Scaling Law of Beam Break-Up for the Single Ultrashort Bunch in RF Linac

TL;DR

This paper proposes a scaling law for beam breakup phenomena in RF linacs caused by ultrashort bunches, estimating the influence of different wakefield effects with specific power factors.

Contribution

It introduces a new scaling law relating beam current to breakup effects and estimates the power factors for various wakefield contributions in RF linacs.

Findings

Scaling power factor is approximately 1/6 for geometry wake.

Scaling power factor is approximately 1/6 for surface roughness wake.

Scaling power factor is approximately 1/3 for resistance wake.

Abstract

Femtosecond bunch is a hot topic in the present world accelerator research community. The high peak current bunch will lead to the beam breakup phenomenon. In this paper, the scaling law with current for the single ultrashort bunch beam breakup in the radio frequency linear accelerator is proposed and obtained. The scaling power factor is roughly estimated to be 1/6, 1/6 and 1/3 for the geometry wake, the surface roughness wake and the resistance wake respectively.