Collisional transport in axisymmetric plasma columns with strong longitudinal flows: application to solar loops

Abstract

In this work we analyze the transport processes in solar loops considering a collisional plasma and high longitudinal plasma flow. The general theory of the neoclassical transport in toroidal configurations with a noncircular cross-section is applied to explain the transport processes in some kinds of solar loops, modeling the solar loop as a toroidal plasma column. The plasma is assumed to be in the collisional regime and to have particle longitudinal flow along the solar loop axis. The poloidal velocity and the radial fluxes of the particles and the ion heat flux are derived in this article. It is shown that the particle poloidal velocity can be measured giving rise to the possibility of having additional connections between the plasma macroscopic parameters, which are very important for the solar loops diagnostic. It is also shown that the particle and heat fluxes are on the "classical" level, within the factor of an order of magnitude. We hope that such an approach (together with other theories) can help to explain the transport processes in solar loops, whose shapes are similar to toroidal configurations.

Stationary axial plasma equilibrium in light of the magnetic polarization force

“…The density of a solar coronal loop is on the order of 10 14 ∼ 10 18 /m 3 , and temperatures are found between 1eV and 1keV, with an polar field of a few mT and a column-aligned field up to several Tesla (Tsypin and Galvão, 2005). Parametrizing the pressure of a plasma column of meter radius by p(r) = p 0 (1 − r a ) with constant a > 0 and using units of eV/m 3 , we consider the parabolic a = 2 profile with a central pressure p 0 ranging from 10 18 to 10 22 in an external field of 100mT, ensuring that the central β 0 H < 1/2.…”

“…With restriction to an axially symmetric configuration, we develop a model in the rest frame of the plasma for a magnetically confined column supporting an axial current. While there are several differences with the usual model for solar coronal loops [see (Tsypin and Galvão, 2005) and references therein], most obviously the presence of gravity and the curvature of the column, we will neglect such effects in order to get at the root of the magnetization problem. Application to axial experimental configurations (Carter and Maggs, 2009;Palmer and Walker, 2009) is apparent.…”