A. Cassak; O. Pezzi; S. Servidio; F. Valentini; G. P. Zank

    We investigate kinetic entropy-based measures of the non-Maxwellianity of distribution functions in plasmas, i.e. entropy-based measures of the departure of a local distribution function from an associated Maxwellian distribution function with the same density, bulk flow and temperature as the local distribution. First, we consider a form previously employed by Kaufmann & Paterson (J. Geophys. Res

    更新日期:2020-10-30
  • Contributions to the linear and nonlinear theory of the beam–plasma interaction
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-22
    Nakia Carlevaro; Matteo Del Prete; Giovanni Montani; Fabio Squillaci

    We focus our attention on some relevant aspects of the beam–plasma instability in order to refine some features of the linear and nonlinear dynamics. After a re-analysis of the Poisson equation and of the assumption dealing with the background plasma in the form of a linear dielectric, we study the non-perturbative properties of the linear dispersion relation, showing the necessity for a better characterization

    更新日期:2020-10-30
  • Thermodynamic processes in dusty plasma
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-23
    K. Avinash

    Here, we propose a thermodynamic model for dusty plasma, where the dust is confined in a small volume within a large plasma background by external fields. In this model, the parameters of dust, e.g. Helmholtz energy, pressure, entropy and enthalpy, etc. can be calculated for given dust density and temperature. The model is solved analytically in the mean field (gaseous) limit and various processes

    更新日期:2020-10-30
  • Zonally dominated dynamics and Dimits threshold in curvature-driven ITG turbulence
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-27
    Plamen G. Ivanov; A. A. Schekochihin; W. Dorland; A. R. Field; F. I. Parra

    The saturated state of turbulence driven by the ion-temperature-gradient instability is investigated using a two-dimensional long-wavelength fluid model that describes the perturbed electrostatic potential and perturbed ion temperature in a magnetic field with constant curvature (a $Z$ -pinch) and an equilibrium temperature gradient. Numerical simulations reveal a well-defined transition between a

    更新日期:2020-10-30
  • Multidimensional Iterative Filtering: a new approach for investigating plasma turbulence in numerical simulations
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-21
    Emanuele Papini; Antonio Cicone; Mirko Piersanti; Luca Franci; Petr Hellinger; Simone Landi; Andrea Verdini

    Turbulent space and astrophysical plasmas exhibit a complex dynamics, which involves nonlinear coupling across different temporal and spatial scales. There is growing evidence that impulsive events, such as magnetic reconnection instabilities, lead to a spatially localized enhancement of energy dissipation, thus speeding up the energy transfer at small scales. Capturing such a diverse dynamics is challenging

    更新日期:2020-10-30
  • Preliminary experimental scaling of the helical mirror confinement effectiveness
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-21
    Anton V. Sudnikov; Aleksey D. Beklemishev; Anna A. Inzhevatkina; Ivan A. Ivanov; Vladimir V. Postupaev; Aleksandr V. Burdakov; Vladimir V. Glinskiy; Konstantin N. Kuklin; Andrey F. Rovenskikh; Viktor O. Ustyuzhanin

    The paper presents experimental results from the SMOLA device that is the first facility with a helical mirror section of the magnetic field. This device is built in the Budker Institute of Nuclear Physics for the verification of the helical mirror confinement idea that is the recently introduced technique of the active control of axial losses from a confinement zone. Theory predicts that with rotating

    更新日期:2020-10-30
  • Compton scattering in particle-in-cell codes
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-27
    F. Del Gaudio; T. Grismayer; R. A. Fonseca; L. O. Silva

    We present a Monte Carlo collisional scheme that models single Compton scattering between leptons and photons in particle-in-cell codes. The numerical implementation of Compton scattering can deal with macro-particles of different weights and conserves momentum and energy in each collision. Our scheme is validated through two benchmarks for which exact analytical solutions exist: the inverse Compton

    更新日期:2020-10-30
  • First experiments on ICRF discharge generation by a W7-X-like antenna in the Uragan-2M stellarator
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-28
    V. E. Moiseenko; Yu. V. Kovtun; T. Wauters; A. Goriaev; A. I. Lyssoivan; A. V. Lozin; R. O. Pavlichenko; A. N. Shapoval; S. M. Maznichenko; V. B. Korovin; E. D. Kramskoy; M. M. Kozulya; N. V. Zamanov; Y. V. Siusko; A. Yu. Krasiuk; V. S. Romanov; A. Alonso; R. Brakel; A. Dinklage; D. Hartmann; Ye. Kazakov; H. Laqua; J. Ongena; T. Stange; the Uragan-2M Team

