Harmonic launching of ion Bernstein waves via mode transformation
Ion Bernstein wave excitation and propagation via finite ion-Larmor-radium mode-transformation are investigated theoretically and experimentally. It is shown that in the ion cyclotron range of frequencies omega less than or equal to 4..cap omega../sub i/, with modest ion temperatures (T/sub i/ less than or equal to 10 eV), the finite-Larmor-radius effect removes the wave singularity at lower-hybrid resonance layer, enabling an externally initiated electron plasma wave to transform continuously into an ion Bernstein wave. In an ACT-1 hydrogen plasma (T/sub e/ approx. = 2.5 eV, T/sub i/ less than or equal to 2.0 eV), externally excited ion Bernstein waves have been observed for omega less than or equal to 2..cap omega../sub i/ as well as for omega less than or equal to 3..cap omega../sub i/. The finite ion-Larmor-radius mode transformation process resulting in strong ion Bernstein wave excitation has been experimentally verified. Detailed measurements of the wave dispersion relation and of the wave-packet trajectory show excellent agreement with theory. The dependence of the excited ion Bernstein wave on the antenna phasing, the plasma density, and on the neutral pressure (T/sub i/) is also investigated.
- Research Organization:
- Princeton Univ., NJ (USA). Plasma Physics Lab.
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 5154818
- Report Number(s):
- PPPL-1905; ON: DE82018630
- Country of Publication:
- United States
- Language:
- English
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BERNSTEIN MODE
COUPLING
CYCLOTRON FREQUENCY
DISPERSION RELATIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
HYBRID RESONANCE
HYDROGEN
ION PLASMA WAVES
ION WAVES
NONMETALS
OSCILLATION MODES
PLASMA WAVES
RADIATIONS
RADIOWAVE RADIATION
RESONANCE
WAVE PROPAGATION