The acceleration of minor ion species in the solar wind

McKenzie, J. F.; Ip, W. H.; Axford, W. I.

doi:10.1007/bf00640041

Cited by 82 publications

(64 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…MHD waves can exert pressure on ions and accelerate them through pressure gradients in a non-resonant and non-discriminating wave-particle interaction. This has been explored by several authors at different occasions, e.g., (McKenzie et al 1979, Isenberg and Hollweg 1982, McKenzie 1994.…”

Section: Minor Species In the Solar Coronamentioning

confidence: 99%

Minor ions in the solar wind

Bochsler

2006

Astron Astrophys Rev

View full text Add to dashboard Cite

Ions heavier than 4 He are treated as "minors" in the solar wind. This is justified for many applications since minor ions have no significant influence on the dynamics of the interplanetary plasma. However, minor ions carry information on many aspects of the formation, on the acceleration and on the transfer of solar plasma from the corona into the interplanetary space. This review concentrates on various aspects of minor ions as diagnostic tracers. The elemental abundance patterns of the solar wind are shaped in the chromosphere and in the lower transition region by processes, which are not fully understood at this moment. Despite this lack of detailed understanding, observed abundance patterns have been classified and are now commonly used to characterize the sources, and to trace back solar-wind flows to their origins in the solar atmosphere. Furthermore, the solar wind is the most important source of information for solar isotopic abundances and for solar abundances of volatile elements. In order to fully exploit this information, a comprehensive understanding of elemental and isotopic fractionation processes is required. We provide observational clues to distinguish different processes at work.

show abstract

Section: Minor Species In the Solar Coronamentioning

confidence: 99%

Minor ions in the solar wind

Bochsler

2006

Astron Astrophys Rev

View full text Add to dashboard Cite

show abstract

“…The right -hand-side of (16) where the Coulomb logarithm has been taken to be lnA -21. Except for the terms involving Q i , equations (14) - (18) are equivalent to the system of equations written by McKenzie, et al ( 1979); some typographical errors appearing in their paper have been corrected. The Coulomb collision terms are equivalent to those given by Burgers (1960).…”

Section: B) Equationsmentioning

confidence: 99%

On the preferential acceleration and heating of solar wind heavy ions

1983

View full text Add to dashboard Cite

We investigate the preferential heating and acceleration of solar wind heavy ions by the resonant cyclotron interaction with parallel‐propagating left‐polarized hydromagnetic waves. We set up a scenario whereby the energy for this interaction is taken from saturated low‐frequency Alfven waves via a cascade to the higher, resonant frequencies. In order to utilize the existing theoretical work, the particles are taken to be thermally isotropic, and the waves are taken to be dispersionless. This scenario is incorporated into a numerical solar wind code describing the flow from an inner radius (taken to be 10 solar radii) to 1 AU. Thus we present the first model of a wave‐driven, three‐fluid, supersonic solar wind. By varying the model parameters we test the ability of the resonant interaction in this model to produce the excess speeds and temperatures of heavy ions that are observed. We find that unrealistically steep wave spectra are required to produce differential speeds of the order of the Alfven speed at 0.3 AU. In the case of He2+, the power spectrum of waves must be steeper than γ ≃ 4.7, where γ is the power law spectral index. Ions of oxygen or iron, with larger mass‐per‐charge ratios, are accelerated more readily than helium, but still require steeper spectra than are observed. This model is also unable to produce the mass‐proportional heavy ion temperatures that are observed. We show that the production of mass‐proportional temperatures is inconsistent with preferential acceleration of heavy ions by this mechanism. The model also produces a heavy ion‐to‐proton temperature ratio at 1 AU which is anticorrelated with solar wind speed, in contradiction to the observed behavior.

show abstract

“…Given that the differential streaming is more prominent in the fast wind, which in general flows out of the equatorial plane, it is necessary to formulate the model such that it treats both protons and alphas on an equal footing, and allows the solar wind to flow outside the equatorial plane. In this sense, this paper also extends the model of McKenzie et al (1979).…”

Section: Introductionmentioning

confidence: 79%

“…Such a behavior has yet to be understood. One possible mechanism is the coupling between the azimuthal and meridional motions, facilitated by the strong magnetic field (McKenzie et al 1979;Hollweg & Isenberg 1981). Although the Poynting flux may still be negligible (cf.…”

Section: Introductionmentioning

confidence: 99%

“…Acuna & Whang 1976;Alexander & de La Torre 1995;Hu et al 2003), the proposed coupling is expected to limit, at least to a non-trivial extent, the ion differential streaming. As pointed out by Hollweg & Isenberg (1983), one shortcoming of the formulation of McKenzie et al (1979) is that protons are privileged over alphas: the azimuthal magnetic field is assumed to be determined entirely by the protons whose azimuthal flow is neglected. Hence the formulation cannot properly account for the azimuthal dynamics of protons or alphas.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of α particles on the angular momentum loss from the Sun

Li¹,

Li²

2006

A&A

View full text Add to dashboard Cite

Aims. The classic Weber-Davis model of the solar wind is reconsidered by incorporating alpha particles and by allowing the solar wind to flow out of the equatorial plane in an axisymmetrical configuration. Methods. In the ion momentum equations of the solar wind, the ion gyro-frequency is many orders of magnitude higher than any other frequency. This requires that the difference between proton and alpha velocity vectors be aligned with the background magnetic field. With the aid of this alignment condition, the governing equations of the multi-fluid solar wind are derived from the standard transport equations. The governing equations are numerically solved along a prescribed meridional magnetic field line located at colatitude 70• at 1 AU and a steady state fast solar wind solution is found. Results. A general analysis concludes, in agreement with the Weber-Davis model, that the magnetic field helps the coronal plasma to achieve an effective corotation out to the Alfvénic radius, where the poloidal Alfvénic Mach number M T equals unity (M T is defined by Eq. (20)). The model computations show that, magnetic stresses predominate the angular momentum loss of the Sun. For the fast wind considered, the proton contribution to the angular momentum loss, which can be larger than the magnetic one, is almost completely canceled by the alpha particles that develop an azimuthal speed in the direction opposite to the solar rotation. The Poynting flux associated with the azimuthal components is negligible in the energy budget. However, the solar rotation can play some role in reducing the relative speed between alpha particles and protons for low latitude fast solar wind streams in interplanetary space.

show abstract

The acceleration of minor ion species in the solar wind

Cited by 82 publications

References 20 publications

Minor ions in the solar wind

Minor ions in the solar wind

On the preferential acceleration and heating of solar wind heavy ions

Effects of α particles on the angular momentum loss from the Sun

Contact Info

Product

Resources

About