Fusion is the energy process that powers the Sun, and hence the ultimate source of all renewable energy.  If realised directly on Earth however, fusion energy promises baseload electricity generation with zero greenhouse gas emissions, a virtually inexhaustible supply of fuel, and significantly reduced radioactive waste, compared to fission and coal. 

In nature, fusion occurs in dense regions of vast stellar interior plasmas.  These conditions are not reproducible on Earth.  Instead, the world’s fusion energy program focuses on magnetic confinement, in which closed magnetic field lines form donut shaped plasmas.  To date, the leading contender along this path is the toroidally symmetric tokamak.  Such devices, while exhibiting good particle confinement and high temperatures are complex machines which require a large toroidal current to create the confining field.  This large current can also drive instabilities that may lead to disruption.

A dipole is a simpler alternative magnetic confinement configuration that produces closed field lines.  Dipole fields are common in nature, and are either constructed by a planetary dynamo (such as the Earth) or by currents in an accretion disc.  In the laboratory a dipole field can be constructing by levitating a superconducting magnetic coil. A challenge along this path is creating and sustaining a current while maintaining cryogenic conditions to sustain the superconducting state.

Recently however, a NZ start-up company OpenStar has designed and is presently building a superconducting dipole in Wellington.  This project would compute the field by solving the Grad-Shafranov equation (the governing equation for the magnetic field) out to the vacuum vessel, and compute particle orbits and confinement.