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Khodachenko, M. L.; Зайцев, В. В.

doi:10.1023/a:1015162131331

Cited by 39 publications

(33 citation statements)

References 24 publications

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“…if the ions and electrons are tightly bound to the magnetic field. Khodachenko & Zaitsev (2002) showed that in the upper photosphere where the plasma is more weakly ionised the positive ions may not be magnetised, i.e. not tightly bound to the magnetic field for certain field strengths.…”

Section: Partially Ionised Plasma In the Lower Solar Atmospherementioning

confidence: 99%

The emergence of magnetic flux through a partially ionised solar atmosphere

Leake¹,

Arber²

2006

A&A

123

175

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We present results from 2.5D numerical simulations of the emergence of magnetic flux from the upper convection zone through the photosphere and chromosphere into the corona. Certain regions of the solar atmosphere are at sufficiently low temperatures to be only partially ionised, in particular the lower chromosphere. This leads to Cowling resistivities orders of magnitude larger than the Coulomb values, and thus to anisotropic dissipation in Ohm's law. This also leads to localised low magnetic Reynolds numbers (R m < 1). We find that the rates of emergence of magnetic field are greatly increased by the partially ionised regions of the model atmosphere, and the resultant magnetic field is more diffuse. More importantly, the only currents associated with the magnetic field to emerge into the corona are aligned with the field, and thus the newly formed coronal field is force-free.

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Section: Partially Ionised Plasma In the Lower Solar Atmospherementioning

confidence: 99%

The emergence of magnetic flux through a partially ionised solar atmosphere

Leake¹,

Arber²

2006

A&A

123

175

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“…1), this condition is satisfied everywhere in the chromosphere. Khodachenko & Zaitsev (2001) showed that this condition does not hold in the upper photosphere where the plasma is more weakly ionised. In Sect.…”

Section: Collisional Friction Damping In a Partially Ionised Plasmamentioning

confidence: 99%

Collisional dissipation of Alfvén waves in a partially ionised solar chromosphere

Leake¹,

Arber²,

Khodachenko³

2005

A&A

111

130

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Certain regions of the solar atmosphere are at sufficiently low temperatures to be only partially ionised. The lower chromosphere contains neutral atoms, the existence of which greatly increases the efficiency of the damping of waves due to collisional friction momentum transfer. More specifically the Cowling conductivity can be up to 12 orders of magnitude smaller than the Spitzer value, so that the main damping mechanism in this region is due to the collisions between neutrals and positive ions (Khodachenko et al. 2004(Khodachenko et al. , A&A, 422, 1073. Using values for the gas density and temperature as functions of height taken from the VAL C model of the quiet Sun (Vernazza et al. 1981, ApJS, 45, 635), an estimate is made for the dependance of the Cowling conductivity on height and strength of magnetic field. Using both analytic and numerical approaches the passage of Alfvén waves over a wide spectrum through this partially ionised region is investigated. Estimates of the efficiency of this region in the damping of Alfvén waves are made and compared for both approaches. We find that Alfvén waves with frequencies above 0.6 Hz are completely damped and frequencies below 0.01 Hz unaffected.

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Section: ¬ñóñðâîßðââ âóíâ ì àíäëäâîçðõðþì àîçíõóëúçôíëì (Rlc) íñðõöóunclassified

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Section: ¬ñóñðâîßðââ âóíâ ì àíäëäâîçðõðþì àîçíõóëúçôíëì (Rlc) íñðõöóunclassified