Kinetic simulations of an electron beam penetrating a density gradient

Summary form only given. In X- ray radiography, an electron beam hits a high Z target material, resulting in the X-ray pulse for the radiograph. In multiphase radiography, a quick succession of electron beam pulses hits the target and generates multiple X-ray pulses. All electron beam pulses but the first must penetrate the material near the target which was blown off by previous pulses. This report presents 3D kinetic simulations of a 18 MeV electron beam propagating through initial density gradients representative of the blow off plasma after it has evolved for various times. The stability of the beam, the increase of emittance, and the change in the distribution function of the beam will be addressed.