In the Ampfion diode, an ion beam is extracted from an anode plasma that is being pushed away from the cathode by a rising magnetic field. There is concern that ion heating in the anode plasma sheath may result in a significant ion beam divergence. To investigate this possibility, a comparison of Z pinches, θ pinches, and Ampfion is made. Ampfion sheath scenarios are examined and a simple argument is presented that indicates that an anomalous resistivity should develop. An upper bound estimate of the ion divergence is calculated, and examples are given for PBFA-II parameters. For a small radius diode with a high density anode plasma, it is shown that ion beam divergence due to plasma heating should not be a problem. For a large radius diode with a low density anode plasma, it is shown that ion beam divergence due to plasma heating is a problem, but that an Ampfion filtering mechanism should select a cool portion of the heated ions and help to alleviate this problem.

Electron-beam sustained discharges can be used in opening and closing switch applications for producing bursts of energy in pulsed power systems. The incorporation of admixtures of attachers with low attachment rate at low values of E/N and high attachment rate at high values of E/N in the gaseous switch dielectric has been proposed to achieve low forward voltage drop in the conduction phase as well as rapid opening when the sustaining e-beam is terminated. This paper presents model calculations on the characteristics and transient behavior of an electron-beam sustained discharge in the high current density regime in N2. The influence of an attacher (N2O), with the property described above, and of the circuit parameters on the discharge is investigated as an illustrative example. The advantage of using such an attacher is demonstrated for the steady state conduction phases and for the opening phase, while the closing process is obstructed by the attacher. Additional possible control mechanisms, such as photodetachment to aid the closing process are discussed.

Ponderomotive force density of an HF field in a dispersive cold collisionless plasma is calculated using two independent methods: energy-momentum-stress tensor with the Abraham choice of momentum density and two-fluid hydrodynamics. The results appear to coincide and show that, even in isotropic plasma, terms proportional to the time derivative of the electric field amplitude appear in the ponderomotive force. It is demonstrated that, in the presence of relativistic electron beams, spatial dispersion is not negligible and the related correction to the ponderomotive force is calculated.

Simple arguments are used to construct a model to explain the conversion efficiency of absorbed laser energy into soft X-rays from laser-irradiated targets. In this model, we postulate that the energy available for conversion is bounded at some low irradiance limit by heat conduction away from the laser heated spot, while at some high irradiance limit it is bounded by the energy lost in plasma blowoff. Consequently, at some appropriate laser intensity, where the sum energy of the conduction and blowoff losses is at a minimum, the X-ray conversion efficiency should reach a maximum. A specific example for gold disk targets irradiated by 0·53 μm laser light will be treated. Simple heuristic scalings of blowoff and conduction as functions of laser intensity are obtained.

In recent years there has been considerable effort to understand the equation of state (EOS) of materials, particularly at high pressures and temperatures. Such studies have direct applications in the laser fusion problem where materials are subjected to radiation induced shock waves which compress material to over 100 times the normal density at temperatures up to 100 million degrees (e.g. Hora 1981). Among the various models which describe the electronic thermodynamic functions in highly compressed matter, the Thomas–Fermi model is the one most often used in hydrodynamic codes, e.g. in the simulation of the inertial confinement fusion problem.

In this paper we discuss the importance of radiation transport in inertial confinement fusion (ICF) target design. It is shown that a self similar solution of non-linear heat conduction can be used to estimate the penetration depth of radiation thermal waves (Marshak Waves) in ion-beam ICF pellets. An improved numerical treatment of non-linear heat conduction has been incorporated into the hydrodynamic code MEDUSA-KA to simulate radiation transport in ICF target design studies. The numerical results have been checked against self-similar solutions and a comparison between the two is presented in this paper. We find good agreement between the two. The necessity of using a high-z radiation shield to protect the fuel from radiative preheat is also discussed.