Three-dimensional particle-in-cell modeling of relativistic electron beam production and transport for KrF laser pumping

The effects of diode geometry and externally applied magnetic fields on electron beam production and transport for KrF laser pumping has been studied using two and three dimensional particle-in-cell models. The efficiency with which electrons may be transported through the foil support structure depends critically on the size of the openings in the structure as well as the magnitude of the applied magnetic fields. As the electron diodes become larger the current which can be produced becomes limited by the self-magnetic field of the beam. Simulations show the diode current is limited to slightly more than the usual “critical current.” However this electron flow is found to be unstable. The application of strong guide fields not only increases the current from the diode but tends to stabilize the electron beam.