Anomalous resistivity caused by lower hybrid drift instabilities (LHDIs) has been extensively studied in the literature, and has been invoked to explain the rates of magnetic diffusion and plasma profile evolution in the low-density plasma periphery of theta and screw pinch plasmas. This article presents a fully kinetic simulation study of LHDIs with a realistic mass ratio using the particle-in-cell

A conventional single null divertor geometry has been proposed for Chinese fusion engineering testing reactor (CFETR) with fusion power up to gigawatt level. Modeling using the SOLPS5.0 code package shows promising results for divertor power exhaust by seeding with neon (Ne) and deuterium (D2). Partial detachment for both inner and outer divertor targets can be achieved with a peak heat load lower

This work presents the results of experimental and theoretical research of impact of tailored density profile and application of external axial magnetic field on initial spatial distribution of the plasma density in the plasma metal puff Z-pinch and on its implosion dynamics. It has been discovered that upon implosion of the plasma metal puff Z-pinch some stripes interpreted as the system of two coaxial

Mix of high-Z material from the capsule into the fuel can severely degrade the performance of inertial fusion implosions. On the Hybrid B campaign, testing the largest high-density-carbon capsules yet fielded at the National Ignition Facility, several shots show signatures of high levels of hot-spot mix. We attribute a ∼ 40 % yield degradation on these shots to the hot-spot mix, comparable to the level

Based on a proposed high-resolution numerical simulation, a qualified development of ionospheric instability triggered by chemical release is first presented in this paper. First, the upwelling, pinching, penetrating, and bifurcating processes of artificial instability are overall produced with electron density patterns generated by using this model. This high-resolution simulation method is first

A study is made of the radiation of whistler waves with helical phase fronts from nonsymmetric sources immersed in a homogeneous cold magnetoplasma. The emphasis is placed on calculating the radiation resistance of an antenna in the form of two orthogonally crossed circular loops with quadrature-phased currents using an approach that is based on an eigenfunction expansion representation of the excited

It is shown that externally magnetized gas-puff z-pinches under compression can exhibit robust axial flux amplification under suitable axial boundary conditions. This effect relies upon the Hall term in the generalized Ohm's law to generate azimuthal currents in the presence of a driving axial electric field. Under dynamic compression, the total current tends to flow in a mostly force-free boundary

The impact of electromagnetic effects on macroscopic dynamics of blobs in hot low-β ( β < m e / m i) edge plasma of fusion devices is analyzed. The physical model governing filament dynamics is presented. The qualitative analysis of the blob motion in electrostatic and electromagnetic regimes is performed. The scalings for the plasma potential and filament advection velocity are obtained along with

The nonlinear evolution of electromagnetic instabilities in reversed shear plasmas is investigated by means of global gyrokinetic simulations. It is found that the kinetic infernal mode (KIM), which is a pressure-driven instability with low to intermediate toroidal mode number excited in a region of low magnetic shear, is unstable at high β, while the ion temperature gradient mode is unstable at low

We report on the self-organization of multiple double layers (MDLs) and self-organized criticality (SOC) behavior through subsequent layer reduction process around the anode during DC glow discharge in a linear cylindrical vacuum vessel. The present study provides an insight into the characteristic features of self-organized MDLs around the anode itself and the effect of an external magnetic field

Plasma devices, as well as some astrophysical objects, are often characterized by the presence of the counterstreaming flows of electrons and positively charged particles in the plasma. In such diodes, more than one stationary solution is possible for the same set of diode parameters. In this paper, we have studied the stability of the most complex solutions, which are characterized by the presence

We develop a conservative gyrofluid model that is suitable for global flux-driven simulations of electrostatic tokamak plasma turbulence. On the basis of the general gyrofluid moment equations, we derive energy equations which enable us to manipulate the impact of a gyrofluid closure on energetics. We demonstrate that an artificial manipulation of high order moment contributions to gyrofluid moment

