Ionospheric heating in the F -region

1964 ◽  
Vol 281 (1384) ◽  
pp. 140-149 ◽  
Keyword(s):  
Electron Temperature ◽  
Energy Input ◽  
Particle Flux ◽  
Electron Interaction ◽  
Ion Temperature ◽  
Ionospheric Heating ◽  
F Region ◽  
Field Lines ◽  
Photo Ionization ◽  
Made In

Measurements of electron temperature made in Ariel I have been analyzed to calculate the ionospheric energy input required to maintain the electron temperature above the ion temperature. The results are found to be consistent with the energy input due to photo-ionization in the daytime, provided that allowance is made for the effects of the escaping flux of photoelectrons spiralling upwards along the geomagnetic field lines which impartenergy to the ionosphere by electron-electron interaction. However, it is found that during the night an energy input of particle origin is observed, a close agreement being found between the distribution of energy input and that of the fluxes of low-energy particles observed by Savenko, Shavrin & Pisavenko 1963. The particle flux contributes less than 30% to the heat input in the daytime and its diurnal variation is small.

scholarly journals Velocity shear and current driven instability in a collisional F-region

2009 ◽  
Vol 27 (1) ◽  
pp. 381-394 ◽  
Author(s):  
P. J. G. Perron ◽  
J.-M. A. Noël ◽  
J.-P. St.-Maurice
Keyword(s):  
Dispersion Relation ◽  
Electron Temperature ◽  
Current Density ◽  
Threshold Current ◽  
Velocity Shear ◽  
Ion Temperature ◽  
Fluid Limit ◽  
Low Frequencies ◽  
F Region ◽  
Threshold Conditions

Abstract. We have studied how the presence of collisions affects the behavior of instabilities triggered by a combination of shears and parallel currents in the ionosphere under a variety of ion to electron temperature ratios. To this goal we have numerically solved a kinetic dispersion relation, using a relaxation model to describe the effects of ion and electron collisions. We have compared our solutions to expressions derived in a fluid limit which applied only to large electron to ion temperature ratios. We have limited our study to threshold conditions for the current density and the shears. We have studied how the threshold varies as a function of the wave-vector angle direction and as a function of frequency. As expected, we have found that for low frequencies and/or elevated ion to electron temperature ratios, the kinetic dispersion relation has to be used to evaluate the threshold conditions. We have also found that ion velocity shears can significantly lower the field-aligned threshold current needed to trigger the instability, especially for wave-vectors close to the perpendicular to the magnetic field. However the current density and shear requirements remain significantly higher than if collisions are neglected. Therefore, for ionospheric F-region applications, the effect of collisions should be included in the calculation of instabilities associated with horizontal shears in the vertical flow. Furthermore, in many situations of interest the kinetic solutions should be used instead of the fluid limit, in spite of the fact that the latter can be shown to produce qualitatively valid solutions.

scholarly journals Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

2017 ◽  
Vol 3 (2) ◽  
pp. 51-53
Author(s):  
Артем Гололобов ◽  
Artem Gololobov ◽  
Иннокентий Голиков ◽  
Innokentiy Golikov ◽  
Илья Варламов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Heat Fluxes ◽  
Winter Period ◽  
Time Interval ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Condi Tions ◽  
Field Lines ◽  
Heat Inflow

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances.

scholarly journals On the usefulness of <i>E</i> region electron temperatures and lower <i>F</i> region ion temperatures for the extraction of thermospheric parameters: a case study

1999 ◽  
Vol 17 (9) ◽  
pp. 1182-1198 ◽  
Author(s):  
J.-P. St.-Maurice ◽  
C. Cussenot ◽  
W. Kofman
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Plasma Temperature ◽  
Ion Temperature ◽  
Heating Rates ◽  
Neutral Winds ◽  
F Region ◽  
E Region ◽  
Effective Electric Field ◽  
Temperature Observations

