Impurity behavior and energy balance on CTCC-spheromak

In CTCC spheromak experiment, a coaxial gun produces initial plasma and ejects in into a confinement region surrounded by metal wall where magnetic flux is conserved, i.e. Flux Conserver (FC). A time of production is only about 0.1 ms and a extinction time of the plasma is about 1.5 ms. There is no supply of energy to spheromak during this duration, and there is scarcely any occurrence of ruinously global instabilities, except for a intermittent instability (stepwise instability). Then spheromak is gradually decaying due to its own resistivity. The present plasma have been studied experimentally from view point of impurity behavior and the physical process about the temporal behavior of the spheromak have been also clarified by the use of zero dimensional energy balance model. (author)