EXPERIMENTAL STUDY OF THE SURFACE RESISTANCE OF THE 141 MHZ QUARTER-WAVE RESONATOR AT TRIUMF

The upgrade (Phase II) of the ISAC-II superconducting linac was completed in the spring of 2010 and subsequently commissioned during August 2010. Two spare 141 MHz Quarter-Wave Resonators made of bulk Niobium are available at TRIUMF to enable more specific systematic studies on surface resistance. This opportunity has also been taken to optimize the surface treatment to improve the accelerating field gradient at the operating power level (7W). The aim of the study presented here is to link together several surface treatments (etching depth, 120C baking) and test conditions (Q-disease, 4.2 K and 2K tests) and sequence them in an appropriate order to understand more deeply their dependencies.