A theoretical model and an analytic theory of current sheet structure are presented for understanding anti-parallel driven magnetic reconnection in 2-1/2 dimension in collisionless plasmas. The theoretical model provides formulation to compute the current sheet y-profiles by specifying the profiles of electron and ion flow velocities V e x ( x , y ) and V i x ( x , y ). The current sheet solutions

We investigate lower-hybrid drift waves (LHDW) in symmetric magnetic reconnection with zero guide field using three-dimensional particle-in-cell simulations. The long-wavelength mode with k ρ i ρ e ∼ 1 develops in the bifurcated electron current layer around the X-line within the width of the electron meandering motion from the mid-plane, where ρ i ( e ) is the ion (electron) gyroradius. The short-wavelength

Using a 2D Viscoresistive Reduced MagnetoHydroDynamic model, the magnetic island coalescence problem is studied in the presence of in-plane, parallel shear flows. Extending the analytical work of Waelbroeck et al. [Phys. Plasmas 14, 022302 (2007)] and Throumoulopoulos et al., [J. Phys. A 42, 335501 (2009)] in the sub-Alfvénic flow shear regime for Fadeev equilibrium, the super-Alfvénic regime is studied

Inhomogeneities in a current-carrying conductor promote non-uniform heating and expansion through the complex feedback between current density, electrical resistivity, Ohmic heating, temperature, and hydrodynamics. Three-dimensional-magnetohydrodynamic (3D-MHD) simulations suggest that μm-scale resistive inclusions or voids seed local overheating and through hydrodynamic explosion generate continuously

The propagation characteristics of terahertz waves in high-temperature magnetized inhomogeneous plasma sheath were investigated theoretically by the shift operator finite difference time domain method. Both the transmission characteristics of left and right circularly polarized terahertz waves propagating in uniform or non-uniform plasma were analyzed. Simulation results reveal that the transmission

We present a one-dimensional model, which gives a novel physical interpretation to the specific state of an ensemble of electrons continuously injected into an electrostatic potential well immersed in a strong applied magnetic field preventing radial expansion. When the space-charge field of the electrons accumulated in the potential well compensates the external electrostatic field, a force-free steady-state

Plasmas that are strongly magnetized in the sense that the gyrofrequency exceeds the plasma frequency exhibit novel transport properties that are not well understood. As a representative example, we compute the friction force acting on a massive test charge moving through a strongly coupled and strongly magnetized one-component plasma using a generalized Boltzmann kinetic theory. Recent works studying

We investigate the time evolution of the six-component electron pressure tensor in a hybrid code studying consequences for the two-dimensional reconnection process in an initially perturbed Harris sheet. We put forward that two tensor components (a diagonal and a non-diagonal one) grow in an unstable way unless an isotropization operator is considered. This isotropization term is physically associated

Using two-dimensional (2D) magnetohydrodynamics simulations, we show that Petschek-type magnetic reconnection can be induced using a simple resistivity gradient in the reconnection outflow direction, revealing the key ingredient of steady fast reconnection in the collisional limit. We find that the diffusion region self-adjusts its half-length to fit the given gradient scale of resistivity. The induced

The pseudo-potential method is applied to derive diverse propagating electron–hole structures in a nonthermal or κ particle distribution function background. The associated distribution function Ansatz reproduces the Schamel distribution of [H. Schamel, Phys. Plasmas 22, 042301 (2015)] in the Maxwellian ( κ → ∞) limit, providing a significant generalization of it for plasmas where superthermal electrons

Perpendicular, magnetized, collisionless shocks in hydrogen and neon plasmas are studied with 2D particle-in-cell simulations for parameters accessible to experiments on OMEGA EP [Maywar et al., J. Phys.: Conf. Ser. 112, 032007 (2008)]. The simulations are performed with realistic ion-electron mass ratios by which the relative importance of different micro-instabilities can be accurately captured.

