Unheated magnetron gun as an electron source for a resonant linear accelerator

Investigations of the operation of a cold-cathode magnetron gun as part of a traveling-wave linear accelerator are described. Two operating regimes of the gun are observed: with and without the microwave field of the prebunch er near the gun. In the regime with no microwave field, short (around 2 ns) pulses of accelerated electrons of up to 0.5 A were obtained with a gun cu rrent up to 20 A. The presence of a microwave field near the gun makes it p ossible to obtain a beam of longer duration (up to 1.0 mu s), but with a cu rrent of up to 20 mA at the accelerator exit and 1 A from the gun. The oper ating mechanism of the gun is attributed to a secondary-electron current ri se and the establishment of self-sustained secondary emission. A comparison between the conditions of beam production from a thermionic gun and that s tudied for the same injection energies indicates that the characteristics o f this gun are acceptable for injection into an accelerator. (C) 1999 Ameri can Institute of Physics. [S1063-7842(99)02807-X].