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Loss-cone stabilization in rotating mirrors: thresholds and thermodynamics J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-15 E.J. Kolmes, I.E. Ochs, N.J. Fisch
In the limit of sufficiently fast rotation, rotating mirror traps are known to be stable against the loss-cone modes associated with conventional (non-rotating) mirrors. This paper calculates how quickly a mirror configuration must rotate in order for several of these modes to be stabilized (in particular, the high-frequency convective loss cone, drift cyclotron loss cone and Dory–Guest–Harris modes)
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Mean-field transport equations and energy theorem for plasma edge turbulent transport J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-15 Reinart Coosemans, Wouter Dekeyser, Martine Baelmans
This paper establishes a mean-field equation set and an energy theorem to provide a theoretical basis in view of the development of self-consistent, physics-based turbulent transport models for mean-field transport codes. A rigorous averaging procedure identifies the exact form of the perpendicular turbulent fluxes which are modelled by ad hoc diffusive terms in mean-field transport codes, next to
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Experimental issues of energy balance in open magnetic trap J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-14 Elena I. Soldatkina, Andrey K. Meyster, Dmitry V. Yakovlev, Peter A. Bagryansky
The paper presents an overview of experimental results of an investigation of different energy loss channels in the gas dynamic trap (GDT), which is a magnetic mirror plasma confinement device in the Budker Institute of Nuclear Physics. Energy losses along magnetic field lines are considered as well as losses onto radial limiters, which restrict the plasma column radius and provide its magnetohydrodynamic
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Development of a new magnetic mirror device at the Korea Advanced Institute of Science and Technology J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-12 D. Oh, M. Choe, G. Baek, D. Kim, B. K. Jung, K. J. Chung, I. Kourakis, C. Sung
A new magnetic mirror machine named KAIMIR (KAIST mirror) has been designed and constructed at the Korea Advanced Institute of Science and Technology (KAIST) to study mirror plasma physics and simulate the boundary regions of magnetic fusion plasmas such as in a tokamak. The purpose of this paper is to introduce the characteristics and initial experimental results of KAIMIR. The cylindrical vacuum
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Nonlinear electron scattering by electrostatic waves in collisionless shocks J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-07 Sergei R. Kamaletdinov, Ivan Y. Vasko, Anton V. Artemyev
We present a theoretical analysis of electron pitch-angle scattering by ion-acoustic electrostatic fluctuations present in the Earth's bow shock and, presumably, collisionless shocks in general. We numerically simulate electron interaction with a single wave packet to demonstrate the scattering through phase bunching and phase trapping and quantify electron pitch-angle scattering in dependence on the
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Modelling a thrust imparted by a highly ionized magnetic nozzle rf plasma thruster J. Plasma Phys. (IF 2.5) Pub Date : 2024-03-07 Kazunori Takahashi
Influence of the local-ionization-induced neutral depletion on the thrust imparted by the magnetic nozzle plasma thruster is discussed by simply considering reduction of the neutral density due to the ionization in the thruster model combining the global source model and the one-dimensional magnetic nozzle model. When increasing the rf power, it is shown that the increase rate of the plasma density
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Modulational instability of the interacting electron whistlers and magnetosonic perturbations J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-28 Jiao-Jiao Cheng, Fang-Ping Wang, Zhong-Zheng Li, Wen-Shan Duan
A modulational instability of nonlinearly interacting electron whistlers and magnetosonic perturbations is studied in the present paper. For typical parameters, there is no modulational instability. However, modulational instability appears in special cases. For example, when the whistler wavenumber is small enough, there is modulational instability. Its growth rate decreases as the angle between the
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Accelerating self-modulated nonlinear waves in weakly and strongly magnetized relativistic plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-27 Felipe A. Asenjo
It is known that a nonlinear Schrödinger equation describes the self-modulation of a large amplitude circularly polarized wave in relativistic electron–positron plasmas in the weakly and strongly magnetized limits. Here, we show that such an equation can be written as a modified second Painlevé equation, producing accelerated propagating wave solutions for those nonlinear plasmas. This solution even
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Magnetic fields with general omnigenity J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-27 Daniel W. Dudt, Alan G. Goodman, Rory Conlin, Dario Panici, Egemen Kolemen
