THEORETICAL ELECTRON DYNAMICS IN THE LOW EMITTANCE GUN

For the pulsed DC gun planned for the LEG project, we explore suitable operating regimes. Assuming smooth current distributions at the cathode, gradients of 500 MV/m and peak currents of 5 A are reasonable design targets. For lower gradients, conventional RF guns start to become competitive. Using a self developed parallel 3D particle-in-cell (PIC) code, more refined simulations are presented, showing the effect of the granularity in the transverse current distribution on the resulting slice emittance of the beam. In order to assess the effect of real world variations in the emissivity of FEAs, spatially uncorrelated tip failure is simulated. The result shows a relatively robust behavior with respect to tip failure rates up to 50%. The emitter model still is in the process of refinement, further results are forthcoming in 2005.