High-Frequency Modulation of Ion-Acoustic Waves

1972 ◽  
Vol 15 (11) ◽  
pp. 2013 ◽  
Author(s):  
N. W. Albright
Keyword(s):  
Frequency Modulation ◽  
Acoustic Waves ◽  
High Frequency ◽  
Ion Acoustic Waves ◽  
Ion Acoustic

scholarly journals HF-induced airglow at magnetic zenith: theoretical considerations

2005 ◽  
Vol 23 (1) ◽  
pp. 47-53 ◽  
Author(s):  
E. V. Mishin ◽  
W. J. Burke ◽  
T. Pedersen
Keyword(s):  
Research Program ◽  
Acoustic Waves ◽  
High Frequency ◽  
Theoretical Framework ◽  
Green Line ◽  
Ion Acoustic Waves ◽  
Heating Facility ◽  
Ion Acoustic ◽  
Theoretical Considerations ◽  
Magnetic Zenith

Abstract. Observations of airglow at 630nm (red line) and 557.7nm (green line) during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP) heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

Influence of High Frequency Electric Field on the Dispersion of Ion-Acoustic Waves in Plasma

1981 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
A. Turky ◽  
M. Čerček ◽  
R. Tavzes J. Stefan
Keyword(s):  
Electric Field ◽  
Acoustic Waves ◽  
High Frequency ◽  
Wave Dispersion ◽  
Plasma Stream ◽  
Ion Acoustic Waves ◽  
Ion Acoustic Wave ◽  
High Frequency Electric Field ◽  
Ion Acoustic ◽  
Frequency Electric Field

The modification of the ion-acoustic wave dispersion under the action of a high frequency electric field was studied experimentally, the wave propagating along and against the plasma stream. The frequency of the field amounted to approximately half the electron plasma frequency. It was found that the phase velocity of the ion wave and the plasma drift velocity decrease as the effective high frequency field power increases

scholarly journals High time resolution PFISR and optical observations of naturally enhanced ion acoustic lines

2009 ◽  
Vol 27 (4) ◽  
pp. 1457-1467 ◽  
Author(s):  
R. G. Michell ◽  
K. A. Lynch ◽  
C. J. Heinselman ◽  
H. C. Stenbaek-Nielsen
Keyword(s):  
High Resolution ◽  
Time Resolution ◽  
Acoustic Waves ◽  
Fast Moving ◽  
High Time ◽  
High Time Resolution ◽  
Ion Acoustic Waves ◽  
Raw Data ◽  
Ion Acoustic ◽  
Auroral Imaging

Abstract. Observations of naturally enhanced ion acoustic lines (NEIALs) taken with the Poker Flat Incoherent Scatter Radar (PFISR) using a mode with very high time resolution are presented. The auroral event took place over Poker Flat, Alaska on 8 February 2007 at 09:35 UT (~22:00 MLT), and the radar data are complemented by common-volume high-resolution auroral imaging. The NEIALs occurred during only one of the standard 15-s integration periods. The raw data of this time show very intermittent NEIALs which occur only during a few very short time intervals (≤1 s) within the 15-s period. The time sampling of the raw data, ~19 ms on average, allows study of the time development of the NEIALs, though there are indications that even finer time resolution would be of interest. The analysis is based on the assumption that the NEIAL returns are the result of Bragg scattering from ion-acoustic waves that have been enhanced significantly above thermal levels. The spectra of the raw data indicate that although the up- and down-shifted shoulders can both become enhanced at the same time, (within 19 ms), they are most often enhanced individually. The overall power in the up-and down-shifted shoulders is approximately equal throughout the event, with the exception of one time, when very large up-shifted power was observed with no corresponding down-shifted power. This indicates that during the 480 μs pulse, the strongly enhanced ion-acoustic waves were only traveling downward and not upward. The exact time that the NEIALs occurred was when the radar beam was on the boundary of a fast-moving (~10 km/s), bright auroral structure, as seen in the high resolution auroral imaging of the magnetic zenith. When viewed with high time resolution, the occurrence of NEIALs is associated with rapid changes in auroral luminosity within the radar field of view due to fast-moving auroral fine structures.

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