scholarly journals HF-Induced Modifications of the Electron Density Profile in the Earth’s Ionosphere Using the Pump Frequencies near the Fourth Electron Gyroharmonic

2021 ◽  
Vol 13 (23) ◽  
pp. 4895
Author(s):  
Alexey V. Shindin ◽  
Evgeny N. Sergeev ◽  
Savely M. Grach ◽  
Gennady M. Milikh ◽  
Paul Bernhardt ◽  
...  
Keyword(s):  
Density Profile ◽  
Ionospheric Plasma ◽  
Pump Wave ◽  
Electromagnetic Emission ◽  
Electron Density Profile ◽  
Radio Waves ◽  
F Region ◽  
Plasma Density Profile ◽  
Hybrid Region ◽  
Hf Heating

We discuss results on plasma density profile modifications in the F-region ionosphere that are caused by HF heating with the frequency f0 in the range [(−150 kHz)–(+75 kHz)] around the fourth electron gyroharmonic 4fc. The experiments were conducted at the HAARP facility in June 2014. A multi-frequency Doppler sounder (MDS), which measures the phase and amplitude of reflected sounding radio waves, complemented by the observations of the stimulated electromagnetic emission (SEE) were used for the diagnostics of the plasma perturbations. We detected noticeable plasma expulsion from the reflection region of the pumping wave and from the upper hybrid region, where the expulsion from the latter was strongly suppressed for f0 ≈ 4fc. The plasma expulsion from the upper hybrid region was accompanied by the sounding wave’s anomalous absorption (AA) slower development for f0 ≈ 4fc. Furthermore, slower development and weaker expulsion were detected for the height region between the pump wave reflection and upper hybrid altitudes. The combined MDS and SEE allowed for establishing an interconnection between different manifestations of the HF-induced ionospheric turbulence and determining the altitude of the most effective pump wave energy input to ionospheric plasma by using the dependence on the offset between f0 and 4fc.

scholarly journals Evidence of <i>L</i>-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith

2018 ◽  
Vol 36 (1) ◽  
pp. 243-251 ◽  
Author(s):  
Thomas B. Leyser ◽  
H. Gordon James ◽  
Björn Gustavsson ◽  
Michael T. Rietveld
Keyword(s):  
Electromagnetic Waves ◽  
Ionospheric Plasma ◽  
Pump Wave ◽  
Topside Ionosphere ◽  
Mode Propagation ◽  
Pump Frequency ◽  
Density Peak ◽  
F Region ◽  
Left Handed ◽  
Magnetic Zenith

Abstract. The response of ionospheric plasma to pumping by powerful HF (high frequency) electromagnetic waves transmitted from the ground into the ionosphere is the strongest in the direction of geomagnetic zenith. We present experimental results from transmitting a left-handed circularly polarized HF beam from the EISCAT (European Incoherent SCATter association) Heating facility in magnetic zenith. The CASSIOPE (CAScade, Smallsat and IOnospheric Polar Explorer) spacecraft in the topside ionosphere above the F-region density peak detected transionospheric pump radiation, although the pump frequency was below the maximum ionospheric plasma frequency. The pump wave is deduced to arrive at CASSIOPE through L-mode propagation and associated double (O to Z, Z to O) conversion in pump-induced radio windows. L-mode propagation allows the pump wave to reach higher plasma densities and higher ionospheric altitudes than O-mode propagation so that a pump wave in the L-mode can facilitate excitation of upper hybrid phenomena localized in density depletions in a larger altitude range. L-mode propagation is therefore suggested to be important in explaining the magnetic zenith effect. Keywords. Space plasma physics (active perturbation experiments)

scholarly journals A Global Empirical Model of Electron Density Profile in the F Region Ionosphere Basing on COSMIC Measurements

Space Weather ◽  
2021 ◽  
Author(s):  
Qiaoling Li ◽  
Libo Liu ◽  
Maosheng He ◽  
He Huang ◽  
Jiahao Zhong ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Profile ◽  
Empirical Model ◽  
Electron Density Profile ◽  
F Region

scholarly journals <i>Letter to the Editor</i>: First direct observations of the reduced striations at pump frequencies close to the electron gyroharmonics

1999 ◽  
Vol 17 (9) ◽  
pp. 1235-1238 ◽  
Author(s):  
F. Honary ◽  
T. R. Robinson ◽  
D. M. Wright ◽  
A. J. Stocker ◽  
M. T. Rietveld ◽  
...  
Keyword(s):  
Large Scale ◽  
Electromagnetic Emission ◽  
Theoretical Models ◽  
Small Scale ◽  
Radio Waves ◽  
Radio Science ◽  
Ionospheric Physics ◽  
F Region ◽  
Direct Observations ◽  
Electron Gyrofrequency

Abstract. It is well known that the ionospheric plasma response to high-power HF radio waves changes drastically as the heater frequency approaches harmonics of the electron gyrofrequency. These include changes in the spectrum of the stimulated electromagnetic emission, reduction in the anomalous absorption of low-power diagnostic waves propagating through the heated volume, and reduction in the large scale F-region heating. Theoretical models as well as previous experimental evidence point towards the absence of small-scale field-aligned plasma density irregularities at pump frequencies close to electron gyroharmonics as the main cause of these changes. Results presented in this paper are the first direct observations of the reduced striations at the 3rd gyroharmonic made by the CUTLASS radar. In addition, simultaneous EISCAT observations have revealed that the "enhanced ion-line" usually present in the EISCAT ion-line spectrum during the first few seconds after heater switch on, persisted at varying strengths while the heater was transmitting at frequencies close to the 3rd electron gyroharmonics.Key words. Ionosphere (active experiments; ionospheric irregularities) · Radio science (ionospheric physics)

SATELLITE STUDIES OF ISOLATED IONOSPHERIC IRREGULARITIES

1965 ◽  
Vol 43 (5) ◽  
pp. 800-817 ◽  
Author(s):  
R. M. Turnbull ◽  
P. A. Forsyth
Keyword(s):  
Density Profile ◽  
Relative Phase ◽  
Electron Density Profile ◽  
Ionospheric Irregularities ◽  
Three Dimensions ◽  
Artificial Satellites ◽  
Radio Waves ◽  
Physical Description ◽  
Additional Information ◽  
Radio Signals

Ground-based observations of the radio signals propagated through the ionosphere from artificial satellites provide useful information about ionospheric irregularities. The technique has been extended to include recordings of the relative phase of the radio waves received at two stations as well as the customary amplitude recordings. This additional information is useful in interpreting the records. In particular, when relatively isolated single irregularities occur, a rather complete physical description can be derived including the location of each irregularity in three dimensions and a quantitative electron-density profile for the irregularity.

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