scholarly journals Enhanced ion acoustic fluctuations and ion outflows

1999 ◽  
Vol 17 (2) ◽  
pp. 182-189 ◽  
Author(s):  
F. R. E. Forme ◽  
D. Fontaine
Keyword(s):  
Electron Temperature ◽  
Temperature Gradients ◽  
Spectral Signature ◽  
Simultaneous Occurrence ◽  
Plasma Parameters ◽  
Strong Electron ◽  
Ion Drift ◽  
Incoherent Scatter ◽  
Ion Acoustic ◽  
Electron Temperature Gradients

Abstract. A number of observations showing enhanced ion acoustic echoes observed by means of incoherent scatter radars have been reported in the literature. The received power is extremely enhanced by up to 1 or 2 orders of magnitude above usual values, and it is mostly contained in one of the two ion acoustic lines. This spectral asymmetry and the intensity of the received signal cannot be resolved by the standard analysis procedure and often causes its failure. As a result, and in spite of a very clear spectral signature, the analysis is unable to fit the plasma parameters inside the regions of ion acoustic turbulence. We present European Incoherent Scatter radar (EISCAT) observations of large ion outflows associated with the simultaneous occurrence of enhanced ion acoustic echoes. The ion fluxes can reach 1014 m-2 s-1 at 800 km altitude. From the very clear spectral signatures of these echoes, a method is presented to extract estimates of the electron temperature and the ion drift within the turbulent regions. It is shown that the electron gas is strongly heated up to 11 000 K. Also electron temperature gradients of about 0.02 K/m exist. Finally, the estimates of the electron temperature and of the ion drift are used to study the possible implications for the plasma transport inside turbulent regions. It is shown that strong electron temperature gradients cause enhancement of the ambipolar electric field and can account for the observed ion outflows.Key words. Ionosphere (auroral ionosphere; ionosphere · magnetosphere interactions; plasma waves and instabilities).

scholarly journals The Chemical Features of Galactic Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 575-575
Author(s):  
P. R. Amnuel
Keyword(s):  
Chemical Composition ◽  
Electron Temperature ◽  
Planetary Nebulae ◽  
Temperature Gradients ◽  
Element Abundances ◽  
Electron Temperature Gradients ◽  
The Masses ◽  
Progenitor Stars

The chemical composition of 218 galactic planatary nebulae is investigated, all the nebulae are divided into four classes according to the masses of the nebulae and progenitor stars. The values of local abundances, galactic abundances and electron temperature gradients are found for each class of nebulae. The correlations between element abundances are also investigated. The results are compared with theorical predictions.

scholarly journals First EISCAT measurement of electron-gas temperature in the artificially heated D-region ionosphere

2000 ◽  
Vol 18 (9) ◽  
pp. 1210-1215 ◽  
Author(s):  
A. Kero ◽  
T. Bösinger ◽  
P. Pollari ◽  
E. Turunen ◽  
M. Rietveld
Keyword(s):  
Electron Temperature ◽  
Electron Gas ◽  
Density Wave ◽  
Integration Time ◽  
Maximum Effect ◽  
Gas Temperature ◽  
Plasma Parameters ◽  
Vhf Radar ◽  
Incoherent Scatter ◽  
D Region

Abstract. The ionospheric electron gas can be heated artificially by a powerful radio wave. According to our modeling, the maximum effect of this heating occurs in the D-region where the electron temperature can increase by a factor of ten. Ionospheric plasma parameters such as Ne, Te and Ti are measured by EISCAT incoherent scatter radar on a routine basis. However, in the D-region the incoherent scatter echo is very weak because of the low electron density. Moreover, the incoherent scatter spectrum from the D-region is of Lorentzian shape which gives less information than the spectrum from the E- and F-regions. These make EISCAT measurements in the D-region difficult. A combined EISCAT VHF-radar and heating experiment was carried out in November 1998 with the aim to measure the electron temperature increase due to heating. In the experiment the heater was switched on/off at 5 minute intervals and the integration time of the radar was chosen synchronously with the heating cycle. A systematic difference in the measured autocorrelation functions was found between heated and unheated periods.Key words: Ionosphere (active experiments; plasma temperature and density; wave propagation)

Bayesian filtering for incoherent scatter radar analysis

2020 ◽  
Author(s):  
Habtamu Tesfaw ◽  
Ilkka Virtanen ◽  
Anita Aikio ◽  
Lassi Roininen ◽  
Sari Lasanen
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Time Resolution ◽  
Plasma Parameter ◽  
Temperature Profiles ◽  
Bayesian Filtering ◽  
Ion Composition ◽  
Ion Temperature ◽  
Plasma Parameters ◽  
Incoherent Scatter

