Transistor bank for pulsed power supply in septum ejection magnets

A large transistor bank, shown in the album, to give a nominal current of 13 000 A was designed at CERN and built by J. Alge (Apparatebau, Austria). It was to be used as the control element of a pulsed power supply (100 V, 13 000 A) for the flat-top current in septum ejection magnets. One of its main advantages was that it enabled the current to be held stable within the order of 10−4 of the nominal value (an improvement of a factor of about ten on the previous power supply). The transistor bank consists of 7580 transistors in a three stage Darlington circuit. The transistors are mounted on water-cooled modules which are stacked in a self-contained cubicle with all electrical and water connections at the rear and with simple arrangements for checking of individual components. Development of the transistor bank, including an extensive test programme to ensure longterm reliability was carried out in the PS Division by F.F. Depping. The new power supply was scheduled to come into operation on the proton synchrotron at the beginning of 1970.