Abstract. Using EISCAT data, we have studied the behavior of the E region electron temperature and of the lower F region ion temperature during a period that was particularly active geomagnetically. We have found that the E region electron temperatures responded quite predictably to the effective electric field. For this reason, the E region electron temperature correlated well with the lower F region ion temperature. However, there were several instances during the period under study when the magnitude of the E region electron temperature response was much larger than expected from the ion temperature observations at higher altitudes. We discovered that these instances were related to very strong neutral winds in the 110-175 km altitude region. In one instance that was scrutinized in detail using E region ion drift measurement in conjunction with the temperature observations, we uncovered that, as suspected, the wind was moving in a direction closely matching that of the ions, strongly suggesting that ion drag was at work. In this particular instance the wind reached a magnitude of the order of 350 m/s at 115 km and of at least 750 m/s at 160 km altitude. Curiously enough, there was no indication of strong upper F region neutral winds at the time; this might have been because the event was uncovered around noon, at a time when, in the F region, the E×B drift was strongly westward but the pressure gradients strongly northward in the F region. Our study indicates that both the lower F region ion temperatures and the E region electron temperatures can be used to extract useful geophysical parameters such as the neutral density (through a determination of ion-neutral collision frequencies) and Joule heating rates (through the direct connection that we have confirmed exists between temperatures and the effective electric field).Key words. Ionosphere (auroral ionosphere; ionosphere atmosphere interactions; plasma temperature and density)

scholarly journals Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

2017 ◽  
Vol 3 (2) ◽  
pp. 54-57
Author(s):  
Артем Гололобов ◽  
Artem Gololobov ◽  
Иннокентий Голиков ◽  
Innokentiy Golikov ◽  
Илья Варламов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Heat Fluxes ◽  
Winter Period ◽  
Time Interval ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Condi Tions ◽  
Field Lines ◽  
Heat Inflow

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances.

scholarly journals Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

2002 ◽  
Vol 20 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
R. Sridharan ◽  
C. V. Devasia ◽  
N. Jyoti ◽  
Diwakar Tiwari ◽  
K. S. Viswanathan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Solar Eclipse ◽  
Equatorial Ionosphere ◽  
Hf Radar ◽  
F Region ◽  
Large Enhancement ◽  
Temporal Structures ◽  
E Region ◽  
Field Lines ◽  
Electric Fields And Currents

Abstract. The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i) the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii) significant increase in h' F immediately following the eclipse and (iii) distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities)

scholarly journals Variation in altitude of high-frequency enhanced plasma line by the pump near the 5th electron gyro-harmonic

2019 ◽  
Author(s):  
Jun Wu ◽  
Jian Wu ◽  
Michael T. Rietveld ◽  
Ingemar Haggstrom ◽  
Haisheng Zhao ◽  
...  
Keyword(s):  
Electron Temperature ◽  
High Frequency ◽  
Langmuir Wave ◽  
Decisive Role ◽  
Bragg Condition ◽  
Pump Frequency ◽  
Ionospheric Heating ◽  
Lower Altitude ◽  
Incoherent Scatter ◽  
Plasma Line

Abstract. During an ionospheric heating campaign carried out at the European Incoherent Scatter Scientific Association (EISCAT), the ultra high frequency incoherent scatter (IS) radar observed a systematic variation in the altitude of the high-frequency enhanced plasma line (HFPL), which behaves depending on the pump frequency. Specifically, the HFPL altitude becomes lower when the pump lies above the 5th gyro-harmonic. The analysis shows that the enhanced electron temperature plays a decisive role in the descent in the HFPL altitude. That is, on the traveling path of the enhanced Langmuir wave, the enhanced electron temperature can only be matched by the low electron density at a lower altitude so that the Bragg condition can be satisfied, as expected from the dispersion relation of Langmuir wave.

scholarly journals Two-temperature magnetohydrodynamic simulations for sub-relativistic active galactic nucleus jets: dependence on the fraction of the electron heating

2020 ◽  
Vol 493 (4) ◽  
pp. 5761-5772 ◽  
Author(s):  
Takumi Ohmura ◽  
Mami Machida ◽  
Kenji Nakamura ◽  
Yuki Kudoh ◽  
Ryoji Matsumoto
Keyword(s):  
Electron Temperature ◽  
X Rays ◽  
Ion Temperature ◽  
Temperature Plasma ◽  
Electron Heating ◽  
Coulomb Collisions ◽  
X Ray ◽  
Jet Plasma ◽  
Magnetohydrodynamic Simulations ◽  
Two Temperature

