An apparatus and method for fast pulsing of a neutron generator is described in which a series of electrodes are used to first extract deuterium or tritium ions from a plasma contained within an ion source, and then either accelerate or stop the flow of ions to the source, depending upon the voltage potential applied to the downstream electrodes. In one embodiment, the extraction/gating system comprises 3 electrodes, a first extraction electrode which is maintained at the same positive potential as the ion sources, a second electrode maintained at a lower potential to extract ions from the source, and a third electrode which depending on the operational mode is maintained either at the same potential as the second electrode (for beam passage) or at a potential higher than that of the first electrode (for beam blockage).
STATEMENT OF GOVERNMENTAL SUPPORT
 The invention described and claimed herein was made in part utilizing funds supplied by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The government has certain rights in this invention.