Advanced Fluid Models of Beam-Wave Interaction in High Power Microwave Sources*

High-power electromagnetic device modeling require a kinetic treatment, especially for saturation of the device at peak power operation. However, advanced fluid models can capture much of the evolution to the saturated state while requiring less computation time.  Fluid models are also especially intriguing considering that many analytic formulations of vacuum electronics devices rely on cold fluid theory.  We present results for advanced single fluid and two fluid models of a 5 GHz klystron.  We compare electrostatic approximations with full electromagnetic models.  We also compare results and computation time with full PIC models.  Finally, we validate these models with klystron theory.