    In support of the ICRF experiments planned on the Wendelstein 7-X (W7-X) stellarator, i.e. fast ion generation, wall conditioning, target plasma production and heating, a first experimental study on plasma production has been made in the Uragan-2M (U-2M) stellarator using W7-X-like two-strap antenna. In all the experiments, antenna monopole phasing was used. The W7-X-like antenna operation with launched

    更新日期:2020-10-30
  • Unitary quantum lattice simulations for Maxwell equations in vacuum and in dielectric media
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-28
    George Vahala; Linda Vahala; Min Soe; Abhay K. Ram

    Utilizing the similarity between the spinor representation of the Dirac and the Maxwell equations that has been recognized since the early days of relativistic quantum mechanics, a quantum lattice algorithm (QLA) representation of unitary collision-stream operators of Maxwell's equations is derived for both homogeneous and inhomogeneous media. A second-order accurate 4-spinor scheme is developed and

    更新日期:2020-10-30
  • Comparison between mirror Langmuir probe and gas-puff imaging measurements of intermittent fluctuations in the Alcator C-Mod scrape-off layer
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-30
    R. Kube; A. Theodorsen; O. E. Garcia; D. Brunner; B. LaBombard; J. L. Terry

    Statistical properties of the scrape-off layer plasma fluctuations are studied in ohmically heated plasmas in the Alcator C-Mod tokamak. For the first time, plasma fluctuations as well as parameters that describe the fluctuations are compared across measurements from a mirror Langmuir probe (MLP) and from gas-puff imaging (GPI) that sample the same plasma discharge. This comparison is complemented

    更新日期:2020-10-30
  • Non-planar coil winding angle optimization for compatibility with non-insulated high-temperature superconducting magnets
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-20
    C. Paz-Soldan

    The rapidly emerging technology of high-temperature superconductors (HTS) opens new opportunities for the development of non-planar non-insulated HTS magnets. This type of HTS magnet offers attractive features via its simplicity and robustness, and is well suited for modest size steady-state applications such as a mid-scale stellarator. In non-planar coil applications the HTS tape may be subject to

    更新日期:2020-10-20
  • Non-resonant acceleration of charged particles driven by the associated effects of the radiation reaction
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-20
    F. Russman; I. Almansa; E. Peter; S. Marini; F. B. Rizzato

    In the present analysis, we study effects of the radiation reaction (RR) on the dynamics of charged particles submitted to the action of localized longitudinal high-frequency carriers travelling at the speed of light. As the wave's crests and troughs keep overtaking particles, dissipative RR forces tend to drag particles alongside the wave in an effort to reduce the relative wave–particle speed. Particles

    更新日期:2020-10-20
  • Stability of a tokamak plasma with diffuse toroidal rotation
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-20
    O. E. López; L. Guazzotto

    The present work considers the stability of a high- $\beta$ , large aspect ratio, circular plasma with diffuse profiles for the safety factor and the angular toroidal frequency (López & Guazzotto, Phys. Plasmas, vol. 24, 032501). An application of the Frieman–Rotenberg formalism results in a system of scalar eigenmode equations whose coupling is retained at the plasma–vacuum transition but is disregarded

    更新日期:2020-10-20
  • Spatial distributions of plasma parameters in conventional magnetron discharges in presence of nanoparticles
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-16
    A. Chami; C. Arnas

    Two-dimensional spatial measurements of magnetic field and plasma parameters have been performed in conventional magnetron DC discharges during the formation of metallic nanoparticles. Correlations between the electron density and temperature distributions, and the magnetic field geometry and strength have been established. A sharp increase of the plasma potential is found on the edge of the last magnetic

    更新日期:2020-10-17
  • Magnetic well and Mercier stability of stellarators near the magnetic axis
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-15
    Matt Landreman; Rogerio Jorge

    We have recently demonstrated that by expanding in small distance from the magnetic axis compared with the major radius, stellarator shapes with low neoclassical transport can be generated efficiently. To extend the utility of this new design approach, here we evaluate measures of magnetohydrodynamic interchange stability within the same expansion. In particular, we evaluate the magnetic well, Mercier's

