Abstract

ASU is pursuing design and construction of compact x-ray light sources to produce brilliant femtosecond pulses for time-resolved science in biology, quantum materials, and atomic-molecular studies. The new sources are based on scattering of intense laser light on short relativistic electron bunches produced by a small linear accelerator operating at kilohertz repetition rate.

The first phase of the project, the Compact X-ray Light Source (CXLS), is now commissioning. CXLS will produce up to 1e8 x-rays per shot in the energy range 2 – 40 keV in pulses as short as 100 fs for use in time-resolved structural biology, phase-contrast imaging, and condensed matter physics. The x-ray pulses have the partial coherence of synchrotron radiation along with tunable energy, pulse length, and polarization. The x-rays are synchronized within 40 fs to high power pump lasers in the UV-IR range.

The second phase of the project, the Compact X-ray Free-Electron Laser (CXFEL), is now in an advanced design phase. CXFEL depends on a novel method to produce transform-limited x-ray output in all dimensions, i.e., with all photons in a single degenerate quantum state. This method avoids the noise amplification of SASE by imprinting a well-defined coherent modulation on the electrons via diffraction in a thin crystal grating. X-ray phase control opens many opportunities from attosecond pulses to stable ultranarrow spectra over the energy range 200 – 2500 eV.