This paper provides perspectives on recent progress in understanding the physics of devices in which the external magnetic field is applied perpendicular to the discharge current. This configuration generates a strong electric field that acts to accelerate ions. The many applications of this set up include generation of thrust for spacecraft propulsion and separation of species in plasma mass separation

Magnetic turbulence is directly observed internally in the pedestal of ELMy H-mode tokamak plasmas using a newly developed Faraday-effect polarimetry measurement. Fluctuation amplitude is δ b r ≥ 15   G (150–500 kHz), with a ratio of magnetic to density fluctuation | δ b r / B | / | δ n / n | ≥ 0.15. Magnetic turbulence is identified as resulting from micro-tearing-instability and mode growth accompanied

We report the direct molecular dynamics simulation results of the ultracold two-component plasma expansion. Interaction between charges is described by Coulomb's law. The number of particles varies from 103 to 105. It is shown in this article that the expansion of the plasma begins with the evaporation of some of the electrons and with the transfer of their kinetic energy to the energy of the electric

Ion temperature anisotropy in an expanding magnetized plasma is investigated using laser induced fluorescence. Parallel and perpendicular ion velocity distribution functions (IVDFs) were measured simultaneously with high spatial resolution in the expanding plasma. Large ion temperature anisotropies ( T ⊥ i / T ∥ i ∼ 10) are observed in a conical region at the periphery of the expanding plasma plume

Particle-in-cell simulations of jets of electrons and positrons in an ambient electron–proton plasma have revealed an acceleration of positrons at the expense of electron kinetic energy. We show that a filamentation instability, between an unmagnetized ambient electron–proton plasma at rest and a beam of pair plasma that moves through it at a non-relativistic speed, indeed results in preferential positron

The ion microfield distribution in neutral and positively charged points is studied for two-component ultracold plasma using molecular dynamics simulation. The calculations are made in a wide range of the strongly coupled parameter. The particles are treated within classical statistical mechanics using an electron–ion Coulomb potential in the entire range of distances between the particles, without

In this paper, we prove that the kappa distribution is the stationary solution of the Vlasov–Poisson system in an inhomogeneous plasma under the polytropic equation of state and an assumption restricting the local velocity distribution to a specific mathematical form. The profiles of density, temperature, and electric potential are obtained theoretically. The kappa index can be determined if the initial

An order of magnitude difference was observed in the energy deposition during a microsecond explosion of thin nickel wires in a vacuum, depending on the design of the wire-holding electrodes. In one case, cylindrical polished stainless steel (ss) electrodes with a rounded edge have a small axial hole of 0.3 mm to hold a thin wire. In the second case, these were the same polished electrodes without

By using particle-in-cell simulations, we study the collision of two plasma flows with one of them carrying a magnetic field. Ion interpenetration results in the formation of a magnetic piston with the magnetic field compression proportional to the density ratio of the colliding plasmas. The counterpropagating ions in the nonmagnetized plasma upstream from the piston excite the ion Weibel instability

Following recent work, we discuss waves in a warm ideal two-fluid plasma consisting of electrons and ions starting from a completely general, ideal two-fluid dispersion relation. The plasma is characterized by five variables: the electron and ion magnetizations, the squared electron and ion sound speeds, and a parameter describing the angle between the propagation vector and the magnetic field. The

Experiments have demonstrated that a Z-pinch can persist for thousands of times longer than the growth time of global magnetohydrodynamic (MHD) instabilities such as the m = 0 sausage and m = 1 kink modes. These modes have growth times on the order of t a = a / v i, where vi is the ion thermal speed and a is the pinch radius. Axial flows with d u z / d r   ≲   v i / a have been measured during the

The effect of increasing strength of the electric field of separated charge due to the capture of laser-accelerated fast electrons in a thin solid target is theoretically substantiated. The target considered is so thin that a fast electron passes through the target during the time less than at least half of the applied laser pulse with the additional requirement that energy loss of a fast electron

