Hydrogen Targets at SLAC

Several types of hydrogen targets are used at SLAC. Some are multiple assemblies that allow the user to select liquid hydrogen, liquid deuterium or any of several solid targets. The most elaborate assembly build to date has a cell with circulating liquid hydrogen, a cell with circulating liquid deuterium, and an array of nine solid targets or holes. The target in use is selected by the computer. Target position is determined by encoders and verified by micro-switches. The operation of the fan circulating the hydrogen is monitored by a magnetic pickup coil. Forced circulation of hydrogen is used in other targets where the heat load is too high to allow stable operation with natural convection, or the length-to-diameter ratio is great enough to inhibit bubble free operation.