Mismatch study of C-ADS main linac

TL;DR

This paper investigates how beam mismatch affects emittance growth and envelope stability in China's CW proton linac for ADS, emphasizing the importance of controlling mismatch factors to ensure low beam loss and high reliability.

Contribution

It provides a detailed analysis of mismatch-induced emittance growth and envelope oscillations, establishing thresholds for mismatch factors to meet beam quality requirements.

Findings

Transverse mismatch factor should be below 0.4

Longitudinal mismatch factor should be below 0.3

Proper mismatch control is crucial for beam stability

Abstract

The ADS accelerator in China is a CW (Continuous-Wave) proton linac with 1.5 GeV in beam energy, 10 mA in beam current, and 15 MW in beam power. To meet the extremely low beam loss rate requirement and high reliability, it is very important to study the beam halo caused by beam mismatch, which is one major source of beam loss. To avoid the envelope instability, the phase advances per period are all smaller than 90 degree in the main linac design. In this paper, the results of the emittance growth and the envelope oscillations caused by mismatch in the main linac section are presented. To meet the emittance growth requirement, the transverse and longitudinal mismatch factors should be smaller than 0.4 and 0.3, respectively.