Effects of wave‐particle interactions on H+ and O+ outflow at high latitude: A comparative study

Barghouthi, I. A.

doi:10.1029/96ja03293

Cited by 31 publications

(74 citation statements)

References 32 publications

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“…However, the adoption of this altitude dependent diffusion coefficient and similar ones such as that adopted by Crew et al (1990), Barghouthi (1997), and Barghouthi et al (1998) results in unrealistically high H + and O + ion temperatures at high altitudes. Also, it did not explained the non-Maxwellian features of ions at middle (∼4 R E ) and high (∼8 R E ) altitudes, such as H + and O + ion toroids and H + and O + ions temperatures.…”

Section: Theoretical Formulationsmentioning

confidence: 99%

“…Therefore, to model the ion perpendicular heating process, we specified a model for D ⊥ as a function of perpendicular velocity v ⊥ and position r/R E along the auroral geomagnetic field line. For the velocity dependence, we chose the above form obtained by Bouhram et al (2004), while for the altitude dependence we chose the form calculated by Barghouthi (1997). Altogether, the velocity and altitude dependent diffusion coefficient is written: …”

Section: Theoretical Formulationsmentioning

confidence: 99%

“…(6) is independent of velocity, and it depends on position (altitude) through the variation of the ion gyrofrequency, , along the geomagnetic field lines. To improve the altitude dependence of D ⊥ , Barghouthi (1997) and Barghouthi et al (1998) processed the data collected by PWI on board the DE-1 spacecraft. They obtained the following expressions for D ⊥ in the region equatorward of the cusp.…”

Section: Theoretical Formulationsmentioning

confidence: 99%

“…In a series of studies, Barakat and Barghouthi (1994a, b), Barghouthi and Barakat (1995), Barghouthi (1997), Barghouthi et al (1998), Pierrard and Barghouthi (2006) and Barghouthi and Atout (2006) used Monte Carlo simulation to investigate the effect of wave-particle interaction on H + and O + outflows in the polar wind and auroral region. They reported that the effect of finite gyroradius is responsible for production of the H + and O + toroids at high altitudes equatorward of the cusp that are observed by TIDE and TIMAS ion instruments on board the polar spacecraft.…”

Section: Introductionmentioning

confidence: 99%

“…Bouhram et al (2004) interpreted these results in terms of finite perpendicular wavelength effects in the wave-particle interaction. Barghouthi (1997) obtained an altitude dependent diffusion coefficient and Bouhram et al (2004) derived velocity dependent diffusion coefficient. In this study, we will use a combined (altitude part from Barghouthi, 1997, and the velocity part from Bouhram et al, 2004) form for the diffusion coefficient to investigate the H + and O + ion outflows in the equatorward of the cusp region.…”

Section: Introductionmentioning

confidence: 99%

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High-altitude and high-latitude O+ and H+ outflows: the effect of finite electromagnetic turbulence wavelength

et al. 2007

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Abstract. The energization of ions, due to interaction with electromagnetic turbulence (i.e. wave-particle interactions), has an important influence on H + and O + ions outflows in the polar region. The effects of altitude and velocity dependent wave-particle interaction on H + and O + ions outflows in the auroral region were investigated by using Monte Carlo method. The Monte Carlo simulation included the effects of altitude and velocity dependent wave-particle interaction, gravity, polarization electrostatic field, and divergence of auroral geomagnetic field within the simulation tube (1.2-10 earth radii, R E ). As the ions are heated due to wave-particle interactions (i.e. ion interactions with electromagnetic turbulence) and move to higher altitudes, the ion gyroradius ρ i may become comparable to the electromagnetic turbulence wavelength λ ⊥ and consequently (k ⊥ ρ i ) becomes larger than unity. This turns the heating rate to be negligible and the motion of the ions is described by using Liouville theorem. The main conclusions are as follows: (1) the formation of H + and O + conics at lower altitudes and for all values of λ ⊥ ; (2) O + toroids appear at 3.72 R E , 2.76 R E and 2 R E , for λ ⊥ =100, 10, and 1 km, respectively; however, H + toroids appear at 6.6 R E , 4.4 R E and 3 R E , for λ ⊥ =100, 10, and 1 km, respectively; and H + and O + ion toroids did not appear for the case λ ⊥ goes to infinity, i.e. when the effect of velocity dependent wave-particle interaction was not included; (3) As λ ⊥ decreases, H + and O + ion drift velocity decreases, H + and O + ion density increases, H + and O + ion perpendicular temperature and H + and O + ion parallel temperature decrease; (4) Finally, including the effect of finite electromagnetic turbulence wavelength, i.e. the effect of velocity dependent diffusion coefficient and consequently, the velocity dependent wave-particle interactions produce realistic H + and O + ion temperatures and H + and O + toroids, and this is, qualitatively, consistent with the observations of H + and O + ions in the auroral region at high altitudes.

