Research of Radiation Process of Electron with Use of a Pulse Stretcher Ring

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Stretcher mode of the electron storage ring, KSR has been designed and equipment needed for the mode have been fabricated. In the stretcher mode, the output beam from the 100 MeV electron linac is injected into the KSR by 3-turn injection and then slowly extracted in about 1 second by the method utilizing the third order resonance together with RF knock out method. With such a scheme, the duty factor of the electron beam is expected to be increased from 2×10ィイD1-5ィエD1to 〜90%.In the first fiscal year 1997, the design of the stretcher mode of KSR is determined fixing the operating point of the KSR. Then the electrostatic septum as the first septum for the slow extraction system was fabricated. Its high-voltage power supply was also purchased.In the second fiscal year 1998, a septum magnet to be used at the down stream of the electrostatic septum was designed and fabricated. Taking the fact that the ultra-high vacuum better than 10ィイD1-9ィエD1 Tore, the septum coil was designed to be located outside the vacuum system.In 1999 as the final fiscal year for the research project, the electrostatic septum and the septum magnet have been installed into the KSR after evaluation of their characteristics. After the baking process, the vacuum pressure has reached required region of 10ィイD1-9ィエD1 Tore. The high voltage up to 70 kV/cm has been applied to the electrostatic septum with the condition without beam bombardment to the septum foil. Through the beam test up to now, the beam life of the stretcher mode was measured to be several tens second, which is long enough for the operation as the stretcher. The RFKO process is also found to be effective to increase the bettor oscillation amplitude. Quantitative measurements of the extraction efficiency and the time structure of the extracted beam are scheduled from now on.