Development of High Power Klystron (3); Development of Klystron N0.2

Hirano, Koichiro  ; not registered; Sato, Isamu

A high power klystron has been developed as the RF source of the high power CW electron linac (10Mev, 100mA, 1.249135GHz). CW power of 1.2MW and efficiencies over 65% at a beam voltage 85kV were the design goal. We developed a long pill-box type beryllia window (long pill-box window) withstood the RF power of 1.7MW(CW) and replaced the standard pill-box window of the prototype klystron with long pill-box window. The high power RF test was carried out with the converted klystron. This klystron has achieved CW RF power of 885kW and efficiency of 47% at beam voltage of 85kV. This paper describes key points of the designs to achieve the RF power over 1.2MW and results of the high power RF test of the second klystron, which has been optimized by simulation codes to improve better efficiency. The second klystron has achieved the maximum efficiency of 56.5% with CW output power of 782kW at a beam voltage of 80kV and cathode current of 20.4A in present. The third klystron will be manufactured to reflect results of this test.