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Section: Theoretical Formulationsmentioning

confidence: 99%

Section: Theoretical Formulationsmentioning

confidence: 99%

Section: Theoretical Formulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-altitude and high-latitude O+ and H+ outflows: the effect of finite electromagnetic turbulence wavelength

et al. 2007

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Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation

Abudayyeh¹,

Barghouthi²,

Slapak³

et al. 2015

JGR Space Physics

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A Monte Carlo simulation was used to study the outflow of O+ and H+ ions along three flight trajectories above the polar cap up to altitudes of about 15 RE. Barghouthi (2008) developed a model on the basis of altitude and velocity‐dependent wave‐particle interactions and a radial geomagnetic field which includes the effects of ambipolar electric field and gravitational and mirror forces. In the present work we improve this model to include the effect of the centrifugal force, with the use of relevant boundary conditions. In addition, the magnetic field and flight trajectories, namely, the central polar cap (CPC), nightside polar cap (NPC), and cusp, were calculated using the Tsyganenko T96 model. To simulate wave‐particle interactions, the perpendicular velocity diffusion coefficients for O+ ions in each region were determined such that the simulation results fit the observations. For H+ ions, a constant perpendicular velocity diffusion coefficient was assumed for all altitudes in all regions as recommended by Nilsson et al. (2013). The effect of centrifugal acceleration was simulated by considering three values for the ionospheric electric field: 0 (no centrifugal acceleration), 50, and 100 mV/m. It was found that the centrifugal acceleration increases the parallel bulk velocity and decreases the parallel and perpendicular temperatures of both ion species at altitudes above about 4 RE. Centrifugal acceleration also increases the temperature anisotropy at high altitudes. At a given altitude, centrifugal acceleration decreases the density of H+ ions while it increases the density of O+ ions. This implies that with higher centrifugal acceleration more O+ ions overcome the potential barrier. It was also found that aside from two exceptions centrifugal acceleration has the same effect on the velocities of both ions. This implies that the centrifugal acceleration is universal for all particles. The parallel bulk velocities at a given value of ionospheric electric field were highest in the cusp followed by the CPC followed by the NPC. In this study a region of no wave‐particle interaction was assumed in the CPC and NPC between 3.7 and 7.5 RE. In this region the perpendicular temperature was found to decrease with altitude due to perpendicular adiabatic cooling.

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O⁺ and H⁺ above the polar cap: Observations and semikinetic simulations

et al. 2016

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A one‐dimensional direct simulation Monte Carlo model is used to study the outflow of O+ and H+ ions from 1.2 RE to 15.2 RE along two flight trajectories originating from the polar cap, namely, the central polar cap (CPC) and the cusp. To study the effect of varying geophysical conditions and to deduce the proper set of parameters, several parameters were varied, and the results were compared to corresponding data from Cluster spacecraft. First, several sets of diffusion coefficients were considered based on using diffusion coefficients calculated by Barghouthi et al. (1998), Nilsson et al. (2013), and Abudayyeh et al. (2015b) for different altitude intervals. It was found that in the central polar cap using the diffusion coefficients reported by Barghouthi et al. (1998) for altitudes lower than 3.7 RE, zero diffusion coefficients between 3.7 and 7.5 RE and diffusion coefficients from Nilsson et al. (2013) for altitudes higher than 7.5 RE provide the best fit for O+ ions. For O+ ions in the cusp the best fit was obtained for using Barghouthi et al. (1998) diffusion coefficients for altitudes lower than 3.7 RE and Nilsson et al. (2013) diffusion coefficients for altitudes higher than that. The best fit for H+ ions in both regions was obtained by using the diffusion coefficients calculated by Abudayyeh et al. (2015b). Also, it was found that along an ion's trajectory the most recent heating dominates. Second, the strength of centrifugal acceleration was varied by using three values for the ionospheric electric field, namely, 0, 50, and 100 MV/m. It was found that the value of 50 MV/m provided the best fit for both ion species in both regions. Finally, the lower altitude boundary conditions and the electron temperature were varied. Increasing the electron temperature and the lower altitude O+ parallel velocity were found to increase the access of O+ ions to higher altitudes and therefore increase the density at a given altitude. The variation of all other boundary conditions only affected the densities of the ions and not the other moments due to the overwhelming effect of wave‐particle interaction. Furthermore, varying the parameters of one ion species has no effect on the other ion species. We also compared the energy gain per ion due to wave‐particle interaction, centrifugal acceleration, and ambipolar electric field and found that wave‐particle interaction is the most important mechanism, while ambipolar electric field is relatively unimportant especially at higher altitudes.

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Effects of wave‐particle interactions on H⁺ and O⁺ outflow at high latitude: A comparative study

Cited by 31 publications

References 32 publications

High-altitude and high-latitude O<sup>+</sup> and H<sup>+</sup> outflows: the effect of finite electromagnetic turbulence wavelength

High-altitude and high-latitude O<sup>+</sup> and H<sup>+</sup> outflows: the effect of finite electromagnetic turbulence wavelength

Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation

O⁺ and H⁺ above the polar cap: Observations and semikinetic simulations

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Effects of wave‐particle interactions on H+ and O+ outflow at high latitude: A comparative study

Cited by 31 publications

References 32 publications

High-altitude and high-latitude O&lt;sup&gt;+&lt;/sup&gt; and H&lt;sup&gt;+&lt;/sup&gt; outflows: the effect of finite electromagnetic turbulence wavelength

High-altitude and high-latitude O&lt;sup&gt;+&lt;/sup&gt; and H&lt;sup&gt;+&lt;/sup&gt; outflows: the effect of finite electromagnetic turbulence wavelength

Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation

O+ and H+ above the polar cap: Observations and semikinetic simulations

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Effects of wave‐particle interactions on H⁺ and O⁺ outflow at high latitude: A comparative study

High-altitude and high-latitude O<sup>+</sup> and H<sup>+</sup> outflows: the effect of finite electromagnetic turbulence wavelength

High-altitude and high-latitude O<sup>+</sup> and H<sup>+</sup> outflows: the effect of finite electromagnetic turbulence wavelength

O⁺ and H⁺ above the polar cap: Observations and semikinetic simulations