Beam Diagnostic of the LINAC for the Compact High-Performance THz-FEL

With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an FEL-based LINAC is employed in HUST THz-FEL, and the LINAC consists of an EC-ITC RF gun, a disk-loaed waveguide structure with a constant gradient and collinear absorbing loads with focusing coils surrounded and so on. To achieve a balance between compactness and high performance, beam diagnostic system should be simple and high-precision. So that a cost-effective measurement scheme for the high-brightness beam extracted by the LINAC is needed. This paper will describe the beam line and beam diagnostic system of the LINAC in the HUST THz-FEL in detail and give corresponding assembly scheme. In addition, online monitor system is introduced.