RECENT DEVELOPMENTS IN MICROWAVE BEAM-POSITION MONITORS AT SLAC*

Summary The design, installation and performance of beam position monitors initially installed at SLAC are reviewed briefly. The use of receiver systems to improve the sensitivity of switchyard monitors is described. Two position-monitoring systems developed especially for polarized electron-beam experiments are described : the first is a homodyne system capable of detecting 10 ~m beam displacements at 100 ~A beam currents, and the second is a traveling­ wave monitor with a limiter-normalized output which can be used down to ZO ~A.