By employing analytic solutions for the electromagnetic field at resonance absorption, first derived by Denisov, the total nonlinear force, in the plane of incidence has been evaluated. This 2-D force results in a conical type emission towards the vacuum and into the plasma which depends critically on the collision frequency and the density scale length. It is found that, for neodynium glass laser intensities of 1014 W/cm2, keV ions can be produced by nonlinear force acceleration. The analysis is limited by the following requirements: the dielectric constant varies linearly with distance, the angle of incidence is not too small and most importantly self consistent and transient wave processes occur at a later time and are neglected.

Numerical simulations and analyses are given for the implosion of a hollow shell target driven by proton beams. The target consists of three layers of Pb, Al and DT. The Pb and Al layers play roles of a tamper and a pusher, respectively. The main part of the beam energy is deposited in the Al layer. But the process of deposition depends strongly on the distribution of incident angles and particle energies. As the Al layer is heated by proton beams, the layer expands and pushes the DT layer toward the target centre. This type of implosion motion is examined by using a similarity solution for the slab model. To obtain an optimum velocity for the DT implosion, the optimum target size and optimum layer thicknesses are determined. The Rayleigh–Taylor instability, accompanied by the implosion motion is investigated, and the implosion is found to be stable with respect to the chosen target structure. The effects of inhomogeneities on implosion are shown to be severe. The initial fluctuation of the temperature or the density in the Al layer must be less than 3% and the maximum amplitude of the ripples on the initial boundary surface should be less than 3 μm with a view to achieving a high target gain.

While the action of electrostatic double layers in the periphery of an expanding laser produced plasma has been discussed and treated many years ago, some new aspects pioneered recently by Alfvén in the theory of cosmic plasmas, indicate the possibility of a new treatment. The thermally produced electrostatic double layer which has been re-derived for a homogeneous plasma shows that a strong upshift of ion energies (by the mass ratio) is possible, in agreement with experiments. The number of accelerated ions is many orders of magnitude smaller than observed at keV and MeV energies. The nonlinear force acceleration could explain the number and energy of the observed fast ions. It is shown, however, that electrostatic double layers can be generated which should produce super-fast ions. This paper presents a derivation of the spread double layers in the case of inhomogeneous plasmas. It is concluded that the hydrodynamically expected multi GeV heavy ions for 10TW laser pulses (generated by relativistic self-focussing and nonlinear forces) should produce super-fast ions up to the TeV range. Further conclusions are drawn from the electrostatically measured upshifted (by 300 keV) DT fusion alphas from laser compressed plasma. An analysis of alpha spectra attempts to distinguish between different models of the stopping power in the plasmas. The analysis preliminarily arrives at a preference for the collective model.

The expansion of laser-produced plasmas in two-dimensions is examined analytically using an asymptotic (time→∞) isothermal self-similar model. The ion emission velocity and energy spectra are calculated and expressions given for the number and energy of expanding ions as a function of angle to the target. By relating the total ion kinetic energy of expansion to the temperature of the initial plasma, it is shown that ion probe signals give a measure of the initial plasma temperature. The model is extended to a plasma with two initial temperatures (a ‘hot’ component and a ‘cold’ component) and it is shown that the ion energy spectra here can be used to deduce the initial temperatures of the ‘hot’ and ‘cold’ ions and the relative number of the ‘hot’ ions to the ‘cold’ ions. The results are used to interpret data from an array of ion probes (at different angles to the target) for a plasma produced by irradiating a 25 μm thick nickel foil with a ∼20 ρs neodymium laser pulse.

The generation of high-energy-density plasmas by the electromagnetic implosion of cylindrical foils (i.e., imploding plasma shells or hollow z-pinches) has been explored analytically and through numerical simulation. These theoretical investigations have been performed for a variety of foil initial conditions (radius, height, and foil mass) for both capacitive and inductive pulsed power systems. The development of the theoretical modeling techniques is presented, covering both circuit models and plasma load models. The circuit models include simple single loop capacitive and multiple loop inductive systems. These circuits are coupled to the imploding plasma loads whose response has been studied by models ranging from simple time varying inductances to complex two-dimensional magnetohydrodynamic numerical simulations. Results from a series of configurations are given, showing the development of modelling techniques used to study the dynamics of the plasma implosion process and the role of instabilities. Interaction between analytic techniques and detailed numerical simulation has led to improvement in all theoretical modeling techniques presently used to study the implosion process. Comparisons of implosion times, shell structure, instability growth rates, and thermalization times have shown good agreement between analytic/heuristic techniques and more detailed two dimensional magnetohydrodynamic simulations. These in turn have provided excellent agreement with experimental results for both capacitor and inductor pulse power systems.

Field emission is identified as the mechanism responsible for high current emission (50 A/cm2 at 300°K) from a dispenser-type cathode. This cathode has advantages for high power operation, and should be suitable for practical applications.