Formation of a homogeneous hydrogen plasma layer for the production of terawatt ion beams

A suitable anode plasma source layer for a high power ion-diode must provide an ion current density of up to 10 kA/cm/sup 2/ for a pulse duration of 50 ns, a minimum of 3*10/sup 15/ ions/cm/sup 2/ is needed. This layer should uniformly cover an area of more than 100 cm/sup 2/ and smoothly conform to the desired anode shape. A proton source layer meeting these requirements is described. It is based on a thin metal-hydride film. A 500-AA-thick Ti layer is used as the hydrogen store. It is covered with a 100-300-AA thick Pd layer to prevent oxidation of the Ti surface. A fast heating pulse desorbs a large fraction of the hydrogen within a few ns from the metal hydride. After a sufficient amount of gas has been released, an electrical discharge is initiated in the gas layer to create the plasma. The dynamics of hydrogen desorption and of plasma layer formation are described. Experimental investigations are conducted to determine the characteristics of the discharge and to measure the plasma parameters. Since the plasma is far from thermodynamic equilibrium, spectroscopic methods with high spatial and temporal resolution are applied.>