A minority relativistic electron component can arise in both laboratory and naturally occurring plasmas. In the presence of high-atomic-number ion species, the ion charge state distribution at a low bulk electron temperature can be dominated by relativistic electrons, even though their density is orders of magnitude lower. This is due to the relativistic enhancement of the collisional excitation and

This article is the first design study of a combined interferometer and polarimeter on a compact, high-field, high-density, net-energy tokamak. Recent advances in superconducting technology have made possible designs for compact, high magnetic field fusion power plants, such as ARC [Sorbom et al., Fusion Eng. Des. 100, 378 (2015)], and experiments, such as SPARC [Greenwald et al., PSFC Report No. RR-18-2

Nonlinear simulations are carried out for the microtearing mode using particle-based δ f gyrokinetic simulations for parameters relevant to spherical tokamaks. The present study finds that the microtearing mode can generate significant electron heat flux, which is predominantly carried out by the electromagnetic component of the heat flux with a negligible contribution from the electrostatic component

A 1D radial diffusion model is developed to study the observed rapid expulsion of argon from the runaway electron plateau in the DIII-D tokamak following secondary massive low-Z ( D 2 or He) gas injection. The expulsion of argon is found to be caused by further cooling of the background plasma due to the added neutrals, accompanied by recombination of argon ions and the greatly increased outward radial

In many plasma applications, the plasma current, which is determined by the plasma density and drift velocity, is an important parameter when investigating the induced phenomenon and its effects. However, it is unclear which physical parameters are responsible for regulating the current. Plasma is generated by a balance between the driving and restricting forces. The driving force originates from the

The velocity particle distributions measured in situ in space plasmas deviate from Maxwellian (thermal) equilibrium, showing enhanced suprathermal tails that are well described by the standard Kappa-distribution (SKD). Despite its successful application, the SKD is frequently disputed due to a series of unphysical implications such as diverging velocity moments, preventing a macroscopic description

Positrons (i.e., antielectrons) find use in a wide variety of applications, and antiprotons are required for the formation and study of antihydrogen. Available sources of these antiparticles are relatively weak. To optimize their use, most applications require that the antiparticles be accumulated into carefully prepared plasmas. We present an overview of the techniques that have been developed to

We determined the shock equation of state of CaF2 at pressures of ∼0.4–1.5 TPa using high-power laser shock techniques. The shock velocity-particle velocity was approximated by the universal Hugoniot relationship known to metallic fluids. Our results do not support the incompressible behavior above ∼100 GPa claimed previously. Warm dense CaF2 is a bonded liquid above the melting point and approaches

Super-thermal ions and electrons occur in both space and fusion plasmas. Because these energetic particles (EP) have large velocities, EP orbits necessarily deviate substantially from magnetic surfaces. Orbits are described by conserved constants of motion that define topological boundaries for different orbit types. Electric and magnetic field perturbations produced by instabilities can disrupt particle

The three-dimensional instability of isothermal ion-acoustic (IIA) solitary waves is examined in a magnetized ultra-relativistic degenerate multicomponent plasma, comprising nondegenerate inertial warm ions and ultra-relativistic degenerate inertialess electrons as well as positrons, by applying a small-k (long wavelength) expansion method. The nonlinear dynamics of IIA solitary waves in such a plasma

A new scheme of Raman scattering of a laser by THz graphene plasmons in the presence of both space charge and electromagnetic surface plasmons is proposed. Plasmon–laser coupling arises through the two dimensional response of electrons in graphene. For optical frequency laser scattering by THz plasmons, phase matching conditions are satisfied for near normal incidence and the Raman scattered wave also

Azimuthal surface waves are well-known to be eigenwaves of coaxial metal waveguides entirely filled by plasma. The present study of electromagnetic energy transfer complements the investigation of the wave dispersion properties carried out earlier. The angular velocity of energy transfer is analyzed as a function of the coaxial-line parameters and compared with three limiting cases. One case is a metal

