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Spheromak Equilibrium Studies

Immediately following formation, the Spheromak is not in an equilibrium state: the field and pressure profiles imposed by the gun are unstable. After formation, the fact that the plasma is a resistive (not perfect) conductor allows the fields embedded in it at startup to 'relax' to a state of lower energy. The resistivity of the plasma means oscillations will be damped, so that the relaxation will tend towards a steady state, or equilibrium between the forces of plasma pressure and magnetic field.

Experiments on SSX over the last year have explored this equilibrium state and the form it takes. A time-resolved fit of models to data determined which theoretical models best fit the data at successive time steps, and whether the spheromak evolved over its lifetime. This gave an indication of the importance of various forces in the determining the equilibrium. Data seem to indicate that the predominant factor is current distribution, in accordance with a nonconstant-lambda force free model with small pressure effects.

For more detailed results and more explanation, please refer to one or all of the following (level of physics indicated for each):

This project is now concluded, and reconnection experiments are underway.

Cameron Geddes / 180796 /