Ponderomotive Acceleration in Coronal Loops

Abstract

Ponderomotive acceleration has been asserted to be a cause of the First Ionization Potential (FIP) effect, the by now well known enhancement in abundance by a factor of 3-4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a "byproduct" of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of a coronal loops with an axial magnetic field from 0.005 Teslas to 0.02 Teslas and lengths from 25000 km to 75000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets which act to heat the loop. As a consequence of coronal magnetic reconnection, small scale, high speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

14 pages, 19 figures, accepted by the Astrophysical Journal

References in corpus (7)

• Instability of current sheets and formation of plasmoid chains
• Self-Feeding Turbulent Magnetic Reconnection on Macroscopic Scales
• Coronal Heating, Weak MHD Turbulence and Scaling Laws
• Self-generated turbulence in magnetic reconnection
• Turbulent Coronal Heating Mechanisms: Coupling of Dynamics and Thermodynamics
• Statistical Evidence for the Existence of Alfvénic Turbulence in Solar Coronal Loops
• Kinetic instability of drift-Alfven waves in solar corona and stochastic heating

Cited by in corpus (3)

• Element Abundances: A New Diagnostic for the Solar Wind
• The First Ionization Potential Effect from the Ponderomotive Force: On the Polarization and Coronal Origin of the Alfven Waves
• Determining the Elemental and Isotopic Composition of the preSolar Nebula from Genesis Data Analysis: The Case of Oxygen