Asymmetric Dual Axis Energy Recovery Linac for Ultra-High Flux sources of coherent X-ray/THz radiation: Investigations Towards its Ultimate Performance

TL;DR

This paper proposes an asymmetric superconducting RF energy recovery linac design to achieve ultra-high flux coherent X-ray and THz radiation, minimizing beam instability issues for compact high-current sources.

Contribution

It introduces a novel asymmetric cavity configuration in SRF ERLs that reduces beam-break up instabilities, enabling higher beam currents for advanced radiation sources.

Findings

Asymmetric cavity design reduces BBU instability start current.

Analytical and numerical models validate the stability improvements.

Potential for more compact, efficient high-brightness radiation sources.

Abstract

In order for sources of coherent high brightness and intensity THz and X-Ray radiation to be accepted by university or industrial R&D laboratories, truly compact, high current and efficient particle accelerators are required. The demand for compactness and efficiency can be satisfied by superconducting RF energy recovery linear accelerators (SRF ERL) allowing effectively minimising the footprint and maximising the efficiency of the system. However such set-ups are affected by regenerative beam-break up (BBU) instabilities which limit the beam current and may terminate the beam transport as well as energy recuperation. In this paper we suggest and discuss a SRF ERL with asymmetric configuration of resonantly coupled accelerating and decelerating cavities. In this type of SRF ERL an electron bunch is passing through accelerating and decelerating cavities once and, as we show in this case, the regenerative BBU instability can be minimised allowing high currents to be achieved. We study the BBU start current in such an asymmetric ERL via analytical and numerical models and discuss the properties of such a system.