Advanced Collimator Systems for the NLC

The Next Linear Collider accelerator will include a large (kilometer scale) and complex collimation system. Its size and complexity could be reduced if the collimator jaws were made immune to damage from the electron beam. We describe two collimation systems currently under development. Construction of a prototype system, which uses wheels that can be moved to a new position after damage, is underway. The second system, currently in the R+D phase, will use rotors that are continuously reformed from a bath of liquid metal as the collimation surface. This second system should allow operation at beam intensities that damage the jaws on every pulse. We describe results of tests on both systems. 1 NLC COLLIMATION SYSTEM REQUIREMENTS The NLC requires collimation both before and after the main linacs. The post linac collimators in particular are technically challenging as the beam intensities and small spot sizes are sufficient to damage any solid material. Designs that avoid damage by increasing the beam size in the collimation section result in a very long system length and a very sensitive optical design. We base the engineering designs here on a beam optics design that provides reasonable tolerances, but may result in collimator surface damage.