A closed-form integral representation of the electromagnetic dispersion relation for plasma waves propagating perpendicular to a magnetic field is derived. Growth rates and oscillation frequencies are calculated for several cases of the Dory–Guest–Harris instability and compared with those calculated from the usual electrostatic version of the dispersion relation. The comparisons show that the electromagnetic

Exact moments of the Boltzmann collision operator are calculated in the irreducible Hermitian moment expansion written in terms of the random-velocity variable of each species. The formulas are presented in closed, algebraic form and can be straightforwardly implemented in computer algebra systems. They are valid for two arbitrary masses, temperatures, and flow velocities, and hence include all other

Intermittent fluctuations in the boundary of magnetically confined plasmas are investigated by numerical turbulence simulations of a reduced fluid model describing the evolution of the plasma density and electric drift vorticity in the two-dimensional plane perpendicular to the magnetic field. Two different cases are considered: one describing resistive drift waves in the edge region and another including

The characteristics of atomic-scale mixing are determined by diffusive processes driven by gradients. One such process is interdiffusion, a process driven by density gradients. We consider the various options for formulating interdiffusion in terms of Green–Kubo autocorrelation functions and the thermodynamic factor. Through models for the direct correlation function, we generalize expressions for

White-light supercontinuum from a femtosecond laser filamentation is essential for many applications due to its broadening spectrum and remote sensing ability. We propose to enhance the supercontinuum intensity by presetting the gaseous lattice in the path of femtosecond laser filamentation. Our results show that the introduction of a gaseous lattice can increase the spectral intensity in both visible

In this paper, simulation study of electron stochastic heating arising from the Raman backscatter radiations during the interaction of the laser pulse with the nitrogen atoms is presented by use of a massively parallel particle-in-cell code. For this purpose, the self-consistent evolutions of the laser pulse via the time–space Fourier transforms of transvers vector potential are investigated at the

Microturbulence close to marginality with inclusion of electron dynamics and in the electrostatic limit [A. Weikl et al., Phys. Plasmas 25, 072305 (2018)] is revisited. In such states the E × B shearing rate ω E × B, i.e., the second radial derivative of the zonal electrostatic potential, a quantity often applied to study zonal flow structure formation, has been found to be dominated by radial fine

The radial density profile of pre-thermal quench (pre-TQ) early-time non-thermal (hot) electrons is estimated by combining electron cyclotron emission and soft x-ray data during the rapid shutdown of low-density ( n e ≲ 10 19   m − 3 ) DIII-D target plasmas with cryogenic argon pellet injection. This technique is mostly limited in these experiments to the pre-TQ phase and quickly loses validity during

The turbulence and transport expected in the SPARC tokamak Primary Reference Discharge (PRD) [P. Rodriguez-Fernandez et al., J. Plasma Phys. 86, 865860503 (2020)] have been investigated with the gyrokinetic code CGYRO [J. Candy et al., J. Comput. Phys. 324, 73–93 (2016)]. Linear and nonlinear simulations that focus on ion ( k θ ρ s < 1.0) and electron-scale ( k θ ρ s > 1.0) turbulence were used to

In the so-called “hybrid” shots characterized by shear-free core with safety factor slightly above 1, an interesting yet unexplained chirping activity has been observed in tokamaks with a high fast ion content. Namely, fishbone modes with m = n = 1 and downward frequency chirping are accompanied by frequency jumps of the tearing modes with m = n + 1 and n > 1 [here m(n) is the poloidal (toroidal) mode

This paper presents a study of the interaction between Alfvén modes and zonal structures, considering a realistic ASDEX Upgrade equilibrium. The results of gyrokinetic simulations with the global, electromagnetic, particle-in-cell code ORB5 are presented, where the modes are driven unstable by energetic particles with a bump-on-tail equilibrium distribution function, with radial density gradient. Two

A fully implicit particle-in-cell method for handling the v ∥-formalism of electromagnetic gyrokinetics has been implemented in XGC. By choosing the v ∥-formalism, we avoid introducing the nonphysical skin terms in Ampère's law, which are responsible for the well-known “cancellation problem” in the p ∥-formalism. The v ∥-formalism, however, is known to suffer from a numerical instability when explicit

Synergistic effects between two frequencies of lower hybrid (LH) waves—operating at 2.45 and 4.6 GHz—were observed in experiment on EAST for the first time. At low density ( n e , lin ≈ 2.0 × 1 0 19   m − 3), simultaneous injection of a 65/35 mix of 2.45/4.6 GHz power achieved an lower hybrid current drive efficiency that was 25% higher than what should be expected from the linear combination of the

