| Popis: |
The spheromak, as a compact toroidal magnetic fusion device, offers substantial advantages as a fusion reactor concept over larger, more complicated, and more costly devices such as the tokamak. The very definite advantages associated with the simply closed geometry, minimized external coil requirements and the possibility of ohmic ignition in the spheromak, represent a substantial improvement over conventional magnetic fusion reactor designs. Furthermore, recent successes in improving confinement parameters (Te~400 eV, Ti~1 keV, ne~5*1014 cm-3, B~1 T) have renewed interest in advancing this concept to a proof of principle, reactor prototype stage. Herein, the initial work by Fowler et al. (Comments Plasma Phys. Control. Fusion 16 (1994) 91), indicating the possibility of ohmic ignition in spheromaks, is extended to a two fluid model that includes direct ion heating. Non-ohmic magnetic dissipation, contributing to direct ion heating, and confinement scaling are quantified through comparison with the latest results from the gun driven Compact Torus Experiment (CTX) spheromak (Phys. Fluids B 2 (1990) 1342). Excellent agreement is demonstrated between experimentally measured plasma parameters and our model predictions. Extrapolation to ignition experiments and reactor relevant conditions is discussed, indicating the possibility of reaching these conditions by gun driven ohmic heating alone and illustrating the merits of direct ion heating. Conservative to pessimistic confinement estimates are used throughout so as to ensure that the promise offered by this concept does not presume unrealizable improvements in energy containment |
