EMPIRICAL CONSTRAINTS ON PROTON AND ELECTRON HEATING IN THE FAST SOLAR WIND

By S. Cranmer, William H. Matthaeus, Ben Breech, Justin C. Kasper. 2009

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We analyze measured proton and electron temperatures in the high-speed solar wind in order to calculate the separate rates of heat deposition for protons and electrons. When comparing with other regions of the heliosphere, the fast solar wind has the lowest density and the least frequent Coulomb collisions. This makes the fast wind an optimal testing ground for studies of collisionless kinetic processes associated with the dissipation of plasma turbulence. Data from the Helios and Ulysses plasma instruments were collected to determine mean radial trends in the temperatures and the electron heat conduction flux between 0.29 and 5.4 AU. The derived heating rates apply specifically for these mean plasma properties and not for the full range of measured values around the mean. We found that the protons receive about 60% of the total plasma heating in the inner heliosphere, and that this fraction increases to approximately 80% by the orbit of Jupiter. A major factor affecting the uncertainty in this fraction is the uncertainty in the measured radial gradient of the electron heat conduction flux. The empirically derived partitioning of heat between protons and electrons is in rough agreement with theoretical predictions from a model of linear Vlasov wave damping. For a modeled power spectrum consisting only of Alfvénic fluctuations, the best agreement was found for a distribution of wavenumber vectors that evolves toward isotropy as distance increases.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/929fe0ca8cb98d44f655473892df9008cc466aef

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Citations in the corpus

ALFVÉN WAVE SOLAR MODEL (AWSoM): CORONAL HEATING (2013, unknown): “(C3) For our standard values α = 1.05 (taken from Cranmer et al. (2009)) and γ = 5/3, we obtain γH ≈ 1.33.”
Origins of the Ambient Solar Wind: Implications for Space Weather (2017, background): “There have been several empirical estimates of heat input rates that indicate the protons receive more “extended coronal heating” than do the electrons (Stawarz et al. 2009; Cranmer et al. 2009; Štverák et al. 2015).”
Electron Thermodynamics in GRMHD Simulations of Low-Luminosity Black Hole Accretion (2015, background): “In a turbulent, magnetised plasma, electrons and ions are heated at different rates depending on the local plasma conditions (e.g., Quataert & Gruzinov 1999; Cranmer et al. 2009; Howes 2010; Sironi 2015).”
Electron and proton heating by solar wind turbulence (2009, methodology): “A companion paper [Cranmer et al., 2009] follows the first avenue, e.g., examines effects of electrons through a more 1NASA Goddard Space Flight Center 2Department of Physics and Astronomy and Bartol Research Institute, University of Delaware 3Harvard-Smithsonian Center for Astrophysics 4Department…”
A TURBULENCE-DRIVEN MODEL FOR HEATING AND ACCELERATION OF THE FAST WIND IN CORONAL HOLES (2009, background): “Similar assumptions work well in understanding observations of solar wind turbulence (Breech et al. 2009; Cranmer et al. 2009).”
INCORPORATING KINETIC PHYSICS INTO A TWO-FLUID SOLAR-WIND MODEL WITH TEMPERATURE ANISOTROPY AND LOW-FREQUENCY ALFVÉN-WAVE TURBULENCE (2011, background): “Moreover, the amplitudes of these turbulent fluctuations are sufficient to explain the heating rates thathave been inferred from the proton and electron temperature profiles (Smith et al. 2001; MacBride et al. 2008; Cranmer et al. 2009; Stawarz et al. 2009).”
PERPENDICULAR ION HEATING BY LOW-FREQUENCY ALFVÉN-WAVE TURBULENCE IN THE SOLAR WIND (2010, background): “In addition, the expected rate at which the measured fluctuations dissipate (based on phenomenological turbulence theories) is comparable to the observationally inferred solar-wind heating rate (Smith et al. 2001; Breech et al. 2009; Cranmer et al. 2009).”
The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere (2019, unknown): “…wind, which is also consistent with the observed non-adiabatic temperature profile suggesting continual heating of the plasma (Mihalov & Wolfe 1978; Marsch et al. 1982; Gazis & Lazarus 1982; Freeman 1988; Richardson et al. 1995; Matthaeus et al. 1999b; Cranmer et al. 2009; Hellinger et al. 2011).”
A prescription for the turbulent heating of astrophysical plasmas (2010, background): “…the solar corona (Velli 2003; Verdini et al. 2009; Chandran 2010), the solar wind (Saito et al. 2008; Valentini et al. 2008; Breech et al. 2009; Cranmer et al. 2009; Lehe et al. 2009; Chandran et al. 2010), and the magnetospheres of the Earth (Chaston et al. 2008) and of other planets (Saur…”