An analytic study is conducted on the impact of poloidal E × B flow on geodesic acoustic mode (GAM) in the edge pedestal of a tokamak plasma. A set of coupled nonlinear equations is derived from a reduced magnetohydrodynamic model. Analytic solutions to the set of coupled equations reveal that the non-geodesic component of a poloidally asymmetric pressure perturbation begins to contribute to GAM when

This work uses the Rutherford model for a cylindrical plasma to study the dynamics of magnetic islands under external magnetic perturbations, including both applied rotational magnetic fields and static error magnetic fields. The results show that, in an unstable tearing situation, magnetic islands are completely suppressed by modulating the frequency of the externally applied rotational magnetic field

The maximum stable pedestal pressure has been shown to increase with core pressure and, in combination with core transport effects, this can lead to a positive feedback mechanism. However, the effect is shown to saturate for a high β in ASDEX-Upgrade simulations [Wolfrum et al. “Impact of wall materials and seeding gases on the pedestal and on core plasma performance,” Nucl. Mater. Energy 12, 18 (2017)]

By exploiting the nonlinear amplification of the power deposition of RF waves, current condensation promises new pathways to the stabilization of magnetic islands. We present a numerical analysis of current condensation, coupling a geometrical optics treatment of wave propagation and damping to a thermal diffusion equation solver in the island. Taking into account the island geometry and relativistic

The synergy of Coriolis force and centrifugal force is proposed to study the influence of poloidal plasma rotation on internal kink and fishbone modes. A new dispersion relation is established by making use of energy principle when Coriolis and centrifugal forces are taken into account in the momentum equation. The significant discovery is that the destabilizing (stabilizing) effect of poloidal flow

The effect of strong electron emission from material surfaces has been proposed to form an “inverse sheath”: a region with a positive potential relative to the near-wall plasma which prevents the flow of ions to the wall [M. D. Campanell, “Negative plasma potential relative to electron-emitting surfaces,” Phys. Rev. E. 88, 033103 (2013); M. D. Campanell and M. V. Umansky, “Strongly emitting surfaces

This paper investigates the subcycling of particle orbits in variational, geometric particle-in-cell methods, addressing the Vlasov–Maxwell system in magnetized plasmas. The purpose of subcycling is to allow different time steps for different particle species and, ideally, time steps longer than the electron gyroperiod for the global field solves while sampling the local cyclotron orbits accurately

We investigate the effects of runaway electron current on the dispersion relation of resistive magnetohydrodynamic modes in tokamaks. We present a new theoretical model to derive the dispersion relation, which is based on the asymptotic analysis of the resistive layer structure of the modes. It is found that in addition to the conventional resistive layer, a new runaway current layer can emerge whose

Helical distortion of the core part of tokamak plasma, which is called a helical core or a long-lived mode, is investigated by means of three-dimensional magnetohydrodynamic equilibrium calculations. It is found that the magnitude of the helical distortion strongly depends on the shape of the plasma boundary for weakly reversed shear plasmas. The triangularity of the boundary enhances the amplitude

The fusion Z-pinch experiment device produces a 0.3 cm radius by 50 cm-long Z pinch between the end of the inner electrode of a coaxial plasma gun and an end wall 50 cm away. The plasma column is stabilized for thousands of instability growth times by an embedded radially sheared axial plasma flow. To investigate the effect of end wall design on Z-pinch plasma behavior, the solid end wall with a central

The observation that ultra-intense lasers acting on solid targets results in high absorption is exciting for applications, but the high divergence of the fast electrons carrying this energy remains a key limitation for developing many concepts. We show using three-dimensional simulations how low-density foam filled resistive guide targets lead to fast electron collimation over extended distance. Our

This paper describes the structure of a higher extreme ultraviolet (XUV) emission and plasma density region which surrounds a pinched dense-plasma column. It is interpreted as a toroidal-like plasma formation, which is flowing by a closed current with poloidal and toroidal components upon its surface. This current produces a local magnetic field, which separates the external discharge current from

