Optimization of Pulsed Operation of the Superconducting Radio-Frequency (SRF) Cavities at the Spallation Neutron Source (SNS)

In order to address the optimization in a pulsed operation, a systematic computational analysis has been made in comparison with operational experiences in superconducting radio-frequency (SRF) cavities at the Spallation Neutron Source (SNS). From the analysis it appears that the SNS SRF cavities can be operated at temperatures higher than 2.1 K, a fact resulting from both the pulsed nature of the superconducting cavities, the specific configuration of the existing cryogenic plant and the operating frequency.

I. Introduction

Thermal breakdown in SRF cavities is one of the major factors that limit the maximum achievable accelerating field. As has been well verified both theoretically and experimentally in steady state, the thermal stability of SRF cavities strongly depends on the operating frequencies, the BCS surface resistances, the cooling schemes, the material properties of niobium such as RRR (residual resistivity ratio) and the presence of material defects on the surface, etc. In many recently initiated or proposed projects for high intensity proton and electron accelerations, the SRF technology has been selected for the main part of the linear accelerator (linac), which uses elliptical shape cavities in a pulsed operation.