Millimeter-Wave Generation Via Plasma Three-Wave Mixing
Abstract
Plasma three-wave mixing is a collective phenomena whereby electron - beam-driven electron plasma waves (EPWs) are nonlinearly coupled to an electromagnetic (EM) radiation field. The basic physics of three-wave mixing is investigated in the mm-wave regime and the scaling of mm-wave characteristics established with beam and plasma parameters. Our approach is to employ two counterinjected electron beams in a plasma-loaded circular waveguide to drive counterstreaming EPWs. The nonlinear coupling of these waves generates an EM waveguide mode which oscillates at twice the plasma frequency and is coupled out into rectangular waveguides. Independent control of the waveguide plasma, beam voltage, and beam current is exercised to allow a careful parametric investigation of beam transport, EPW dynamics and three-wave-mixing physics. The beam-plasma experiment, which employs a wire-anode discharge to generate high- density plasma in a 3.8-cm-diameter waveguide, has been used to generate radiation at frequencies from 7 to 60 GHz. Two cold-cathode, secondary-emission electron guns are used to excite the EPWs. Output radiation is observed only when both beams are injected, and the total beam current exceeds a threshold value of 3 A. The threshold is related to the self-magnetic pinch of each beam which increases the beam density and growth rate of the EPWs. the radiation characteristics have a low-frequency (10 to 40 MHz) component which is controlled by the ion dynamics, and a high-frequency (about 350 MHz) component.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1988
- Accession Number
- ADA204487
Entities
People
- Joseph Santoru
- Robert W. Schumacher
Organizations
- HRL Laboratories