LAMPF Line D fast deflector system

The Weapons Neutron Research Facility is only one of many experimental areas which utilize the 800 MeV proton beam from LAMPF. Designated as Line D, this area may use entire beam pulses of 500 μs width at pulse rates up to 12 Hz or it can choose to take the last 5 μs of each pulse at a 120 Hz rate. The deflection system employed to accommodate the latter of these two modes of operation is described. The deflection of the proton beam into Line D is accomplished in a 1.09 m, 1.25 kG ferrite magnet, pulsed at up to 7000 A, 120 Hz by a 2 ohm 6 section lumped element pulse forming network (pfn). The current pulse into the magnet has a rise and fall time of about 1 μs with a usable flat top portion of 9 μs. This line is tuned to produce a current pulse with +-0.2% ripple across the flat top portion. The low ripple current is necessary to minimize beam jitter as it enters Line D