Study of klystron modulator system availability for PLS 2-GeV electron linac

The PLS linac has been injecting 2-GeV electron beams to the Pohang Light Source (PLS) storage ring since September 1994. PLS 2-GeV linac has 11 units of high-power pulsed klystron-modulator (K&M) system for the main RF sources for the beam acceleration. The klystron has rated output peak power of 80-MW at 4 μsec pulse width with 120 pps, and the matching modulator has 200-MW peak output power. The total accumulated high voltage run time of the oldest unit has reached beyond 20000 hours and the sum of all the high voltage run time is approximately 180000 hours. In this paper, we review overall system performance of the high power K&M system together with the description of the K&M system. A special attention is paid on the analysis of all failures and troubles of the K&M system which affected the linac RF operations as well as beam injection operations for the period of 1994 to May 1996