Performance tests of a superconducting quarter wave resonator

Abstract The performance of a superconducting quarter wave resonator, suitable for heavy-ion linac use, has been tested. The resonator was built using the lead-plated copper scheme. Measured performance established the anticipated advantages of this structure in such an application. The Q value of 2 × 10 8 is independent of the average accelerating gradient up to 3 MV/m where the onset of field emission dominates the losses. Excellent short term frequency stability accounts for the fact that the resonator can be phase-locked with as little as 2 W of tuning power at 2.5 MV/m.