50 MW S-Band PPM Klystron

This proposal addresses the need for a high efficient 50 MW S-Band pulsed klystron with Permanent Magnet Focusing (PPM) for the X-FEL linac proposed by Los Alamo National Laboratory, This klystron will have a minimum pulse width of 4 microseconds at a pulse repetition frequency of 50 Hz resulting in an average RF output power of 10 kW. We will employ a passive PPM focusing arrangement in place of a large water cooled electromagnet and a DC power supply. This arrangement increases the overall efficiency and reduces the size of the klystron. Calabazas Creek Research Inc., based on technology developed through a Phase I grant for a 500 kW PPM L-Band klystron and an ongoing Phase II grant for a 10 kW CW PPM S-band klystron, proposes to develop this 50 MW PPM klystron employing the in-house klystron large signal code KLSC and the leased large signal code TESLA for simulation of the interaction circuit. These two codes have been authenticated with experimental results. We will also employ our unique PPM structure, which relies on 4 disc shaped permanent magnets in lieu of the conventional half round magnets. This arrangement provides complete access to the cavities for cooling and tuning. The electron gun will be a simple cathode-anode diode and will be cathode pulsed. Complete simulation of both the interaction circuit and electron gun will be accomplished in Phase I.