Dielectric And Grating Cerenkov Amplifiers using Pencil and Sheet Electron Beams

We describe research on low-voltage < 100 kV). moderate power. millimeter-wave Cerenkov amplifiers. Dispersion relations and growth rates have been theoretically studied for sheet beam configurations employing both gratings and dielectric liners. The effects of sidewalls on pencil beam configurations have also been investigated. Cerenkov grating and dielectric liner tapers for input and output coupling are being designed. Plans for an experiment to study basic critical physics issues will be presented. Experimental research topics will include linear and nonlinear gain in rectangular geometry amplifiers using pencil beams, as well as low voltage sheet beam stability and transport with periodic magnetic focusing.