Rf breakdown and field emission

One of the crucial parameters in the design of TeV e/sup +-/ linear colliders is the maximum electric field gradient that can be attained and used safely in the accelerating structure. In the absence of definitive knowledge on the availability and cost of rf power sources, the optimum machine length for a given energy cannot be determined at this time. However, the designs considered in this report could require gradients as high as 200 MV/m at rf frequencies of 11.424 GHz or 17.136 GHz, corresponding to peak powers of up to 1 GW/m. On the basis of research done at SLAC and at Varian, it now appears that such gradients are reachable, at least in short standing-wave (SW) structures. Considerably more work, however, is needed to determine if the required gradients are achievable in long and complicated structures, and to verify that the accompanying field emitted currents which can absorb power, cause parasitic wakefields and spurious x-rays along the accelerator, are tolerable. 1 ref., 1 fig