We show that, under Braginskii magneto-hydrodynamics, anti-parallel gradients in an average ion charge state and electron temperature can be unstable to the growth of self-generated magnetic fields. The instability is analogous to the field-generating thermomagnetic instability, although it is driven by the collisional thermal force magnetic source term rather than the Biermann battery term. The gradient

The Hamiltonian formulations for the perturbed Vlasov–Maxwell equations and the perturbed ideal magnetohydrodynamics (MHD) equations are expressed in terms of the perturbation derivative ∂ F / ∂ ϵ ≡ [ F , S ] of an arbitrary functional F [ ψ ] of the Vlasov–Maxwell fields ψ = ( f , E , B ) or the ideal MHD fields ψ = ( ρ , u , s , B ), which are assumed to depend continuously on the (dimensionless)

Development and stability of heavy ion ring beams created by high speed neutral atom injection in the Earth's ionosphere is analyzed in view of the upcoming space measurement of a rocket-released turbulence (SMART) mission. It is found that due to velocity dispersion of the injected neutral atoms, an ensemble of ion ring beams will be formed at a given location upon photoionization. Associated with

The collision of two expanding plasma flows is investigated with an emphasis on the mixing flow. The study adheres to laboratory experiments where two Ohmically exploding parallel wires launch hot plasma coronas toward each other. The interpenetration and mixing of the coronas is followed by the collision and mixing of the slowly moving phases of the melted wires. In a recent publication [M. A. Malkov

Interaction of coherent structures known as blobs in the scrape-off layer of magnetically confined plasmas is investigated. Isolated and interacting seeded blobs, as well as full plasma turbulence, are studied by two-dimensional numerical simulations. The features of the blobs (position, size, amplitude) are determined with a blob tracking algorithm, which identifies them as coherent structures with

The effects of nitrogen gas seeding in the edge and scrape-off layer (SOL) regions of a tokamak plasma are studied through 2D fluid simulations using the BOUT++ code. Proper account is taken of the presence of multiple charged states of nitrogen ions due to ionization, recombination, and dissociation processes, and a self-consistent study of the interaction of these ions with the turbulent plasma in

The generations of zonal flow (ZF) and density (ZD) and their feedback on the resistive drift wave turbulent transport are investigated within the modified Hasegawa-Wakatani model. With proper normalization, the system is only controlled by an effective adiabatic parameter, α, where the ZF dominates the collisional drift wave (DW) turbulence in the adiabatic limit α > 1. By conducting direct numerical

A purely magnetic applied field may provide plasma confinement under conditions where the bulk of the plasma is effectively free of the applied magnetic field. The applied magnetic field surrounds the bulk of the plasma, and plasma particles that are incident on the applied magnetic field can be reflected back into the effectively unmagnetized region of plasma. The concept belongs to a class of magnetic

The Solov'ev ansatz is employed to solve the equilibrium equation for plasmas rotating in the toroidal direction. The plasma shape can be controlled by fixing the values of the aspect ratio, elongation, triangularity, and curvature at the equatorial points. In addition, it is possible to set the values of the plasma current, total β, and Mach number. Analytic expressions for the shape coefficients

The method of solving the linear resistive plasma response, based on the asymptotic matching approach, is developed for full toroidal tokamaks by upgrading the resistive DCON code [A. H. Glasser, Z. R. Wang, and J.-K. Park, Phys. Plasmas 23, 112506 (2016)]. The derived matching matrix, asymptotically matching the outer and inner regions, indicates that the applied three dimension (3-D) magnetic perturbations

The statistical characteristics of the scrape-off layer (SOL) turbulence have been investigated in the first divertor plasma operation of W7-X using a reciprocating probe. The turbulence spectra, auto-correlation time and the statistical parameters are analyzed in three magnetic configurations. In standard and high mirror configurations, the SOL turbulence can be classified into four patterns from

An extensive validation effort performed for a modest-beta NSTX NBI-heated H-mode discharge predicts that electron thermal transport can be entirely explained by electron-scale turbulence fluctuations driven by the electron temperature gradient mode (ETG), both in conditions of strong and weak ETG turbulence drive. Thermal power-balance estimates computed by TRANSP as well as the shape of the high-k

