Speaker
Description
The Los Alamos Neutron Science Center (LANSCE) User Facility has just celebrated 54 years of beam operations. LANSCE is a kilometer-long H+/H- linear accelerator serving five active and unique user facilities. The Drift Tube Linac section of LANSCE has embedded quadrupole electromagnets in most of the drift tubes. During the 2024 run cycle, a water leak developed on one of the drift tube water cooling lines that was impacting the embedded magnet. Initially, a clay-based water leak sealant process was used to repair this leak. The leak was in an inaccessible location and a ready spare for the drift tube was not available. LANSCE has had significant success with this leak-sealing process. After several iterations, it seemed that the leak sealant had completely sealed the leak. A process error then allowed the drift tube linac to operate with the cooling water for that drift tube valved off. Soon after, the leak seal failed again. Repeated attempts to use the sealant failed. Using pressurized nitrogen in the area to keep out water ingress through the leak hole was also tried with some success. Eventually an alternative solution was implemented to bypass this drift tube quadrupole magnet and retune the drift tube linac. Transport models were used to determine needed changes to the field strengths in adjacent magnets. Once operations was recovered, a tune with this configuration change was implemented successfully. A ready spare is expected to be available before the next scheduled extended maintenance period. In the longer term, this whole system will be replaced by a modern Drift Tube Linac as part of the LANSCE Accelerator Modernization Project (LAMP).