Low Voltage, Four Beam Ka-Band TWT Experiment

We present experimental hot testing of a novel low voltage, multi-electron beam, serpentine Ka-band traveling wave tube amplifier utilizing a cathode in an immersed magnetic field. The amplifier is designed to run at 430 mA of total beam current spread across four beamlets in an immersed, zero-compression flow. At present, the device is characterized at 225 mA of cathode current with 95% beam transmission at a maximum output power of 68 W. Using a four-segment beam collector, the beams are measured individually and exhibit good current sharing with a standard deviation of about 3 mA.