A Gas Foil Stripper System for a Heavy Ion Van de Graaff

The charge exchange process in the centre terminal of the 30 MV tandem Van de Graaff under construction at Daresbury Laboratory is achieved by a combined unit with an option of gas or foil stripping. The foil stripper can hold 280 foils, any one of which can be selected at any time. The gas stripper, using nitrogen originally, is cryo-pumped to maintain the tube vacuum pressure of 10-7 torr, and the whole is controlled via the serial data link using a modulated light system.