    更新日期:2020-10-16
  • Elasticity of tangled magnetic fields
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-15
    D. N. Hosking; A. A. Schekochihin; S. A. Balbus

    The fundamental difference between incompressible ideal magnetohydrodynamics and the dynamics of a non-conducting fluid is that magnetic fields exert a tension force that opposes their bending; magnetic fields behave like elastic strings threading the fluid. It is natural, therefore, to expect that a magnetic field tangled at small length scales should resist a large-scale shear in an elastic way,

    更新日期:2020-10-16
  • Introduction of Zeeman splitting in CHIANTI
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-09
    M. Giarrusso; E. Landi; G. Del Zanna; F. Leone

    High-resolution spectra emitted by laboratory plasmas provide invaluable diagnostic tools for the measurement of plasma properties. To be implemented, they require a large amount of atomic data and transition rates, which are available in several spectral codes. In this paper we present a new feature added to the CHIANTI code, which allows us to calculate the Zeeman splitting of spectral lines in the

    更新日期:2020-10-11
  • Magnetic energy dissipation during the current quench of disruption in EAST
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-08
    T. Tang; L. Zeng; D. L. Chen; R. S. Granetz; S. T. Mao; Y. M. Duan; L. Zhang; H. D. Zhuang; X. Zhu; H. Q. Liu; B. Shen; Y. X. Jie; X. Gao

    A disruption database characterizing the current quench of disruptions with ITER-like tungsten divertor has been developed on EAST. It provides a large number of plasma parameters describing the predisruptive plasma, current quench time, eddy current, and mitigation by massive impurity injection, which shows that the current quench time strongly depends on magnetic energy and post-disruption electron

    更新日期:2020-10-08
  • Comparative study of the surface potential of magnetic and non-magnetic spherical objects in a magnetized radio-frequency discharge
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-05
    Mangilal Choudhary; Roman Bergert; Slobodan Mitic; Markus H. Thoma

    We report measurements of the time-averaged surface floating potential of magnetic and non-magnetic spherical probes (or large dust particles) immersed in a magnetized capacitively coupled discharge. In this study, the size of the spherical probes is taken greater than the Debye length. The surface potential of a spherical probe first increases, i.e. becomes more negative at low magnetic field ( $B

    更新日期:2020-10-05
  • Advancing the physics basis for quasi-helically symmetric stellarators
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-01
    A. Bader; B. J. Faber; J. C. Schmitt; D. T. Anderson; M. Drevlak; J. M. Duff; H. Frerichs; C. C. Hegna; T. G. Kruger; M. Landreman; I. J. McKinney; L. Singh; J. M. Schroeder; P. W. Terry; A. S. Ware

    A new optimized quasi-helically symmetric configuration is described that has the desirable properties of improved energetic particle confinement, reduced turbulent transport by three-dimensional shaping and non-resonant divertor capabilities. The configuration presented in this paper is explicitly optimized for quasi-helical symmetry, energetic particle confinement, neoclassical confinement and stability

    更新日期:2020-10-02
  • Implementation of fictitious absorbing layers with deceleration effects for one-dimensional Schrödinger equations
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-10-01
    Hitoshi Kanai; Tomo Tatsuno

    Absorbing boundary conditions or layers are used in simulations to reduce or eliminate wave reflections from the boundary; one of the most widely used absorbing layers is Berenger's perfectly matched layer (PML). In this paper, PML is extended to a compound absorbing layer which has multiple effects of damping and deceleration, and is applied to linear and nonlinear Schrödinger equations. The deceleration

    更新日期:2020-10-02
  • Progress on the small modular stellarator SCR-1: new diagnostics and heating scenarios – ERRATUM
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-30
    F. Coto-Vílchez; V. I. Vargas; R. Solano-Piedra; M. A. Rojas-Quesada; L. A. Araya-Solano; A. A. Ramírez; M. Hernández-Cisneros; J. E. Pérez-Hidalgo; A. Köhn-Seemann; F. Cerdas; F. Vílchez-Coto; D. Jiménez; L. Campos-Duarte; E. Meneses; M. González-Vega; S. Arias

