Compact beam transport system for a 6 MeV electron beam to a race-track-microtron accelerator

The design of a compact system for the transport of a 6 MeV electron beam from a photo-cathode linac to a race-track-microtron is described. The high quality of the electron beam has to be maintained during transport. The geometrical limitations make the system necessarily a compact one. The parameters found by the application of rules for double achromaticity and a one-to-one imaging of the system are used as starting values for simulations with the code TRACE-3D. The slightly adjusted parameters are checked by calculations with the particle tracking code PARMELA. Although a slight degradation of the beam shows up, the system with four dipoles and a quadrupole have enough flexibility to transport the beam under various conditions. Special care is taken with the design of the dipoles. The finite element program ANSYS is used for a detailed calculation of the field including the trajectories of the electrons. Results of the calculations lead to a slight adjustment of the dipole design.