ABSTRACT We present the results of two-temperature magnetohydrodynamic simulations of the propagation of sub-relativistic jets of active galactic nuclei. The dependence of the electron and ion temperature distributions on the fraction of electron heating, fe, at the shock front is studied for fe = 0, 0.05, and 0.2. Numerical results indicate that in sub-relativistic, rarefied jets, the jet plasma crossing the terminal shock forms a hot, two-temperature plasma in which the ion temperature is higher than the electron temperature. The two-temperature plasma expands and forms a backflow referred to as a cocoon, in which the ion temperature remains higher than the electron temperature for longer than 100 Myr. Electrons in the cocoon are continuously heated by ions through Coulomb collisions, and the electron temperature thus remains at Te &gt; 109 K in the cocoon. X-ray emissions from the cocoon are weak because the electron number density is low. Meanwhile, X-rays are emitted from the shocked intracluster medium (ICM) surrounding the cocoon. Mixing of the jet plasma and the shocked ICM through the Kelvin–Helmholtz instability at the interface enhances X-ray emissions around the contact discontinuity between the cocoon and shocked ICM.

scholarly journals Review of progress in gathering, distributing and using satellite data for activities within COST 238 (PRIME)

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
I. Kutiev ◽  
S. Stankov
Keyword(s):  
Satellite Data ◽  
Satellite Orbit ◽  
Testing Procedure ◽  
Satellite Orbits ◽  
Neutral Atmosphere ◽  
Recombination Rates ◽  
F Region ◽  
Field Lines ◽  
The Given ◽  
To Receive

Recent progress in using the satellite data for various PRIME purposes is briefly presented. The satellite data base is already in operation and contains data of local plasma and neutral atmosphere parameters taken from several ionospheric satellites. A method of tracing the locally measured parameters along the magnetic field lines down to hmF2 is developed using a theoretical F-region code. This method is applied to receive f0F2sat needed to test monthly median and instantaneous mapping methods. In order to reduce the uncertainties arising from the unknown photoionization and recombination rates, f0F2 is calibrated at one point on the satellite orbit with a Vertical Incident (VI) f0F2 and their ratio is then assumed constant along the whole satellite track over the PRIME area. The testing procedure for monthly median maps traces the measured plasma density down to a basic height of 400 km, where individual f0F2sat values are accumulated in every time/subarea bin within the given month, then their median is calibrated with the available medians from the VI ionosonde network. From all available satellite orbits over the PRIME area, 35 of them were found to pass over two VI ionosonde stations. The second station in these orbits was used to check the calculated f0F2sat with the measured VI f0F2. The standard deviation was found to be only 0.15 MHz.

scholarly journals Kinetic infernal modes for Wendelstein 7-X-like -profiles

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Alessandro Zocco ◽  
Alexey Mishchenko ◽  
Axel Könies
Keyword(s):  
Electron Temperature ◽  
High Performance ◽  
Ion Temperature ◽  
Electron Temperature Gradient ◽  
Average Value ◽  
Toroidal Plasma ◽  
Rotational Transform ◽  
Ideal Magnetohydrodynamic ◽  
The One ◽  
Sawtooth Oscillations

We show analytically that for $\unicode[STIX]{x1D704}$ -profiles similar to the one of the Wendelstein 7-X stellarator, where $\unicode[STIX]{x1D704}$ is the rotational transform of the equilibrium magnetic field, a highly conducting toroidal plasma is unstable to kinetically mediated pressure-driven long-wavelength reconnecting modes, of the infernal type. The modes are destabilized either by the electron temperature gradient or by a small amount of current, depending on how far from unity the average value of $\unicode[STIX]{x1D704}$ is, which is assumed to be slowly varying. We argue that, for W7-X, a broad mode with toroidal and poloidal mode numbers $(n,m)=(1,1)$ can be destabilized due to the strong geometric side-band coupling of the resonant kinetic electron response at locations where $\unicode[STIX]{x1D704}$ is rational for harmonics that belong to the mode family of the $(n,m)=(1,1)$ mode itself. In many regimes, the growth rate is insensitive to the plasma density, thus it is likely to persist in high performance W7-X discharges. For a peaked electron temperature, with a maximum of $T_{e}=5~\text{keV}$ , larger than the ion temperature, $T_{i}=2.5~\text{keV}$ , and a density $n_{0}=10^{19}~\text{m}^{-3}$ , instability is found in regimes which show plasma sawtooth activity, with growth rates of the order of tens of kiloHertz. Frequencies are either electron diamagnetic or of the ideal magnetohydrodynamic type, but sub-Alfvénic. The kinetic infernal mode is thus a good candidate for the explanation of sawtooth oscillations in present-day stellarators and poses a new challenge to the problem of stellarator reactor optimization.

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