System for uniform radiation fied formation in electron linacs for study on fast processes

Description of two systems of shaping radiation electron fields of linacs intended for investigations in the range of pulse radiolysis and study of short-lived radiation defects in semiconductors is presented. The first shaping system comprises pulse magnet in combination with sector magnets with opposite-directed constant fields which form the system of parallel beam transfer (SPTB) with variable geometry. The system is intended for obtaining radiation fields with 300x50 mm maximal sizes for electron energy within 1-10 MeV range. SPTB length along the beam is 35 cm, radius of particle rotation in a pulsed magnet is 16 cm, in the constant - 14.5 cm and field in gaps 0.21 T and 0.23 T respectively. The coefficient of using SPTB beam is equal to 85%. SPTB permits to investigate processes with time up to 10-7 s. A statistic shaping system is developed for investigating faster processes, when interacting with the system of scatterers and reflecting screen the accelerator beam increases up to 50 mm in diameter and it acquires uniforms distribution of current density by cross section. The beam shaped in this way is transformed by a doublet of magnetic quadrupolar lenses 3 up to the required dimensions. The statistic shaped system has coefficient of beam use 60% and distortion of beam isochronism in the target plane is proportional to the square of dose field dimension and for 30 cm it is equal to 10-9 s