Physics
Scientific paper
May 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agusmsh22a..02s&link_type=abstract
American Geophysical Union, Spring Meeting 2002, abstract #SH22A-02
Physics
7509 Corona, 7511 Coronal Holes, 0654 Plasmas, 2164 Solar Wind Plasma, 2169 Sources Of The Solar Wind
Scientific paper
We are in the process of developing a semi-empirical model of the electron heat conduction which is based on both theoretical and observational considerations. Most specifically we are most interested in applying this model to the polar regions of the Sun during solar minimum where suprathermal tails may form. This model is a 'local model' which uses the Krook's anzatz in the Boltzmann equation using the collision term (δ f*/δ t)coll=-(f*-f0*)/τ where τ = (λ w/wc)(u3/(u4 + λ w/λ coul)) is the collision time, λ w is a characteristic 'local' scattering length due to waves, λ coul is a characteristic collision length 'local' due to coulomb collisions, u = (w/wc), wc is the thermal speed of the core electrons, w is the electron speed in the electron proper frame, and f* = f0* + f1* where f* is the proper frame electron distribution function, f0* is the unperturbed electron distribution function and f1* is the perturbed correction term due to plasma gradients and collisions. Assuming a kappa distribution function for f0* we can compute an expansion of the Boltzmann equation and derive an expression for f1* with some undetermined parameters. Then by imposing constraint of particle conservation ∫ fe1*d3w = 0, the zero current condition j∥ * = -e∫ fe1*w∥ d3w = 0 to give us a relationship for the interplanetary potential, and we can then reduce the number of free parameters. Then by specifying the logarithmic derivative of the electron density ne, core electron temperature Tc and the magnetic field B from the base of the corona to 1 AU using SOHO and Ulysses data we can derive a relationship for κ and thus f1* with λ w as a free parameter. Once this is done we can use the relationship qe∥ * = 1/2me∫ fe1*w2w∥ d3w to give us the electron heat flux along B and then set it equal to qeff from the semi-empirical MHD model by Sittler and Guhathakurta (1999,2002) to constrain λ w which tell us how important waves are (i.e., whistler mode waves) with respect to coulomb collisions as a function of radial distance from the Sun. The results of our calculations will be presented at the meeting.
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