Characterisation Of A Laser Plasma Betatron Source For High Resolution X-Ray Imaging

We report on the characterisation of an x-ray source, generated by a laser-driven plasma wakefield accelerator. The spectrum of the optimised source was consistent with an on-axis synchrotron spectrum with a critical energy of 13.8(-1.9)(+2.2) keV and the number of photons per pulse generated above 1 keV was calculated to be 6(-0.9)(+1.2) x 10(9). The x-ray beam was used to image a resolution grid placed 37 cm from the source, which gave a measured spatial resolution of 4 mu m x 5 mu m. The inferred emission region had a radius and length of 0.5 +/- 0.2 mu m and 3.2 +/- 0.9 mm respectively. It was also observed that laser damage to the exit aperture of the gas cell led to a reduction in the accelerated electron beam charge and a corresponding reduction in x-ray flux due to the change in the plasma density profile.