Afterglow mode and the new micropulsed beam mode applied to an electron cyclotron resonance ion source.

An increasing number of experiments in the field of low energy ion physics (< 25 keV/charge) requires pulsed beams of highly charged ions. Whereas for high-intensity beams (greater than microampere) a pulsed beam chopper, installed downstream to the analyzing dipole, is used. For low-intensity beams (< 100 nA) the ion intensity delivered during the pulse may be increased by operating the electron cyclotron resonance discharge in the afterglow mode. This method gives satisfactory results (i.e., average current during the beam pulse is higher than the current in the cw mode) for high charge state ions. In this paper, we report on results of the afterglow mode for beams of Ne-22(q+), Ar-36(q+), and Kr-84(q+) ions. Furthermore, a new promising "micropulsed beam" mode will be described with encouraging preliminary results for Kr-84(27+) and Ar-36(17+) ions. (c) 2008 American Institute of Physics.