Tests and Description of Beam Containment Devices and Instrumentation - A New Dimension in Safety Problems

The destructive capability of the beam power of some accelerators was dramatically demonstrated in a series of tests at SLAC using an 18 GeV e- beam at average powers ranging from 165 to 880 kW. The purpose of the experiments was to examine a series of devices which simulated beam stoppers, protection collimators and burnthrough monitors as presently applied at SLAC. Specific attention was given to the recording of burnthrough times, temperature behavior, and to the analysis of failure modes. A summary of the test data is presented. The design of an extensive electronic system to prevent damage to mechanical devices and to detect onset of destruction is discussed. Various sensors are connected to integrating and peak reading circuits to form power, beam verification and errant beam monitors. Burnthrough monitors shut down the accelerator if damage occurs to critical items. New features such as self-checking, protected wiring and rapid on-line calibration are described.