An Ultra-Compact X-ray Regenerative Amplifier Free-Electron Laser

Abstract

There is a growing interest in designing and building compact X-ray Free Electron Lasers (FELs) for scientific and industry applications. In this paper, we report an X-ray Regenerative Amplifier FEL (XRAFEL) design based on a proposed Ultra Compact X-ray FEL configuration. Our results show that an XRAFEL can dramatically enhance the temporal coherence and increase the spectral brightness of the radiation in the hard X-ray regime without increasing the footprint of the FEL configuration. The proposed compact, fully coherent, and high-flux hard X-ray source holds promise as a valuable candidate for a wide range of high-impact applications in both academia and industry.

A High-Flux Compact X-ray Free-Electron Laser for Next-Generation Chip Metrology Needs

“…In concentrating on a UCXFEL-based design for our current application, the XFEL per se is changed in two important ways: first, to obtain hard (7 keV) X-rays, we must increase the beam energy nearly two and a half times to 2.44 GeV; second, FEL design is extended to a regenerative amplifier (RAFEL) scheme based on a periodic train of electron pulses. This so-termed XRAFEL serves to greatly increase the X-ray flux and coherence [50].…”

“…The outcoupling of the XRAFEL radiation from the cavity is accomplished based on a recently developed scheme [50] termed the electron-beam-based Q-switching scheme. It relies on the introduction of an initial energy.…”

“…The application of this technique to our current scenario was studied in [50], and further details beyond the present discussion are given there. In the following studies based on the methods introduced in Ref.…”

“…In the following studies based on the methods introduced in Ref. [50], we consider eight electron bunches (each separated by 40 ns) that can be supported with a relatively short RF pulse of 300 ns. As a representative example, we consider a rectangular cavity composed of four diamond mirrors oriented at 45 degrees (see Figure 22), with Bragg resonance centered at 6.95 keV (Miller indices 220).…”

“…The longer current spikes (FWHM ∼120 nm) of the 3 µm current modulation are notably longer than the slippage length and hence have better FEL performance, both in power output and in spectral width. Detailed simulation studies are discussed in another article of the same proceedings [50]; here, we only report the 3 µm current modulation SASE and XRAFEL results.…”