The development of hydrodynamic instability (HDI) in laser targets is studied by means of 2D numerical code “ATLANT.” The scaling of HDI development for the condition of “DELFIN-1” laser setup experiments is derived. It is shown that there is the possibility to improve the shell compression condition for the case of long-wave perturbation of laser flux (determined by particular target irradiation geometry) by using the shell with “relief.”

Various problems involved in the simulation of current X-ray laser experiments are discussed. The methods are based on laser-plasma simulation techniques with simultaneous calculation of the ionization dynamics, and are particularly appropriate for collisional and recombination pumped systems.

The achievement of hypervelocities (40 km/s or more) is considered by the electrostatic simultaneous acceleration of dust particles positively and negatively charged. This ensures current neutralization. Beams carrying several grams of matter look feasible. The mutual impact of these macroparticles results in temperatures in the fusion range.

Zero-dimensional numerical computation of electrical discharge-pumped excimer lasers is extended to a one-dimensional model that is used to study the effects of the density perturbations of the background neutral gas and the nonuniform predischarge (which means preionization in this paper) electron density on the transition of the uniform discharge to the nonuniform prestage state leading to the onset of arc formation (which is not included in this particular model). It was found that a local density depression of 1% or an enhancement of the local electric field of 1% can increase the local energy input by several hundred percent. The initial electron density perturbations, on the other hand, are found to modify the energy input by the same order of magnitude as the initial perturbations.

The radiation hydrodynamics in laser-produced high-energy-density plasmas has been successfully simulated by means of the MULTI hydrocode. It is used in combination with the SNOP atomic physics code, which uses a steady-state screened hydrogenic explicit ion model and which generates non-LTE opacity tables for MULTI. After a brief general review of the modeling of the radiation hydrodynamics in laser-produced plasmas, the underlying physical models of MULTI and SNOP are described in detail, with particular emphasis on atomic physics. Examples of simulations of the radiation transport in laser plasmas are presented. They include a laser-irradiated gold foil and a radiatively heated carbon foil.

The idea of controlling the plasma flows in laser targets by action of a strong external magnetic field (H ≥ 1 MG) is presented. The magnetic control of plasma flows for the keeping of a transparency of entrance holes of indirect-compression targets and other type targets operating at an introduction of the laser beams into the interior of the target is suggested. It is shown that the magnetic field, transverse versus the direction of the propagation of the plasma flow with an intensity of 2–4 MG, causes a decrease (1.5–3 times) of the closing speed of holes for the laser beam introduction into the hohlraum target.

Results of the analysis and numerical calculations of continuous spectra of multicomponent multicharged plasma radiation are presented. Possibilities of control of the radiation spectrum by the mixture composition variation and programming in time the pulsed discharge current of the supply source are considered. Free and forced (by energy deposition or additional cooling) relaxation time estimations permit the definition of discharge parameters when plasma formation goes on under nonequilibrium conditions, leading to controlled energy redistribution over the spectrum.

Inertial confinement fusion (ICF) targets can be imploded by heavy-ion beams (HIBs) in order to obtain a highly compressed fuel microsphere. The hydrodynamic efficiency of the compression can be optimized by tuning the ablation process in order to produce the total evaporation of the pusher material by the end of the implosion. Such pusherless compressions produce very highly compressed targets for relatively short confinement times. However, these times are long enough for a fusion burst to take place, and burnup fractions of 30% and higher can be obtained if the volume ignition requirements are met. Numerical simulations demonstrate that targets of 1-mg DT driven by a few MJ can yield energy gains of over 70. Although direct drive is used in these simulations, the main conclusions about volume ignition are also applicable to indirect drive.

A new method of intense relativistic electron beam modulation at frequencies up to ∼1 GHz is suggested. Current modulation is provided by using the azimuthal magnetic field of the beam to control the beam reflection from the magnetic mirror. The results of computer simulations for a 2-MeV, 20–50-kA beam are presented.

A physical-mathematical model for the development of the boundary instability of a spherical incompressible-liquid shell, with due regard for the ablation effect, is considered.

Modern numerical simulations of hot dense plasma require atomic data including equations of state, opacities, and coupling coefficients for energy exchange between photons, electrons, and fast and thermal ions. While these coefficients may be calculated by complicated quantum-statistical theories, in many cases the simpler semi-classical theory gives a reasonably accurate first approximation.

It is the aim of this article to design a fusion power plant whose electric output power is 1 GW and find a way for breaking through fusion technically and energy economically. Proton beams whose total energy is 12 MJ, pulse width 30 ns, and beam number 6 are chosen here as the energy driver. Because of the low quality of these proton beams, the target should be indirect driven and its radius should be large. The target with the radius of 8.7 mm is the spherical cryogenic hollow one, which has double shells and five layers. The reactor has double solid walls. The inner wall rotates around the axis to induce a centrifugal acceleration. Flibe as the coolant protects the solid walls from damage and breeds tritium. The key technology of this power plant is for beam focusing and propagation. To suppress beam divergence by the electrostatic force due to unneutralized proton charge, simultaneous electron beam launching is proposed. When the excess electron beam current is –50 kA, the induced magnetic field in the azimuthal direction confines the beam in a radius of 5 mm, provided that the beam path is covered by the metal guide whose radius is 6 mm.