The dynamics of plasma and ejection characteristics of spheromaks produced by a magnetized coaxial plasma gun are studied. By placing three magnetic probes at various axial positions, the distribution of current paths in the gun is found to vary in two distinct discharge modes. During the first half-period of a discharge, the plasma moves forward in the form of a current sheet, while the diffuse distribution

We study the possibility of constructing steady magnetic fields satisfying the force balance equation of ideal magnetohydrodynamics with tangential boundary conditions in asymmetric confinement vessels, i.e., bounded regions that are not invariant under continuous Euclidean isometries (translations, rotations, or their combination). This problem is often encountered in the design of next-generation

A numerical integration method for guiding-center orbits of charged particles in toroidal fusion devices with three-dimensional field geometry is described. Here, high order interpolation of electromagnetic fields in space is replaced by a special linear interpolation, leading to locally linear Hamiltonian equations of motion with piecewise constant coefficients. This approach reduces computational

The nonlinear evolution of the m/n = 2/1 double tearing mode (DTM) is investigated by the toroidal resistive magnetohydrodynamic code CLT. It is found that the m/n = 2/1 DTM can lead to either a core pressure crash or an off-axis pressure crash. Unlike the core pressure crash, the plasma pressure at the magnetic axis remains almost unchanged during the off-axis pressure crash. The pressure crash only

Two existing particle-in-cell gyrokinetic codes, GEM for the core region and XGC for the edge region, have been successfully coupled with a spatial coupling scheme at the interface in a toroidal geometry. A mapping technique is developed for transferring data between GEM's structured and XGC's unstructured meshes. Two examples of coupled simulations are presented to demonstrate the coupling scheme

The effects of a radial electric field, which is ubiquitous in stellarators, are considered when a system of reduced-MHD equations is derived from a gyro-kinetic Vlasov–Maxwell system. The resulting equations for the MHD continuum have been implemented into the continuum code CONTI. For a tokamak case, the MHD continuum is calculated and compared with a gyro-kinetic continuum calculated using the EUTERPE

The self-similar nonlinear evolution of the multimode ablative Rayleigh–Taylor instability (RTI) and the ablation-generated vorticity effect are studied for a range of initial conditions. We show that, unlike classical RTI, the nonlinear multimode bubble-front evolution remains in the bubble competition regime due to ablation-generated vorticity, which accelerates the bubbles, thereby preventing a

Recent interest in fielding direct drive multi-shell targets on the NIF [K. Molvig et al., Phys. Rev. Lett. 116, 255003 (2016) and S. X. Hu et al., Phys. Rev. E 100, 063204 (2019)] has highlighted the need for a low density structure to support the inner shell(s) and to avoid energy loss in the acceleration and collision process. We have developed a two-shell platform to evaluate the use of low density

In indirect drive inertial confinement fusion (ICF), laser induced Hohlraum preheat radiation (so-called M-band, >1.8 keV) asymmetry will lead to asymmetric ablation front and ablator–fuel interface hydrodynamic instability growth in an imploding capsule. First experiments to infer the M-band asymmetries at the capsule were performed on the National Ignition Facility for high density carbon (HDC) ICF

Simulating warm dense matter that undergoes a wide range of temperatures and densities is challenging. Predictive theoretical models, such as quantum-mechanics-based first-principles molecular dynamics (FPMD), require a huge amount of computational resources. Herein, we propose a deep learning based scheme called electron temperature dependent deep potential molecular dynamics (TDDPMD), which can be

In the shock-ignition inertial confinement fusion scheme, high-intensity lasers propagate through an inhomogeneous coronal plasma, driving a shock designed to cause fuel ignition. During the high-intensity ignitor laser pulse, in the long scale length coronal plasma, back-scattered stimulated Raman scattering (SRS) is likely to be in the kinetic regime. In this work, we use one-dimensional particle-in-cell

In high-temperature density functional theory simulations (from tens of eV to keV), the total number of Kohn–Sham orbitals is a critical quantity to get accurate results. To establish the relationship between the number of orbitals and the level of occupation of the highest energy orbital, we derived a model based on the homogeneous electron gas properties at finite temperature. This model predicts

