Study of ELF/VLF wave generation by HF heater-modulated electrojet
- Polytechnic Univ., Farmingdale, NY (United States). Dept. of Electrical Engineering
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center
- Phillips Lab., Hanscom AFB, MA (United States)
Generation of ELF/VLF waves by the modulation of the electrojet by the powerful HF heater is of current interest. It is done by applying an amplitude modulated HF heater to modify the electron temperature of the electrojet in time. This in turn causes the modulation of the conductivity and thus, the electrojet current. Emissions are then produced at the modulation frequency and its harmonics. The present work extends the previous one of thermal instability to the nonlinear saturation regime. Two heater-modulation schemes are considered. One, corresponding to the one adopted in the Tromsq heating experiments, modulated the heater by a rectangular periodic pulse. The other one needs two overlapping heater waves (beat wave) having a frequency difference equal to the desired modulation frequency. It is essentially a sinusoidal amplitude modulation and is the approach adopted in the Arecibo heating experiments. The nonlinear evolutions of the generated ELF/VLF waves are determined numerically. Their spectra are also evaluated. The results show that the signal quality of the beat wave scheme is better (i.e., harmonic components have relatively lower intensities than that of the fundamental line). The field intensity of the emission at the fundamental modulation frequency is found to increase with the modulation frequency, consistent with the Tromsq results.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
- OSTI ID:
- 330581
- Report Number(s):
- CONF-970559-; TRN: 99:004670
- Resource Relation:
- Conference: 24. IEEE international conference on plasma science, San Diego, CA (United States), 19-23 May 1997; Other Information: PBD: 1997; Related Information: Is Part Of IEEE conference record -- Abstracts; PB: 354 p.
- Country of Publication:
- United States
- Language:
- English
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