Intense light-ion beam (LIB) propagation through a plasma channel is numerically investigated by using a two-dimensional simulation code. Analyses are given for the LIB propagation which couples with the motion of the channel plasma. Although the electron back current neutralizes the LIB current under typical beam and channel plasma conditions, the Lorentz force of the electron back current expands the LIB radially. The expansion of the LIB depends strongly on the density of the channel plasma. A strong current of the order of 1 MA is shown to propagate stably in an argon plasma channel.

A simple model is presented for the thermodynamic and hydrodynamic behaviour of solid targets heated by intense charged particle beams. The model gives the temperature and pressure generated by the beam and allows a direct comparison with the pressure generated by laser beams. The model is in good agreement with a coupled thermodynamic hydrodynamic computer simulation.

The effect of small-scale wavefront perturbations on laser radiation is investigated at flux densities close to maximum. The model and calculated results for the effect of the degree of radiation coherence on the laser radiation brightness as functions of flux density and length and shape of the active medium are presented. For the restricted coherence of the laser radiation, the rate of small-scale perturbation growth is shown to decrease in theactive medium. The principal optical scheme of a laser for fusion experiments, with the maximum radiation brightness, is given as an example.

It is shown that appropriate conditions for DL formation may be created in laser produced plasma. In particular, a ‘feedback’ mechanism is suggested:

Wave instabilities → absorption of laser energy → inward heat flux → DL formation → heat flux inhibition → wave instabilities

Plasma-target potentials and plasma-currents, produced by Nd. laser intensities (IL) between 1012 to 1015 W/cm2, were measured in situ. These measurements seem to be the first direct evidence of DLs in laser produced plasma. Electric fields of EDL ∼ 5 × 105 to 5 × 106 Volts/cm and widths of 10 to 100 Debye lengths are estimated for the DL.

Scaling laws are derived for the measured extremum potentials (V) and currents (I): . Two different slopes were obtained experimentally, one slope equal to α = β = 1·0 for IL < 1014 W/cm2 and another of α = β = 0·4 for IL > 1014 W/cm2. These data are explained for temperature scaling law for the low irradiance and for the high irradiance. While the first scaling law is consistent with inverse bremsstrahlung absorption, the second scaling necessitates other absorption processes. Potential and current probes are suggested as useful devices in detecting wave plasma instabilities.

A model of laser interaction with a preformed target plasma is developed for the conditions of so called stimulated Brillouin backscattering (SBS) model experiments and its applicability is demonstrated by various tests. Most of the features can be understood from analytical approximations. A consequence of irradiation by a narrow beam, typical of model experiments, is the stabilization of electron temperature at low values. Another consequence equally unexpected is the SBS threshold dependence on beam radius and the particular power law dependence on plasma density. On the basis of this model the wide scatter of the SBS threshold between model experiments can be explained. It is also demonstrated that, for the conditions of these model experiments, classical Spitzer heat conduction suffices.

Computer calculations have been made for a plasma composed of electron and ion fluids, with the electrostatic field as an additional variable described by Poisson's equation, allowing for the first time a hydrodynamic study of the electrostatic phenomena in plasmas, where very short time steps, large computer capacity and special numerical procedures were used. The numerically observed oscillations of the fields and electron fluid and the waves and their damping by collisions have been evaluated and an analytical model has been derived to study damping by Coulomb collisions. The magnitudes of the electrostatic fields in inhomogeneous plasma have been evaluated as functions of temperature and density gradient. For laser irradiation of 1016 W/cm2, including nonlinear forces with the complete intensity dependent (nonlinear) optical response for heating and dielectric force effects, electrostatic fields exceeding 108 V/cm are generated.

Starting from two-wave coupled plasma equations the parametric decay instabilities appearing in homogeneous plasmas are discussed as a first step. If damping is present, the instabilities may appear, and when the damping is so small that it can be neglected, there exists only spatial gain. The analytic solution for inhomogeneous plasma, as a second step, with density varying almost linearly is obtained and the conditions for the instabilities to occur are discussed.

Most of the observed features of magnetically insulated transmission lines are derived from the simple considerations of pressure balance and the space-charge flow limit. These include the mean electron drift velocity and the relationship between line voltage and the currents in the positive and negative lines. This voltage-current relationship is compared with experimental data.

Possible modifications of some of the properties of an electromagnetic wave by a medium in which it propagates, are studied. The mechanism for mass generation is investigated. It is shown that, for some purposes, a medium may be replaced by a curved space. Furthermore, if the nonlinear interaction terms between the electromagnetic wave and the curvature of space-time are included, the resulting Maxwell equations are modified. These additional terms may be identified with the photon's mass, which is proportional to the curvature scalar. A laser intensity above 1020 W/cm2 produces a mass of the photons of about 10−5 times the mass of the electrons.