Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high energy density and inertial confinement fusion science. The 80-TW “Z” pulsed power facility at Sandia National Laboratories is the largest pulsed power device in the world today. Z discharges up to 22 MJ of energy stored in its capacitor banks into a current pulse that rises in

Plasma medicine is an innovative research field combining plasma physics, life science, and clinical medicine. It is mainly focused on the application cold atmospheric plasma (CAP) in therapeutic settings. Based on its ability to inactivate microorganisms but also to stimulate tissue regeneration, current medical applications are focused on the treatment of wounds and skin diseases. Since CAP is also

This article first gives the authors' perspectives on how the field of plasma-based acceleration (PBA) developed and how the current experiments, theory, and simulations are motivated by long term applications of PBA to a future linear collider and an x-ray free electron laser. We then focus on some early applications that will likely emerge from PBA research such as electron beam radiotherapy, directional

It is shown that the variational principle of multi-region relaxed magnetohydrodynamics (MRxMHD) can be used to predict the stability and nonlinear saturation of tearing modes in strong guide field configurations without resolving the dynamics and without explicit dependence on the plasma resistivity. While the magnetic helicity is not a good invariant for tearing modes, we show that the saturated

The electric multipole polarizabilities of one-electron atoms embedded in weakly coupled Debye plasmas are calculated in the non-relativistic framework. The static dipole, quadrupole, octopole, and hexadecapole polarizabilities for hydrogen atoms in both ground and excited states at a variety of Debye screening parameters are calculated in high precision based on the sum-over-states method, where the

The stability theory of the inductively coupled plasma (ICP) is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. The theory predicts the existence of the instabilities of the ICP which are driven by the current formed in the skin layer by the accelerated motion of electrons relative to ions under the action of the

The solution of the linear dispersion relation of electromagnetic oblique instabilities, for two counterstreaming electron beams, is investigated by using an extended fluid approach that includes the full dynamics of the pressure tensor. Numerical solutions of the simplified polynomial formulation so obtained are analyzed and compared to full kinetic solutions. They correspond to two classes of eigenmodes:

The nonlinear regime of electromagnetic oblique instabilities is investigated by means of a “noiseless” semi-Lagrangian Vlasov–Maxwell solver. Starting from an initial equilibrium configuration with two counterstreaming electron beams, qualitatively different nonlinear regimes are shown to exist depending on the nature of the solutions of the linear dispersion relation, whose properties have been discussed

The description of the plasma effect using an accurate screened potential, which is crucial for many applications of plasma physics, represents a hitherto challenge for theory. Here, we present a theoretical determination of the level delocalization and transition rate of an exemplary hydrogen atom immersed in plasmas. Specific forms of the screened potentials include the average-atom, the standard

The closure problem in fluid modeling is a well-known challenge to modelers aiming to accurately describe their systems of interest. Over many years, analytic formulations in a wide range of regimes have been presented but a practical, generalized fluid closure for magnetized plasmas remains an elusive goal. In this study, as a first step toward constructing a novel data-based approach to this problem

Rayleigh–Taylor instability (RTI) has critical importance for a broad range of plasma processes, from supernovae to fusion. In most instances, RTI is driven by variable acceleration, whereas the bulk of existing studies have considered only constant and impulsive acceleration. This work focuses on RTI driven by acceleration with a power-law time-dependence. We review the existing theoretical approaches

Previous work has invoked kinetic and magnetic spatial complexities, associated with velocity and magnetic fields u ( x , t ) and B ( x , t ), respectively, in order to study magnetic reconnection and diffusion in turbulent and magnetized fluids. In this paper, using the coarse-grained momentum equation, we argue that the fluid jets associated with magnetic reconnection events at an arbitrary scale

The physical processes taking place at the separatrix and scrape-off layer regions are crucial for the operation of tokamaks as they govern the interaction of hot plasma with the vessel walls. Numerical modeling of the edge with state-of-the-art codes attempts to elucidate the complex interactions between neoclassical drifts, turbulence, poloidal, and parallel flows that control the physical set-up

