The paper presents results of an investigation of energy transport in 6-μm aluminum foils covered with a silver or gold layer irradiated with 1·06-μm, 1-ns laser-pulse at intensities 1013to 1014 W/cm2. The increase in mass ablation rate and volume heating of accelerated fragment of the foil as well as the increased range of lateral energy transport were registered. The measured plasma parameters from aluminum foils were used for testing the one-dimesional numerical code.

In this paper we present main parameters of the thermonuclear fuel and relations connecting the thickness of an isothermal homogeneous cryolayer with gaseous microballoon parameters. A model of the temperature field calculation (the azimuthal temperature gradient and the temperature distribution) and the way of shaping it under practical experimental conditions by the contact-point method is presented. The temperature distribution calculation explains the “sag” effect observed in many experiments.

A formalism for the analysis of the Rayleigh–Taylor instability in the multi-structured solid or shell targets is presented. The formulation covers both the plane and the curved geometry targets. A generalized eigenvalue equation for the exponential growth rate of the instability is derived along with the necessary boundary conditions. Analytical solutions for the growth rate are presented for some elementary density profiles and a comparative study is made between the plane, cylindrical and spherical targets. The solution for the step function density profile is generalized for any number Nof zones forming an arbitrary density profile. This general formulation is illustrated with the explicit calculations for N = 3 and 4. A qualitative treatment of the effects of the ablative flow is also presented. This study predicts a stabilizing effect of the ablative flow on the growth of the instability. Further, a dynamic analysis of the instability growth rate is presented for a representative inertial confinement fusion spherical solid target driven by the laser beams. This study demonstrates that an approximate analysis of the instability with the time independent initial density profile gives the conservative results for the instability growth rate.

Use is made of the Vlasov–Maxwell equations to derive an eigenvalue equation describing the extraordinary–mode stability properties of relativistic, non-neutral electron flow in high-voltage diodes. The analysis is based on well-established theoretical techniques developed in basic studies of the kinetic equilibrium and stability properties of nonneutral plasmas characterized by intense self fields. The formal eigenvalue equation is derived for extraordinary-mode flute perturbations in a planar diode. As a specific example, perturbations are considered about the choice of self-consistent Vlasov equilibrium , where . is the electron density at the cathode (x = 0), H is the energy, and Py is the canonical momentum in the Y-direction (the direction of the equilibrium electron flow). As a limiting case, the planar eigenvalue equation is further simplified for low-frequency long-wavelength perturbations with |ω − kvd, ≪ ωυ where and and ⋯c = eB0/mc, and B0ệz is the applied magnetic field in the vacuum region xb < x ≤ d. Here, the outer edge of the electron layer is located at x = xb; ω is complex oscillation frequency; k is the wavenumber in the y-direction; ωυ is the characteristic betatron frequency for oscillations in the x′-orbit about the equilibrium value x′ = x0 = xb/2; and Vd is the average electron flow velocity in the y-direction at x = x0. In simplifying the orbit integrals, a model is adopted in which the eigenfunction approximated by , where x′(t′) is the x′-orbit in the equilibrium field configuration. A detailed analysis of the resulting eigenvalue equation for , derived for low-frequency long-wavelength perturbations, is the subject of a companion paper.

The kinetic stability properties of relativistic nonneutral electron flow in planar diode geometry are examined for extraordinary-mode perturbations about the self-consistent Vlasov equilibrium . Here, the cathode is located at x = 0; the anode is located at x = d the outer edge of the electron layer is located at is the equilibrium flow velocity in the x-direction; n^b is the electron density at the cathode (x = 0); and is the axial magnetic field, with const. in the vacuum region (xb < x ≤ d). The extraordinary-mode eigenvalue equation, derived in a companion paper for low-frequency, long-wavelength perturbations, is solved exactly. This leads to a formal dispersion relation, which can be used to determine the complex eigenfrequency ω over a wide range of system parameters and wavenumber k in the y-direction. The formal dispersion relation is further simplified for and , assuming low-frequency perturbations about a tenuous electron layer with and . Here, , and , where denotes the average equilibrium orbit, and [γ(x) − 1]mc2 is the average kinematic energy of an electron fluid element. The resulting approximate dispersion relation is solved numerically over a wide range of system parameters to determine the detailed dependence of stability properties on electromagnetic effects, layer thickness, and electron energy, as measured by , and γb − 1, respectively. Here, γb = γ(xb) denotes the electron energy at the outer edge of the electron layer. As a general remark, it is found that increasing the electron energy (γb − 1), increasing the strength of electromagnetic effects , and/or decreasing the layer thickness (xb/d) all have a stabilizing influence.