Omnigenity is a desirable property of toroidal magnetic fields that ensures confinement of trapped particles. Confining charged particles is a basic requirement for any fusion power plant design, but it can be difficult to satisfy with the non-axisymmetric magnetic fields used by the stellarator approach. Every ideal magnetohydrodynamic equilibrium previously found to approximate omnigenity has been
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Confinement of transitioning particles in bi-helical Wendelstein-type configurations J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-26 A.V. Tykhyy, Ya.I. Kolesnichenko
Recently, stochastic motion of 3.5-MeV alpha particles with orbits that vary between locally trapped and locally passing states (transitioning particles) in a Helias reactor was observed numerically. This validated the theoretical predictions that (i) the stochastic diffusion represents a mechanism of considerable delayed loss of fast ions in quasi-isodynamic stellarators and (ii) it is possible to
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Turbulence spreading effects on the ELM size and SOL width J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-23 Nami Li, X.Q. Xu, P.H. Diamond, Y.F. Wang, X. Lin, N. Yan, G.S. Xu
BOUT++ turbulence simulations were performed to investigate the impact of turbulence spreading on the edge localized mode (ELM) size and divertor heat flux width $({\lambda _q})$ broadening in small ELM regimes. This study is motivated by EAST experiments. BOUT++ linear simulations of a pedestal radial electric field (Er) scan show that the dominant toroidal number mode (n) shifts from high-n to low-n
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Emission of terahertz pulses from near-critical plasma slab under action of p-polarized laser radiation J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-21 A.A. Frolov
The theory of the terahertz (THz) waves emission from a near-critical plasma slab under the action of the focused p-polarized laser pulse is developed. The spectral, angular and energy characteristics of the THz signal are studied as functions of the focusing degree and the incidence angle of laser radiation, as well as the density and thickness of the plasma slab. It is shown that the extremely strong
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Effects of guard and boom on needle Langmuir probes studied with particle-in-cell simulations J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-21 S.M. Brask, S. Marholm, W.J. Miloch, R. Marchand
We investigate the effects of different guard geometries on the currents to needle-type Langmuir probes. The results are based on particle-in-cell numerical simulations. We show that if the guard length is less than 6–8 Debye lengths there can be a significant effect on the currents to the probe. A guard radius should not be larger than the Debye length, otherwise it can also significantly affect the
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Transverse magnetic field effects on the high-voltage pulsed discharge plasma in helium J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-21 C. Chen, K. M. Rabadanov, N. A. Ashurbekov, C. Yuan, A. M. Shakhrudinov
This study investigates the effect of a transverse magnetic field on high-voltage pulsed discharge in helium at a pressure of 30 Torr. A simple two-dimensional fluid model that describes the high-voltage pulsed discharge in helium in a transverse weak magnetic field (B = 0.4 T) is presented, which uses an empirical relation to account for the magnetic field. The results of using the empirical relation
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Calibrated heating rate measurements using electric-field-induced electron extraction in ultracold neutral plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-15 John M. Guthrie, Puchang Jiang, Jacob L. Roberts
The heating rate of plasma electrons induced by external fields or other processes can be used as an experimental tool to measure fundamental plasma properties such as electrical conductivity or electron–ion collision rates. We have developed a technique that can measure electron heating rates in ultracold neutral plasmas (UNPs) with $\sim 10\,\%$ precision while simultaneously referencing the measurement
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Trivelpiece–Gould modes and low-frequency electron–ion instability of non-neutral plasma J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-15 Yuriy N. Yeliseyev
The frequency spectra of the Trivelpiece–Gould modes of a waveguide partially filled with non-neutral plasma are determined numerically by solving the dispersion equation. The modes having azimuthal number $m = 1$ are considered. The results are presented for the entire acceptable range of electron densities, magnetic field strengths, for different values of the charge neutralization coefficient. The
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The magnetohydrodynamic equations in terms of waveframe variables J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-15 T. Van Doorsselaere, N. Magyar, M.V. Sieyra, M. Goossens