Simulations and theory are presented of an ITER locked mode thermal quench (TQ). In present experiments, locked mode disruptions have a long precursor phase, followed by a rapid termination and thermal quench, which can be identified with a resistive wall tearing mode (RWTM). In ITER, the RWTM will be slowed by the highly conductive vacuum vessel. The rapid termination might be absent, and the plasma

In saturated Ohmic confinement regime of the experimental advanced superconducting tokamak, significant changes in the relative electron temperature fluctuations T ̃ e / T ¯ e, measured by a correlation electron cyclotron emission system, have been observed. It was found that T ̃ e / T ¯ e is strongly dependent on the normalized electron temperature and density gradient, R / L T e = R ∇ T e / T e and

When the low-confinement mode (L-mode) edge has relatively high electron temperature and weak ion temperature gradient, for example, as observed in the ECH-heated low-density plasmas, the trapped electron mode (TEM) can play an important role in the low to high confinement (L-H) transition as well as the L-mode edge transport, instead of the resistive ballooning or ion temperature gradient mode (RBM

We study Alfvén eigenmodes (AEs) in the TJ-II heliac in hydrogen plasmas heated by hydrogen co-field neutral beam injector. Taking advantage of the unique TJ-II flexibility in a varying plasma current, we have observed strong variation of the AE frequency from fAE ∼ 30 to ∼220 kHz for selected modes. An advanced heavy-ion beam probe diagnostic determines the spatial location and internal amplitudes

Equilibria with extended regions of weak magnetic shear, including some tokamak scenarios and stellarators, can be susceptible to pressure-driven internal MHD instabilities even though there is no mode rational surface in the plasma. Nonresonant modes, in particular, can have properties that are unattractive for confinement, including displacing substantial volumes of the plasma and leading to more

The increase in entropy from the physical mixing of two adjacent materials in inertial confinement fusion (ICF) implosions and gas-filled hohlraums is analytically assessed. An idealized model of entropy generation from the mixing of identical ideal-gas particles across a material interface in the presence of pressure and temperature gradients is applied. Physically, mix-driven entropy generation refers

The role of flux-limited thermal conduction on the fusion performance of the uniaxially driven targets studied by Derentowicz et al. [J. Tech. Phys. 18, 465 (1977) and J. Tech. Phys. 25, 135 (1977)] is explored as part of a wider effort to understand and quantify uncertainties in inertial confinement fusion (ICF) systems sharing similarities with First Light Fusion's projectile-driven concept. We examine

A simple model of piston-driven spherical and cylindrical shocks is suggested. The model is based on a consistent use of two factors: (a) an almost uniform pressure across the shocked layer and, (b) continuous geometrical stretching of the surface elements of the expanding piston. It turns out that for a uniform pre-shock medium the gas between the piston and the shock behaves essentially as an incompressible

Experiments and simulations have been conducted to investigate the efficacy of Ta2O5-lined Hohlraum walls at reducing stimulated Brillouin backscattering (SBS) as well as any subsequent effects on the Hohlraum dynamics and capsule implosions in indirect drive experiments at the National Ignition Facility. Using a 1.1 MJ 400 TW, 351 nm, shaped laser pulse, we measure a 5× reduction in SBS power in the

Resorcinol/formaldehyde (RF) foam-aluminum-quartz-layered targets were shock compressed up to 0.9 TPa in quartz to quantitatively evaluate the pressure-amplification effect of using a low-density RF foam as an ablator. The velocimetry and pyrometry were used to obtain the shock pressure and temperature in the quartz. The results show the use of an RF foam ablator with a density of 100 mg/cm3 increases

HYBRID-E is an inertial confinement fusion implosion design that increases energy coupled to the hot spot by increasing the capsule scale in cylindrical hohlraums while operating within the current experimental limits of the National Ignition Facility. HYBRID-E reduces the hohlraum scale at a fixed capsule size compared to previous HYBRID designs, thereby increasing the hohlraum efficiency and energy

Electromagnetic ion cyclotron (EMIC) waves have been studied in this manuscript which are triggered by hot proton thermal anisotropy having energy ranging from 7 to 26 keV with a minimum resonant energy of 6.9 keV. However, an opposite effect can be observed for the hot protons for energy less than the minimum resonant energy. When the intensity of EMIC waves is large, the cold protons (ions) having

