62nd Annual Meeting of the APS Division of Plasma Physics
Volume 65, Number 11
Monday–Friday, November 9–13, 2020;
Remote; Time Zone: Central Standard Time, USA
Session TO16: Space Physics: Sun and Solar Wind
9:30 AM–12:18 PM,
Thursday, November 12, 2020
Chair: Shan Wang, University of Maryland, College Park
Abstract: TO16.00007 : Electric Fields and Currents of the Sun and Solar Wind*
10:42 AM–10:54 AM
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Abstract
Author:
Charles Driscoll
(University of California, San Diego)
A simple model of solar electric fields explains the solar wind energetics
and coronal "heating", invoking only thermo-electric and photo-electric
forces. In the (collisional) solar interior, thermal electron pressure
\textit{necessarily} generates a radial electric field, integrating to a surface field
eE$_{\mathrm{th}}$(R$_{\mathrm{s}})\cong $1.4eV/Mm, comparable to the
proton weight m$_{\mathrm{p}}$g$=$2.8eV/Mm. In the (less collisional) plasma
"sheath" of the photosphere and corona, the outward photon flux $\Gamma
_{\mathrm{\gamma }}=$60.MW/m$^{\mathrm{2}}$ causes additional electron
displacement, giving eE$_{\mathrm{\gamma }}$(r) $= \quad \sigma
_{\mathrm{\gamma e}} \quad \Gamma_{\mathrm{\gamma }}$ /c. Here, the main
uncertainty is the photon cross-section $\sigma_{\mathrm{\gamma e}}$ for
electrons \textit{correlated} with protons: H-minus and "rydberg" hydrogen states have $\sigma
_{\mathrm{\gamma e}}\cong $0.5x10\textasciicircum -20m$^{\mathrm{2}}$,
whereas \textit{isolated} electrons have Thompson cross-section $\sigma_{\mathrm{\gamma
e}}\cong $0.7x10\textasciicircum -28m$^{\mathrm{2}}$. An average
cross-section $\sigma_{\mathrm{\gamma e}}\cong $3x10\textasciicircum
-24m$^{\mathrm{2}}$ can generate the observed solar wind, as "collisional
runaway" protons accelerate out of the 2.keV gravity well and up to 1.3 keV
kinetic energy within several R$_{\mathrm{s}}$. This coherent
proton/electron flow will glow as the K-Corona, obviating the traditional
T$=$100eV hydrostatic models. Fluctuating 3D electric fields and charge
currents will arise from convective surface granulation ("roiling") and from
"current pinch" propagation dynamics, generating the observed \textit{fluctuating} magnetic
fields. Some characteristics of solar wind currents can be ascertained from
the extensive databases of satellite magnetic field measurements.
*Supported in part by AFOSR grant FA-9550-19-0099