Generalising the Elsässer variables, we introduce the $Q$ -variables. These are more flexible than the Elsässer variables, because they also allow us to track waves with phase speeds different than the Alfvén speed. We rewrite the magnetohydrodynamics (MHD) equations with these $Q$ -variables. We consider also the linearised version of the resulting MHD equations in a uniform plasma, and recover the
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Nonlinear Hall effect in a stationary cylinder with a radial heat flux J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-15 G.S. Bisnovatyi-Kogan, M.V. Glushikhina
A conducting cylinder with a uniform magnetic field along its axis and radial temperature gradient is considered at the stationary state. At large temperature gradients the azimuthal Hall electrical current creates an axial magnetic field whose strength may be comparable with the original one. It is shown that the magnetic field, generated by the azimuthal Hall current, leads to the decrease of a magnetic
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Electromagnetic oscillations and anomalous ion scattering in the helically symmetric multiple-mirror trap J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-12 Mikhail S. Tolkachev, Anna A. Inzhevatkina, Anton V. Sudnikov, Ivan S. Chernoshtanov
The paper presents an investigation of the plasma fluctuation in the SMOLA helical mirror, which is suspected to be responsible for anomalous scattering. The helical mirror confinement is effective when the ion mean free path is equal to the helix pitch length. This condition can be satisfied in hot collisionless plasma only by anomalous scattering. The wave, which scatters the passing ions, is considered
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Ion transport and gas collision effects in a radio frequency quadrupole cooler: installation in the Eltrap solenoid and beam calculations J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-12 M. Cavenago, M. Romé, G. Maero, F. Cavaliere, M. Comunian, M. Maggiore, A. Ruzzon
Radio frequency quadrupole coolers (RFQCs) are very suitable to cool ion beams with moderate energy spread, typically ions of exotic nuclear species (like $^{132}$ Sn $^{1+}$ ) as in the Selective Production of Exotic Species project at the Laboratori Nazionali di Legnaro, whose ion source supplies 40 keV ions. Beam dynamics includes ion–gas collisions (with a balance of cooling and diffusion effects)
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Laser-machined two-stage nozzle optimised for laser wakefield acceleration J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-08 V. Tomkus, M. Mackevičiūtė, J. Dudutis, V. Girdauskas, M. Abedi-Varaki, P. Gečys, G. Račiukaitis
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 ${\rm \mu}$ m diameter nozzle
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Transformation of a plasma boundary curvature into electrical impulses moving along a plasma surface J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-08 O.M. Gradov
The self-consistent propagation of electrical impulses and of the accompanying distortions of the electron surface in the framework of a cold plasma model with a sharp boundary has been described with help of a derived system of two equations. The method of ‘shallow water theory’ has been applied for the case of bounded plasma and deriving an equation with which to link the spatial and temporal structures
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Role of the edge electric field in the resonant mode-particle interactions and the formation of transport barriers in toroidal plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-06 Giorgos Anastassiou, Panagiotis Zestanakis, Yiannis Antonenas, Eleonora Viezzer, Yannis Kominis
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
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A two-dimensional numerical study of ion-acoustic turbulence J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-02 Zhuo Liu, Ryan White, Manaure Francisquez, Lucio M. Milanese, Nuno F. Loureiro
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
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Hydrodynamic and kinetic representation of the microscopic classic dynamics at the transition on the macroscopic scale J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-02 Pavel A. Andreev
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
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Space–time structure of weak magnetohydrodynamic turbulence J. Plasma Phys. (IF 2.5) Pub Date : 2024-02-01 Augustus A. Azelis, Jean C. Perez, Sofiane Bourouaine
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 $\varepsilon$ , describing the ratio of time scales corresponding to Alfvénic propagation and nonlinear interactions between counter-propagating
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Polarization effects in higher-order guiding-centre Lagrangian dynamics J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-30 Alain J. Brizard
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
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Resonant excitation of terahertz surface magnetoplasmons by optical rectification over a rippled surface of n-type indium antimonide J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-25 Rohit Kumar Srivastav, A. Panwar
