• K. Umemori, T. Furuya, H. Sakai, T. Takahashi
  KEK, Ibaraki
• M. Sawamura
  JAEA/ERL, Ibaraki
• K. Shinoe
  ISSP/SRL, Chiba

A construction of the Compact ERL is planned in KEK, Japan. A demonstration of the performance of the main linac super-conducting accelerating system is one motivation of the project. We have been designing a cryo-module, which works under CW operation, and contains two 9-cell cavities, with input couplers, frequency tuners and HOM dampers. Most of these components have been specially developed for ERL operation. Two proto-type of the 9-cell cavity were constructed. First one was vertically tested and suffered from field emissions. Second one is now waiting a measurement. High power component tests have been carried out for input coupler. At first, large temperature rise was observed at a ceramic window part due to unexpected dipole resonance. After that, new version of window was designed and successfully passed 20kW CW power with reflection. Proto-types of HOM damper were also constructed. Cooling tests have been performed for them to verify cooling ability against more than 100W heat load, under vacuum condition. A cryo-module will be completed in 2012, and cooling tests and beam tests will follow.

• T. Kubota, N. Abe, J. Hori, T. Takahashi
  KURRI, Osaka

Electron beam can be accelerated in two accelerator tubes up to 46 MeV at KURRI-LINAC. The development of irradiation field is planned to provide lower energy electron beam. For this purpose we had regulated several parameters, which results showed that low energy electron beam was obtained by acceleration in only the first accelerator tube, without the second one, which was filled with microwave from klystron operated at reduced voltage. Moreover, the timing between electron emission and microwave introduction into the first accelerator tube was varied to increase the electron energy loss in the second one, thereby reducing high-energy component of the beam. In this study we obtain lower energy electron beam by the following regulations: 1) the increase of the emission current from the electron gun relative to energy filled into the first accelerator tube results in the decrease of acceleration energy for each electron and 2) the total control of the timing and the buncher phase of microwave and the width of electron pulse eliminates a part of electron expected to be high-energy component. The regulations described above yield the low-energy electron beam with peak of 5.2 MeV.