Vacuum commissioning for the SWLS absorber inside a kicker-chamber at TLS storage ring

A 6 T super-conducting wiggler, so called wavelength shifter, (SWLS) has been installed in the injection section of the 1.5 GeV Taiwan Light Source (TLS) electron storage ring. The intensive synchrotron radiation emitted from SWLS causes severe problems in the downstream kicker-chamber, such as radiation hitting on the ceramic parts, interfered non-uniform field and induced arcing from the absorber during kicker firing, etc. A new absorber, designed to solve those problems, has been developed and installed in the kicker-chamber downstream the SWLS. The earlier stage of vacuum commissioning shows a high pressure-rise, stimulated by the photons, localized near the head of absorber that seriously constrains the beam lifetime. However, the pressure reduces by continuous beam cleaning. The injection efficiency of the electron beam is not degraded much. The temperature rise on the downstream chambers, behaves not so according to the beam current, is kept within allowable values.