Anti-Breakdown Coatings for High-Gradient Accelerator Structures

Accelerator structures that can sustain acceleration gradients in the range of 150 MeV/m are required in order to build a future multi-TeV collider with an energy reach beyond present or planned electron-positron colliders. However, limitations arise from RF breakdown and from difficulties in developing the necessary RF drive power. This project will apply high-melting-point insulated coatings to accelerator structures to mitigate against the explosive emission and surface melting that accompany RF breakdown. In Phase I, high-melting-point insulated coatings will be applied: first to test samples, and later to parts from an experimental SLAC accelerator cavity. Strong adherence of the coating to the underlying copper will be achieved by the use of a graded coating, in which the composition varies smoothly from the copper outwards to the pure insulator. Tests will be conducted to determine whether the coatings on the cavity parts can survive thermal cycling from room temperature up to the brazing temperature for the accelerator cavities. Commercial Applications and other Benefits as described by the awardee: Structures that can sustain high accelerating gradients without an undue frequency of breakdown would be the basis for a future multi-TeV electron-positron collider and would hasten the day when commercial companies can obtain multi-million dollar manufacturing contracts for the accelerator structures.