We study with a one-dimensional particle-in-cell simulation the expansion of a pair cloud into a magnetized electron–proton plasma as well as the formation and subsequent propagation of a tangential discontinuity that separates both plasmas. Its propagation speed takes the value that balances the magnetic pressure of the discontinuity against the thermal pressure of the pair cloud and the ram pressure

The local magnetic field in a Penning–Malmberg trap is found by measuring the temperatures that result when electron plasmas are illuminated by microwave pulses. Multiple heating resonances are observed as the pulse frequencies are swept. The many resonances are due to electron bounce and plasma rotation sidebands. The heating peak corresponding to the cyclotron frequency resonance is identified to

The effect of collisions on driven electrostatic phase space vortices is analyzed by means of Eulerian simulation for two different collision models. It was demonstrated recently [P. Trivedi and R. Ganesh, Phys. Plasmas 23, 062112 (2016)] that in the absence of collisions, at late times, steady state phase space vortices manifest to form a plateau in the resonant region of the particle velocity distribution

Accurate and efficient plasma models are essential to understand and control experimental devices. Existing magnetohydrodynamic or kinetic models are nonlinear and computationally intensive and can be difficult to interpret, while often only approximating the true dynamics. In this work, data-driven techniques recently developed in the field of fluid dynamics are leveraged to develop interpretable

Relativistic mirrors can be realized with strongly nonlinear Langmuir waves excited by intense laser pulses in underdense plasma. On reflection from the relativistic mirror, the incident light affects the mirror motion. The corresponding recoil effects are investigated analytically and using particle-in-cell simulations. It is found that if the fluence of the incident electromagnetic wave exceeds a

Magnetosonic periodic perturbations in a uniform and infinite plasma model are considered. Damping due to compressional viscosity, electrical resistivity, and thermal conduction are taken into account, as well as some heating–cooling function, which may destroy the isentropicity of wave perturbations. The wave vector forms arbitrary angle θ with the equilibrium straight magnetic field, and all perturbations

In this paper, we report theoretical modeling for parametric decay instability of the high-intensity elliptically polarized laser beam [pump wave, ( ω 0)]. A wave–wave interaction model is investigated, based on the decay of the high-intensity elliptically polarized laser ( ω 0) into an oblique whistler wave (OWW, ( ω 1 )) and a kinetic Alfvén wave (KAW, ( ω 2 )). The importance of oblique whistler

Approximated forms of the third and fourth moments of a velocity distribution function are derived by using a perturbed velocity distribution function around a characteristic spatial scale on the gyroradius derived by Thompson [Rep. Prog. Phys. 24, 363–424 (1961)]. Then, they are evaluated by using a two-dimensional full kinetic Vlasov simulation result of the transverse Kelvin–Helmholtz instability

The effects of exchange and correlation on the filamentation instability of a high-density current-driven plasma are theoretically investigated under diffusion conditions by applying the quantum hydrodynamic (QHD) model and the Ampère-Maxwell law. Based on the dispersion relation, a new instability condition is presented, according to which, the important characteristic quantities are identified. Moreover

A model calculation is presented to characterize the anomalous cross field transport of electrons in a Hall thruster geometry. The anomalous nature of the transport is attributed to the chaotic dynamics of the electrons arising from their interaction with fluctuating unstable electrostatic fields of the electron cyclotron drift instability that is endemic in these devices. The electrons energy gain

We present nonlinear NIMROD resistive MHD simulations of the response of a rotating plasma to an error field when the plasma has weakly damped linear tearing modes (TMs), stabilized by a pressure gradient and favorable curvature. The favorable curvature leads to the Glasser effect: the occurrence of real frequencies and stabilization with positive stability index Δ ′. A cylinder with hollow pressure

In magnetic fusion plasmas, mounting evidence suggests the possibility of sustained turbulence below the linear stability threshold or more generally global turbulence bistability. The usual reduced models for turbulence spreading are unistable/supercritical and incompatible with this result. The older models also cannot realistically support fronts connecting laminar and turbulent domains. In this