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
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The gap-size influence on the excitation of magnetorotational instability in cylindricTaylor–Couette flows J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-23 G. Rüdiger, M. Schultz
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
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Development of the ambipolar electric field in a compressed current sheet and the impact on magnetic reconnection J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-19 Ami M. DuBois, Chris Crabtree, Gurudas Ganguli
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 $\boldsymbol{E} \times \boldsymbol{B}$ velocity shear and result from compression. The presence and location of shear-driven waves
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On hydromagnetic wave interactions in collisionless, high-β plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-19 S. Majeski, M.W. Kunz
We describe the interaction of parallel-propagating Alfvén waves with ion-acoustic waves and other Alfvén waves, in magnetized, high- $\beta$ 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
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Prospects for a high-field, compact break-even axisymmetric mirror (BEAM) and applications J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-17 C.B. Forest, J.K. Anderson, D. Endrizzi, J. Egedal, S. Frank, K. Furlong, M. Ialovega, J. Kirch, R.W. Harvey, B. Lindley, Yu.V. Petrov, J. Pizzo, T. Qian, K. Sanwalka, O. Schmitz, J. Wallace, D. Yakovlev, M. Yu
This paper explores the feasibility of a break-even-class mirror referred to as BEAM (break-even axisymmetric mirror): a neutral-beam-heated simple mirror capable of thermonuclear-grade parameters and $Q\sim 1$ conditions. Compared with earlier mirror experiments in the 1980s, BEAM would have: higher-energy neutral beams, a larger and denser plasma at higher magnetic field, both an edge and a core
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Self-organization in the avalanche, quench and dissipation of a molecular ultracold plasma J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-17 K.L. Marroquín, R. Wang, A. Allahverdian, N. Durand-Brousseau, S. Colombini, F. Kogel, J.S. Keller, T. Langen, E.R. Grant
Spontaneous avalanche to plasma begins in the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion of NO $^+$ draws energy from avalanche-heated electrons. Then, cycles of long-range resonant electron transfer from Rydberg molecules to ions equalize their relative velocities. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy
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Coupling multi-fluid dynamics equipped with Landau closures to the particle-in-cell method J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-17 Rouven Lemmerz, Mohamad Shalaby, Timon Thomas, Christoph Pfrommer
The particle-in-cell (PIC) method is successfully used to study magnetized plasmas. However, this requires large computational costs and limits simulations to short physical run times and often to set-ups of less than three spatial dimensions. Traditionally, this is circumvented either via hybrid-PIC methods (adopting massless electrons) or via magneto-hydrodynamic-PIC methods (modelling the background
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Electron cyclotron resonance during plasma initiation J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-15 C. Albert Johansson, Pavel Aleynikov
Electron-cyclotron resonance heating (ECRH) is the main heating mechanism in the Wendelstein 7-X (W7-X) stellarator. Although second-harmonic ECRH (X2) has been used routinely for plasma startup, startup at third harmonic (X3) is known to be much more difficult. In this work, we investigate the energy gain of particles during nonlinear wave–particle interaction for conditions relevant to second- and
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Improved numerical simulation model for nuclear reaction rate calculations in high-speed plasma collisions J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-11 Bo Zeng, Zijia Zhao, Xiaohu Yang, Shaowu Yang, Yanyun Ma
Beam–target reactions in fusion plasmas play an important role in both magnetic confinement fusion and inertial confinement fusion in the condition of low-density plasmas with high-velocity interactions. The traditional method for calculating beam–target reaction rate neglects the transport process of incident particles in inhomogeneous plasmas, leading to errors providing that the temperature and
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Design and construction of the near-earth space plasma simulation system of the Space Plasma Environment Research Facility J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-11 W. Ling, C. Jing, J. Wan, A. Mao, Q. Xiao, J. Guan, J. Cheng, C. Liu, P. E
Our earth is immersed in the near-earth space plasma environment, which plays a vital role in protecting our planet against the solar-wind impact and influencing space activities. It is significant to investigate the physical processes dominating the environment, for deepening our scientific understanding of it and improving the ability to forecast the space weather. As a crucial part of the National
