Mathematical structure of transport equations for multispecies flows

Schunk, R. W.

doi:10.1029/rg015i004p00429

Cited by 339 publications

(344 citation statements)

References 48 publications

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“…Blelly and Schunk, 1993, Figure 4d]. Of the two velocity correction terms for Coulomb collisions, ij goes to zero with increasing relative velocity much faster than ij [Schunk, 1977]. Thus, Coulomb collisions are ineffective at equalizing the ion temperatures when supersonic velocity differences exist, but frictional heating can still be important.…”

Section: 1002/2013ja019378mentioning

confidence: 99%

“…im , and D (4) im for Coulomb and Maxwell molecule collisions are given by Schunk [1977] and Schunk and Nagy [2009]. For the hard sphere-like treatment of resonant ion-neutral interactions, the corresponding numbers are…”

Section: 1002/2013ja019378mentioning

confidence: 99%

“…Instead, the model uses the expressions for these correction terms which come from the general five-moment collision terms for Coulomb collisions [see Schunk, 1977;Schunk and Nagy, 2009]. If the relative drift between ions i and j is small, these terms are both nearly unity, but if the relative drift becomes large compared to…”

Section: 1002/2013ja019378mentioning

confidence: 99%

“…Fluid theories are constructed by assuming the distribution functions have a particular form which is characterized by a small number of moments and then deriving equations for the evolution of these moments [e.g., Schunk, 1977]. Blelly and Schunk [1993] compared the four most commonly used fluid approximations in ionospheric physics for vertical open field lines.…”

Section: Model Descriptionmentioning

confidence: 99%

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Heating of the sunlit polar cap ionosphere by reflected photoelectrons

2014

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Photoelectrons escape from the ionosphere on sunlit polar cap field lines. In order for those field lines to carry zero current without significant heavy ion outflow or cold electron inflow, field-aligned potential drops must form to reflect a portion of the escaping photoelectron population back to the ionosphere. Using a 1-D ionosphere-polar wind model and measurements from the Resolute Bay Incoherent Scatter Radar (RISR-N), this paper shows that these reflected photoelectrons are a significant source of heat for the sunlit polar cap ionosphere. The model includes a kinetic suprathermal electron transport solver, and it allows energy input from the upper boundary in three different ways: thermal conduction, soft precipitation, and potentials that reflect photoelectrons. The simulations confirm that reflection potentials of several tens of eV are required to prevent cold electron inflow and demonstrate that the flux tube integrated change in electron heating rate (FTICEHR) associated with reflected photoelectrons can reach 10 9 eV cm −2 s −1 . Soft precipitation can produce FTICEHR of comparable magnitudes, but this extra heating is divided among more electrons as a result of electron impact ionization. Simulations with no reflected photoelectrons and with downward field-aligned currents (FAC) primarily carried by the escaping photoelectrons have electron temperatures which are ∼250-500 K lower than the RISR-N measurements in the 300-600 km region; however, simulations with reflected photoelectrons, zero FAC, and no other form of heat flux through the upper boundary can satisfactorily reproduce the RISR-N data.

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Section: 1002/2013ja019378mentioning

confidence: 99%

Section: 1002/2013ja019378mentioning

confidence: 99%

Section: 1002/2013ja019378mentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

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Heating of the sunlit polar cap ionosphere by reflected photoelectrons

2014

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“…The set of transport equations (continuity, momentum, energy and heat flow) corresponding to this approach is derived from Schunk (1977). It solves the temporal evolution of the concentration, the field-aligned velocity, and the temperature and the fieldaligned heat flow of each species.…”

Section: Physical Modelsmentioning

confidence: 99%

From the Sun’s atmosphere to the Earth’s atmosphere: an overview of scientific models available for space weather developments

et al. 2002

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Abstract. Space weather aims at setting operational numerical tools in order to nowcast, forecast and quantify the solar activity events, the magnetosphere, ionosphere and thermosphere responses and the consequences on our technological societies. These tools can be divided in two parts. The first has a geophysical base (Sun, interplanetary medium, magnetosphere, atmosphere). The second concerns technological applications (telecommunications, spacecraft orbits, power plants ...). In this paper, we aim at giving an overview of the models that belong to the first class (geophysics) that might serve in the future as a basis for building global operational codes. For each model, we consider the physics underneath, the input and output parameters, and whether it is already operational, whether it may become operational in the near future, or if it is an academic research tool. Relevant references are given in order to serve as a starting point for further readings.

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Auroral ionospheric F region density cavity formation and evolution: MICA campaign results

et al. 2014

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Scatter Radar) during the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) sounding rocket campaign are critically examined alongside complementary numerical simulations. Particular processes of interest include cavity formation due to intense frictional heating and Pedersen drifts, evolution in the presence of structured precipitation, and refilling due to impact ionization and downflows. Our analysis uses an ionospheric fluid model which solves conservation of mass, momentum, and energy equations for all major ionospheric species. These fluid equations are coupled to an electrostatic current continuity equation to self-consistently describe auroral electric fields. Energetic electron precipitation inputs for the model are specified by inverting optical data, and electric field boundary conditions are obtained from direct PFISR measurements. Thus, the model is driven in as realistic a manner as possible. Both incoherent scatter radar (ISR) data and simulations indicate that the conversion of the F region plasma to molecular ions and subsequent recombination is the dominant process contributing to the formation of the observed cavities, all of which occur in conjunction with electric fields exceeding ∼90 mV/m. Furthermore, the cavities often persist several minutes past the point when the frictional heating stops. Impact ionization and field-aligned plasma flows modulate the cavity depth in a significant way but are of secondary importance to the molecular generation process. Informal comparisons of the ISR density and temperature fits to the model verify that the simulations reproduce most of the observed cavity features to a reasonable level of detail.

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Mathematical structure of transport equations for multispecies flows

Cited by 339 publications

References 48 publications

Heating of the sunlit polar cap ionosphere by reflected photoelectrons

Heating of the sunlit polar cap ionosphere by reflected photoelectrons

From the Sun’s atmosphere to the Earth’s atmosphere: an overview of scientific models available for space weather developments

Auroral ionospheric F region density cavity formation and evolution: MICA campaign results

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