Fokker-Planck (FP) codes have become useful tools for modeling nonlocal heat-transport phenomena in laser-produced plasmas. Several possible simplifications to the FP equation as well as different numerical techniques available for its solution are investigated. The most robust and efficient approach is found to involve the diffusive approximation of the FP equation and the alternating-direction-implicit method of solution. The SPARK FP code, which has been developed along these principles, is described in detail. It incorporates fluid ions and solves for transport on either a two-dimensional Eulerian grid or a one-dimensional Lagrangian grid. Sample simulation results are presented, together with a discussion of possible improvements to the code.

The interaction of femtosecond laser pulses with solid-state density plasmas in regime of normal skin effect is investigated by means of numerical simulation. For short-wavelength lasers and laser pulses with length ≲ 120 fs full width at half maximum, the regime of normal skin effect is shown to hold for peak intensities up to 1017 W/cm2. The basic characteristics of the interaction are revealed and certain departures from simplistic models in electron distribution function, in plasma dielectric constant, and in laser absorption are pointed out. Comparison with the published experimental results is made.

The classical linear Spitzer-Härm formula has been shown to lead to an overestimation of the electron heat flux in laser-plasma interaction experiments. We briefly review the classical theory of heat transport in a plasma, and give a simplified demonstration of the Spitzer-Härm formula. The electron heat conductivity is calculated for a large value of the ion charge Z. Correction due to a finite value of Z is evaluated with a simplified electron-electron collision operator. We then show that in a steep temperature gradient, the collisional mean free path of the electrons that transport the energy may be larger than the scale length of the temperature gradient. In this case the Spitzer-Härm formula overestimates the actual heat flux in the main part of the temperature gradient, and predicts a too small heat flux slightly away from the location of the large temperature gradient.A nonlocal macroscopic formula, which is a sort of convolution of the Spitzer-Härm heat flux by a delocalization function, is shown to accurately describe the electron heat flow in both smooth and steep temperature gradients. This nonlocal formula for the heat flow is analytically justified. A selection of slightly different delocalization functions proposed in the literature is compared to the original one and to the results of Fokker-Planck calculations of the heat flow.

Rayleigh-Taylor (RT) and Richtmyer–Meshkov (RM) instabilities at the pusher–fuel interface in inertial confinement fusion (ICF) targets may significantly degrade thermonuclear burn. Present-day supercomputers may be used to understand the fundamental instability mechanisms and to model the effect of the ensuing mixing on the performance of the ICF target. Direct three-dimensional numerical simulation is used to investigate turbulent mixing due to RT and RM instability in simple situations. A two-dimensional turbulence model is used to assess the effect of small-scale turbulent mixing in the axisymmetric implosion of an idealized ICF target.

The application of random-phase plates in laser beams to improve the uniformity of target ablation is investigated by combining the simultaneous X-ray and particle emission measurements of ablation characteristics. It is shown that if some hot spots with dimensions of a few µm exist on target they persist at least during the initial stages of the laser interaction process, producing a local maximum in the ablation pressure. Lateral energy transport, inferred from the neutral particle measurements, has little influence on absorbed energy redistribution (only 1% of the energy is transported from the laser focal spot to an outer region of 2 mm size).

ELBA is a three-dimensional, particle-in-cell, simulation code that has been developed to study the propagation and transport of relativistic charged particle beams. The code is particularly suited to the simulation of relativistic electron beams propagating through collisionless or slightly collisional plasmas or through external electric or magnetic fields. Particle motion is followed via a coordinate “window” in the laboratory frame that moves at the speed of light. This scheme allows us to model only the immediate vicinity of the beam. Because no information can move in the forward direction in these coordinates, particle and field data can be handled in a simple way that allows for very large scale simulations. A mapping scheme has been implemented that, with corrections to Maxwell's equations, allows the inclusion of bends in the simulation system.

The production of a long scale-length plasma of electron density 1020–1021 cm-3, measuring 10 X 0.5 mm using a laser-heated capillary discharge is reported. X-ray spectroscopic measurements have been performed which show that the plasma constituents can be varied by changing the material that lines the exit slit of the device. The capillary thus provides a useful source of large underdense plasmas created from solid materials suitable for laser-plasma interaction studies. Numerical simulations consistent with spectroscopic studies suggest that temperatures up to about 700 eV were achieved following irradiation of these plasmas by high-power laser light.

An atomic model to describe the density and temperature effects on inelastic electron-ion collisions in dense plasmas is presented. This model has been used for Na-like iron to compute the optically allowed and forbidden collision rates from the ground configuration 1s2 2s2 2p6 3s to the 1s2 2s2 2p6 41 excited levels with l = 0,1,2. The focus is on temperature and density ranges 100–300 eV and 1022–1024 cm-3.