Generation and detection of super small striations by F region HF heating

Recent theoretical models and preliminary observations indicate that super small striations (SSS) in the plasma density with scale size of 10 cm can be excited by F region HF heating at frequencies close to multiples of the electron gyrofrequency. We present here new experimental results using the H...

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Bibliographic Details
Published in:Journal of geophysical research. Space physics 2014-07, Vol.119 (7), p.6000-6011
Main Authors: Najmi, A., Milikh, G., Secan, J., Chiang, K., Psiaki, M., Bernhardt, P., Briczinski, S., Siefring, C., Chang, C.L., Papadopoulos, K.
Format: Article
Language:English
Subjects:
F region
Heating
HF heating
super small striations
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Summary:Recent theoretical models and preliminary observations indicate that super small striations (SSS) in the plasma density with scale size of 10 cm can be excited by F region HF heating at frequencies close to multiples of the electron gyrofrequency. We present here new experimental results using the High Frequency Active Auroral Research Program ionospheric heater at a frequency close to the fourth electron gyroharmonic with simultaneous GPS, Stimulated Electromagnetic Emission, ionosonde, and occasional Incoherent Radar Scattering diagnostics. Differential phase measurements of GPS signals through the heated region indicated the presence of SSS with extremely high amplitude (δn/n = 0.2–0.3) at scale size comparable to the electron gyroradius. The highest amplitude of GPS scintillations coincide with the highest level of the Broad Upshifted Maximum (BUM) and occurred when the HF frequency is slightly above the fourth harmonic of the electron cyclotron frequency. Frequency sweeps indicate that the scintillation amplitude exhibits hysteresis similar to that observed for the BUM amplitude when the HF frequency is cycled about the fourth harmonic of the cyclotron frequency. The results favor a four wave parametric process as the physical mechanism of the SSS. Additional experiments allowed the determination of the excitation and decay rates of the SSS. Key Points Two independent diagnostic techniques were used to study SEE and SSS STEC indicates density perturbation grows rapidly when BUM appears in SEE Hysteresis is detected in the BUM, DM, and STEC potentially via two methods
ISSN:2169-9380
2169-9402
DOI:10.1002/2014JA020038