3:30 pm Zoom
Multi-turn Energy Recovery Linacs (ERLs) powered by Superconducting Radio Frequency (SRF) cavities enable the production of continuous bright high-current beams while being very efficient. Contributing to this efficiency is the reduction of heat dissipation on the cavity surface and the optimization of rf power used to maintain stable accelerating field inside the cavities. The latter is achieved by increasing the loaded quality factor of the resonant cavities and optimizing the energy recovery process. In this talk, I will discuss the use of these techniques in the Cornell BNL ERL Test Accelerator (CBETA), the first multi-turn SRF ERL, which achieved an energy recovery efficiency of 99.4 % during high-current operations in the single turn mode. I will further present an analysis of transients in the energy recovery process using a novel linear model which predicts the existence of reactive beam loading arising from relativistic effects in the presence of low energy beam. Finally, I will describe a new thermometry system used to image local heating and thermal runaway on the surface of SRF cavities, thus aiding the development of more efficient SRF materials for future ERLs.