Terahertz radiation has broad application prospects due to its ability to penetrate deep into many organic materials without the damage caused by ionizing radiations.A free electron laser(FEL)-based THz source is the best choice to produce high-power radiation.In this paper,a 14 MeV injector is introduced for generating high-quality beam for FEL,is composed of an EC-ITC RF gun,compensating coils and a travelling-wave structure.Beam dynamics simulations have been done with ASTRA code to verify the design and to optimize parameters.Simulations of the operating mode at 6 MeV have also been executed.
An EC-ITC(External-Cathode Independently Tunable Cells) RF gun was employed with the aim of obtaining short-pulse bunches with high peak current for a terahertz radiation source. A gridded DC gun plays a key role as the external injecting electron source of the ITC RF gun, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 keV at most. A proper structure of the gridded gun with double-anode is shown to overcome the strong space- charge force on the cathode, which is able to generate 6 μs beam with 4.5 A current successfully.
