A HIGH-DENSITY PULSED ION-TRAP

By exploiting the synergy of two discharges in low pressure gases or gaseous mixtures, a pulsed electron beam with exceptional radial stability has been obtained having a diameter less than 50 mu m over 40 mm. It acts as a pulsed high density ion trap for the ions created by electron impact along the beam. From the measured electron beam characteristics and using a simple model, an ionic density of about 10(16) cm(-3) and a depth of the potential well of the order of a few keV has been inferred. The parameters of the trap can be tuned to assure a full ionization of the gas inside the tube current with a significant probability for multiple ionization, the recombination rate being reduced due to the mismatch between the electron and ion velocities. Preliminary results on Ar III and Ar IV emission lines from the plasma channel associated with the beam are reported.