CAN PLASMA EXPANSION EXPLAIN THE OBSERVED ACCELERATION OF Ne{sup 7+} IONS IN A CORONAL MAGNETIC FUNNEL?

Journal Article · Fri May 20 04:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/733/1/L6· OSTI ID:21562671

Singh, Nagendra; Araveti, Sudeepth ^[1]

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1. Department of Electrical and Computer Engineering, University of Alabama, Huntsville, AL 35899 (United States)

Tu et al. measured outflow of Ne{sup 7+} at a height of 20 Mm above the photosphere demonstrating that the solar wind originates in coronal funnels footed in the chromospheric magnetic networks. We suggest that when the bottom of a coronal flux tube is populated by the chromospheric plasma consisting of protons as the major ions, Ne{sup 7+} as minor ions, and heated electrons in the magnetic networks, large-scale plasma expansion could accelerate the Ne{sup 7+} ions to a velocity {approx}10 km s{sup -1} at a height {approx} 20 Mm as measured. Two scenarios are discussed here, one with the bulk heating of the electrons to a temperature T{sub e} > 64 eV and another with a small fraction of the electrons heated to high temperatures T{sub eh} > 158 eV, appearing as an energetic tail to the electrons' velocity distribution function. In the former scenario, the expansion produces weak ambipolar electric fields distributed along the entire length of the funnel. In the latter one the electric field is concentrated in a double layer. The electric fields accelerate the ions against the solar gravity. The required electron temperatures in the above scenarios are large enough to ionize neon atoms yielding Ne{sup 7+}.

• OSTI ID: 21562671
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 733; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
ATMOSPHERES
CHARGED PARTICLES
CHROMOSPHERE
ELECTRIC FIELDS
ELECTRONS
ELEMENTARY PARTICLES
EXPANSION
FERMIONS
HEATING
IONS
LEPTONS
MAGNETIC RECONNECTION
NEON IONS
PLASMA EXPANSION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR WIND
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR WINDS