Noise In Intense Electron Bunches

TL;DR

This paper investigates density fluctuations and noise in relativistic electron bunches, highlighting their impact on various accelerator-based light sources and cooling techniques, with implications for improving beam quality and radiation coherence.

Contribution

It provides new insights into the nature of noise in intense electron bunches and its effects on coherent electron cooling and free-electron laser performance.

Findings

Noise influences beam microbunching in FELs

Density fluctuations affect cooling efficiency in CEC

Initial beam noise impacts FEL bandwidth and seed laser requirements

Abstract

We report on our investigations into density fluctuations in electron bunches. Noise and density fluctuations in relativistic electron bunches, accelerated in a linac, are of critical importance to various Coherent Electron Cooling (CEC) [1-5] concepts as well as to free-electron lasers (FELs). For CEC, the beam noise results in additional diffusion that counteracts cooling. In SASE FELs, a micro-wave instability starts from the initial noise in the beam and eventually leads to the beam microbunching yielding coherent radiation, and the initial noise in the FEL bandwidth plays a useful role. In seeded FELs, in contrast, such noise interferes with the seed signal, so that reducing noise at the initial seed wavelength would lower the seed laser power requirement [6-8]. Status of the project will be presented.