A new fluid model describing backward stimulated Raman scattering (SRS) is presented based on parametric three-wave coupling in multidimensional geometry. It takes into account kinetic effects in the description of the plasma wave via a nonlinear frequency shift due to trapped electrons. This model is valid in the regime of hot and weakly inhomogeneous plasmas under conditions relevant for inertial

Lower-than-expected deuterium–tritium fuel areal densities have been experimentally inferred across a variety of high-convergence, nominally low-adiabat implosion campaigns at the National Ignition Facility (NIF) using cylinder-shaped Hohlraums [Hurricane et al., Phys. Plasmas 26, 052704 (2019)]. A leading candidate explanation is the presence of atomic mix between the fuel and ablator from hydrodynamic

Radiographs of pure-DT cryogenic imploding shells provide critical validation of progress toward ignition-scalable performance of inertial confinement fusion implosions [J. Nuckolls et al., Nature 239, 139 (1972)]. Cryogenic implosions on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] can be self-radiographed by their own core spectral emission near ≈2 keV. Utilizing the

Shock wave formation in dusty plasma consisting of mobile positive and negative ions, nonthermal electrons, and negatively charged static dust particles is theoretically studied in the presence of a magnetic field. Using the reductive perturbation technique, the basic set of fluid equations is reduced to the three-dimensional Zakarov–Kuznetsov Burgers nonlinear wave equation. The dissipation generated

Large-amplitude electromagnetic ion cyclotron (EMIC) waves induce unique dynamics of charged particle movement in the magnetosphere. In a recent study, modulation of the ion pitch angle in the presence of large-amplitude EMIC waves is observed, and a good explanation for this phenomenon is lacking. In this paper, we investigate this modulation primarily via a one-dimensional hybrid simulation model

Modulation heating of the ionosphere using high-power high-frequency (HF) radio waves can generate an extremely low frequency (ELF) radiation source in the ionosphere, such as amplitude-modulation (AM) heating of the auroral electrojet or using two HF radio waves to illuminate the same region of the ionosphere to form beat-wave (BW) modulation. We first present observations of ELF waves received on

Waves in bi-ion plasmas are affected by asymmetry. The kinetic theory of the Maxwellian and Lorentzian/kappa-distributed bi-ion plasma is ameliorated to incorporate the transfer of orbital angular momentum from the helical electric field to the plasma modes. By operating the Laguerre–Gaussian function, the perturbed distribution function and helical electric field are decomposed into characteristic

Magnetic reconnection efficiently converts magnetic energy into kinetic and thermal energy of plasmas. It is recently found that energy conversion mainly occurs at reconnection fronts (characterized by the enhancement of the reconnected magnetic field component Bz) and the reconnection exhaust during single X-line reconnection. However, magnetic islands are produced in multiple X-line reconnection

A number of recent experiments at the VULCAN laser at the Rutherford Appleton Laboratory involving high intensity ( 10 19   W / cm 2) sub-picosecond laser pulses incident on thin ( ∼ 10   μ m) metal foils for use as a proton probe have suggested that the addition of a gas cell behind the foil results in a significant increase in the production of hard x rays, particularly in the direction counter to

The role played by temporal asymmetry in a linearly polarized laser pulse on the acceleration of an electron in vacuum in the presence of an axial magnetic field has been investigated. The temporal shapes of the laser pulses considered here are Gaussian, positive skew (sharp rise and slow fall), and negative skew (slow rise and sharp fall). Since the pulse amplitude rises sharply in the case of positive

Very efficient generation of a high-charge electron beam by a laser pulse propagating in a self-trapping mode in near-critical density plasma makes it possible to produce a high yield of gamma rays for radiography of samples located deep in a dense medium. The three-dimensional particle-in-cell and Monte Carlo simulations performed with end-to-end modeling from laser–plasma interaction to the final

The dependence of the laser-driven ion acceleration from thin titanium foils in the Target Normal Sheath Acceleration (TNSA) regime on target and laser parameters is explored using two dimensional particle-in-cell simulations. The oblique incidence ( θ L = 45 °) and large focal spot size ( w 0 = 40 μ m) are chosen to take an advantage of quasi one-dimensional geometry of sheath fields and effective