We investigate the drift wave–zonal flow interaction formulated on a channel domain geometry approximating an isolated plasma edge region with zero net radial transport across the boundary. The recent two-field flux-balanced Hasegawa–Wakatani (BHW) model with improved treatment for a parallel electron response is adapted to the channel geometry configuration, which allows for generalized non-uniform

Transport in the edge and scrape-off layer mediated by turbulent fluctuations is often studied using drift fluid models. In this work, we expand previous work on a two-fluid single ion species drift model to a multi-ion-species model that incorporates collisional interactions between the individual species while conserving energy. The model is simplified into a set of equations that are computationally

Large amplitude fast ion-acoustic solitons are revisited in a three-component plasma composed of cold ions, warm (adiabatic) ions, and hot Boltzmann electrons to determine where the limits occur in the ranges of the warm ion-to-electron temperature ratio τ and the charge-to-mass ratio of the cold ions relative to the warm ions μ for the existence of stopbands. The warm (adiabatic) ion limiting curve

In the present work, a simple analytical approach is presented in order to clarify the physics behind the edge current density behavior of a hot plasma entering in contact with a resistive conductor. As has been observed in recent simulations [C. R. Sovinec and K. J. Bunkers, Plasma Phys. Controlled Fusion 61(2), 024003 (2019)], when a plasma comes in contact with a highly resistive wall, large current

In this work, we study the transport and confinement properties of runaway electrons (RE) in the presence of magnetic fields with perturbations producing different levels of stochasticity. We use Kinetic Orbit Runaway Electron Code (KORC) [Carbajal et al., Phys. Plasmas 24, 042512 (2017) and del-Castillo-Negrete et al., Phys. Plasmas 25, 056104 (2018)] for simulating the full-orbit (FO) and guiding-center

Effects of dynamic wall outgassing on divertor plasma during an edge localized mode (ELM)-like heat pulse are modeled using the newly coupled edge plasma code UEDGE and wall reaction-diffusion code FACE. Different divertor regimes are simulated depending on the degree of the plasma detachment. It is shown that hydrogen outgassing from the divertor target plate induced by ELM pulse in the semi-detached

Axisymmetric Alfvén continuous spectra are derived using the ideal MHD equations. The usual toroidal coupling effect due to the variation of the magnetic field strength is neglected, but the curvature coupling of the pressure fluctuation and the geodesic compressional effect are included. The cylindrical continuous spectrum of Alfvén waves splits into two branches due to these effects. The frequency

A brute-force, long-time gyrokinetic simulation of plasma profile evolution in magnetic fusion devices is not desirable due to large computational resource requirements and a possible accumulation of numerical error. The equation-free projective integration method of Keverekidis et al. [Commun. Math. Sci. 1(4), 715–762 (2003)] is one of the outstanding candidates in projecting micro-scale simulations

Comparison between an open divertor and a more-closed divertor in DIII-D demonstrates detachment up to 40% lower pedestal density ( n e , ped) in the closed divertor due to a combination of decreased fueling of the pedestal and increased dissipation in the scrape off layer (SOL) in the closed divertor, both resulting from increased neutral trapping in the divertor. Predicting whether the relationship

Techniques developed in the domain of optical theory are applied to investigate the behavior of Geodesic Acoustic Modes (GAMs). In this context, we show that this approach represents a powerful basis for the description of many characteristics of radial propagation and spreading of GAMs. The most attractive feature of these techniques is represented by their universality and intuitive applicability

Interactions between energetic particles (EPs) and neoclassical tearing mode (NTM) islands in the DIII-D tokamak are studied using the global gyrokinetic toroidal code (GTC). GTC simulations find that the EP radial profile is partially flattened within the magnetic island regions and that there are stochastic regions in the particle phase space. Radial particle flux is induced mainly around the magnetic

The ubiquitous sawtooth phenomena in tokamaks are so named because the central temperature rises slowly and falls rapidly, similar to the blades of a saw. First discovered in 1974, it has so far eluded a theoretical explanation that is widely accepted and consistent with experimental observations. We propose here a new theory for the sawtooth phenomena in auxiliary heated tokamaks, which is motivated

