Thermal electron energy distribution measurements in the ionosphere

Hays, P. B.; Nagy, Andrew F.

doi:10.1016/0032-0633(73)90222-5

Cited by 16 publications

(6 citation statements)

References 29 publications

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“…Finally, the electron temperatures that are deduced in energy intervals less than 1.5 V agree with temperatures deduced from Langmuir probes [Hays and Nagy, 1973]. We thus believe that the instrument is understood and hence that the discrepancy between experimentally deduced loss functions and theory is probably due to theoretical rather than in- 1.…”

supporting

confidence: 74%

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Low-energy auroral electrons

Sharp¹,

Hays²

1974

J. Geophys. Res

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A measurement of the low‐energy auroral electron flux distribution between 0.5 and 80 eV reveals structure between 0.5 and 10.0 eV. The structure is due to the thermal electron Maxwellian distribution and electron energy loss to thermal electrons, molecular nitrogen, and atomic oxygen. Some physical process in the auroral plasma causes the deduced loss function to differ from theory. Reasonable agreement is obtained between calculated and measured N2 second positive emission.

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supporting

confidence: 74%

“…A hyperbolic electrostatic analyzer (Harp) is used as the electron spectrometer. The theory of this instrument and its placement in the pay load are described elsewhere [Hays and Sharp, 1973]. For this flight the Harp was not configured to sample pitch angles.…”

mentioning

confidence: 99%

Low-energy auroral electrons

Sharp¹,

Hays²

1974

J. Geophys. Res

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“…me experimental evidence for the validity of this assumption; the data shown in Figure 1 indicate that a single M axwellian distribution can be used to fit the data from 1-2k Te out to over 2 eV [Hays and Nagy, 1973]. Following the bulk of the literature, we will use this artificial division between thermal electrons and photoelectrons in this paper, although the separation between the regions is not a simple matter [Krinberg, 1973;Hays and Nagy, 1973;Ashihara and Takayanagi, 1973].In section B we will present our present-day understanding of the theory of F region electron temperature, while in section C we attempt to provide a representative cross section of electron temperature measurements. In section D we discuss the quality of agreement between theoretical predictions and observations and outline the areas where further work is necessary for a complete, comprehensive understanding of the thermal structure of the F region.…”

mentioning

confidence: 93%

Electron temperatures in the F region of the ionosphere: Theory and observations

Schunk¹,

Nagy²

1978

Reviews of Geophysics

443

339

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The theory and observations relating to electron temperatures in the F region of the ionosphere are reviewed. The review is divided into three basic parts. In the first part the theory concerning electron heating, cooling, and energy transport processes is reviewed, and all the relevant expressions are updated. In the second part the behavior of F region electron temperatures, as measured by satellites, rockets, and incoherent scatter radars, is discussed. This portion covers electron temperature variations with altitude, latitude, local time, season, geomagnetic activity, and solar cycle. The third part is primarily devoted to a discussion of the various attempts to compare measured and calculated F region electron temperatures.

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“…This measurement is extremely difficult because the negative spacecraft potentials typically observed in these regions are significant in magnitude compared to the low energies of the targeted electron distribution. As early as the 1960s, Hays and Sharp developed an instrument to measure the coldest electrons in the F region and below [ Sharp and Hays , 1974; Hays and Nagy , 1973]. However, early measurements lacked sufficient time and energy resolution for determining the distribution function of the thermal electrons.…”

Section: Introductionmentioning

confidence: 99%

In situ measurement of thermal electrons on the SIERRA nightside auroral sounding rocket

et al. 2006

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[1] In January 2002 the SIERRA sounding rocket was launched from Alaska into active substorm expansion aurora. Direct measurements of the cold ionospheric population in darkness were made by the Thermal Electron Detector (TED), which was designed to measure thermal electrons that can carry auroral currents coupling the lower ionosphere and the magnetosphere. Measurement of thermal electrons must be accompanied by a careful study of electrostatic potentials forming near conducting bodies in a plasma. The TED instrument measurements show that a nonmonotonic potential barrier can form in the sheath around the attractively biased detector and prevent measurements of the core of the thermal electrons. The TED instrument design and response are discussed along with the current balance conditions which can lead to the formation of a potential barrier. A plasma distribution reconstruction technique enables key measurements of temperature, density, spacecraft potential, and an estimate of field-aligned current flow. Observed thermal electron core temperatures vary greatly, from $0.1 eV in the polar cap to $0.8 eV in auroral arcs. Outside active precipitation, the electron density agrees with an independent calculation based on measurements from the high-frequency (HF) wave receiver, verifying the method used for estimating the spacecraft potential. In the auroral regions the HF measurement of electron plasma density must be used to extract more accurate results for the spacecraft potential. The thermal electron data indicate that in the dark the nonnegligible auroral and secondary emission currents must be accounted for in order to understand the spacecraft potential and its impact on thermal electron measurements.

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Thermal electron energy distribution measurements in the ionosphere

Cited by 16 publications

References 29 publications

Low-energy auroral electrons

Low-energy auroral electrons

Electron temperatures in the F region of the ionosphere: Theory and observations

In situ measurement of thermal electrons on the SIERRA nightside auroral sounding rocket

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