Design Criteria for High-Gradient Radio-Frequency Linacs

This article will review methods used at the SLAC National Accelerator Laboratory and other world accelerator laboratories to design high-gradient normal conducting accelerating structures. A quest for compact radio-frequency linacs fueled decades of studies toward a higher accelerating gradient. A major phenomena limiting the increase of the gradient is vacuum radio-frequency breakdown; therefore, this paper will address the breakdown physics and discuss approaches that reduce the breakdown probability. This discussion will cover both the electrical design and fabrication technology of the accelerating structures to achieve practical operating accelerating gradients in excess of 100 MV/m. Most of the data described here were obtained during the development of 11 GHz linacs for electron-positron linear colliders, so extrapolation of the results to other frequencies should be performed cautiously.

Automated summary

This article reviews design methods used at SLAC National Accelerator Laboratory and other accelerator laboratories worldwide for high-gradient normal conducting accelerating structures. The paper discusses the limitations posed by vacuum radio-frequency breakdown and explores approaches to reduce the probability of breakdown. It covers both electrical design and fabrication technology of the accelerating structures to achieve practical operating gradients exceeding 100 MV/m. Extrapolation of the results to other frequencies should be done cautiously as most of the data described here were obtained during the development of 11 GHz linacs for electron-positron linear colliders.