Present status of laser undulator compact X-ray source (LUCX)

We have been developing a compact X-ray source based on laser Compton scattering (LCS) between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray source (LUCX) accelerator in KEK. The accelerator consists of a 3.6-cell photo-cathode rf-gun, a 12-cell standing wave accelerating tube and a 4-mirror planar optical cavity. Our aim is to take a clear X-ray image in a shorter period of times. The target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500 nC/train with 1000 bunches at 30 MeV and the intensity of a laser pulse to 6 mJ/pulse respectively. Presently, we have achieved the generation of 24 MeV beam with total charge of 600 nC in 1000 bunches with the bunch-by-bunch energy difference is within 1.3% peak to peak. The beam-loading has been compensated by injecting the beam before rf power has been filled (ΔT method) and by modulating the amplitude of the rf pulse. On the other hand, we have obtained the laser pulse with 750 μJ/pulse in the optical cavity now. In this paper, the present status and the results of beam tuning and X-ray generation of the LUCX accelerator will be reported. (author)