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Ionospheric modification at twice the electron cyclotron frequency
F T Djuth1, T R Pedersen, E A Gerken
1Geospace Research, Inc., El Segundo, California 90245, USA.
Physical Review Letters
|May 21, 2005
Summary
The High-frequency Active Auroral Research Program (HAARP) facility observed enhanced airglow when transmission frequencies matched the second electron cyclotron harmonic. This indicates the presence of accelerated electrons in the ionosphere.
Area of Science:
- Space Physics
- Atmospheric Science
- Plasma Physics
Background:
- The High-frequency Active Auroral Research Program (HAARP) facility was upgraded in 2004 with a new transmission band.
- This band covers the second electron cyclotron harmonic at altitudes of 220-330 km.
Purpose of the Study:
- To investigate the effects of the new HAARP transmission band on the ionosphere.
- To analyze the relationship between transmission frequency and observed airglow emissions.
Main Methods:
- Utilizing the HAARP facility's high-frequency transmission capabilities.
- Observing and measuring airglow emissions at specific altitudes.
- Correlating optical emissions with transmission frequencies and plasma characteristics.
Main Results:
- Greatly enhanced airglow was observed when transmission frequency matched the second electron cyclotron harmonic at the upper hybrid resonance height.
- This phenomenon is contrary to observations at higher electron cyclotron harmonics.
- Measured optical emissions provided evidence for accelerated electrons within the plasma.
Conclusions:
- The HAARP facility's second electron cyclotron harmonic band can induce significant ionospheric disturbances.
- Accelerated electrons are confirmed by optical emissions, impacting ionospheric plasma behavior.
- Findings offer new insights into high-frequency wave-particle interactions in the ionosphere.