Momentum Transfer and Viscosity from Proton‐Hydrogen Collisions Relevant to Shocks and Other Astrophysical Environments

Schultz, David; Krstić, Predrag; Lee, Teck G; Raymond, J. C.

doi:10.1086/533579

Cited by 46 publications

(65 citation statements)

References 29 publications

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“…The values presented here are the most accurate that exist. The physics of this difference between various cross sections is described partly in a recent work [11] and in much more detail in [10,12], and in [13] The quantum-mechanical indistinguishability of particles used here implies overlapping of particle quantum wave functions at low energies. As described in [10], when the nuclei are identical and the collision energy is relatively low, in the process of collisions it is not possible to distinguish the ion which is elastically scattered from the ion which originates from charge transfer unless they are additionally labeled (e.g., by their spin).…”

Section: The Alfvén Wave In Partially Ionized Plasmasmentioning

confidence: 97%

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On the Alfvén wave cut-off in partly ionized collisional plasmas

Vranjes

Kono

2014

Physics of Plasmas

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The cut-off of the Alfvén wave, caused by plasma collisions with neutrals in multi-component partially ionized plasmas, is discussed. Full multi-component theory is used, and similarities and differences regarding the classic magnetohydrodynamic theory are presented. It is shown that the cut-off in partially ionized plasma in principle may remain the same as predicted in classic magnetohydrodynamic works, although multi-component theory also yields some essential differences. Due to electric field, the ion motion is intrinsically two-dimensional and this results in additional forced oscillations of neutrals. One new small parameter, containing the ion inertial length, appears in the multi-component theory. This new small parameter is missing in the magnetohydrodynamic description, and it turns out that for some parameters it may be greater than the ions-to-neutrals density ratio which is the only small parameter in the magnetohydrodynamic description. Due to this the Alfvén wave behavior can become much different as compared to classic magnetohydrodynamic results. It is shown also that in plasmas with unmagnetized ions, Alfvén waves cannot be excited. This by all means applies to the solar photosphere where the ion collision frequency may be far above the ion gyro-frequency.

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Section: The Alfvén Wave In Partially Ionized Plasmasmentioning

confidence: 97%

“…The condition (13) clearly includes the case ν ni = 0 as well. From our starting equation (4) with omitted electron effects we see that this is equivalent to assuming neutrals as a static background (fairly well justified for short wavelengths).…”

Section: Small Ratio ν Ni /|ω N | Explicit Absence Of Alfvén Wave Fomentioning

confidence: 99%

On the Alfvén wave cut-off in partly ionized collisional plasmas

Vranjes

Kono

2014

Physics of Plasmas

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“…Charge transfer rates are taken from (Schultz et al 2008) using the quadrature sum of the thermal speed and the ion-neutral relative speed. Ionization and excitation rates are computed from cross sections from Janev & Smith (1993) by integrating over the electron velocity distribution including the relative electron-neutral flow speed.…”

Section: Model Calculationsmentioning

confidence: 99%

Effects of Neutral Hydrogen on Cosmic-Ray Precursors in Supernova Remnant Shock Waves

Raymond

Vink

Helder

et al. 2011

ApJ

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Many fast supernova remnant shocks show spectra dominated by Balmer lines. The Hα profiles have a narrow component explained by direct excitations and a thermally Doppler broadened component due to atoms that undergo charge exchange in the post-shock region. However, the standard model does not take into account the cosmic-ray shock precursor, which compresses and accelerates plasma ahead of the shock. In strong precursors with sufficiently high densities, the processes of charge exchange, excitation and ionization will affect the widths of both narrow and broad line components. Moreover, the difference in velocity between the neutrals and the precursor plasma gives rise to frictional heating due to charge exchange and ionization in the precursor. In extreme cases, all neutrals can be ionized by the precursor.In this paper we compute the ion and electron heating for a wide range of shock parameters, along with the velocity distribution of the neutrals that reach the shock. Our calculations predict very large narrow component widths for some shocks with efficient acceleration, along with changes in the broad-to-narrow intensity ratio used as a diagnostic for the electron-ion temperature ratio. Balmer lines may therefore provide a unique diagnostic of precursor properties. We show that heating by neutrals in the precursor can account for the observed Hα narrow component widths, and that the acceleration efficiency is modest in most Balmer line shocks observed thus far.

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“…As in a number of our previous studies regarding the el, mt, and vi cross sections, 17,18,24,26,27 the calculations here utilize a fully quantum mechanical ͑QM͒ approach that provides the best available result at lower collision energies and an approximate, quasiclassical approach based on the classical trajectory Monte Carlo ͑CTMC͒ method for comparison and to extend the results to higher collision energies ͑Ͼ100 eV͒. The QM approach 13,14,16,19,22,25 is based on the solution of the radial Schrödinger equation for each relevant partial wave ͑angular momentum͒ component on the adiabatic quasimolecular state potential energy curve of the systems under consideration, namely ͑LiH͒ + , ͑BeH͒ + , ͑BH͒ + , and LiH.…”

Section: Theoretical Methodsmentioning

confidence: 89%

Mean free paths and elastic and related transport cross sections for neutrals and singly charged ions of Li, Be, and B in hydrogen plasmas

Krstić

Schultz

2009

Physics of Plasmas

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The mean free paths are computed from the momentum transfer cross sections associated with collisions of protons with Li, Be, and B and for Li, Li+, Be+, and B+ colliding with atomic hydrogen, for center of mass energies between 0.0001 and 10 000 eV. The elastic and viscosity cross sections are also calculated for these collision systems. A fully quantum mechanical approach has been used up to 100 eV along with a more approximate, quasiclassical method between ∼0.1 and 10 000 eV.

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Momentum Transfer and Viscosity from Proton‐Hydrogen Collisions Relevant to Shocks and Other Astrophysical Environments

Cited by 46 publications

References 29 publications

On the Alfvén wave cut-off in partly ionized collisional plasmas

On the Alfvén wave cut-off in partly ionized collisional plasmas

Effects of Neutral Hydrogen on Cosmic-Ray Precursors in Supernova Remnant Shock Waves

Mean free paths and elastic and related transport cross sections for neutrals and singly charged ions of Li, Be, and B in hydrogen plasmas

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