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On the role of numerical diffusivity in MHD simulations of global accretion disc dynamos J. Plasma Phys. (IF 2.5) Pub Date : 2024-01-05 C.J. Nixon, C.C.T. Pringle, J.E. Pringle
Observations, mainly of outbursts in dwarf novae, imply that the anomalous viscosity in highly ionized accretion discs is magnetic in origin and requires that the plasma ${\beta \sim 1}$ . Until now, most simulations of the magnetic dynamo in accretion discs have used a local approximation (known as the shearing box). While these simulations demonstrate the possibility of a self-sustaining dynamo,
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Proton and helium ions acceleration in near-critical density gas targets by short-pulse Ti:Sa PW-class laser J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-28 J.L. Henares, P. Puyuelo-Valdes, C. Salgado-López, J.I. Apiñaniz, P. Bradford, F. Consoli, D. de Luis, M. Ehret, F. Hannachi, R. Hernández-Martín, A. Huber, L. Lancia, M. Mackeviciute, A. Maitrallain, J.-R. Marquès, J.A. Pérez-Hernández, C. Santos, J.J. Santos, V. Stankevic, M. Tarisien, V. Tomkus, L. Volpe, G. Gatti
The ability to quickly refresh gas-jet targets without cycling the vacuum chamber makes them a promising candidate for laser-accelerated ion experiments at high repetition rate. Here we present results from the first high repetition rate ion acceleration experiment on the VEGA-3 PW-class laser at CLPU. A near-critical density gas-jet target was produced by forcing a 1000 bar H $_2$ and He gas mix through
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Guiding centre motion for particles in a ponderomotive magnetostatic end plug J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-28 T. Rubin, J.M. Rax, N.J. Fisch
The Hamiltonian dynamics of a single particle in a rotating plasma column, interacting with an magnetic multipole is perturbatively solved for up to second order, using the method of Lie transformations. First, the exact Hamiltonian is expressed in terms of canonical action-angle variables, and then an approximate integrable Hamiltonian is introduced, using another set of actions and angles, which
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Rotating Alfvén waves in rotating plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-28 J.-M. Rax, R. Gueroult, N.J. Fisch
Angular momentum coupling between a rotating magnetized plasma and torsional Alfvén waves carrying orbital angular momentum (OAM) is examined. It is demonstrated not only that rotation is the source of Fresnel–Faraday rotation – or orbital Faraday rotation effects – for OAM-carrying Alfvén waves, but also that angular momentum from an OAM-carrying Alfvén wave can be transferred to a rotating plasma
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A simple model for internal transport barrier induced by fishbone in tokamak plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-28 Zhaoyang Liu, Guoyong Fu
Fishbone bursts have been observed to strongly correlate to internal transport barrier (ITB) formation in a number of tokamak devices. A simple model incorporating the fishbone dynamics and ion pressure gradient evolution is proposed in order to investigate the key physics parameters assisting the triggering of ITB. The time evolution of fishbone is described by the well-known predator–prey model.
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Intermittency of density fluctuations and zonal-flow generation in MAST edge plasmas J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-27 A. Sladkomedova, I. Cziegler, A.R. Field, A.A. Schekochihin, D. Dunai, P.G. Ivanov, the MAST-U Team and the EUROfusion MST1 Team
The properties of the edge ion-scale turbulence are studied using the beam emission spectroscopy (BES) diagnostic on MAST. Evidence of the formation of large-scale high-amplitude coherent structures, filamentary density blobs and holes, 2–4 cm inside the plasma separatrix is presented. Measurements of radial velocity and skewness of the density fluctuations indicate that density holes propagate radially
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Loss and revival of coherence in the interaction between a positron beam and a photon field J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-27 F. Castelli, S. Cialdi, G. Costantini, R. Ferragut, M. Giammarchi, G. Gittini, M. Leone, G. Maero, S. Olivares, M. Romé, A. Simonetto, V. Toso
We study the interaction between a positron beam in the single-particle regime in an interferometric configuration and a microwave electromagnetic field. We discuss the conditions under which quantum interference can be affected by the field and we outline its possible experimental study in the framework of QUantum interferometry and gravitation with Positrons and LASers (QUPLAS) experiment.
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Gyrokinetic moment-based simulations of the Dimits shift J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-27 A.C.D. Hoffmann, B.J. Frei, P. Ricci
We present a convergence study of the gyromoment (GM) approach, which is based on projecting the gyrokinetic distribution function onto a Hermite–Laguerre polynomial basis, focused on the cyclone base case (CBC) (Lin et al., Phys. Rev. Lett., vol. 83, no. 18, 1999, pp. 3645–3648) and Dimits shift (Dimits et al., Phys. Plasmas, vol. 7, no. 3, 2000, pp. 969–983) as benchmarks. We report that the GM approach
