A Liquid Hydrogen Target for Slac's 30 mA Electron Beam

A unique liquid hydrogen target capable of handling SLAC's high current (30 mA), high energy (20 GeV) electron beam is described. A small axial fan submerged in the liquid hydrogen circulates the liquid through the target cell and heat exchanger. Density variations as high as 10% due to beam heating were experienced in similar targets which did not employ this circulating technique. Experimental results show that in the circulating target these density variations were reduced to less than ±1% with heat fluxes as high as 5 kW/cm2 per cm of target length.