Linear and non-linear excitation of slow waves in the ion cyclotron frequency range
Linear and nonlinear excitation of slow waves in the ion cyclotron frequency range were studied in a finite-ion-temperature magnetized plasma. Loop antennas designed to induce electric fields either parallel or perpendicular to the static magnetic field were used to investigate coupling to the ion Bernstein wave (IBW). The experiments are modeled and the plasma is described using a self-adjoint equation that includes ion kinetic effects. Both in theory and experiment, the antenna loading is found to be insensitive to antenna polarization. Faraday shielded fast wave polarized antennas (previously thought not to excite slow waves) are shown to couple to the IBW by means of the plasma density gradient. The dependence of Bernstein wave radiation resistance on plasma density, parallel wavenumber, and wave frequency are investigated. Nonlinear (parametric) excitation of ion Bernstein waves is observed and the wave-wave coupling is compared to uniform pump theory. Variation of the decay growth rate with pump wave frequency and plasma density (collisionality) are observed. Harmonic generation associated with the use of electrostatic plate antennas is observed and found to agree with sheath rectification. Subsequent parametric coupling of the second harmonic (lower hybrid) wave with a nonresonant quasimode and with the slow ion cyclotron wave are observed. Decay wave amplitude scaling indicates nonlinear saturation of the process.
- Research Organization:
- Princeton Univ., NJ (USA)
- OSTI ID:
- 5464181
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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