The NSNS front end accelerator system

The National Spallation Neutron Source (NSNS) front-end accelerator comprises a 65 keV LEBT, a 2.5 MeV RFQ and a matching accelerating a 55 mA H beam with a 6% duty factor. Critical design issues are the 6% beam duty factor, the 5 free space-wavelength long 402.5 MHz RFQ, and nanosecond chopping of the beam before it enters the first DTL. The conceptual design of the front-end systems will be presented, with experimental validation of some of the proposed subsystems.