Subharmonic Drive Experiment at W-Band in the NLCTA

Accelerating structures at mm-wave frequencies are under investigation at SLAC for the purpose of high gradient acceleration. Power sources adequate for substantial acceleration of a beam in a W-band structure are presently not available. An alternative way to achieve high eld levels in a mm wave structure is to drive the structure with a beam that is bunched at a subharmonic frequency. Since the frequency chosen for W-band accelerators is f0 = 91:392 = 8 11:424GHz these structures can be driven by the NLCTA beam which is bunched at 11:424GHz and contains typically 1000 bunches in one pulse. Basic parameters of the NLCTA are given in Table 1.