Impurity Radiation and Energy Balance in Field Reversed Configurations
The impurity radiation and energy balance for Field Reversed Configurations (FRCs) formed in the Large s Experiment (LSX) are studied. A newly developed silicon bolometer is used to measure the radiative energy losses. A first burnthrough peak and a subsequent lower radiation stage (typically 20-100 MW), present during the equilibrium/decay phase of the FRC, are observed. The total radiation is then related to the D_2 fill pressure and compared with spectroscopic measurements and existing radiation models. The radiative energy losses can be explained by a fixed amount of impurities present in the plasma. A new 1-D numerical model is used to study the energy balance for the FRCs. This 1-D model incorporates most of the confinement properties directly from the experiment. This allows the effects of the electron thermal conduction and the influence of the edge layer confinement to be studied. Results are presented showing that with theoretically reasonable edge confinement properties the electron collisionality governing electron thermal conduction is not far (within an order of magnitude) from that governing particle diffusion. While the electron energy losses are partitioned between conduction and convection, the ion losses are dominated by particle convection. The radiative losses become increasingly important as the overall confinement of the FRC improves.
- Pub Date:
- LARGE S EXPERIMENT;
- Physics: Fluid and Plasma