• D. Yu, Y. Luo
  DULY Research Inc., Rancho Palos Verdes, California

A Gallium Arsenide (GaAs) photocathode RF electron gun is useful if high polarization (>85%) and low emittance are required as, for example, in the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility. DULY Research is developing a normal-conducting, L-band photoelectron gun in an ultra high vacuum accelerating structure called the Plane-Wave-Transformer (PWT) integrated with an activated, strained-lattice GaAs photocathode, as a continuous wave polarized electron source. We compare two designs (1-cell and ½ cell) of an L-Band PWT photoelectron gun in this paper. This RF gun will simplify the CEBAF photoinjector design by replacing the direct current (DC) gun, buncher cavities and the capture section. The new compact design provides a stiffer beam that is less subject to space charge blowup. In addition, a higher field gradient at the photocathode would mitigate electron and ion backbombardment problems. Cooling for a CW PWT gun is challenging but manageable.

• D. Yu, P. Chen, M. Lundquist
  DULY Research Inc., Rancho Palos Verdes, California

Marx modulators, operated by the solid-state switches of Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) or Insulated Gate Bipolar Transistors (IGBTs), offer an alternative to conventional high voltage modulators for rf power sources. They have the advantages of compact size, high-energy efficiency, high reliability, pulse width control and cost reduction. However, Marx modulators need a complex voltage compensation circuit if they are employed in long pulse applications such as the ILC project. We describe novel schemes to compensate the voltage droop of the Marx modulator and minimize the flattop fluctuation of the voltage pulse output through the utilization of inductances and the fast switching properties of solid-state switches. The feasibility of the schemes has been analyzed and relevant data will be presented.