Electron cyclotron harmonic (ECH) waves play a significant role in driving the diffuse aurora, which constitutes more than 75% of the particle energy input into the ionosphere. ECH waves in magnetospheric plasmas have long been thought to be excited predominantly by the loss cone anisotropy (velocity–space gradients) that arises naturally in a planetary dipole field. Recent THEMIS observations, however

We investigate ion-scale kinetic plasma instabilities at the collisionless shock using linear theory and nonlinear particle-in-cell (PIC) simulations. We focus on the Alfvén ion cyclotron (AIC), mirror, and Weibel instabilities, which are all driven unstable by the effective temperature anisotropy induced by the shock-reflected ions within the transition layer of a strictly perpendicular shock. We

Proton beams with energies beyond 100 MeV are essential for a wide range of applications, including modern cancer therapies. The generation of high-energetic protons beyond 100 MeV in experiments using PW-level laser pulses normally requires laser energies of 10–200 J. We propose an efficient hybrid scheme using tabletop (tens of TW) dual-laser pulses with laser energy of a few Joules with tandem solid

The transmission of an electron beam with a low magnetic field is theoretically and experimentally investigated. In a high frequency band, due to a narrow tunnel of the electron beam, the transmission of the electron beam highly depends on beam parameters. The transmission of the electron beam is analyzed through the beam envelope equation, and accordingly, the relationship between beam parameters

Ultra-intense lasers are a promising source of energetic ions for various applications. An interesting approach described in Ferri et al. [Commun. Phys. 2, 40 (2019)] argues from particle-in-cell simulations that using two laser pulses of half energy (half intensity) arriving with close to 45° angle of incidence is significantly more effective at accelerating ions than one pulse at full energy (full

Ultra-short high-power lasers can deliver extreme light intensities ( ≥ 10 20 W/cm2 and ≤ 30   fs) and drive large amplitude Surface Plasma Wave (SPW) at over-dense plasma surface. The resulting current of energetic electron has great interest for applications, potentially scaling with the laser amplitude, provided that the laser–plasma transfer to the accelerated particles mediated by SPW is still

Ultraviolet laser driven radiation pressure acceleration of Cu crystals is investigated by using particle-in-cell simulations. When an ultrathin Cu crystal is irradiated by a circularly polarized pulse with wavelength λ = 72 nm, waist radius w 0 = 4 λ, and normalized magnitude a 0 = 20 (energy of 85 mJ), a plasma with a lattice structure is generated first. Then, an acceleration field of 14.2 TV/cm

An improved L-band inverted relativistic magnetron powered by a virtual cathode is presented. An extra emitter is introduced at the end of a slow-wave structure to reduce the desired π mode start-oscillation time, which is critical when short radiation pulses are required. Electrons produced by both upstream and downstream emitters are injected into the interacting space simultaneously, and the rapid

We detail results of an experiment performed at the Laser Mégajoule facility aimed at studying transition from supersonic radiation front to shock front in a low density CHOBr foam enclosed in a plastic tube driven by thermal emission produced in a laser heated spherical gold cavity. Time resolved 2D hard x-ray radiography imaging using a Sc source (photon energy at ∼4.3 keV) is employed to measure

In this paper, we experimentally investigate femtosecond laser-induced nitrogen fluorescence emission at different air pressures (0.1 Pa–100 kPa). The variation of nitrogen molecule ( N 2) and molecular nitrogen ion ( N 2 +) characteristic fluorescence spectral lines' intensity as a function of air pressure is observed. When the air pressure is between 10 Pa and 100 kPa, the intensity of fluorescence

Being able to generate a remote plasma plume, the atmospheric pressure plasma jet has become an indispensable tool for extensive application fields. A plasma plume usually has a straight column morphology, which results from straight-line or stochastic snake-like propagations of streamers. The snake-like propagation of streamers is unclear in the mechanism. In this paper, a meandering plume is generated

The time interval between pulses is the key parameter of sound synthesis generated by repetitive nanosecond pulse discharge. In this paper, the experimental studies on repetitive nanosecond pulse discharges at different intervals using a pin–pin electrode were carried out and the time-domain sound waveforms were obtained using a capacitor microphone. The experiment results show that a single pulse

