scholarly journals Intermediate downshifted maximum of stimulated electromagnetic emission at high-power HF heating: A new twist on an old problem

2015 ◽  
Vol 120 (1) ◽  
pp. 666-674 ◽  
Author(s):  
S. M. Grach ◽  
E. N. Sergeev ◽  
E. V. Mishin ◽  
A. V. Shindin ◽  
M. McCarrick
Keyword(s):  
High Power ◽  
Electromagnetic Emission ◽  
Downshifted Maximum ◽  
Stimulated Electromagnetic Emission ◽  
Hf Heating

scholarly journals Stimulated electromagnetic emission polarization under different polarizations of pump waves

2015 ◽  
Vol 33 (3) ◽  
pp. 295-300 ◽  
Author(s):  
E. D. Tereshchenko ◽  
R. Y. Yurik ◽  
L. Baddeley
Keyword(s):  
Pump Wave ◽  
Electromagnetic Emission ◽  
Space Plasma ◽  
Wave Polarization ◽  
Generation Efficiency ◽  
Heating Facility ◽  
Polar Geophysical Institute ◽  
Downshifted Maximum ◽  
Stimulated Electromagnetic Emission ◽  
Pump Waves

Abstract. The results of investigations into the stimulated electromagnetic emission (SEE) polarization under different modes of the pump wave polarization are presented. The present results were obtained in November 2012 during a heating campaign utilizing the SPEAR (Space Plasma Exploration by Active Radar) heating facility, transmitting in both O- and X-mode polarization, and a PGI (Polar Geophysical Institute) radio interferometer capable of recording the polarization of the received radiation. The polarization ellipse parameters of the SEE DM (downshifted maximum) components were determined under both O-mode and X-mode polarization of the pump waves. The polarization direction of the SEE DM component was preserved under different polarizations of the pump waves. Different polarizations of the pump waves have a different SEE generation efficiency. The intensity of the DM component is observed to be greater during O-mode pumping. In addition, the numbers of observed SEE features are also greater during O-mode pumping.

Downshifted maximum features in stimulated electromagnetic emission spectra

1994 ◽  
Vol 99 (A10) ◽  
pp. 19555 ◽  
Author(s):  
T. B. Leyser ◽  
B. Thidé ◽  
M. Waldenvik ◽  
E. Veszelei ◽  
V. L. Frolov ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Electromagnetic Emission ◽  
Downshifted Maximum ◽  
Stimulated Electromagnetic Emission

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.

Dependence of stimulated electromagnetic emission on the ionosphere and pump wave

1990 ◽  
Vol 95 (A10) ◽  
pp. 17233 ◽  
Author(s):  
T. B. Leyser ◽  
B. Thidé ◽  
H. Derblom ◽  
Å. Hedberg ◽  
B. Lundborg ◽  
...  
Keyword(s):  
Pump Wave ◽  
Electromagnetic Emission ◽  
Stimulated Electromagnetic Emission

scholarly journals An interferometer experiment to explore the aspect angle dependence of stimulated electromagnetic emission spectra

2005 ◽  
Vol 23 (1) ◽  
pp. 55-74 ◽  
Author(s):  
◽  
Yu. Yurik ◽  
La Hoz ◽  
◽  
◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Electromagnetic Emission ◽  
Density Fluctuations ◽  
Spectral Features ◽  
Langmuir Turbulence ◽  
Angular Structure ◽  
Frequency Spectra ◽  
Aspect Angle ◽  
Angle Dependence ◽  
Stimulated Electromagnetic Emission

Abstract. When the Earth's ionosphere is irradiated by a radiofrequency (RF) electromagnetic wave of sufficiently high power density and tuned to match a natural E- or F-region plasma frequency, ionospheric magnetoionic wave modes may be excited and may generate RF electromagnetic sideband waves via nonlinear interactions. These secondary emissions, which may then escape from the ionosphere, have been termed stimulated electromagnetic emission or SEE. The frequency spectra of this radiation has been studied extensively, and a number of characteristic spectral features have been identified and in some cases related to particular plasma processes. The separation in frequency between the RF pump and the harmonics of the local electron gyrofrequency is critical in determining the amount of anomalous absorption suffered by the pump wave and the spectral properties of the stimulated sidebands. The pump can excite electrostatic waves which do not propagate away but can in some cases be observed via radio-wave scattering from the electron density fluctuations associated with them. These enhanced density fluctuations are created by processes commonly referred to as upper-hybrid and Langmuir turbulence. Langmuir turbulence has been the subject of 930-MHz scattering observations with antenna scanning through several pre-selected angles between the geographic and geomagnetic zenith directions, and a preference for pointing angles between the Spitze angle and geomagnetic field-aligned was identified. Other phenomena, such as the generation of enhanced electron temperatures and artificial aurora, have more recently been shown to have special behavior at similar angles, near but apparently not quite at field-aligned. In view of this evidence for angular structure in several pump-induced effects, in light of the rich variety of SEE phenomena strongly dependent on the geomagnetic field via the frequency interval between the pump and the gyrofrequency harmonics, and in view of the not yet understood but complex relationship between electrostatic fluctuations and SEE, it is of interest to investigate experimentally whether a similar angular structure is present in the various spectral features of the SEE signals and to compare the results with radar and other observations of RF-pump-induced effects. To this end we describe a simple two-element radio interferometer designed to search for aspect angle dependence of SEE features. We present an example of the initial data produced by this system, and draw preliminary conclusions based on the example data.

scholarly journals A coupled ionosphere-raytrace model for high-power HF heating

2015 ◽  
Vol 42 (22) ◽  
pp. 9650-9656 ◽  
Author(s):  
K. A. Zawdie ◽  
J. D. Huba ◽  
D. P. Drob ◽  
P. A. Bernhardt
Keyword(s):  
High Power ◽  
Hf Heating

scholarly journals A new upshifted spectral stimulated electromagnetic emission structure, observed between electron cyclotron harmonics

1997 ◽  
Vol 24 (13) ◽  
pp. 1647-1650 ◽  
Author(s):  
V. L. Frolov ◽  
E. N. Ermakova ◽  
L. M. Erukhimov ◽  
G. P. Komrakov ◽  
E. N. Sergeev ◽  
...  
Keyword(s):  
Electromagnetic Emission ◽  
Electron Cyclotron ◽  
Cyclotron Harmonics ◽  
Stimulated Electromagnetic Emission
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