We have investigated the new in-vacuum undulator (IVU-II) for the future upgrade of SPring-8, SPring-8-II. A production version of IVU-II was installed and has been successfully used during one year at BL10 in SPring-8. Because we need to replace almost all the undulators for SPring-8-II, in which the electron-beam energy is reduced to 6 GeV, IVU-II has various differences from the conventional IVUs to reduce the cost and time for the construction and installation. In the seminar, we will present the new features of IVU-II, for example, the lightweight and compact mechanical frame based on the force compensation system using multipole monolithic magnets as repulsive magnets, the modular magnetic array to reduce the number of parts and the efforts of the magnetic tuning, the compact and simply fixturable transition section, and the efficient assembling with the in-situ magnetic-field-measurement system and the laser tracker. Addition to them, we will introduce the results of the irradiation experiments to find the optimum magnetic circuit for IVU-II in view point of the resistance to the radiation-induced demagnetization.
For details, contact Marco Calvi