Regulation of the output energy of a backward-wave linear accelerator by the duration of the rf power pulse

The problems of regulating the output energy of the accelerated beam of a backward-wave linear proton accelerator over a wide range without altering the beam intensity are investigated. The proton energy is regulated by adjusting the duration of the rf power pulse delivered to the accelerator and by regulating the delay time between the instant of injection and the instant at which the leading edge of the rf pulse arrives at the output end of the accelerator. The method is tested on the interdigital-type accelerating section of length 1.25 m of a linear proton accelerator. It is shown experimentally that the electron beam energy at the accelerator output can be varied approximately threefold without any appreciable sacrifice of the beam intensity by varying the duration of the rf pulse in the given accelerator section. (C) 1998 American Institute of Physics. [S1063-7842(98)02805-0].