Characterization of the plasma column used in studies of a plasma-loaded relativistic backward wave oscillator

Summary form only given. A series of experiments were made to characterize the electron component of a transient plasma column immersed in magnetic field. These long plasma columns (radius /spl ap/1 cm and length /spl ap/100 cm) were used to fill the slow wave structure of a relativistic backward wave oscillator (BWO). The addition of plasma increased the efficiency of microwave generation, the operating frequency, and the maximum allowable beam current. The plasma was generated by a coaxial hydrogen flashover gun located just outside the solenoid on the center axis. The plasma electron radial and axial density profiles and the plasma electron temperature were studied over a range of magnetic fields (2-15 kG), gun positions (24-40 cm from the solenoid end), and gun voltages (10-14 kV). This knowledge will allow more precise control of the operating conditions of plasma-loaded BWOs. A single movable Langmuir probe and a cylindrical resonant cavity were used.