Calculation of transmission efficiency and orbit correction in transfer line of THz-FEL device

The inject beam of the beam transfer line of THz-FEL device has a long tail since there is no beam cutting device, due to the space limitation. A slit was set in the transfer line to cut the tail. Only the electron at the head of the beam which satisfy the requirement of FEL was left. The calculation using Elegant indicated that the transfer line could transmit the effective part of the beam to the exit. The orbit distortion caused by tolerance of magnets should get reduced to a reasonable level. The calculation using AT for MATLAB indicated that the orbit distortion was minimized ultimately after corrections.