A flexible injector test stand design

The Advanced Photon Source (APS) has constructed an injector test stand (ITS) for high-brightness electron beam research. The test stand includes three rf ports with independent phase and power control, beamline supports designed for rapid reconfiguration, and a control and diagnostics system based on the design of the APS linac. The beamline design features a high-resolution electron spectrometer that includes provision for operation as a dispersion-free dogleg, and a rapidly reconfigurable gun-to-spectrometer transport line. Picosecond and nanosecond photocathode drive lasers are available; the room shielding is also adequate for the high average beam powers typically produced by thermionic-cathode rf guns. The initially installed gun is a ballistic-compression gun, which requires all three rf ports to be connected to the gun. Plans include the installation of a higher-order mode photoinjector, requiring one rf connection; this will free the other ports to provide power to a small TW linac section and deflector cavity for bunch-length measurements. The test stand is also capable of being used as an operator training facility, and serves as a validation facility and test bed for the APS main injector rf guns.