Broadband X-Ray Source Development with Laser Wakefield Accelerators

Ultrashort broadband x-ray sources are desirable for radiography of materials at pressures and temperatures often encountered in High Energy Density (HED) science experiments. Relativistic electron beams from a Self-Modulated Laser Wakefield Accelerator (SM-LWFA) provide such x-rays through three independent mechanisms: Betatron radiation (∼10keV), inverse Compton scattering (50 ∼ 300keV), and bremsstrahlung (> 1MeV). In this experiment the Titan laser (pulse energy 150J, length ∼ 1ps) produces a SM-LWFA in a 4mm He gas jet and generates a 10nC directional (∼ 100mrad) beam of electrons with energies of up to 300MeV, measured with a magnetic electron spectrometer. We measure the spectra of x-rays produced by each mechanism using differential filtering and evaluate their imaging characteristics, including source size and angular resolution, with several resolution targets.