# ForceFreeFluxRope

class plasmapy.plasma.cylindrical_equilibria.ForceFreeFluxRope(B0, alpha)[source]

Bases: object

Representation of the analytical Lundquist solution for force-free magnetic flux ropes .

Parameters:

Notes

The Lundquist solution [also known as the Bessel Function Model (BFM)] is a cylindrically symmetric force-free equilibrium which is often used to approximate the magnetic structure of interplanetary coronal mass ejections (ICMEs).

Methods Summary

 Compute the total magnetic field. Compute the component of the magnetic field in the azimuthal direction. Compute the axial component of the magnetic field.

Methods Documentation

B_magnitude(r)[source]

Compute the total magnetic field.

The magnitude of the magnetic field is given by

$B(r) = \sqrt{B_z(r)^2 + B_θ(r)^2}.$
Parameters:

r (Quantity) – Radial distance from flux rope axis in units convertible to meters.

Return type:

Quantity

B_theta(r)[source]

Compute the component of the magnetic field in the azimuthal direction.

$B_θ(r) = B_0 J_1(α r)$

where $$α$$ is the eigenvalue and $$J_1$$ is the Bessel function of the first kind of order 1.

Parameters:

r (Quantity) – Radial distance from flux rope axis in units convertible to meters.

Return type:

Quantity

B_z(r)[source]

Compute the axial component of the magnetic field.

$B_z(r) = B_0 J_0(α r)$

where $$α$$ is the eigenvalue and $$J_0$$ is the Bessel function of the first kind of order 0.

Parameters:

r (Quantity) – Radial distance from flux rope axis in units convertible to meters.

Return type:

Quantity