The problems concerning the development of high f-number spectrographs with high spectral and spatial resolution using holographic reflecting gratings, for the study of processes of harmonic generation in laser plasmas are considered. The concave holographic gratings and spectrograph schemes used in the “Delfin-1” installation are described. The anomalous generation of ω0 and 2ω0 harmonics from the subcritical density plasma region has been observed experimentally. Possible interpretations of the observed effect are given.

A comparison of the recombination and photo-pumping approaches for producing X-ray lasing on the hydrogen-like Balmer alpha line is presented. An approximate analytic expression for the ratio of the populations of the n = 3 and 2 quantum states of the hydrogen-like ion is derived and used to delineate the plasma parameter space where Balmer alpha gain can occur in a recombining plasma. The photo-pumping intensities required to produce Balmer alpha gain for plasmas initially in the steadystate are calculated using a collisional-radiative code and compared to intensities required to produce the initial plasmas for a recombination Balmer alpha laser with comparable gain. The recombination approach becomes relatively more efficient compared to the photo-pumping approach with increasing atomic number Z of the hydrogen-like ion with an estimated break-even at approximately Z = 16.

We show that the thermal transport in laser produced plasmas can be inhibited due to the outward plasma blow-off which is in the opposite direction to the inward heat transport. A simple model is proposed in which the steady state heat transfer equation, including the convective term for a point heat source, is solved. A simple analytical expression for the ratio of effective to classical conductivity depending on the blow-off velocity is obtained. With this model, present experimental data on thermal transport can be qualitatively, but consistently described.

Filamentary and jet-like structures are observed in the interaction of a laser beam with aluminum and gold targets. The range of irradiance is 1013 to 5 × 1014 W cm−2 with nanosecond pulses. According to theoretical predictions these structures can be attributed to thermal instabilities. We show that the electrothermal instability grows more probably at the 0.35 μm laser wavelength whilst the magnetothermal instability develops at 1·06 μm. The jet-like structures occurring on the rear side of thin targets are discussed.

The hitherto successful hydrodynamic plasma theory needed the simplifying assumption of quasi-neutrality. Earlier known ambipolar fields in plasma surfaces were considered as exceptions and Alfvén's model of a complementary description by plasma currents was criticized. Fields in plasmas were derived from the kinetic theory of turbulence. Following a model for the nonlinear force of laser–plasma interaction, we needed a general description of the plasma without space charge neutrality which succeeded numerically and analytically. High electric fields due to inhomogeneities inside plasmas were derived explaining for the first time quantitatively the reduction of thermal conduction in laser-fusion, the measured inverted double layers including a new type of resonance process, the MeV α-upshift by nonlinear-force driven caviton fields and the radial fields in tokamaks which cause plasma rotation.

Attempts to accelerate and implode laser targets are hindered by the non-uniformities present in real laser beams. The effects of non-uniform illumination are ‘smoothed’ by thermal transport in the low density ablation plasma but amplified by the fluid instabilities (Rayleigh–Taylor) present in the high density accelerated material. In this paper the effects of different assumptions concerning the plasma thermal conductivity are analysed and the inclusion of the full fluid equations is shown to introduce oscillatory (acoustic) and growing (Rayleigh–Taylor) phenomena into the fluid response.

The radiation hydrodynamics of material layers for energy conversion of intense ion beams into black body radiation is investigated, both analytically and numerically. Conversion efficiency and hydrodynamic losses are the main topics. The basic scaling relations are derived and compared with computer simulations. Although the analysis is done for slab geometry, a generalization to converters of arbitrary shape and deposition geometry is outlined. The code MINIRA is briefly described. The influence of varying layer density, optical thickness and beam power on radiation emission as well as the effect of Bragg peak deposition are discussed in detail. High conversion efficiencies of more than 50% can be obtained provided that the converter is operated in the radiative regime. For typical beam intensities, this requires low-density layers. Another essential feature is supersonic heat transport which occurs in the radiative regime.

The self consistent electrostatic field due to plasma inhomogeneities and associated with free expansion of a plasma into a vacuum is evaluated in the framework of two-fluid hydrodynamics and the corresponding generalized Rieman's self-similar solution found. The case of an adiabatic expansion is also discussed and the results obtained are applied to a laser produced plasma with a characteristic electron temperature of 1 keV and a characteristic time scale of 1 nsec.

The Proto-I experiment for a proof-of-principle experiment is described resulting in a beam divergence for ions of only 14mrad at 1·5 MV—420 KA operation and 6 KA/cm2 anode current density before focusing. This is a better beam divergence than required for Sandia National Laboratories' PBFA I and II installations, for which scaling is discussed. Ion source development is reported and the PBFA II experiment described for 30 MV operation with short pulses (10–15 nsec) of lithium ions. Pulses of 50 nsec width and 130 KJ energy have been achieved from the prototype module for PBFA II.