Dependence of the TMCI threshold on the space charge tune shift

TL;DR

This paper investigates how the transverse mode coupling instability (TMCI) threshold varies with space charge tune shift using the boxcar model, finding a consistent increase in the threshold with higher space charge.

Contribution

It provides the first detailed analysis showing a monotonous increase of TMCI threshold with space charge tune shift, challenging previous assumptions of non-monotonic behavior.

Findings

TMCI threshold increases monotonically with space charge tune shift

Results are based on the boxcar model analysis

Contradicts previous beliefs of possible non-monotonic behavior

Abstract

Transverse mode coupling instability of a bunch with space charge is considered in frameworks of the boxcar model. Presented results demonstrate a monotonous growth of the TMCI threshold at increasing space charge tune shift, and do not support the supposition that the monotony can be violated at a higher SC.