DESIGN AND DEVELOPMENT OF BEAM TRANPORT ELEMENTS FOR BARC-ECIL LINAC

A 10 MeV, 2 kW RF electron linac is under development for cargo scanning. It consists of electron gun, RF linac structure, solenoid focusing magnets, steering magnet, beam diagnostics and x-ray target. To obtain properly resolved x-ray images, a beam diameter of 2mm is required at the target. Since the beam diameter at the target is critical; the transverse beam optics of the whole RF accelerator from gun end to the target has been simulated by solving the beam envelope equation. The envelope equation has been solved using Runga Kutta method consisting of external focusing field, RF field, space charge field and emittance. Various combinations of solenoid magnet focusing have been studied. It has been found that two solenoid magnets in the gun region and one after the linac region are sufficient to transport the beam and focus to a diameter of 2mm at the target. Based on these studies three solenoid magnets have been designed and fabricated.