Within the inertial confinement fusion (ICF) framework, the solid-to-plasma transition of the ablator arouses increasing interest, in particular due to the laser-imprint issue. Phase evolution of the ablator is linked to the evolution of the electron collision frequency, which is of crucial importance since it drives electron heating by laser energy absorption and lattice-ion heating due to collisions

Mixing between fuel and shell materials in ICF implosions can affect implosion dynamics and even prevent ignition. We use data from a series of separated reactant experiments on the National Ignition Facility to calibrate and test the predictive power of gas–shell mix models. Two models are used to estimate fuel–shell mix: a Reynolds-averaged turbulence model and molecular diffusion. Minor uncertainties

Cylindrical foil liners, with foil thicknesses on the order of 400 nm, are often used in university-scale Z-pinch experiments (∼1 MA in 100 ns) to study physics relevant to inertial confinement fusion efforts on larger-scale facilities (e.g., the magnetized liner inertial fusion effort on the 25-MA Z facility at Sandia National Laboratories). The use of ultrathin foil liners typically requires a central

Using two first-principles computer simulation techniques, path integral Monte Carlo and density functional theory molecular dynamics, we derive the equation of state of magnesium in the regime of warm dense matter, with densities ranging from 0.43 to 86.11   g   cm − 3 and temperatures from 20 000 K to 5 × 10 8 K. These conditions are relevant for the interiors of giant planets and stars as well as

In this paper, we introduce a novel experimental platform for the study of the Richtmyer–Meshkov instability in a cylindrically converging geometry using a magnetically driven cylindrical piston. Magnetically driven solid liner implosions are used to launch a shock into a liquid deuterium working fluid and, ultimately, into an on-axis rod with a pre-imposed perturbation. The shock front trajectory

Magnetic reconnection in quasi-parallel shocks, relevant to the Earth's bow shock, is studied by means of two-dimensional full particle-in-cell simulations. As the Alfvénic Mach number increases, the propagation direction of the waves excited in the transition region changes, and the shock becomes more turbulent with more reconnection sites. In the higher Mach number shock, abundant electron-only reconnection

Dayside magnetic reconnection at the magnetopause, which is a major driver of space weather, is studied for the first time in a three-dimensional (3D) realistic setup using a hybrid-Vlasov kinetic model. A noon–midnight meridional plane simulation is extended in the dawn–dusk direction to cover 7 Earth radii. The southward interplanetary magnetic field causes magnetic reconnection to occur at the subsolar

Laser-heated capillary discharge waveguides are novel, low plasma density guiding structures able to guide intense laser pulses over many diffraction lengths and have recently enabled the acceleration of electrons to 7.8 GeV by using a laser-plasma accelerator (LPA). These devices represent an improvement over conventional capillary discharge waveguides, as the channel matched spot size and plasma

Acceleration of a rest electron bunch in vacuum by a Laguerre–Gauss (LG) laser pulse is studied using three-dimensional test-particle simulations. It is found that the ponderomotive force and the phase synchronization process, with the help of each other, cause rest electrons to reach high energies in the laser interaction. The ponderomotive force due to the spatial distribution of a high-intensity

Many high power electronic devices operate in a regime where the current they draw is limited by the self-fields of the particles. This space charge limited current poses particular challenges for numerical modeling where common techniques like over-emission or Gauss' Law are computationally inefficient or produce nonphysical effects. In this paper, we show an algorithm using the value of the electric

The breakdown problem in the relativistic backward wave oscillator (RBWO) limits the microwave pulse energy and should be solved. The slow wave structure (SWS) is the most key component of the RBWO. The breakdown of SWS may be triggered by field-induced electron emission and electron bombardment on the wall. This paper demonstrates that the space charge field of the relativistic electron beam (REB)

Using high-resolution, two-dimensional particle-in-cell simulations, we investigate numerically the mechanisms of terahertz (THz) emissions in sub-micrometer-thick carbon solid foils driven by ultraintense ( ∼ 10 20   W   cm − 2), ultrashort ( 30   fs) laser pulses at normal incidence. The considered range of target thicknesses extends down to the relativistic transparency regime that is known to optimize