The plasma response to an externally generated, static, n = 2, resonant magnetic perturbation (RMP) in the pedestal region of DIII-D H-mode discharge #158115 is investigated using a toroidal generalization of the asymptotic matching model presented by Fitzpatrick [Phys. Plasmas 27, 042506 (2020)]. Just as in a recent paper [Q. M. Hu et al., Phys. Plasmas 26, 120702 (2019)], it is hypothesized that

Effects of anisotropic thermal transport on the linear stability of the resistive plasma resistive wall mode (RPRWM) are investigated by the magnetohydrodynamic-kinetic hybrid code MARS-K [Liu et al., Phys. Plasmas 15, 112503 (2008)], including the kinetic contribution from energetic particles (EPs). It is found that thermal transport can further stabilize the RPRWM in the presence of drift kinetic

We develop a diffusive, bistable, tri-unstable cellular automata (CA) model to study the dynamics of H-mode pedestal with edge localized modes (ELMs) and their control by supersonic molecular beam injection (SMBI) and pellet injection (PI). It is shown that the new CA model can reproduce the key features of H-mode pedestals with various types of ELM, including Type-I ELM. SMBI and PI are modeled as

A global eigenvalue solver code is used to analyze the kinetic damping of radially localized kinetic toroidal Alfvén eigenmodes (KTAEs). By including the finite-Larmor-radius effects of ions, KTAEs are found in the Alfvén continuum well above the upper boundary of the TAE gap. The numerical calculations reveal that the real frequency and the kinetic damping of the KTAEs increase with increasing ion

A two-temperature Hall-magnetohydrodynamic (Hall-MHD) model, which evolves the electron and ion temperatures separately, is implemented in the PSI-Tet 3D MHD code and used to model plasma dynamics in the Helicity Injected Torus–Steady Inductive (HIT-SI) experiment. The two-temperature model is utilized for HIT-SI simulations in both the PSI-Tet and NIMROD codes at a number of different injector frequencies

The DC and radio frequency (RF) properties of RF driven sheaths were studied in the Large Plasma Device (LAPD) at the University of California, Los Angeles. The experiments diagnosed RF sheaths on field lines connected to a grounded plate at one end and an ion cyclotron range of frequencies antenna at the other end. The experimental setup permitted measurement of the RF sheath impedance at the plate

We present global linear and nonlinear simulations of ion temperature gradient instabilities based on a fluid formulation, with an adapted version of the JOREK code. These simulations are performed in realistic global tokamak equilibria based on the solution of the Grad–Shafranov equation. Benchmarking of linear growth rates was successfully completed with respect to previously published data. We find

The dynamics at the edge of fusion confinement devices is driven by interchange instabilities and involves the motion of plasma across two regions—the “core region” and the scrape-off layer (SOL)—distinguished by whether field lines are, respectively, closed or connected to the wall. Motivated by this phenomenon, we present an extensive linear stability analysis of a two-layer plasma model encompassing

A model is proposed which accounts for the modification in the electron cyclotron (EC) resonance condition for Gaussian beams injected in inhomogeneous plasmas, due to the finite width of the transversal spectrum caused by the paraxial character of the beams, within the framework of the complex geometrical optics. The resonance modification due to the non-uniformity of the equilibrium magnetic field

A new electron drift instability driven by resonance with precession reversed fast trapped ions in reversed magnetic shear tokamak plasmas is identified from gyrokinetic simulations. Results from the initial value GKW code and eigenmode analysis in the ballooning space are in broad agreement with predictions from the local analytic theory [B. J. Kang and T. S. Hahm, Phys. Plasmas 26, 042501 (2019)]

The Enhanced Pedestal (EP) H-mode regime is an attractive wide-pedestal high-βp scenario for the National Spherical Torus Experiment Upgrade (NSTX-U) and next-step devices as it achieves enhanced energy confinement (H98y,2 > 1.5), large normalized pressure (βN > 5), and significant bootstrap fraction (fBS > 0.6) at Ip/BT = 2 MA/T. This regime is realized when the edge ion collisionality becomes sufficiently

