The formation and evolution of reconnection-driven, slow-mode shocks in a partially ionised plasma

Hillier, Andrew; Takasao, Shinsuke; Nakamura, Naoki

doi:10.1051/0004-6361/201628215

Cited by 47 publications

(82 citation statements)

References 41 publications

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“…The difference between ion and neutral velocities grows with height, reaching a magnitude of about 14 m s −1 at the transition region which is located at y ≈ 2.1 Mm. As at higher altitudes the acoustic wave profiles steepen into shocks, these differences are present at these shocks and they result from structured nature of shocks in two-fluids regime (Hillier et al 2016), which are well seen in Fig. 1 (top and panel b).…”

Section: Numerical Resultssupporting

confidence: 56%

Heating of a Quiet Region of the Solar Chromosphere by Ion and Neutral Acoustic Waves

Kuźma

Wójcik

Murawski

2019

ApJ

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Using high-resolution numerical simulations we investigate the plasma heating driven by periodic two-fluid acoustic waves that originate at the bottom of the photosphere and propagate into the gravitationally stratified and partially ionized solar atmosphere. We consider ions+electrons and neutrals as separate fluids that interact between themselves via collision forces. The latter play an important role in the chromosphere, leading to significant damping of short-period waves. Long-period waves do not essentially alter the photospheric temperatures, but they exhibit the capability of depositing a part of their energy in the chromosphere.This results in up about a five times increase of ion temperature that takes place there on a time-scale of a few minutes. The most effective heating corresponds to waveperiods within the range of about 30-200 s with a peak value located at 80 s. However, we conclude that for the amplitude of the driver chosen to be equal to 0.1 km s −1 , this heating is too low to balance the radiative losses in the chromosphere.

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Section: Numerical Resultssupporting

confidence: 56%

Heating of a Quiet Region of the Solar Chromosphere by Ion and Neutral Acoustic Waves

Kuźma

Wójcik

Murawski

2019

ApJ

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“…There have been several approaches proposed to overcome the limitations introduced by large collisional terms. Hillier et al (2016) noticed that, since collisional terms introduce a very different time scale, the solution can be obtained semi-analytically. In their approach, the equations with only collisional terms are solved analytically and then the rest of the terms are evolved numerically using an explicit scheme.…”

Section: Discussionmentioning

confidence: 99%

Two-fluid simulations of waves in the solar chromosphere

Braileanu

Lukin

Khomenko

et al. 2019

A&A

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Solar chromosphere consists of a partially ionized plasma, which makes modeling the solar chromosphere a particularly challenging numerical task. Here we numerically model chromospheric waves using a two-fluid approach with a newly developed numerical code. The code solves two-fluid equations of conservation of mass, momentum and energy, together with the induction equation, for the case of the purely hydrogen plasma with collisional coupling between the charged and neutral fluid components. The implementation of a semi-implicit algorithm allows us to overcome the numerical stability constraints due to the stiff collisional terms. We test the code against analytical solutions of acoustic and Alfvén wave propagation in uniform medium in several regimes of collisional coupling.The results of our simulations are consistent with the analytical estimates, and with other results described in the literature. In the limit of a large collisional frequency, the waves propagate with a common speed of a single fluid. In the other limit of a vanishingly small collisional frequency, the Alfvén waves propagate with an Alfvén speed of the charged fluid only, while the perturbation in neutral fluid is very small. The acoustic waves in these limits propagate with the sound speed corresponding to either the charges or the neutrals, while the perturbation in the other fluid component is very small. Otherwise, when the collision frequency is similar to the real part of the wave frequency, the interaction between charges and neutrals through momentum transfer collisions cause alterations of the waves frequencies and damping of the wave amplitudes.

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“…Arber et al 2007; Leake & Linton 2013a). The effect also changes the energy flux of Alfvén wave (Vranjes et al 2008), the structure of slow-mode MHD shocks (Hillier et al 2016), the thermodynamic structure of quiet-Sun magnetic features (Cheung & Cameron 2012), and the structure of the solar prominences (Hillier et al 2010). Furthermore, it has significant impact on the angular momentum transport by magnetic fields in the formation and evolution of circumstellar disks and stars (e.g.…”

Section: Introductionmentioning

confidence: 99%

Differences between Doppler velocities of ions and neutral atoms in a solar prominence

Anan

Ichimoto

Hillier

2017

A&A

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Context. In astrophysical systems with partially ionized plasma the motion of ions is governed by the magnetic field while the neutral particles can only feel the magnetic field's Lorentz force indirectly through collisions with ions. The drift in the velocity between ionized and neutral species plays a key role in modifying important physical processes like magnetic reconnection, damping of magnetohydrodynamic waves, transport of angular momentum in plasma through the magnetic field, and heating. Aims. This paper investigates the differences between Doppler velocities of calcium ions and neutral hydrogen in a solar prominence to look for velocity differences between the neutral and ionized species. Methods. We simultaneously observed spectra of a prominence over an active region in H I 397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion spectrograph of the Domeless Solar Telescope at Hida observatory, and compared the Doppler velocities, derived from the shift of the peak of the spectral lines presumably emitted from optically-thin plasma.Results. There are instances when the difference in velocities between neutral atoms and ions is significant, e.g. 1433 events (∼ 3 % of sets of compared profiles) with a difference in velocity between neutral hydrogen atoms and calcium ions greater than 3σ of the measurement error. However, we also found significant differences between the Doppler velocities of two spectral lines emitted from the same species, and the probability density functions of velocity difference between the same species is not significantly different from those between neutral atoms and ions. Conclusions. We interpreted the difference of Doppler velocities as a result of motions of different components in the prominence along the line of sight, rather than the decoupling of neutral atoms from plasma.

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The formation and evolution of reconnection-driven, slow-mode shocks in a partially ionised plasma

Cited by 47 publications

References 41 publications

Heating of a Quiet Region of the Solar Chromosphere by Ion and Neutral Acoustic Waves

Heating of a Quiet Region of the Solar Chromosphere by Ion and Neutral Acoustic Waves

Two-fluid simulations of waves in the solar chromosphere

Differences between Doppler velocities of ions and neutral atoms in a solar prominence

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