Diagnostics of effusing plasmas

A no. of diagnostics to measure all plasma properties in the vicinity of the hollow cathode are described. The momentum balance in the plasma and the source properties of the hollow cathode are detd. The main driving term in the momentum balance is the pressure gradient of ions and electrons. The deceleration of the ions is mainly caused by ion viscosity and to some extent by friction with neutrals. At high currents the ion flux almost equals the gas flux. At high gas flows the ion flux sats. [on SciFinder (R)

Plasma flow in an argon cascade arc

A model is described for the plasma flow in an Ar cascade arc which takes into account the heating and pressure effects. As the pressure increases the elec. field increases and the arc temp. decreases. The results agree with exptl. detns. [on SciFinder (R)

Experiments on the longitudinal ion momentum balance in a magnetized plasma

In the magnetized plasma of a hollow cathode arc the longitudinal and rotational drift velocities of ions have been measured, together with the electron and neutral densities and the temperatures of ions, electrons, and neutrals. The radial and longitudinal gradients of these quantities have been established. The ions drift against the electric field towards the anode with velocities between about 500 and 2500 m/s, driven by the plasma pressure gradient which is balanced by viscous deceleration and by friction against the surrounding neutral gas. The classical theory of the momentum balance with a turbulent contribution to the viscosity provides a good description of the longitudinal ion transport and explains direction and magnitude of the occurring drift velocity

Collective CO2 laser scattering on moving discharge structures in the submillimeter range in a magnetohydrodynamic generator

Collective scattering of CO/sub 2/ laser light on electrons is used to determine the radial scale length of the discharge structures occurring in a closed cycle magnetohydrodynamic generator. Heterodyne detection of scattered radiation is used to obtain a spatial resolution in the submillimeter range and to increase the signal to noise ratio. A discharge model is formulated to interpret the measured signals. The scale length of the electron density fluctuations is found to be (2.5+or-0.5)*10/sup -4/