fusion Theory & Computation

LDX and Innovative Concepts

There are three fundamental magnetic field configurations that have been utilized for magnetic plasma confinement: configurations. They posses either irrational flux surfaces (i.e. tokamak, stellarator), open magnetic field lines (i.e. magnetic mirror), or closed magnetic field lines (i.e. dipole, Z-pinch, octopole). The focus of research worldwide has been on tokamak devices. Closed field line systems have received much less attention; however, they possess several uniquely useful properties including the possibility of confinement of high beta plasmas with low turbulent transport, and confinement in a steady state configuration created by a small number of non-interlocking coils.

The confinement of plasma by the dipole magnetic field produced by a levitated superconducting ring offers a new and unorthodox approach to magnetic confinement. This approach was first suggested by Hasegawa who was inspired by observations of the confinement of high beta plasma in the Jovian magnetosphere. MIT, in collaboration with Columbia University has pioneered the early conceptual development in the dipole approach and the first physics exploration experiment the Levitated Dipole Experiment (LDX) has been built and is operating at the PSFC as a MIT/Columbia collaboration.

Examples of recent accomplishments:
* Developed a complete description of resistive MHD modes in dipoles
* Full treatment of hot electron effects on stability in closed field line geometry
* Analyzed fusion power by a helium catalyzed D-D fuel cycle in dipoles
* Developed a resistive MHD transport model for a reversed field pinch

Representative current research topics:
* Apply the full treatment of hot electron interchange effects on stability to LDX
* MHD stability and transport predictions of beta and confinement time in LDX
* Large aspect ratio Grad-Shafranov equilibria to the predict heat load on the LDX coil
* Non-linear dipole simulations of convective flows in LDX using NIMROD

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