Abstract: An electron beam stop for use with high power electron beam accelerators can be used to measure beam parameters including energy, current, scan width, scan offset and scan uniformity. The beam stop is split in two segments in the direction of electron travel, with the first segment closest to the beam source absorbing a portion of the electrons incident thereon and the second segment farthest from the beam source absorbing all of the electrons that pass through the first segment. The ratio of charges deposited in the two segments is a sensitive index of the energy of the primary electrons, i.e., a measure of beam energy. The sum of the charges in the two segments is a direct measure of the number of electrons incident on the absorbing medium, i.e., a measure of the beam current.

Abstract: A method and apparatus for controlling the delivered dose across a target area from an electron beam produced by a high energy, high power pulsed rf linear accelerator. Pulse width modulation as a function of scan position is applied to the rf drive pulses of the accelerator operated in a long pulse mode and fast feedback control is used to maintain uniform rf field intensity on an intra-pulse basis. In an alternative embodiment, rf drive pulses are inhibited as a function of scan position.