History of kinetic polar wind models and early observations

Lemaire, J.; Peterson, W. K.; Chang, Tom; Schunk, R. W.; Barakat, A. R.; Demars, H. G.; Khazanov, G. V.

doi:10.1016/j.jastp.2007.08.011

Cited by 26 publications

(24 citation statements)

References 151 publications

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“…The strahl is usually observed in the range of about 40 eV to 1.5 keV. A highly energetic quasi-isotropic population, known as the superhalo, may also be found within the energy range of several tens of keV up to about 100 keV (Marsch 2006;Hammond et al 1996;Lemaire et al 2007;Štverák et al 2009;Pierrard et al 1999Pierrard et al , 2001Gosling 1990;Gosling et al 1993;Lin 1998).…”

Section: Introductionmentioning

confidence: 99%

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

Pavan

Viñas

Yoon³

et al. 2013

ApJ

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This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

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Section: Introductionmentioning

confidence: 99%

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

Pavan

Viñas

Yoon³

et al. 2013

ApJ

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“…Also, Barakat and Barghouthi (1994); Barghouthi et al (1998); Lemaire et al (2007); and Tam et al (2007) found that wave-particle interactions (WPI) play an important role in determining the behavior of ion outflows in the polar wind region. To include the effect of WPI in a collisionless region, we replace the right-hand side of Boltzmann equation by the term that represents the interaction between ions and the electromagnetic turbulence, which is resonant interactions at ion gyrofrequency.…”

Section: Theoretical Formulationsmentioning

confidence: 99%

“…Most of the models of the classical polar wind theory did not deal with O + ions but they dealt with H + outflows. As mentioned above, Lemaire et al (2007) reviewed early observations of polar wind and Yau et al (2007) continued and reviewed recent observations of polar wind. They concluded that satellite-borne ion composition observations over the past 4 decades have confirmed the existence of the polar wind as well as its basic characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…The characteristics of the polar wind mentioned in that paper and other polar wind measurements obtained by several space instruments aboard DE-1 satellite were the major source of observations for comparisons with different polar wind models. Lemaire et al (2007) reviewed the history of kinetic polar wind models and early observations (i.e. observations of the polar wind conducted by space instruments before the data from Akebono and Polar satellites were available).…”

Section: Introductionmentioning

confidence: 99%

“…To our knowledge, most of the comparisons between observations (ion velocity distribution, density, drift velocity, parallel and perpendicular temperatures, anisotropy, etc.) and simulations obtained from different models produce few agreements and fail to explain many observations (see Yau et al, 2007;Lemaire et al, 2007;Tam et al, 2007;Su et al, 1998;Engwall et al, 2009). This paper presents many close agreements between observations and simulations obtained by Barghouthi model, for O + and H + ions at different altitudes i.e.…”

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A comparison study between observations and simulation results of Barghouthi model for O<sup>+</sup> and H<sup>+</sup> outflows in the polar wind

2011

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Abstract. To advance our understanding of the effect of wave-particle interactions on ion outflows in the polar wind region and the resulting ion heating and escape from low altitudes to higher altitudes, we carried out a comparison between polar wind simulations obtained using Barghouthi model with corresponding observations obtained from different satellites. The Barghouthi model describes O + and H + outflows in the polar wind region in the range 1.7 R E to 13.7 R E , including the effects of gravity, polarization electrostatic field, diverging geomagnetic field lines, and waveparticle interactions. Wave-particle interactions were included into the model by using a particle diffusion equation, which depends on diffusion coefficients determined from estimates of the typical electric field spectral density at relevant altitudes and frequencies. We provide a formula for the velocity diffusion coefficient that depends on altitude and velocity, in which the velocity part depends on the perpendicular wavelength of the electromagnetic turbulence λ ⊥ . Because of the shortage of information about λ ⊥ , it was included into the model as a parameter. We produce different simulations (i.e. ion velocity distributions, ions density, ion drift velocity, ion parallel and perpendicular temperatures) for O + and H + ions, and for different λ ⊥ . We discuss the simulations in terms of wave-particle interactions, perpendicular adiabatic cooling, parallel adiabatic cooling, mirror force, and ion potential energy. The main findings of the simulations are as follows: (1) O + ions are highly energized at all altitudes in the simulation tube due to wave-particle interactions that heat the ions in the perpendicular direction, and part of this gained energy transfer to the parallel direction by mirror force, resulting in accelerating O + ions along geomagnetic field lines from lower altitudes to higher altitudes.(2) The effect of wave-particle interactions is negligible for Correspondence to: I. A. Barghouthi (barghouthi@science.alquds.edu) H + ions at altitudes below ∼7 R E , while it is important for altitudes above 7 R E . For O + wave particle interaction is very significant at all altitudes. (3) For certain λ ⊥ and at points, altitudes, where the ion gyroradius is equal to or less than λ ⊥ , the effect of wave-particle interactions is independent of the velocity and it depends only on the altitude part of the velocity diffusion coefficient; however, the effect of waveparticle interactions reduce above that point, called saturation point, and the heating process turns to be self-limiting heating. (4) The most interesting result is the appearance of O + conics and toroids at low altitudes and continue to appear at high altitudes; however, they appear at very high altitudes for H + ions. We compare quantitatively and qualitatively between the simulation results and the corresponding observations. As a result of many comparisons, we find that the best agreement occurs when λ ⊥ equals to 8 km. The quantitative comparisons show that ma...

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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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History of kinetic polar wind models and early observations

Cited by 26 publications

References 151 publications

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

A comparison study between observations and simulation results of Barghouthi model for O<sup>+</sup> and H<sup>+</sup> outflows in the polar wind

Heating of the sunlit polar cap ionosphere by reflected photoelectrons

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History of kinetic polar wind models and early observations

Cited by 26 publications

References 151 publications

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

A comparison study between observations and simulation results of Barghouthi model for O&lt;sup&gt;+&lt;/sup&gt; and H&lt;sup&gt;+&lt;/sup&gt; outflows in the polar wind

Heating of the sunlit polar cap ionosphere by reflected photoelectrons

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A comparison study between observations and simulation results of Barghouthi model for O<sup>+</sup> and H<sup>+</sup> outflows in the polar wind