Lower hybrid wave resonance cone detection via CO/sub 2/ laser scattering

Technical Report · Sun Apr 01 04:00:00 EST 1984

DOI:https://doi.org/10.2172/6845525· OSTI ID:6845525

Wurden, G A; Wong, K L; Ono, M

Lower hybrid waves are studied in the Princeton ACT-I steady-state toroidal plasma device using a radially scanning CO/sub 2/ laser scattering system with both amplitude and phase sensitive detection techniques. Clearly defined resonance cones launched from external electrostatic antennas are seen to disappear as the plasma density is raised. Scaling of LHW laser signal with RF power in the presence of resonance cones shows nonlinearities associated with RF induced changes in the effective laser scattering volume. Absolute fluctuation level estimates suggest this occurs when e PHI/T/sub e/ greater than or equal to 1. Wavefront curvature effects can cause a complete loss of resonance cone laser signals, even though probes indicate that cones are still present. Measurements of the wave k/sub perpendicular/-spectrum in the plasma show direct evidence for electron Landau filtering of the original wave k/sub parallel/-spectrum launched from the antenna at the plasma edge, and strong dependence on antenna phasing. Finally, frequency shifts and loss of the resonance cone signal are associated with high levels of plasma density edge turbulence.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• OSTI ID: 6845525
• Report Number(s): PPPL-2101; ON: DE84013098
• Country of Publication: United States
• Language: English

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