Method for creating a three-dimensional magnetic null point topology with an accurate spine axis

Area of Science:

• Plasma Physics
• Magnetohydrodynamics
• Magnetic Field Generation

Background:

• Three-dimensional magnetic null points (3D nulls) are crucial for understanding plasma dynamics in astrophysical and laboratory settings.
• Previous methods for generating 3D nulls with coils produced fields that deviated from ideal mathematical forms away from the central null.

Purpose of the Study:

• To develop an algorithm for precisely controlling magnetic fields to create a mathematically pure spine axis in 3D null topologies.
• To investigate the adaptability of this method to various coil configurations and its limitations.

Main Methods:

• An inverse problem-solving approach was used to determine unique current modulations for axially-aligned circular coils.
• The algorithm was tested on spherical, cylindrical, and cone-shaped coil assemblies.
• Vector magnetic field mapping was employed to verify the accuracy of the generated magnetic field topology.

Main Results:

• The algorithm successfully generates a mathematically pure spine axis along the entire length of the coil assembly.
• Magnetic field accuracy is well-maintained along the spine but decays toward the outer edges of the fan plane.
• The method demonstrated effectiveness across diverse coil geometries.

Conclusions:

• A novel inverse method allows for the precise generation of 3D null spine axes using modulated coil currents.
• This technique offers a significant improvement over previous methods in maintaining field purity.
• The inverse method is versatile and applicable to generating other theoretical magnetic field forms along an axis.