In this paper, we theoretically study the propagation dynamics of a q-Gaussian laser beam in a plasma by considering the relativistic and ponderomotive nonlinearities. The q-Gaussian laser beam exhibits unique characteristics while interacting with the plasma. The q-Gaussian laser beam redistributes the plasma density in a different way, which affects the laser self-focusing. A comparative study of

Ab initio theoretical simulations are performed for charge state distribution and energy loss of a 100 keV proton beam propagating in partially ionized discharge H plasmas. In the simulation, all transition processes are calculated accurately among eight main projectile electronic configurations including the most relevant excited states. Projectile configuration evolution is computed by solving rate

We investigate the interaction of electromagnetic waves and electron beams in a 4 m long traveling wave tube (TWT). The device is specifically designed to simulate beam-plasma experiments without appreciable noise. This TWT presents an upgraded slow wave structure (SWS) that results in more precise measurements and makes new experiments possible. We introduce a theoretical model describing wave propagation

Lateral interaction between two geometrically modified plasma plumes in the presence of a transverse magnetic field has been investigated. Characteristic behavior of both seed plumes and the interaction region in the presence of the field is compared with those for the field free case. Contrary to the field free case, no sharp interaction zone is observed; rather large enhancement in emission intensities

Z-pinch dynamic hohlraum experiments have been carried out at the Julong-1 facility by imploding a nested tungsten wire array, which is configured with 20/10 mm diameter and 168/84 wires of 6.0 μm in diameter for the outer/inner array, onto a 10 mg/cc C15H20O6 foam converter with a radius of 2.3 mm. Detailed processes of shock formation, propagation, and radiation transfer of dynamic hohlraum were

When the plasma is unable to provide the positive anode sheath with ions (small anode, low anode plasma conductivity, ablating anode), the ions must be generated inside the sheath itself. The Poisson equation for the sheath with ion generation is solved. The ion flux from the sheath to the neutral plasma is obtained as a function of the anode voltage drop. It is shown that in the case of highly intensive

In this paper, a Monte Carlo simulation method was proposed to investigate the initial cascade process of low-pressure microwave air breakdown. Calculations were performed by tracing electrons only, with the assumption that space charge was negligible. Two main electron generation mechanisms, electron-impact ionization and surface secondary electron emission (SEE), were introduced to simulate the initial

The equations of the two-fluid model of low-pressure plasmas with warm ion gas are taken into consideration including collisions between charged particles and neutrals, the charge exchange, and the ionization. The basic equations contain a removable singularity at the ion sonic speed. These equations are ill-conditioned in the subsonic interval of the ion flux, but they are well-conditioned in the

We developed a hybrid plasma source combined with an inductively coupled plasma (ICP) antenna and a capacitively coupled plasma (CCP) electrode. The ICP antenna and the CCP electrode are connected to a single RF power generator in parallel and a variable capacitor Cv is connected to the ICP antenna in series. The currents flowing through each source and the CCP electrode voltage are measured for analysis

Due to large particle exhaust velocity and specific impulse, electric propulsion systems have an edge over chemical propulsion for missions targeting regions outside the Earth's atmosphere. Stationary plasma thrusters and helicon plasma thrusters (HPTs) are commonly used electric propulsion devices for a space mission. In HPTs or expanding magnetic field plasma thrusters, plasma expands from the source

In negative ion sources, a cusped magnetic field is generated by magnets placed around each aperture of the extraction grid in order to limit the co-extracted electron current. In spite of this suppression magnetic field, the co-extracted electron current is large, on the same order as the negative ion current extracted from the plasma. In this paper, we study the mechanisms of electron extraction

