Pulsed X-Ray Radiography with Electron Linear Accelerator (I) Precise Control of Electron Linear Accelerator

Abstract

A control method is studied to make an electron linear accelerator radiate accurately the required number of pulses of beam. Counting circuits are used to pre-set the number of pulses. All parts of the accelerator are operated in a fully warmed-up state. A magnetic shutter is placed between the electron gun and acceleration tube to control the radiation. The phase relation between the periodical operation of the accelerator and the starting time of switching is chosen to take away the error caused by the transient state of the shutter. The coincidence of the accelerating field and injected electrons are controlled also to diminish the effect of unexpected radiation due to the leakage of the electrons through the shutter. The experiment shows that the beam radiation is reliably controlled by this method, e.g. the quantity of the electrons included in each pulse is kept constant independently of the required number of the pulses. There is no indication which suggests that the beams radiated are not homogeneous. The intensity of the leakageradiation is small enough and not detected even by an ion-chamber roentgenmeter.