• M.M. Allen
  Xavier University of Louisiana, New Orleans, Louisiana
• J. Bisognano, R.A. Legg
  UW-Madison/SRC, Madison, Wisconsin

For many years it has been speculated that uniformly filled ellipsoidal electron bunches, with their linear fields, would be ideal to produce high charge density with low emittance beams. This may be particularly advantageous with bunch compression schemes required for operation of an FEL. The “blow-out” mode is a method of producing the desired electron bunch distribution: an initial charge pancake is produced at the cathode and allowed to expand to an ellipsoidal shape under the influence of its own space charge. In earlier studies a constant, DC electric field has been assumed in the production of ellipsoidal bunch distributions using “blow-out” mode. In this paper we look at the effects of a time varying, non-constant electric field on the development of the electron bunches as they are emitted from the photocathode and travel through an accelerating RF cavity. We present the effects of frequency in the cavity, field strength of the cavity,, as well as the phase of the electron bunch. These three variables change the spatial curvature and the temporal slope of the electric field as observed by the electron bunch. This results in changes in bunch development and formation.