An adequate confinement of α-particles is fundamental for the operation of future fusion powered reactors. An even more critical situation arises for stellarator devices, whose complex magnetic geometry can substantially increase α-particle losses. A traditional approach to transport evaluation is based on a diffusive paradigm; however, a growing body of literature presents a considerable amount of

The accuracy with which the Thomas–Fermi (TF) model can provide electronic specific heat capacities for use in calculations relevant to fast electron transport in laser-irradiated solids is examined. It is argued that the TF model, since it neglects the quantum shell structure, is likely to be significantly inaccurate for low- and intermediate-Z materials. This argument is supported by examining the

Several approaches to Inertial Confinement Fusion (ICF), including double-shell, pushered-single-shell, and the Revolver designs, have fuel surrounded by pushers made from high-Z materials. An advantage of these designs is that radiation emitted by the hot fuel will be absorbed and re-radiated into the fuel to reduce cooling. This process is referred to as radiation-trapping, and it lowers the fuel

Nonlinear evolution of the ablative Rayleigh–Taylor instability (ARTI) is investigated on the Shenguang-II laser facility using a target specifically designed for this purpose. The evolution of the excited bubbles and spikes is tracked and their displacement amplitudes are quantitatively measured with the help of a Kirkpatrick–Baez microscope coupled with an x-ray framing camera. Radiation-hydrodynamic

We present a simple model to scope out parameter space for indirect-drive, inertial confinement fusion designs for the National Ignition Facility laser. Because the parameter space is large, simple models can be used to identify regions of parameter space for further study with more sophisticated models and experiments. We include a model for Hohlraum radiation drive and symmetry—both based on empirical

Deuterium gas-puff z-pinches are very efficient laboratory sources of neutron pulses. Using a novel hybrid gas-puff load on the GIT-12 generator, a significant increase in the neutron yields up to 5.6 × 10 12 is reached. At the same time, a very broad neutron energy spectrum up to energies on the order of tens of MeV is observed. In these experiments, the neutrons are produced not only by the D(d,n)3He

The hydrodynamic growth of pre-imposed isolated defects has been studied with varied laser drive. Targets were machined at NRL by etching narrow isolated grooves into thin polystyrene (CH) foils using femtosecond laser ablation. Two laser pulse shapes were used to drive the foils with and without a thin high-Z overcoat which produced a hybrid indirect–direct drive. The growth rate and saturation time

Engineering features are known to cause jets of ablator materials to enter the fuel hot-spot in inertial confinement fusion implosions. The Biermann battery mechanism wraps them in a self-generated magnetic field. We show that higher-Z jets have an additional thermoelectric magnetic source term that is not present for hydrogen jets, verified here through a kinetic simulation. It has similar magnitude

In this article, we study Beltrami equilibria for plasmas near the horizon of a spinning black hole and develop a framework for constructing the magnetic field profile in the near horizon limit for Clebsch flows in the single-fluid approximation. We find that the horizon profile for the magnetic field is shown to satisfy a system of first-order coupled ODEs dependent on a boundary condition for the

Frequency power spectra are computed theoretically for shear Alfvén waves excited in a solar coronal arcade by two separate perturbations, a cosine-modulated Gaussian perturbation and an impulsive driver. The arcade is assumed to consist of potential magnetic field lines embedded in a stratified plasma. It is shown that although the power spectra have discrete frequencies for each field line, a cumulative

Solar wind is often known as a source of energizing Earth's magnetosphere and it is a highly complex system displaying various phenomena. Alfvén waves are believed to play a crucial role in its dynamics. The dispersive Alfvén waves (DAWs) may explain various plasma processes, for example, the transfer of energy over different length scales, particle energization, etc., and it is one of the promising

The generation of low-frequency radiation from a short pulse (∼100 fs) laser with mJ energy incident on a metal surface is investigated. The electrons within the metal surface absorb energy from the laser pulse, increasing in temperature to a few electron volts and resulting in some at the high-energy tail of the distribution to overcome the work function barrier. Emission of these electrons from the

