TEMPORAL RESPONSE OF A LITHIUM-NITRATE ELECTROHYDRODYNAMIC ION-SOURCE

The first measurements of electrohydrodynamic (EHD) ion emission from thin films of molten lithium nitrate under pulsed field conditions are presented. Pulse widths from approximately 20 ns to 50 mus were used to initiate ion emission from the apex of a stainless-steel field emit ter tip coated with molten lithium nitrate. Current densities >100 A/c m2 were obtained from a single emission site. As the pulse width was i ncreased from 20 ns to several microseconds the electric field require d to initiate ion emission decreased and asymptotically approached the electric field value characteristic of dc operation. In contrast to d c operation, Li+ was the dominant species (>90%) for pulse durations l ess than 1 mus. The abundance of Li+ was independent of pressure betwe en 10(-3) and 10(-8) Torr of water vapor. The use of a lithium nitrate EHD ion source for the production of intense lithium ion beams in lig ht-ion inertial confinement fusion reactors is foreseen.