Klystron-modulator system availability of PLS 2 GeV electron linac

PLS Linac has been injecting 2 GeV electron beams to the Pohang Light Source(PLS) storage ring since September 1994. PLS 2 GeV linac employs 11 sets of high power klystron-modulator(K&M) system for the main RF source for the beam acceleration. The klystron has rated output peak power of 80 MW at 4 microsec pulse width and at 60 pps. The matching modulator has 200 MW peak output power. The total accumulated high voltage run time of the oldest unit has reached beyond 23,000 hour and the sum of all the high voltage run time is approximately 230,000 hour as of May 1996. In this paper, we review overall system performance of the high-power 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 high power RF operations as well as beam injection operations for the period of 1994 to May 1996.