Investigation and characterization of elliptical X-ray profiles from laser wakefield acceleration at the ZEUS laser facility

We will be presenting the results from laser wakefield acceleration experiments at the ZEUS laser facility at the University of Michigan. We produced elliptical betatron X-ray profiles with an elliptical focal spot (2:1 aspect ratio) in a low density (5 x 10¹⁷ cm^-3) plasma. This phenomenon is investigated through experiments and particle in cell simulations. The angle between the major axis of the elliptical betatron profile and the laser polarization axis fluctuated from -15 degrees to 15 degrees during the experiment. The pointing stability of the betatron beams was quite stable compared to the divergence of the X-ray beam. The divergence of the X-ray beam was 5 mrad and the standard deviation of the pointing angle of the centroid of the profile was 0.5 mrad. Additionally, we demonstrate that the betatron X-rays have a significant portion of the spectrum with energies exceeding 100 keV. This is demonstrated in a practical radiography application.