A new interactive tool to propagate magnetic flux ropes in the heliosphere!

What the tool does:

you specify a set of parameters to initialise the structure near the Sun (3-D orientation, poloidal magnetic flux, strength of confinement field),

the tool will generate a magnetic flux rope in 3-D and propagate the structure from the Sun to any point in the inner heliosphere (takes 4 minutes at most), it will compute the elongation-variation of the flux rope on a J-map,

you specify a target and if the magnetic structure passes over that target, the tool will compute the in-situ signature of the flux rope at that target,

you can check that a flux rope was indeed measured in situ by directly accessing from the tool the CDPP database or that a CME erupted near the Sun by accessing imagery data at MEDOC.

Some theoretical background…
The basic forces and instabilities acting on a plasma embedded in a toroidal magnetic field have been studied since the seminal papers by Shafranov (1966) and Bateman (1978). Bending a cylindrical screw pinch into a torus generates a set of toroidal forces (hoop, tire-tube and 1/R forces) directed outwardly along the major radius of the toroid. Xue and Chen (1983) and Chen (1989) proposed that these toroidal forces provides the necessary mechanism for CME to accelerate in the solar corona and overcome the confining coronal field as well as the gravitational force. For the sake of mathematical simplicity, the geometries used by Chen (1989) and following workers assumed either an exponential or else linear rise of the variation of minor-axis length from the footpoint to the apex of the varying cross-sectional area of the toroid. For a circular toroidal current axis, this leads to discontinuities in the variation of the flux surfaces near the apex of the CME. To obtain a topologically more realistic 3-D magnetic field lines, we modified the assumed geometry (Figure 1) and derived a new analytical formulation of both the inductance and the 3-D magnetic field. We model the forces acting on the flux rope erupting in the corona: they include the toroidal forces, the effect of the confining field, the gravitational force and the drag force. As CMEs erupt in the corona they sweep up coronal material and their mass increases, we included this ‘snow-plow’ effect by using a simple analytical formulation based on the observational study of Feng et al. (2015). Like Chen (1989), we inject poloidal magnetic field that we convert into toroidal current (to compute the toroidal forces) using the inductance approach (Shafranov 1966).

Contacts: Alexis Rouillard, Michael Lavarra, Anthony Bourdelle, Valbona Kunkel, Nicolas Dufourg, Myriam Bouchemit