Development of a high power 1.2 MW CW L-band klystron

The high power CW L-band klystron has been developed as the RF source of the PNC high power CW electron linac (10 MeV, 100 mA). CW power of 1.2 MW at 1.249135 GHz and efficiencies over 65% were the design goals. The prototype klystron window was replaced with a long pill-box type beryllia window as a result of the simulation and hardware tests. The klystron with the long window (klystron No. 1) has reached CW power of 885 kW with efficiency above 47%. The klystron No. 2 has been manufactured. Peak power of 4.1 MW with pulse width 100 μsec at a beam voltage 147 kV is required for future applications. The klystron No. 2 had achieved CW power of 782 kW with efficiency above 57% at a 75 kV beam voltage and peak power of 4.55 MW with efficiency of 44% at a 150 kV beam voltage. This paper describes key points of the designs and results of the high power RF tests. (author)