Laser produced plasma (LPP) soft x-ray and extreme ultraviolet sources utilize various types of targets. Some of them are based on gaseous targets. The most important disadvantage of such targets is the very limited number of elements that can be used in the gaseous form under normal conditions, including chemical compounds in the gaseous state. In this paper, the authors propose a new type of target

It is known that the gyrotron theory is developed in a general form that allows one to draw many important conclusions about gyrotron operation, which are valid for gyrotrons operating in arbitrary modes, at arbitrary frequencies, and driven by electron beams with different voltages and currents. One of important issues in this theory is the analysis of possible start-up scenarios, i.e., the methods

The advantages of using symmetrical and asymmetric eigenmodes of a slow-wave system (SWS) in a relativistic traveling-wave tube (TWT) with multi-pass amplification are discussed. The nonlinear theory of such a TWT amplifier is developed. The parameters of the SWS of the Ka-band TWT amplifier based on a combination of the lower symmetric E01 mode and the asymmetric hybrid HE11 mode are calculated. The

The plasma density grating induced by intersecting intense laser pulses can be utilized as optical compressors, polarizers, waveplates, and photonic crystals for the manipulation of ultra-high-power laser pulses. However, the formation and evolution of plasma density grating are still not fully understood as linear models are adopted to describe them usually. In this paper, two theoretical models are

We propose to use a 10 petawatt (PW) laser irradiating onto a target with a concave surface, which can focus the laser beam and attain a more intense laser field, so as to increase both the yield and mean energy of emitted γ-rays. 2D particle-in-cell simulation results show that the peak electric field after the reflection of the laser from the target in this new scheme can reach ∼ 1.8 times as high

In this paper, a numerical simulation is used to investigate the influence of applied voltage rise time on negative corona current characteristics in SF6 at atmospheric pressure. There were 23 particle species and 67 kinds of reactions considered in plasma chemical reactions. The influence of different rise times of the applied voltage is investigated. The spatial distributions of the radial electric

The helium (He) non-thermal atmospheric pressure plasma jet (APPJ) source was configured, and the He spectra were measured by applying AC power to the source. A He collisional-radiative (CR) model was developed to investigate the He spectra obtained from the APPJ source. Different atmospheric pressure (AP) processes were evaluated, and the dominant processes among them that contribute to the He spectra

A two-dimensional fluid model was used to investigate the characteristics of helium dielectric-barrier discharge (DBD) equipped with double-ring electrodes at atmospheric pressure. Simulation results show that although the temporal evolutions of discharge current and current density at different radial positions exhibit the same or similar characteristics to those in traditional DBD, a distinctive

In recent years, more stringent environmental protection requirements have led to increasingly higher voltage power equipment that adopt SF6 mixed gas as an insulation medium. In this paper, the streamer development in SF6 mixed gas and the distribution of each gas component were studied over time. Thus, a discharge model of the needle plate electrode with SF6 mixed gas was established. The hydrodynamic

The effects of capacitive coupling on electron and ion density profiles are studied in an argon inductively coupled plasma. Electron energy probability functions and two-dimensional ion density profiles were measured by changing the termination capacitance from 200 to 1000 pF. Experimental results show that a termination capacitor creates a virtual ground on a coil, and the virtual ground suppresses

The genesis of the ion axial velocity distribution function (VDF) is analyzed for collisionless Hall thruster discharges. An analytical form for the VDF is obtained from the Vlasov equation, by applying the Tonks–Langmuir theory in the thruster channel, under the simplifying assumptions of monoenergetic creation of ions and steady state. The equivalent set of 1D unsteady anisotropic moment equations

The volume-averaged global plasma model has been widely used to analyze the characteristics of plasma, although the spatial variation of plasma parameters cannot be obtained from it. It has also been used to obtain temporal plasma parameters for pulsed plasma sources. In this work, we analyzed the effect of an edge-to-center density ratio (h factor) and an electron heating model on the plasma parameters