The effect of thermal flux transport inhibition on the coupling of the spherical dense pellet core with the hot electron halo produced at the plasma resonance layer has been investigated. The analytic expressions for the core-corona coupling and the optimum temperature of the overlapping region (at which this coupling is maximum) have been derived as a function of ‘flux limit’ parameter and the laser wavelength. Relevant calculations indicate that the core-corona coupling is sensitive to the mean electron temperature and the scaling of its maximum value with the laser wavelength remains absolutely unaffected by plasma ablation. The subsequent results on laser wavelength scaling are compared and contrasted with the predictions of other investigations. The heat transfer from the hot electron cloud to the dense core can be increased by an order of magnitude in case of the uninhibited flux.

In this paper we have theoretically studied the field distributions and resonance absorption in a laser-produced plasma filament. Under the condition of the cold plasma we derive the field equations, as well as their analytical solutions, to the radial and axial components of the electric field. Then, by the numerical calculations, we find that there exists a tunnel effect along the radial direction of the filament, i.e., the electric field reaches a maximum near the radial resonance point r0. Thus, the curves of variance of the radial and axial field components are obtained.

The linear conversion theory of laser produced plasma filaments is studied in this paper. By calculations for the energy flux of the second harmonic emission on the basis of the planar wave-plasma interaction model, it has been found that there exists no 2ω0 harmonic emission in the direction perpendicular to the incident laser, in contradiction with the experiments. Therefore, we have proposed a linear conversion theory on the second harmonic emission from a plasma filament and discovered the intense 2ω0 harmonic emission in the direction perpendicular to the incident laser, which is in agreement with the experiments.

Experimental studies on high power ∼ 10 μs electron beam generation have been carried out. High efficiency (about 75%) of energy transfer from a capacitor storage to the electron beam with total energy about 150 kJ has been attained.

In order to investigate the gasdynamic laser (GDL) a conventional pressure driven shock tube equipped with the nozzle apparatus was used. Kinetic study of CO2 formation in CO–N2O–H2 system behind a reflected shock wave was carried out by measuring 4·25 μm emission of CO2. Then, population inversions of the vibrational level of CO2 in an expanding flow of mixtures containing CO2 produced by high temperature reaction of CO–N2O–H2 system behind reflected shock wave were observed by measuring 10.6 μm small signal gains. The experimental data are compared with those obtained by computer simulation assuming quasi-one dimensional steady flow and three vibrational energy modes model. The optimum conditions for CO2 gasdynamic laser by using the shock heated CO–N2O–H2 system are discussed.

Ion emission from laser-produced plasma with small focal spots (20 μm) has been investigated for s- and p-polarization of the Nd–YAG laser at IL = 6 * 1013 W/cm2. The target has been Plexiglas (Hg, C5, O2) n, and the ion analysis has been charge, mass and velocity resolved for emission angles between 15° and 65°. It is found that additional resonance absorption mainly leads to an enhancement of the number of totally emitted ions which is essentially uniform for a large region of the velocity spectrum. The total increase in plasma expansion energy is by a factor of more than 3·5. The relatively low enhancement of the average initial temperature produces an unexpected asymptotic charge distribution with higher charges if resonance absorption is not present.

Empirical expressions are proposed for the frequency and damping rate of electron plasma waves and ion acoustic waves in an unmagnetized, partly collisional plasma.