Study of the homogeneity of an electron beam using Cerenkov emission

The RKA is a single shot generator which is capable of producing 500 keV, 30 kA, 100 ns electron beams. The beam, emitted by field emission in a diode, is propagated and focused on a target. To improve the understanding of its interaction with a given material, the beam must be characterized in terms of homogeneity, energy and angular dispersion. In this work, we present the results of an experiment where Cerenkov emission is the physical process we use to characterize the beam homogeneity. Two cameras are installed: a high speed gated camera and a streak camera. The code GEANT4 allows us to simulate the Cerenkov emission and the main interactions of electrons/photons inside the target. The initial conditions of the electrons in GEANT4 are provided by “MAGIC” simulations. This particle-in-cell code computes beam emission in the diode and its transportation towards the target. Extensive simulations have allowed us to optimize the full system, in particular in terms of anode thickness and material. The experimental results have confirmed these predictions. In addition, we present experimental tests of several cathode materials as well as the first results of beam propagation in gaseous Argon at a low pressure (order mbar).