High-power, single-beam plasma wave tube

Short-pulse, ultra-broadband sources of RF radiation are needed for a variety of new applications. To meet this demand, we have developed and optimized a single-beam Plasma Wave Tube (PWT), The PWT is a unique microwave/millimeter-wave source which utilizes the interaction between beamexcited electron plasma waves to generate kilowatt-power (/spl sim/10 kW) radiation at microwave to millimeter-wave frequencies with a beam-to-radiation conversion efficiency of /spl ges/0.4%. In a single-beam PWT, an electron beam (/spl les/40 kV, /spl ges/200 A, 5-to-20-/spl mu/s pulse width) is injected into a gas-filled (e,g., hydrogen) cylindrical waveguide. The beam first ionizes the gas to generate a plasma, and then nonlinearly interacts with the plasma to generate radiation from 6-to-60 GHz. Slew rates of up to 7 GHz//spl mu/s have been measured during a single beam pulse. The radiation has a wide instantaneous bandwidth, typically 10 GHz or wider. Electron-beam transport through the waveguide is accomplished with no externally applied magnetic fields because the beam space charge is cancelled by the background plasma.< >