An improved thermionic microwave gun and emittance-preserving transport line

The positron/electron linac for the Advanced Photon Source (APS) at Argonne National Laboratory can be used to accelerate electrons to 650 MeV. As part of a project, to use this linac to test the quality of insertion devices, work has been done to develop a higher-brightness thermionic microwave gun of the SSRL type. The new gun design has smaller emittance by a factor of 3 to 4. The ratio of cathode field to maximum surface field is more than doubled. The new alpha-magnet-based transport line design produces negligible emittance degradation due to chromatic aberrations, in spite of the ±5% momentum spread