Beam Dumps, Energy Slits and Collimators at SLAC--Their Final Versions and First Performance Data

This paper discusses the final as-built versions of high power beam dumps, slits and collimators, which are capable of absorbing 1 to 2 MW electron beams continuously. Some of the important design features are illustrated with pictures. Experimental results of testing a beam dump window and a small module prototype are added. The remote control and read-out system of variable aperture slits and collimators is emphasized and performance data are given. Then the criteria for safely achieving high beam power dissipation (heat transfer rates, nucleate and film boiling conditions, thermal stress, thermal shock and fatigue) are reviewed. Solutions to problems encountered in operating equipment in a corrosive, high radiation area where organic lubricants fail are presented. Finally, radiolysis of water and evolution of free hydrogen are dealt with. Experimental results from high power electron beams are reported. Disposal of hydrogen and radioactive gases evolving in surge tanks is discussed and solutions are proposed.