Thomson scattering was applied to measure the electron density and temperature in laser-induced SF 6 plasmas at various pressures (0.2–2 atm). The plasma was induced by the Nd:YAG laser (1064 nm, 200 mJ, and 7 ns) focused into a chamber filled with SF 6. A second harmonic Nd:YAG laser (532 nm, 50 mJ, and 6 ns) was used to probe the distributions of electron density and temperature. The images after

The transition from snowplow mode to deflagration mode of a parallel-plate plasma accelerator under gas-prefilled conditions is studied. The accelerator is powered by a sinusoidal-wave power supply with a first half-period current of 24.3 μs. The current distribution of the current conduction channel is measured by magnetic probes, the optical emission spectrum by a spectroscopic system, and the plasma

A major scientific success story of magnetic fusion research in the past several decades has been the theoretical development and experimental testing of the process of turbulence decorrelation and stabilization by sheared E × B flow, which shows that E × B shear effects are ubiquitous in magnetized plasmas. This concept of turbulence decorrelation and stabilization has the universality needed to explain

Hydroxyl (OH) radicals were generated by dielectric barrier discharge (DBD) from water vapor in a multi-pass cell with a volume of 8000 cm3. The cell was filled with the following water vapor at reduced pressure. The absolute OH number density was accurately determined by direct absorption spectroscopy using a tunable laser operating at 2.8 μm. The absolute OH number density was around 1012 molecules/cm3

A tutorial is presented on advances in spectroscopic diagnostic methods developed for measuring key plasma properties in pulsed-power systems such as Z-pinches, magnetized-plasma compression devices, ion and electron diodes, and plasma switches. The parameters measured include the true ion temperature in Z-pinch implosions, which led to a discovery that much of the ion kinetic energy at stagnation

The effect of an initially uniform magnetic field of arbitrary orientation on the Richtmyer–Meshkov instability in Hall-magnetohydrodynamics (MHD) and ideal MHD is considered. Attention is restricted to the case where the initial density interface has a single-mode sinusoidal perturbation in amplitude and is accelerated by a shock traveling perpendicular to the interface. An incompressible Hall-MHD

Parametric decay instabilities (PDIs) exciting daughter waves trapped inside a magnetized plasma with a non-monotonic density profile are investigated numerically. The investigation is motivated in particular by observations of low threshold PDI signatures during second harmonic electron cyclotron resonance heating experiments in magnetically confined fusion experiments. We use the particle-in-cell

A model for plasma/neutral fluid interaction was developed and included in the implementation of non-linear MHD equations to a new code framework. The source rates of ion, electron, and neutral fluid momentum and energy due to ionization and recombination are derived using a simple method that enables the determination of the volumetric rate of thermal energy transfer from electrons to photons and

Zebra-like patterns have been observed in the electron cyclotron emission spectra from strongly nonequilibrium plasma confined in a table-top mirror magnetic trap. The analysis of the experimental data suggests that the formation of zebra-like patterns could eventually be related to the modulation of the whistler waves by the ion-acoustic waves excited during the abrupt ejection of electrons into a

In a relativistic backward-wave oscillator operating at a low magnetic field, forward intense relativistic electron beams propagate with large transverse velocities and form a non-uniform beam-density distribution. This paper first investigates periodical density bunching by bombarding targets with electron beams in a relativistic drift tube. Then, the dependence of the density-bunching phase on interaction

The kinetic theory of a low-voltage beam discharge instability in He is developed in the conditions, when the distance between electrodes is of the order of electron–atom collision length and the density of electrons in a primary beam is up to ten percent of the plasma density. The dispersion equation and its numerical and analytical solutions are obtained. The stability loss of this discharge is described

We examine with particle-in-cell simulations how a parallel shock in pair plasma reacts to upstream waves, which are driven by escaping downstream particles. Initially, the shock is sustained in the two-dimensional simulation by a magnetic filamentation (beam-Weibel) instability. Escaping particles drive an electrostatic beam instability upstream. Modifications of the upstream plasma by these waves