SNS beam in gap removal

Stringent particle loss constraints for the SNS accumulator ring require that the beam gap must be kept clean. A fixed amplitude stripline kicker capable of reversing polarity turn by turn is being designed for this purpose. We present simulations of the beam in gap cleaning process, using the ORBIT code and modeling the kicker as a constant amplitude kick of programmable polarity sequence. We find that particles of any particular tune can be removed from the beam in a small number of turns. For distributions of particles with tune spread, we consecutively apply sequences of kicks for different tunes covering the spread. Even for cases of very large tune spread we find that we can extract the gap beam within seventy turns of the accelerator.