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

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:160781

Weaver, J; Kobayashi, S; Carmel, Y; Rodgers, J; Destler, W W; Granatstein, V L ^[1]; Shkuvarunets, A ^[2]

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1. Univ. of Maryland, College Park, MD (United States). Inst. for Plasma Research
2. Russian Academy of Science, Moscow (Russian Federation). General Physics Inst.

A series of experiments were made to characterize the electron component of a transient plasma column immersed in magnetic field. These long plasma columns 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, gun positions, and gun voltages. 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. The axial and radial density profiles were deduced from a large number of such measurements. These results were also compared to data gathered by an electromagnetic technique based on a plasma-loaded resonant cavity. The measured plasma electron density decreased from 10{sup 12} cm{sup {minus}3} to 10{sup 9} cm{sup {minus}3} in {approximately} 1 ms. The transverse profile of the column was bell-shaped with an effective radius on the order of 1 cm. Dependence of the peak value and the width of this distribution as a function of the magnetic field, gun voltage, and gun position will be presented. The measured plasma temperature was on the order of 1 eV for a typical shot.

• OSTI ID: 160781
• Report Number(s): CONF-950612--; ISBN 0-7803-2669-5
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BACKWARD WAVE TUBES
CAVITY RESONATORS
ELECTRON TEMPERATURE
OPERATION
PERFORMANCE
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA PRODUCTION