    This work presents updates in the diagnostics systems, magnetohydrodynamics (MHD) calculations and simulations of microwave heating scenarios of the small modular Stellarator of Costa Rica 1 (SCR-1). Similarly, the design of a flexible bolometer and magnetic diagnostics (a set of Mirnov coils, Rogowski coils and two diamagnetic loops) are introduced. Furthermore, new MHD equilibrium calculations for

    更新日期:2020-09-30
  • Design, construction and utilization of a university plasma laboratory – ERRATUM
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-30
    W. Gekelman; P. Pribyl; Z. Lucky; S. W. Tang; J. Han; Y. Qian

    We present the elements required to construct two devices used in an undergraduate plasma physics laboratory. The materials and construction costs of the sources, the vacuum systems and probe drives and electrical circuits are presented in detail in the text and the first appendix. We also provide the software for probe motion and data acquisition as well as the electrical schematics for key components

    更新日期:2020-09-30
  • Overview of the SPARC tokamak
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    A. J. Creely; M. J. Greenwald; S. B. Ballinger; D. Brunner; J. Canik; J. Doody; T. Fülöp; D. T. Garnier; R. Granetz; T. K. Gray; C. Holland; N. T. Howard; J. W. Hughes; J. H. Irby; V. A. Izzo; G. J. Kramer; A. Q. Kuang; B. LaBombard; Y. Lin; B. Lipschultz; N. C. Logan; J. D. Lore; E. S. Marmar; K. Montes; R. T. Mumgaard; C. Paz-Soldan; C. Rea; M. L. Reinke; P. Rodriguez-Fernandez; K. Särkimäki; F.

    The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ( $B_0 = 12.2$ T), compact ( $R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks

    更新日期:2020-09-29
  • Predictions of core plasma performance for the SPARC tokamak
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    P. Rodriguez-Fernandez; N. T. Howard; M. J. Greenwald; A. J. Creely; J. W. Hughes; J. C. Wright; C. Holland; Y. Lin; F. Sciortino; the SPARC team

    SPARC is designed to be a high-field, medium-size tokamak aimed at achieving net energy gain with ion cyclotron range-of-frequencies (ICRF) as its primary auxiliary heating mechanism. Empirical predictions with conservative physics indicate that SPARC baseline plasmas would reach $Q\approx 11$ , which is well above its mission objective of $Q>2$ . To build confidence that SPARC will be successful,

    更新日期:2020-09-29
  • Projections of H-mode access and edge pedestal in the SPARC tokamak
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    J. W. Hughes; N. T. Howard; P. Rodriguez-Fernandez; A. J. Creely; A. Q. Kuang; P. B. Snyder; T. M. Wilks; R. Sweeney; M. Greenwald

    In order to inform core performance projections and divertor design, the baseline SPARC tokamak plasma discharge is evaluated for its expected H-mode access, pedestal pressure and edge-localized mode (ELM) characteristics. A clear window for H-mode access is predicted for full field DT plasmas, with the available 25 MW of design auxiliary power. Additional alpha heating is likely needed for H-mode

    更新日期:2020-09-29
  • Divertor heat flux challenge and mitigation in SPARC
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    A. Q. Kuang; S. Ballinger; D. Brunner; J. Canik; A. J. Creely; T. Gray; M. Greenwald; J. W. Hughes; J. Irby; B. LaBombard; B. Lipschultz; J. D. Lore; M. L. Reinke; J. L. Terry; M. Umansky; D. G. Whyte; S. Wukitch; the SPARC Team

    Owing to its high magnetic field, high power, and compact size, the SPARC experiment will operate with divertor conditions at or above those expected in reactor-class tokamaks. Power exhaust at this scale remains one of the key challenges for practical fusion energy. Based on empirical scalings, the peak unmitigated divertor parallel heat flux is projected to be greater than 10 GW m−2. This is nearly

    更新日期:2020-09-29
  • Physics basis for the ICRF system of the SPARC tokamak
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    Y. Lin; J. C. Wright; S. J. Wukitch

    Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary heating method on SPARC for both full-field (Bt0 ~ 12 T) D–T operation and reduced field (Bt0 ~ 8 T) D–D operation. Using the fast wave at ~120 MHz, good wave penetration and strong single-pass absorption is expected for D–T(3He), D(3He), D(H) and 4He(H) heating scenarios. The dependences of wave absorption on ${k_\parallel

