A slotted beam pipe kicker magnet with solid state drive for SPEAR III

The SPEAR III kicker system uses three magnets, K1, K2, and K3, to inject a 3.3 GeV beam into a light source. A slotted beam pipe magnet design is used. Individual induction type solid state modulators power the magnets. Modulators for K1 and K3 use ten IGBTs to drive ten single turn primaries of a transformer. Bi-polar outputs are achieved by passing two conductive rods in opposite directions through the centers of ten FINEMET cores. Two 22.5 Ω cables connect each of the output terminals to the corresponding magnet busses. Magnet K2 is half the length of the other kickers, and thus has one half the inductance. It is required that the pulse shape of each kicker be identical in order to have a closed orbit for the injected beam, so the output impedance of K2 must also be half. Therefore, K2 uses a stack of five cores with four cables connected to each of the output terminals. The modulators for K1 and K3 are designed to produce bi-polar 20 kV, 3 kA pulses of 1 μs at 10 Hz, with rise and fall times of less than 350 ns. Prototypes of both the magnet and the modulator have been built, and components for installation are in fabrication. Details of the design, and test data from the prototype system are presented.