Design of a high current H/sup -/-RFQ injector

High current H/sup -/-RFQs are injectors for the planned new spallation sources like ESS and NSNS. Critical points are the high current, the low emittance and the high duty factor of the injector. The strongest existing spallation source ISIS at RAL presently is still operating with a Cockroft-Walton injector. RAL now will upgrade that column by a new RFQ injector, where some of the features of the new proposed ESS injectors can be tested. A four-rod RFQ at 202 MHz with a duty factor up to 10% and H/sup -/ currents of 50 mA are input values for the RF-structure design and beam dynamics. Results of this design work will be presented.