<p>Electron precipitation and ion frictional heating events cause rapid variations in electron temperature, ion temperature and F1 region ion composition of the high-latitude ionosphere. Four plasma parameters: electron density, electron temperature, ion temperature, and plasma bulk velocity, are typically fitted to incoherent scatter radar (ISR) data.</p><p>Many ISR data analysis tools extract the plasma parameters using an ion composition profile from an empirical model. The modeled ion composition profile may cause bias in the estimated ion and electron temperature profiles in the F1 region, where both atomic and molecular ions exist with a temporally varying proportion.</p><p>In addition, plasma parameter estimation from ISR measurements requires integrating the scattered signal typically for tens of seconds. As a result, the standard ISR observations have not been able to follow the rapid variations in plasma parameters caused by small scale auroral activity.</p><p>In this project, we implemented Bayesian filtering technique to the EISCAT’s standard ISR data analysis package, GUISDAP. The technique allows us to control plasma parameter gradients in altitude and time.</p><p>The Bayesian filtering implementation enabled us to fit electron density, ion and electron temperatures, ion velocity and ion composition to ISR data with high time resolution. The fitted ion composition removes observed artifacts in ion and electron temperature estimates and the plasma parameters are calculated with 5 s time resolution which was previously unattainable.</p><p>Energy spectra of precipitating electrons can be calculated from electron density and electron temperature profiles observed with ISR. We used the unbiased high time-resolved electron density and temperature estimates to improve the accuracy of the estimated energy spectra. The result shows a significant difference compared to previously published results, which were based on the raw electron density (backscattered power) and electron temperature estimates calculated with coarser time resolution.</p><p> </p>

scholarly journals Electron temperatures during rapid subauroral ion drift events

1998 ◽  
Vol 16 (4) ◽  
pp. 450-459 ◽  
Author(s):  
R. J. Moffett ◽  
A. E. Ennis ◽  
G. J. Bailey ◽  
R. A. Heelis ◽  
L. H. Brace
Keyword(s):  
Electron Temperature ◽  
Vibrational Excitation ◽  
Molecular Nitrogen ◽  
Electron Gas ◽  
Topside Ionosphere ◽  
Ion Temperature ◽  
Plasma Parameters ◽  
Ion Drift ◽  
Ionosphere Model ◽  
Subauroral Ion Drift

Abstract. Examples of data from DE-2 satellite instruments are presented. These illustrate the behaviour of plasma parameters in the F-region and adjacent topside ionosphere during rapid sub-auroral ion drift (SAID) events. In particular, a variety of behaviours of the electron temperature (Te) is demonstrated, both within and equatorward of the SAID region. The Sheffield University plasmasphere-ionosphere model (SUPIM) is used to perform calculations in which a model SAID is applied to a plasma flux tube. The model results indicate that strongly elevated ion temperature (a recognised signature of SAID events) is on occasion sufficient to raise Te to observed values by ion-electron heat transfer. On other occasions, an additional heat source is required. It is suggested that such a source for the electron gas may be due to interaction between the ring current and the plasmasphere at high altitudes. The magnitude of the downward heat flux is consistent with that necessary to produce sub-auroral red arcs. The resulting strongly heated electron gas causes vibrational excitation of molecular nitrogen in the thermosphere. Key words. Electron temperature · Subauroral ion drift · Plasmasphere-ionosphere SUPIM

Measurement of Plasma Parameters of Fe-Lines in Lipstick Using Laser-Induced Breakdown Spectroscopy

2021 ◽  
Vol 19 (10) ◽  
pp. 01-07
Author(s):  
M.H. Asmaa ◽  
Sami A. Habana
Keyword(s):  
Electron Temperature ◽  
Debye Length ◽  
Nuclear Data ◽  
Laser Induced Breakdown Spectroscopy ◽  
Current Investigation ◽  
Plasma Parameters ◽  
Data Set ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Business Sectors

Electron thickness and temperature of laser prompted Iron plasma boundaries, among different boundaries, were estimated. Plasma was delivered through the connection of high pinnacle power Nd: YAG laser at the key frequency of 1064 nm with a pellet target contains a limited quantity of lipstick from nearby business sectors. Lines from Fe II at 238.502 nm, Fe II at 254.904 nm, Fe II at 262.370 nm, Fe II at 286.545 nm and Fe I at 349.779 nm were utilized to assess the plasma boundaries. The current investigation was completed to assess electron temperature (Te), electron thickness (ne), plasma recurrence, Debye length and Debye number (ND). Laser-incited breakdown spectroscopy LIBS method was used for examining and deciding ghastly discharge lines. ID of change lines from all spectra was completed by contrasting ghostly lines and NIST nuclear data set.

scholarly journals Ionospheric anomalies associated with the Haiti earthquake of 12 January 2010 observed by DEMETER satellite

2012 ◽  
Vol 12 (3) ◽  
pp. 671-678 ◽  
Author(s):  
S. Sarkar ◽  
S. Choudhary ◽  
A. Sonakia ◽  
A. Vishwakarma ◽  
A. K. Gwal
Keyword(s):  
Electron Temperature ◽  
Satellite Data ◽  
Strong Earthquake ◽  
Plasma Parameter ◽  
Statistical Processing ◽  
Haiti Earthquake ◽  
Plasma Parameters ◽  
Demeter Satellite ◽  
Parameter Variations ◽  
Precursory Phenomena

Abstract. This paper examines the ionospheric anomalies around the time of a strong earthquake (M = 7.0) which occurred in Haiti region (18.457° N, 72.533° W) on 12 January 2010. DEMETER satellite data have been used to study the plasma parameters variation during the Haiti earthquake. One day (11 January 2010) before the earthquake there is a significant enhancement of electron density and electron temperature near the epicenter. Decrease of electron temperature is observed few days after the earthquake. Anomalous plasma parameter variations are detected both in day and nighttimes before the quake. Statistical processing of the DEMETER data demonstrates that satellite data can play an important role for the study of precursory phenomena associated with earthquakes.

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.

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