Coherent transition radiation is used to evaluate fast electron transport of a laser-driven relativistic electron beam in ultrathin targets in selected materials. By preheating the targets with a low-intensity laser pulse, the bulk resistivity effects on electron transport in heated and unheated aluminum foils were compared with those in polyethylene (CH) foils. Unheated aluminum foils showed a pinched

It has been proposed that laser-induced relativistic plasma mirror can accelerate if the plasma has a properly tailored density profile. Such accelerating plasma mirrors can serve as analog black holes to investigate Hawking evaporation and the associated information loss paradox. Here we reexamine the underlying dynamics of mirror motion in a graded-density plasma to provide an explicit trajectory

An experimental investigation of electrode voltage/discharge current, plasma density, including negative ions and ion flux, and ion energy distributions (IEDs) is performed in a low-pressure oxygen discharge excited by a multi-tile electrode, very high frequency (162 MHz) capacitively coupled plasma system. The results show a mode transition vs RF power. An inflection point is observed in the measured

Coulomb collisions in plasmas are typically modeled using the Boltzmann collision operator, or its variants, which apply to weakly magnetized plasmas in which the typical gyroradius of particles significantly exceeds the Debye length. Conversely, O'Neil has developed a kinetic theory to treat plasmas that are so strongly magnetized that the typical gyroradius of particles is much smaller than the distance

We report experiments characterizing the stratified and filamentary structures formed in the dense core of nanosecond electrical explosion of aluminum wires to understand the physical scenario of electrothermal instability. Direct experimental observations for stratification and filamentation instabilities, as well as the coexistence state of azimuthal strata and vertical filament in the dense plasma

The drift-Alfvén instabilities of the sheared flow along the magnetic field of a finite beta ( 1 > β ≫ m e / m i ) plasma with comparable inhomogeneous ion temperature and homogeneous electron temperature are examined by the numerical analysis of the derived linear dispersion equation. Accounting for the electromagnetic ion kinetic response, which has been neglected in conventional discussions of the

In this paper, we propose a relativistic quantum many-body theory for the collective modes in spinor quantum electrodynamic plasma. Different from the usual quantization scheme, we use the self-consistency nontrivial background field method in the framework of thermo field dynamics, in which the resulting quanta are temperature-dependent particles instead of the observable ones such as electrons, positrons

In this work, we treat a plasma semi-bounded by a sphere, where the plasma particles are reflected back to the plasma upon collision with the sphere's surface, and investigate the effects of such reflections on longitudinal electrostatic waves. A dispersion relation as a function of the sphere's radius is obtained, and its roots are compared to Langmuir and ion-sound modes. We have found that it is

We study with a two-dimensional particle-in-cell simulation the stability of a discontinuity or piston, which separates an electron–positron cloud from a cooler electron–proton plasma. Such a piston might be present in the relativistic jets of accreting black holes separating the jet material from the surrounding ambient plasma and when pair clouds form during an x-ray flare and expand into the plasma

In this paper, we develop a new method to study the plasmon energy band structure in multispecies plasmas. Using this method, we investigate a plasmon dispersion band structure of various quasineutral plasma systems with arbitrary degree of electron degeneracy. The linearized Schrödinger–Poisson model is used to derive an appropriate coupled pseudoforce system from which the energy dispersion structure

Multipactor is a resonant nonlinear electron multiplication effect that may occur in high power microwave devices at very low pressures, such as those operating in particle accelerators and satellite subsystems. In this research, multipactor of a rectangular waveguide was analyzed using the commercially available, numerical simulation software “Spark3D.” The electromagnetic wave in the simulation was

A new mechanism for damping of slow magnetosonic waves (SMWs) by pressure induced oscillations of the ionization degree is proposed. An explicit formula for the damping rate is quantitatively derived. Physical conditions where the new mechanism will dominate are briefly discussed. For high frequencies, the ionization–recombination damping is frequency independent according to the Mandelstam–Leontovich