QPS Confinement and Transport
Abstract
Quasi-poloidal symmetry is a new approach to stellarator confinement optimization that we have used to design very low plasma aspect ratio configurations ( < R > / < a > ~ 2.6 , 1/2 - 1/4 that of existing stellarators). An experiment, the Quasi-Poloidal Stellarator (QPS), is being developed to test the main features of this approach. QPS has < R > = 0.9 m , < a > = 0.35 m , < B0 > = 1 T for a 0.5-s pulse, and P_heating = 1-3 MW . An important criterion for our optimization has been to achieve sufficiently low levels of neoclassical transport so that the dominant losses are from anomalous transport. A number of recently developed transport tools have been used to evaluate confinement in this configuration. These include: the DKES transport coefficient code, the DELTA5D Monte Carlo model, and several 0-D and 1-D models. We will apply these models to the QPS configuration and discuss neoclassical properties of the various transport regimes. In addition to perpendicular transport, the parallel transport properties (bootstrap current, neoclassical resistivity enhancement) are also important since this device relies on plasma current to supply a fraction of its rotational transform. Bootstrap current has been calculated using both the DKES and Monte Carlo approaches as well as using an asymptotic low collisionality calculation.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2001
- Bibcode:
- 2001APS..DPPCP1047S