352-mhz Klystron Performance at the Advanced Photon Source

The general performance of the Advanced Photon Source (APS) 352-MHz/1-MW continuous wave (CW) klystrons is discussed. The original seven-klystron inventory at the Advanced Photon Source has been in operation since 1995 with good results. Five tubes are presently in accelerator operation, with two tubes as spares. The overall performance of the tubes has been very good. Two tubes were removed from service due to intolerable operational problems: one suffered collector heat damage and was subsequently rebuilt and placed back in service; the other developed a suspected high-voltage (HV) leakage path between the mod-anode terminal and body. One tube has a history of high 3rd to 5th harmonic power production and is presently kept as a spare. Several of the tubes have experienced damage to the oil-tank HV connectors due to over-tightening of the bayonet clamps, and one tube had high leakage current in an ion pump that gave a false indication of bad vacuum.