Emittance Growth by Beam-Gas Scattering in Single Pass Accelerator

TL;DR

This paper investigates how beam-gas scattering causes emittance growth in single-pass accelerators, deriving and validating formulas to predict this effect for electron energies above 100 MeV, crucial for maintaining beam quality in light sources.

Contribution

It provides a new analytical expression for emittance increase due to beam-gas scattering applicable to electrons above 100 MeV, validated against existing formulas.

Findings

Derived a useful expression for emittance growth from beam-gas scattering.

Validated the expression for energies above 100 MeV.

Provides insights for minimizing emittance growth in accelerators.

Abstract

In order to ensure proper SASE lasing of a fourth Generation light source, one of the goal is to produce an electron beam of small emittance and to conserve it until its used in the machine undulator. One of the non recoverable emittance increase is the collision of the electron beam during its transport with the residual gas. Based on previous work by others, we have derived a useful expression of emittance increase for electrons of any energy and cross check its validity for energies above 100 MeV with an analytical formula.