Numerical simulations of subsonic and supersonic nonequilibrium air inductively coupled plasmas (ICPs) were carried out inside a medium-power 100-kW ICP wind tunnel (ICPWT), which is widely used to study the thermal protection system and the blackout phenomenon of reentry vehicles in the aerospace field. A thermochemical nonequilibrium magneto-hydrodynamic numerical model, which takes into account

Changing the RF bias is widely used to control the ion energy in inductively coupled plasma (ICP). Here, the plasma densities were measured using the floating harmonic method at various ICP powers and RF bias power frequencies. It is observed that there is an RF bias power (PB,min) that minimizes the plasma density. With increasing ICP power, PB,min is increased. When the frequency is changed from

This work was carried out in a frame of the study of the discharge propagation in noble gases in focused beams of the terahertz frequency range radiation. A 40 kW at 670 GHz pulsed gyrotron was used as a source of heating radiation. The propagation velocity of the discharge front in various noble gases (argon, krypton, and a helium–argon mixture) was measured over a wide pressure range (from several

An accurate state to state model describing the plasma kinetics in reacting oxygen plasma has been built up giving particular attention to vibrational–translational O–O2 processes, as well as O–O2(v) dissociation and recombination, direct electron impact dissociation, and resonant electron–vibration (e–V) processes for O2. Moderate and low pressure situations are investigated for both discharge and

Secondary electron emission from copper is probed utilizing Monte Carlo simulations that take account of elastic scattering based on the Mott theory and inelastic collisions based on energy-dependent energy loss functions. The loss function and stopping power were obtained through first-principles density functional theory. Angular assignment of electrons following elastic scattering or the creation

The ion energy and angular distributions of H+, H 2 +, and H 3 + impinging on an extraction aperture (3 mm in radius) have been investigated with a hybrid model of an inductively coupled H2 ion source. A dc is applied at the end of the cylinder discharge chamber, which pulls these three ions toward the extraction aperture. With an increase in the bias voltage, their ion angular distributions (IADs)

Taking into account the dust grain size distribution, the Bohm criterion is revisited by means of a one-dimensional, stationary, and non-magnetized theoretical model. An argon plasma is considered where the electrons are characterized by the Boltzmann distribution; however, the other species are described by the fluid equations. The dust grain charge number is described by the orbit motion limited

When a hypersonic vehicle flies near space, a layer of complex dusty plasma will form around the vehicle under the influence of high temperature, which will cause radar signal attenuation (ATT) to different degrees and lead to communication barriers. Therefore, studying the interaction mechanism between electromagnetic waves and dusty plasma is important. In this paper, the Bhatnagar–Gross–Krook collision

Magnetic reconnection in strongly magnetized astrophysical plasma environments is believed to be the primary process for fast energy release and particle energization. Currently, there is strong interest in relativistic magnetic reconnection in that it may provide a new explanation for high-energy particle acceleration and radiation in strongly magnetized astrophysical systems. We review recent advances

Motional Stark effect data acquired during large fast-ion stabilized sawteeth are critically reexamined. The safety factor at the sawtooth crash changes by Δ q ≃ 0.15, much more than any likely errors.

A novel regime of the saturation of the Pierce-type ion-sound instability in a bounded ion-beam-plasma system is revealed in 1D particle-in-cell simulations. It is found that the saturation of the instability is mediated by the oscillating virtual anode potential structure. The periodically oscillating potential barrier separates the incoming beam ions into two groups. One component forms a supersonic

Recent experiments demonstrated that the cyclotron cooling rate of an electron plasma in a Penning–Malmberg trap can be increased by placing the plasma in a cavity and adjusting the magnetic field to make the cyclotron motion resonant with a cavity mode. Here this physics is studied with a coupled oscillator model and analyzed both analytically and numerically. Plasma cooling performance is evaluated

The space-filter approach has been proved as a fundamental tool in studying turbulence in neutral fluids, providing the ability to analyze scale-to-scale energy transfer in configuration space. It is well known that turbulence in plasma presents challenges different from neutral fluids, especially when the scale of interest includes kinetic effects. The space-filter approach is still largely unexplored