Operational experience with compressed geometry acceleration tubes in the Oak Ridge 25URC tandem accelerator

Installation of compressed geometry acceleration tubes and other associated modifications have increased the effective voltage capability of the Oak Ridge 25URC tandem accelerator by about 3 MV. Since mid-September 1988, the accelerator has been operated routinely at terminal potentials up to 24 MV and occasionally near 25 MV. In 3500 h of full-column operation, including 1100 h at potentials above 22 MV, no significant spark-induced damage was observed. Some considerations related to further improvements in voltage performance are discussed.