A high current sinusoidal pulse generator for the diluter magnets of the LHC beam dump system

CERN is constructing the Large Hadron Collider (LHC), a superconducting accelerator that will collide protons at a center of mass energy of 14 TeV. The two colliding beams will each store an energy of up to 540 MJ, which must be safely deposited within one beam revolution of 89 mu s on two external absorbers located about 700 m from the extraction points at the end of dedicated extraction tunnels. To avoid evaporation of the graphite absorber material by the very high energy density of the incident beams, the deposition area of the beams on the absorber front face will be increased. This is done by a pair of sinusoidally powered orthogonal magnet systems producing approximately an e-shape figure of about 35 mm diameter, with a minimum velocity of 10 mm/ mu s during the dumping process. The pulse generators of the horizontally and vertically deflecting diluter magnets are composed of capacitor banks, discharged by stacks of solid state closing switches. They are connected to the magnets by 28 m long low inductance transmission lines. The discharge switches of both generators are triggered simultaneously. The generators of the vertical magnets include additional elements to obtain an automatic phase shift of 90 degrees with respect to the horizontal magnets. The capacitor banks, charged to a voltage of 10 and 22 kV, produce a damped sinusoidal oscillation of 27 kA maximum amplitude with a period of 73 and 79 mu s. This oscillation is stopped after 90 and 115 mu s. The fast solid state closing switches are designed for a hold-off voltage of 30 kV and are of the same type as those developed for the LHC beam extraction generators. (2 refs).