An undulator at PETRA II-a new synchrotron radiation source at DESY

PETRA, currently operating as a proton and positron injector for HERA, has been modified to serve also as a synchrotron radiation source in 1995. Running at 12 GeV with currents up to 60 mA the machine will be a unique source. The PETRA injector optic will be changed locally to suit the requirements of an undulator beam. In addition a new low emittance optic has been examined both theoretically and experimentally. The undulator with a period length of 33 mm and a maximum field of 0.59 T at a gap of 14 mm has been installed in the straight section North East. The photon energy range up to 200 keV can be covered using the 1st, 3rd and 5th harmonics. At 12 GeV, 60 mA and using the low emittance optic a photon brilliance in excess of 10¹⁸ photons/(s 0.1%BW 0.1 mrad² mm²) will be obtained. To allow for compatibility between injector and synchrotron radiation operation a keyhole shaped vacuum chamber, with both a wide and narrow aperture for the two operational modes respectively has been constructed. The photon beam travels along a 120 m long beamline until it reaches the experimental hall. The beamline includes elements of the beam position control system and the safety system needed to avoid damage to machine components due to the high power undulator beam