Laser based sub-picosecond electron bunch characterization using 90/spl deg/ Thomson scattering

X-rays produced by 90/spl deg/ Thomson scattering of a femtosecond, near infrared, terawatt laser pulse off a 50 MeV electron beam are shown to be an effective diagnostic to measure transverse and longitudinal density distributions of an electron beam (e-beam) with subpicosecond time resolution. The laser beam was focused onto the e-beam waist, generating 30 keV X-rays in the forward direction. The transverse and longitudinal e-beam structure have been obtained by measuring the intensity of the X-ray beam, while scanning the laser beam across the e-beam in space and time. The e-beam divergence has been obtained through measurement of spatial and spectral characteristics of the scattered X-ray beam.