An experimental klystron for LAMPF

The klystrons of the Los Alamos Meson Physics Facility (LAMPF) must have 1¼ MW of power output, 50 dB of gain, 50% conversion efficiency and must operate at a 12% duty factor at 805 MHz. The design of the klystron to meet the above specifications under the constraints of operation in an existing focusing magnet at a beam voltage of 86 kV is the subject of this paper. Numerical studies of the problem indicated two solutions: one with a long (0.2 λq) penultimate drift length and the other with a second harmonic cavity. An experimental six-cavity klystron in which both designs could be evaluated was built. The fourth cavity has a tuning range from 1540 to 1610 MHz. At the lower tuning position, the klystron behaves as a five cavity device with a long penultimate drift length.