Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

TL;DR

This paper presents a compact, high-repetition-rate x-ray source based on inverse Compton scattering, utilizing a novel linac and laser system to achieve high flux and brilliance suitable for laboratory applications.

Contribution

The design introduces a high-efficiency standing-wave linac and a synchronized laser system enabling operation at 100 kHz, significantly surpassing existing laboratory x-ray sources.

Findings

Achieves x-ray flux of 5×10^11 photons/sec at 12.4 keV

Brilliance of 2×10^12 photons/(sec·mm^2·mrad^2·0.1%)

Operates with a 1-meter-long accelerator producing tunable hard x-rays

Abstract

A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standing-wave linac and RF photoinjector powered by a single ultrastable RF transmitter at x-band RF frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire accelerator is approximately 1 meter long and produces hard x-rays tunable over a wide range of photon energies. The colliding laser is a Yb:YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is $5 \times 10^{11}$ photons/second in a 5% bandwidth and the brilliance is $2 \times 10^{12}\mathrm{photons/(sec\ mm^2\ mrad^2\ 0.1\%)}$ in pulses with RMS pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.