Electrostatically focused high power klystron amplifier

A three-cavity metal-ceramic klystron amplifier operating at S-band has been developed. The focusing of the electron beam is performed by a single electrostatic Einzel-lens located between the first and second cavity. The gaps of the cavities are ungridded allowing operation of the klystron at high average beam powers. The perveance of the electron gun is 1 \times 10^{-6} a/v3/2. Under pulsed conditions and with a beam voltage of 23 kv, a saturated rf output power of 16 kw was observed at 3125 Mc/s. Saturation gain is 24 db and with the cavities synchonously tuned, the small signal gain is 34 db. An improved version of the above klystron, presently under construction, is expected to result in higher efficiency, power output, and gain.