Abstract
The US Spallation Neutron Source* (SNS) has recently begun producing neutrons and is currently on track to becoming a world-leading facility for materials science based on neutron scattering. The facility is comprised of an H- ion source, a linear accelerator, an accumulator ring, a liquid-Hg target and a suite of neutron scattering instruments. Over the next several years the average H- current from the ion source will be increased in order to meet the baseline facility requirement of providing 1.4 MW of beam-power to the target and the SNS power upgrade power requirement of 2+ MW on target. Meeting the latter goal will require H- currents of 70-100 mA with an RMS emittance of 0.20-0.35 �� mm mrad and a ~7% duty-factor. To date, the RF-driven multicusp SNS ion source has only been able to demonstrate sustained operation at 33 mA of beam current at a ~7% duty-factor. This report details our efforts to develop variations of the current ion source which can meet the final requirements: designs and experimental results are presented for source versions featuring helicon plasma generators, high-power external antennas employing Cs, glow-discharge plasma guns supplying supplemental electrons and advanced Cs collars.
