Narrowband Emission in Thomson Sources Operating in the High-Field Regime

TL;DR

This paper introduces a method to control and eliminate ponderomotive line broadening in high-field Thomson scattering by using laser pulse frequency modulation, enhancing spectral brilliance for practical applications.

Contribution

It proposes a novel approach to correct spectral broadening in high-field Thomson sources through laser pulse frequency modulation and suggests a feasible implementation with free electron laser oscillators.

Findings

Broadening can be effectively corrected by frequency modulation.

Significant compensation achievable even with imperfect matching.

Enhanced spectral brilliance in Thomson scattering at high fields.

Abstract

We present a novel and quite general analysis of the interaction of a high-field chirped laser pulse and a relativistic electron, in which exquisite control of the spectral brilliance of the upshifted Thomson-scattered photon is shown to be possible. Normally, when Thomson scattering occurs at high field strengths, there is ponderomotive line broadening in the scattered radiation. This effect makes the bandwidth too large for some applications and reduces the spectral brilliance. We show that such broadening can be corrected and eliminated by suitable frequency modulation of the incident laser pulse. Further, we suggest a practical realization of this compensation idea in terms of a chirped-beam driven free electron laser oscillator configuration and show that significant compensation can occur, even with the imperfect matching to be expected in these conditions.