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A buffer-gas trap for the NEPOMUC positron beam: optimization studies with electrons J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-21 A. Deller, C.W. Rogge, S. Desopo, E.V. Stenson, J.R. Danielson, M.R. Stoneking, C. Hugenschmidt, T. Sunn Pedersen, C.M. Surko
Buffer-gas traps (BGTs) use inelastic interactions with nitrogen molecules to capture positrons from a continuous beam. These devices are invaluable for high-resolution studies of matter–antimatter interactions, antihydrogen research and positronium laser spectroscopy. We present a new project with the goal of producing a non-neutral plasma containing ${\sim }10^8$ low-energy positrons by installing
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Quadruple Langmuir probe characterization of different fuel gases in a plasma deflagration accelerator J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-20 Aduragbemi A.T. Jibodu, Arnaud M. Ballande, Mark A. Cappelli
Astrophysical flows may be studied by reproducing similar conditions using a coaxial plasma accelerator operating in the deflagration regime (or plasma deflagration accelerator). This allows for the recreation and investigation of dynamics present in complex highly coupled plasma systems at the laboratory scale. We report on measurements of the plasma density, temperature, plasma potential and velocity
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Helicity of the magnetic axes of quasi-isodynamic stellarators J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-18 Katia Camacho Mata, Gabriel G. Plunk
In this study, we explore the influence of the helicity of the magnetic axis – defined as the self-linking number of the curve – on the quality of quasi-isodynamic stellarator-symmetric configurations constructed using the near-axis expansion method (Plunk et al., J. Plasma Phys., vol. 85, 2019, 905850602; Camacho Mata et al., J. Plasma Phys., vol. 88, 2022, 905880503). A class of magnetic axes previously
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Slow positron production and storage for the ASACUSA-Cusp experiment J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-18 D.J. Murtagh, C. Amsler, H. Breuker, M. Bumbar, S. Chesnevskaya, G. Costantini, R. Ferragut, M. Giammarchi, A. Gligorova, G. Gosta, H. Higaki, E.D. Hunter, C. Killian, V. Kraxberger, N. Kuroda, A. Lanz, M. Leali, G. Maero, C. Malbrunot, V. Mascagna, Y. Matsuda, V. Mäckel, S. Migliorati, A. Nanda, L. Nowak, F. Parnefjord Gustafsson, S. Rheinfrank, M. Romé, M.C. Simon, M. Tajima, V. Toso, S. Ulmer, L
The ASACUSA (atomic spectroscopy and collisions using slow antiprotons) Cusp experiment requires the production of dense positron plasmas with a high repetition rate to produce a beam of antihydrogen. In this work, details of the positron production apparatus used for the first observation of the antihydrogen beam, and subsequent measurements, are described in detail. This apparatus replaced the previous
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The nonlinear evolution of whistler-mode chorus: modulation instability as the source of tones J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-12 Daniel J. Ratliff, Oliver Allanson
We review the modulation stability of parallel-propagating/field-aligned whistler-mode chorus (WMC) waves propagating in a warm plasma from a formal perspective with a focus on wave–particle interactions via ponderomotive forces. The modulation instability criteria are characterised by the group velocity dispersion, $d c_g/dk$ , for whistler-mode waves and a condition on the ratio between the group
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Deciphering the physical basis of the intermediate-scale instability J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-12 Mohamad Shalaby, Timon Thomas, Christoph Pfrommer, Rouven Lemmerz, Virginia Bresci
We study the underlying physics of cosmic ray (CR)-driven instabilities that play a crucial role for CR transport across a wide range of scales, from interstellar to galaxy cluster environments. By examining the linear dispersion relation of CR-driven instabilities in a magnetised electron–ion background plasma, we establish that both the intermediate and gyroscale instabilities have a resonant origin
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Hall magnetohydrodynamics in a relativistically strong mean magnetic field J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-12 Y. Kawazura
This paper presents a magnetohydrodynamic model that describes the small-amplitude fluctuations with wavelengths comparable to ion inertial length in the presence of a relativistically strong mean magnetic field. The set of derived equations is virtually identical to the non-relativistic Hall reduced magnetohydrodynamics (Schekochihin et al., J. Plasma Phys., vol. 85, 2019, 905850303), differing only
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Complex structure of turbulence across the ASDEX Upgrade pedestal J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-01 L.A. Leppin, T. Görler, M. Cavedon, M.G. Dunne, E. Wolfrum, F. Jenko, the ASDEX Upgrade Team