A hydrodynamic shear mixing layer experiment at the National Ignition Facility had previously demonstrated Eulerian scaling of integrated, late-time quantities, including turbulent kinetic energy. In this manuscript, the experiment is repeated with new materials. Using the new dataset, we demonstrate that Euler-number scalings hold not just for late time, but dynamically throughout the experiment,

The two-laser entrance hole (LEHs) spherical hohlraum energetic experiments with all 48 laser beams and two laser pulse shapes at the 100 kJ level laser facility were investigated. In this work, the time-resolved radiation temperature measured by multi-angle x-ray diodes agreed well with LARED simulations, and the peak radiation temperature was up to 260 eV with the laser power of 45 TW. Meanwhile

The micrometer-scale tube that fills capsules with thermonuclear fuel in inertial confinement fusion experiments at the National Ignition Facility is also one of the implosion's main degradation sources. It seeds a perturbation that injects the ablator material into the center, radiating away some of the hot-spot energy. This paper discusses how the perturbation arises in experiments using high-density

Low-mode asymmetries have emerged as one of the primary challenges to achieving high-performing inertial confinement fusion (ICF) implosions. In direct-drive ICF, an important potential seed of such asymmetries is the capsule stalk mount, the impact of which has remained a contentious question. In this paper, we describe the results from an experiment on the OMEGA laser with intentional offsets at

Ultra-short untraintense laser interacting with solid targets can produce significant electromagnetic pulses (EMPs), which are strongly pertinent to laser and target parameters. In this study, EMPs' generation due to pulsed laser (30 fs, 6 × 10 19 W/cm2) irradiating aluminum foils are recorded and analyzed. The experimental results indicate a pre-ablation pulse (200 ps, 1 × 10 12 W/cm2) that tends

This work details a model used to infer the 3-D structure of the stagnated hot-spot and shell of inertial confinement fusion implosion experiments at the National Ignition Facility. The model assumes that 3-D low-mode drive perturbations can account for the majority of stagnation asymmetries experimentally observed. It uses an adaptive sampling algorithm to navigate the 24-D input parameter space to

Many space and astrophysical environments are dominated by magnetohydrodynamic plasma interactions that are virtually collisionless. However, pseudo-elastic collisions are present through mechanisms of ion-neutral charge-exchange. In this paper, we investigate how charge-exchange collisions affect the balance of momentum and energy between ions and neutrals within the plasma. Our primary application

Cold ions of the ionospheric origin mainly contribute to the ion population in the Earth's magnetosphere. These cold ions can be modulated by Pc5 ultralow frequency waves or wake electric fields in the dayside outer magnetosphere, through which their energy can increase to hundreds of eV. Using measurements of Magnetospheric Multiscale mission, this paper reports a new finding of the cold ion modulation

An analytical formalism is developed for the nonlinear frequency shift of intense laser pulse, due to relativistic mass nonlinearity (in the sub-relativistic regime), on reflection from the critical layer in an inhomogeneous plasma. As a higher and higher intensity front of the pulse approaches the critical layer, the reflection layer moves forward to higher densities, due to the relativistic increase

Magnetic fields driven by a laser in coil targets were studied for laser energies of ∼25 J and two pulse durations of 2.8 ns and 70 ps. Axial magnetic fields in the coils were measured by continuous wave Faraday rotation diagnostics. The diagnostics indicated magnetic fields of 6–14 T in the coil and currents of 10–20 kA. Magnetic fields were compared for similar laser targets, focusing conditions

For ultra-high-intensity lasers irradiating nanometer-sized targets, Coulomb explosion (CE) is one of the main ion acceleration schemes. Previous studies have shown that the CE of solid nanospheres can produce quasi-monoenergetic ions. However, the development of optimized hollow nanospheres has yet to be achieved. Currently, the technology for the production of various types of hollow nanospheres

An analysis of Smith–Purcell (SP) radiation is presented for a cylindrical grating filled with dielectrics and an annular electron beam propagating along the grating axis. The dispersion relations are obtained for the azimuthally symmetric modes when the transverse perturbation of the electron beam is included, and it is compared with the case when the beam motion is restricted in the z-direction.

