Fast raster scanning system for active dose field formation

A fast system for raster scanning of a 250 MeV beam is described. The system provides the active formation of a dose field with dimensions 40×40 cm2 with a rate of 1000 lines and 10 shots per second. The principal feature of the system is that only switch mode devices (thyristors) are used in power circuits. This removes the limitations on the commutated power, allows to increase scanning frequency and makes the system more reliable.