The theoretical investigation of relevant turbulent transport mechanisms in H-mode pedestals is a great scientific and numerical challenge. In this study, we address this challenge by global, nonlinear gyrokinetic simulations of a full pedestal up to the separatrix, supported by a detailed characterisation of gyrokinetic instabilities from just inside the pedestal top to the pedestal centre and foot
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Generalized cross-helicity in non-ideal magnetohydrodynamics J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-01 Prachi Sharma, Asher Yahalom
The objective of the present paper is to investigate the constancy of the topological invariant, denoted the non-barotropic generalized cross-helicity in the case of non-ideal magnetohydrodynamics (MHD). Existing work considers only ideal barotropic MHD and ideal non-barotropic MHD. Here, we consider dissipative processes in the form of thermal conduction, finite electrical conductivity and viscosity
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Inverse cascading for initial magnetohydrodynamic turbulence spectra between Saffman and Batchelor J. Plasma Phys. (IF 2.5) Pub Date : 2023-12-01 Axel Brandenburg, Ramkishor Sharma, Tanmay Vachaspati
In decaying magnetohydrodynamic (MHD) turbulence with a strong magnetic field, the spectral magnetic energy density is known to increase with time at small wavenumbers $k$ , provided the spectrum at low $k$ is sufficiently steep. This process is called inverse cascading and occurs for an initial Batchelor spectrum, where the magnetic energy per linear wavenumber interval increases like $k^4$ . For
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Guiding-centre orbit-following simulations of charge exchange loss of NBI ions with the finite Larmor radius effect J. Plasma Phys. (IF 2.5) Pub Date : 2023-11-29 Yingfeng Xu, Fuqiong Wang, Yongliang Li, Fangchuan Zhong
Guiding-centre orbit-following simulations of the charge exchange (CX) loss of neutral beam injection (NBI) ions are presented. The finite Larmor radius (FLR) effect in the fast ion–neutral collision can be included in guiding-centre orbit-following simulations by using the gyroaverage method. It is proved that the neutralization probability of fast ions computed by using the gyroaverage method in
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Generation of energetic electrons by an electron cyclotron wave through stochastic heating in a spherical tokamak J. Plasma Phys. (IF 2.5) Pub Date : 2023-11-28 Mingyuan Wang, Shikui Cheng, Bing Liu, Shaodong Song, Dong Guo, Yunyang Song, Wenjun Liu, Debabrata Banerjee, Songjian Li, Tiantian Sun, Xiang Gu, Yingying Li, Jiaqi Dong, Yuejiang Shi, Y.-K. Martin Peng, Adi Liu
This study presents novel findings on stochastic electron heating via a random electron cyclotron wave (ECW) in a spherical tokamak. Hard x ray measurements demonstrate the time evolution of hard x ray counts at different energy bands, consistent with predictions from the stochastic heating model. The ECW heating rate shows a positive correlation with applied power, confirming the effectiveness of
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Nonlinear interaction of Alfvénic instabilities and turbulence via the modification of the equilibrium profiles J. Plasma Phys. (IF 2.5) Pub Date : 2023-11-21 A. Biancalani, A. Bottino, D. Del Sarto, M.V. Falessi, T. Hayward-Schneider, P. Lauber, A. Mishchenko, B. Rettino, J.N. Sama, F. Vannini, L. Villard, X. Wang, F. Zonca, the ASDEX Upgrade team
Nonlinear simulations of Alfvén modes (AMs) driven by energetic particles (EPs) in the presence of turbulence are performed with the gyrokinetic particle-in-cell code ORB5. The AMs carry a heat flux, and consequently they nonlinearly modify the plasma temperature profiles. The isolated effect of this modification on the dynamics of turbulence is studied by means of electrostatic simulations. We find
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Using rational surfaces to improve pellet fuelling in stellarators J. Plasma Phys. (IF 2.5) Pub Date : 2023-11-16 N. Panadero, K. J. McCarthy, B. Pégourié, R. Carrasco, I. García-Cortés, R. García, J. Hernández-Sánchez, F. Köchl, J. Martínez-Fernández, R. Sakamoto, the TJ-II team
Pellet injection is currently the primary candidate for achieving efficient plasma fuelling, one of the key issues for steady-state operation in large fusion devices. In this paper, pellet injection experiments are performed for several magnetic configurations of the TJ-II stellarator. The aim of this study is to increase the understanding of the role played by rational surfaces in plasmoid drift and
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Resonant excitation of single Kelvin–Helmholtz high-order waves in a magnetized electron fluid vortex J. Plasma Phys. (IF 2.5) Pub Date : 2023-11-13 G. Maero, N. Panzeri, L. Patricelli, M. Romé
Thanks to the isomorphism between the drift-Poisson and Euler equations, inviscid two-dimensional fluid experiments can be performed in magnetized, single-component plasmas in Penning–Malmberg traps. Within this analogy, a trapped electron plasma column is equivalent to a two-dimensional vortex. Here, we focus our attention on the generation of V-states, i.e. $l$ -fold symmetric rotating vorticity