Coherent Terahertz synchrotron radiation mastered by controlling the irregular dynamics of relativistic electron bunches

TL;DR

This paper demonstrates how to control irregular patterns in relativistic electron bunches within synchrotron sources, significantly enhancing terahertz radiation power by stabilizing desirable regular solutions through chaos control techniques.

Contribution

It introduces a novel application of chaos control theory to stabilize regular spatio-temporal patterns in electron bunches, improving THz source stability and power.

Findings

Successful stabilization of regular solutions in the SOLEIL storage ring.

Enhanced terahertz radiation power by factors exceeding 10,000.

Potential for new high-charge, stable synchrotron radiation source designs.

Abstract

Spontaneous formation of spatial structures (patterns) occurs in various contexts, ranging from sand dunes and rogue wave formation, to traffic jams. These last decades, very practical reasons also led to studies of pattern formation in relativistic electron bunches used in synchrotron radiation light sources. As the main motivation, the patterns which spontaneously appear during an instability increase the terahertz radiation power by factors exceeding 10000. However the irregularity of these patterns largely prevented applications of this powerful source. Here we show how to make the spatio-temporal patterns regular (and thus the emitted THz power) using a point of view borrowed from chaos control theory. Mathematically, regular unstable solutions are expected to coexist with the undesired irregular solutions, and may thus be controllable using feedback control. We demonstrate the stabilization of such regular solutions in the Synchrotron SOLEIL storage ring. Operation of these "controlled unstable solutions" enables new designs of high charge and stable synchrotron radiation sources.