Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

We propose an injection system for a high-current electron linear
accelerator with a standing wave operating mode. It allows avoiding the
problem associated with back bombardment of electron gun cathode by
electrons which had not been captured into accelerating regime. This system
consists of bending magnet and focusing solenoid placed in the drift space
between the magnet and accelerating structure. Optimal characteristics of
injection system are given. The efficiency of additional transversal beam
focusing by a solenoid magnetic field and the possibility of injection current
variation has also been analyzed.