    更新日期:2020-09-29
  • MHD stability and disruptions in the SPARC tokamak
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    R. Sweeney; A. J. Creely; J. Doody; T. Fülöp; D. T. Garnier; R. Granetz; M. Greenwald; L. Hesslow; J. Irby; V. A. Izzo; R. J. La Haye; N. C. Logan; K. Montes; C. Paz-Soldan; C. Rea; R. A. Tinguely; O. Vallhagen; J. Zhu

    SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$ , a normalized density of $n_G=0.37$ and a safety factor of $q_{95}\approx 3.4$ , providing a comfortable margin to their respective disruption limits. Further, a low beta poloidal $\beta _p=0.19$ at the safety factor $q=2$ surface reduces the drive for neoclassical tearing modes, which together with a frozen-in classically

    更新日期:2020-09-29
  • Fast-ion physics in SPARC
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    S. D. Scott; G. J. Kramer; E. A. Tolman; A. Snicker; J. Varje; K. Särkimäki; J. C. Wright; P. Rodriguez-Fernandez

    Potential loss of energetic ions including alphas and radio-frequency tail ions due to classical orbit effects and magnetohydrodynamic instabilities (MHD) are central physics issues in the design and experimental physics programme of the SPARC tokamak. The expected loss of fusion alpha power due to ripple-induced transport is computed for the SPARC tokamak design by the ASCOT and SPIRAL orbit-simulation

    更新日期:2020-09-29
  • Effects of oblique incidence and colliding pulses on laser-driven proton acceleration from relativistically transparent ultrathin targets
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-29
    J. Ferri; E. Siminos; L. Gremillet; T. Fülöp

    The use of ultrathin solid foils offers optimal conditions for accelerating protons to high energies from laser–matter interactions. When the target is thin enough that relativistic self-induced transparency sets in, all of the target electrons get heated to high energies by the laser, which maximizes the accelerating electric field and therefore the final ion energy. In this work, we first investigate

    更新日期:2020-09-29
  • How eigenmode self-interaction affects zonal flows and convergence of tokamak core turbulence with toroidal system size
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-28
    Ajay C. J.; Stephan Brunner; Ben McMillan; Justin Ball; Julien Dominski; Gabriele Merlo

    Self-interaction is the process by which a microinstability eigenmode that is extended along the direction parallel to the magnetic field interacts non-linearly with itself. This effect is particularly significant in gyrokinetic simulations accounting for kinetic passing electron dynamics and is known to generate stationary $E\times B$ zonal flow shear layers at radial locations near low-order mode

    更新日期:2020-09-28
  • A class of three-dimensional gyroviscous magnetohydrodynamic models
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-22
    Manasvi Lingam; Philip J. Morrison; Alexander Wurm

    A Hamiltonian and action principle formalism for deriving three-dimensional gyroviscous magnetohydrodynamic models is presented. The uniqueness of the approach in constructing the gyroviscous tensor from first principles and its ability to explain the origin of the gyromap and the gyroviscous terms are highlighted. The procedure allows for the specification of free functions, which can be used to generate

    更新日期:2020-09-22
  • Fluctuation dynamo in a weakly collisional plasma
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-22
    D. A. St-Onge; M. W. Kunz; J. Squire; A. A. Schekochihin

    The turbulent amplification of cosmic magnetic fields depends upon the material properties of the host plasma. In many hot, dilute astrophysical systems, such as the intracluster medium (ICM) of galaxy clusters, the rarity of particle–particle collisions allows departures from local thermodynamic equilibrium. These departures – pressure anisotropies – exert anisotropic viscous stresses on the plasma

    更新日期:2020-09-22
  • Nonlinear gyrokinetic PIC simulations in stellarators with the code EUTERPE
    J. Plasma Phys. (IF 2.238) Pub Date : 2020-09-17
    E. Sánchez; A. Mishchenko; J. M. García-Regaña; R. Kleiber; A. Bottino; L. Villard; the W7-X team

    In this work, the first nonlinear particle-in-cell simulations carried out in a stellarator with the global gyrokinetic code EUTERPE using adiabatic electrons and realistic plasma parameters are reported. Several studies are conducted with the aim of enabling reliable nonlinear simulations in stellarators with this code. First, EUTERPE is benchmarked against ORB5 in both linear and nonlinear settings

    更新日期:2020-09-18
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