We demonstrate a novel approach to the generation of femtosecond electron bunch trains via laser-driven wakefield acceleration. We use two independent high-intensity laser pulses, a drive, and an injector, each creating their own plasma wakes. The interaction of the laser pulses and their wakes results in a periodic injection of free electrons in the drive plasma wake via several mechanisms, including

The multi-stage technique in the laser driven acceleration of electrons has become a critical part for full-optical jitter-free accelerators. Several independent laser drivers and shorter plasma targets allow the stable and reproducible acceleration of electron bunches (or beam) at the GeV energies with narrower energy spreads. Moreover, the charge coupling, necessary for efficient acceleration in

We report an efficient scheme to improve the proton acceleration and energy conversion efficiency by using double laser pulses with foil interaction. We find a significant increase in the peak energy, the total number, and the maximum energy of the accelerated protons for the double laser pulses with foil interaction compared to those in the single laser pulse case, while the total laser energy is

In this paper, we present the mechanisms of ionization of a thin gold film irradiated by a high-intensity, short-pulse laser in the range of I = 10 20 − 22   W / cm 2 and the associated acceleration of multiply charged gold ions. A numerical one-dimensional simulation using an extended particle-in-cell code, which includes atomic and collisional relaxation processes, indicates that two types of acceleration

Radiative-shocks induced by laser–cluster interactions are modeled using radiation-hydrodynamic simulations. A good agreement—in both shock velocity and density profiles—is obtained between experiment and simulations, indicating that non-local thermodynamic equilibrium (NLTE) radiative effects are important in the experimental regime examined, particularly at early times ( ≤30 ns) due to the elevated

In the present study, the transfer of energy between a pair of donor–acceptor molecules as point-like dipoles located nearby a plasmonic nanoparticle is investigated, in which an electric point charge is placed at a distance rq from the center of metallic nanoparticle or nanoshell. It is shown that the process of energy transfer between pairs of molecules is affected when an external point charge is

Hydrodynamic motion of radiation-ablated high-Z plasma has a significant influence on the radiation transport in a slot. This work focuses on the closure problem of slots filled with low-Z foam of density varying from 10−2 to 100 g cm−3. A simple one-dimensional model is proposed to study the motion of the ablated high-Z wall plasma in the slot. According to the model, the high-Z plasma first expands

This paper presents an overview of waves and instabilities in relativistic degenerate plasma using magnetohydrodynamic double polytropic laws. The model equations are closed by the double polytropic laws. The general dispersion relation has been derived using the normal mode analysis, which consists of two interesting modes, i.e., shear Alfvén mode and modified magnetosonic modes (both slow and fast)

Sharp temperature gradients in a magnetically confined plasma can lead to turbulent motion of the plasma. This turbulence in turn enhances the transport of heat across magnetic field lines. The enhanced transport impacts the temperature differential that can be sustained in magnetic islands between the island center and its periphery. It is shown here that, by limiting this temperature differential

Gyrokinetic simulations are fundamental to understanding and predicting turbulent transport in magnetically confined fusion plasmas. Previous simulations have used model collision operators with approximate field-particle terms of unknown accuracy and/or have neglected collisional finite Larmor radius (FLR) effects. We have implemented the linearized Fokker–Planck collision operator with exact field-particle

Few, if any, of the many papers on turbulence spreading address the key question of how turbulence spreading actually affects the profile structure. Here, we are using a reduced model to answer that question. Turbulence spreading is most relevant near regions where the profiles support a strong intensity gradient ∇ I. One such case is at the edge of an L mode discharge, near a source of turbulence

Inboard/outboard asymmetry of the toroidal flow has been observed in the large helical device (LHD), especially when the radial electric field is large. We investigate the effect of the Pfirsch–Schlüter flow on the toroidal flow in LHD plasma. As a result, we find that the Pfirsch–Schlüter flow can be significantly large when the electron root solution of the neoclassical ambipolarity condition is