The recently developed quantum path integral Monte Carlo approach [Filinov et al., Phys. Rev. E 102(3), 033203 (2020)] has been applied for the entropy difference calculations for the strongly coupled degenerated uniform electron gas (UEG), a well-known model of simple metals. The used approach includes the Coulomb and exchange interaction of fermions in the basic Monte Carlo cell and its periodic

Exact solutions for quasineutral plasma acceleration of magnetized plasma in the paraxial magnetic nozzle are obtained. It is shown that the non-monotonic magnetic field with a local maximum of the magnetic field is a necessary condition for the formation of the quasineutral accelerating potential structure. A global nature of the accelerating potential that occurs as a result of the constraint due

A mechanism is presented whereby relativistic electron beams localized in phase space are deterministically scattered by coherent circularly polarized electromagnetic waves without stochastic processes. It is shown via an exact single-particle analysis that the condition for maximal scattering is an off-resonant condition, contrary to previous kinetic analyses that predict maximal diffusion or interaction

Subpicosecond coincidence timing from nonlocal intensity interference of entangled photons allows quantum interferometry for plasmas. Using a warm plasma dispersion relation, we correlate phase measurement sensitivity with different plasma properties or physics mechanisms over six orders of magnitude. Due to N α ( α ≤ − 1 / 2) scaling with the photon number N, quantum interferometry using entangled

The properties of materials under extreme conditions of pressure and density are of key interest to a number of fields, including planetary geophysics, materials science, and inertial confinement fusion. In geophysics, the equations of state of planetary materials, such as hydrogen and iron, under ultrahigh pressure and density provide a better understanding of their formation and interior structure

The friction force on a test particle traveling through a plasma that is both strongly coupled and strongly magnetized is studied using molecular dynamics simulations. In addition to the usual stopping power component aligned antiparallel to the velocity, a transverse component that is perpendicular to both the velocity and Lorentz force is observed. This component, which was previously only characterized

The 1D bump-on-tail problem is studied in order to determine the influence of drag on quasi-steady solutions near marginal stability ( 1 − γ d / γ L ≪ 1) when effective collisions are much larger than the instability growth rate ( ν ≫ γ). In this common tokamak regime, it is rigorously shown that the paradigmatic Berk–Breizman cubic equation for the nonlinear mode evolution reduces to a much simpler

A fourth-order accurate continuum kinetic Vlasov solver and a systematic method for constructing customizable kinetic equilibria are demonstrated to be powerful tools for the study of nonuniform collisionless low-beta plasmas. The noise-free methodology is applied to investigate two gradient-driven instabilities in 4D ( x , y , v x , v y ) phase space: the Kelvin–Helmholtz instability and the lower

This study presents the results of 2D particle-in-cell (PIC) simulations of the electron temperature anisotropy driven whistler instability for plasmas in which the electron species is modeled by a bi-kappa velocity distribution. These simulations utilize our previously developed method to generate the initial multi-dimensional kappa velocity distributions. The use of multi-dimensional kappa loadings

Three dimensional (3D) wave group dynamics of ion acoustic wave is studied in electron–positron–ion (EPI) plasmas incorporating the effects of an external uniform magnetic field through the Laedke–Spatschek equation. In the presence of self-interaction (self-focusing effect), the wave group dynamics is shown to be governed by a (3 + 1) nonlinear Schrödinger equation. The derived nonlinear equations

The debate surrounding fast magnetic energy dissipation by magnetic reconnection has remained a fundamental topic in the plasma universe, not only in the Earth's magnetosphere but also in astrophysical objects such as pulsar magnetospheres and magnetars, for more than half a century. Recently, nonthermal particle acceleration and plasma heating during reconnection have been extensively studied, and

This paper discusses temporally continuous and discrete forms of the speed-limited particle-in-cell (SLPIC) method first treated by Werner et al. [Phys. Plasmas 25, 123512 (2018)]. The dispersion relation for a 1D1V electrostatic plasma whose fast particles are speed-limited is derived and analyzed. By examining the normal modes of this dispersion relation, we show that the imposed speed-limiting substantially