Compact X-ray Sources With Laser Undulators: Design and Commissioning results from the ASU CXFEL Project

Bright sources of sub-picosecond hard x-rays such as x-ray free electron lasers (XFELs) have made their mark on any field of science interested in atomic structure, from biochemistry to earth science. However, the cost and scale of these facilities is prohibitive for routine use at research institutes such as universities, and thus limits the scope and impact of these sources. Inverse Compton Scattering (ICS) is a promising approach to developing scalable ultrafast x-ray sources at a much lower cost per facility than full-scale x-ray free electron lasers (XFELs), filling a gap between single-user anode-based sources and large user facilities like synchrotrons and XFELs. ICS-based x-ray sources use the oscillating electromagnetic field of a laser to replace the magnetic undulators at synchrotrons and XFELs, thus reducing the required accelerator beam energy and cost by orders of magnitude.

In this presentation, I will provide updates on two ICS-based x-ray sources at ASU, the Compact X-ray light source (CXLS) and the Compact X-ray Free Electron Laser (CXFEL). The ASU Compact x-ray light source (CXLS) is an inverse Compton scattering (ICS) source that produces 10⁹ photons/sec on target at 1 kHz repletion rate with 300 fs pulse duration. I will discuss our early commissioning results and science opportunities in materials science and structural biology at CXLS.

I will discuss the design and construction progress of CXFEL, which is a fully spatiotemporally coherent XFEL that uses a combination of emittance exchange (EEX) with a silicon grating to microbunch the beam, and an crossed-beam laser interaction geometry to generate fully coherent soft x-rays with an average flux of 10¹¹/s and an average brightness of 10²² at 1 keV, comparable to a modern undulator beamline. The sources are compact, with accelerators approximately ten meters long, and both sources and support labs fit into a 1,000 m² university laboratory space.