QPS confinement and transport

Quasi-poloidal symmetry is a new approach to stellarator confinement optimization that we have used to design very low plasma aspect ratio configurations (/□ ∼ □ 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 0.9 m, □ = 0.35 m, □ = 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/improved tools have been used to evaluate both perpendicular and parallel transport properties (bootstrap current, neoclassical resistivity enhancement) in this device. 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 the neoclassical properties of the various transport regimes it can access. Copyright (2002) Australian National University- Research School of Physical Sciences and Engineering