The cooler synchrotron COSY was intended from its inception to provide also deuteron beams which, in addition to protons, could considerably expand the range of experiments accessible at this accelerator facility. A major obstacle to deliver the required D¯ beams with the injector cyclotron JULIC has been its electrostatic septum deflector at extraction. After the conversion of JULIC into a negative ion machine, operation of the original deflector at the voltage levels necessary for D¯ extraction proved to be impossible with reversed polarity due to severe electrical strength problems like sparking and dark currents. The design and development of a suitable septum deflector turned out to be a challenging and tedious process lasting several years. The new device is in operation since January 2000 and the cyclotron was successfully tested in October for delivering D¯ beams at 75 MeV with an extracted current in the order of 10 µA. Development, test procedures and characteristics of the new electrostatic septum deflector are reported together with its operational performance to date. Results achieved during the first test run with D¯ ions are presented, including injection and acceleration of the deuteron beam in COSY.

A proton irradiation facility was built under collaboration between Fraunhofer-INT and the Nuclear Physics Institute of the Research Centre Jülich (formerly KFA Jülich). It is designated for the testing of space electronics with low to medium energy protons

To improve the external beam quality at JULIC, three different measures have been undertaken: the development of a systematic procedure for beam phase optimization, the precise adjustment of the center region to nominal values as well as the installation of harmonic coils near the cyclotron center and the introduction of two axial phase slits according to calculations for proper axial imaging. Starting with a cyclotron as it was tuned in the former day by day operation, the successive application of the above means resulted in an improvement of the radial emittance by a factor of 2 to 10 mm.mrad and of the energy resolution by a factor of 3 to below 1.510-3. The three different means for better machine tuning and their effect on the external beam quality are described.