Accelerator plan for a light-source study at the TRISTAN MR

Abstract

A three-month operation with a beam is scheduled for the autumn of 1995 at the TRISTAN MR for the sake of light-source development and research programs using it. The lattice will be modified so as to enable the installation of an undulator 5.4 m long and achieve a very low-emittance beam of 5 nm at 10 GeV. The emittance damping wigglers will enhance the radiation-damping rate, which will stabilize the coherent beam instabilities as well as reduce the emittance more. A considerable number of accelerating cavities will be removed from the ring in order to minimize the impedance of the higher-order modes of the cavities that may cause coupled-bunch instabilities and limit the intensity of the stored beam. For the stability of the light beam, a local feedback system will be applied to the electron orbit in the MR. The beam emittance will be measured by detecting the angular distribution of the Compton scattering of laser photons from the beam electrons. To measure the beam emittance in an independent way, visible synchrotron light from a bending magnet and 100 keV x rays from an undulator will be utilized.