The Beam-Matching System between Pre- and Main-Accelerator for the Van De Graaff-Cyclotron-Combination Vicksi

The matching system connects the Van de Graaff preaccelerator with the isochrounous split pole cyclotron of the heavy ion accelerator combination VICKSI and prepares the beam for injection into the cyclotron. The charge state of the ions is increased by a stripper (gas or carbon foil). This however enlarges the phase space occupied by the beam due to angle- and energy straggling. To minimize this deterioration of beam quality a sharp focus at the stripper is provided in all three dimensions. A longitudinal (time) focus both at the stripper and in the center of the cyclotron is achieved by means of two identical clystron-type bunchers. The magnetic focusing system between the two bunchers contains two doubly achromatic bending units of 90 degrees. Telescopic focusing is used onto the stripper and from the stripper to the second buncher. The last section just before the cyclotron comprises one more bending unit and several quadrupoles for dispersion matching and adapting the horizontal and vertical phase space for injection.