Plasma driven superpermeation and its possible applications to ion sources and neutral beam injectors

A metal-membrane of macroscopic thickness can, under certain conditions, become superpermeable to hydrogen particles whose energy (kinetic, internal, or chemical) exceeds 1 eV. Such a membrane can transfer the energetic hydrogen almost like an opening of the same area. Superpermeable membranes can also compress the permeating gas by orders of magnitude and clean it from any impurities. Due to these characteristics superpermeable membranes could be employed in ion sources and neutral beam injectors: (a) for pumping and recycling hydrogen from ion sources, (b) for pumping hydrogen gas from the extraction area and recycling the gas into the ion source, (c) for pumping deuterium or hydrogen in the plasma neutralizer of a negative ion based neutral beam injector. We will describe the possible use of superpermeable membranes in these devices, the experiments which we effected demonstrating this new technique, and projects for its future use. (C) 1998 American Institute of Physics.