Neoclassical transport in the CHS device and its outlook for improvement

The 1/upsilon neoclassical transport is computed for the standard, the drift-orbit-optimized and the quasi-axisymmetric: versions of CHS. For the computations, a new method is used which is based on the integration along magnetic field lines. The calculations show the advantage of the quasi-axisymmetric CHS configuration over the standard configuration resulting in a reduced 1/upsilon transport. It is shown that also for the drift-orbit-optimized configuration the 1/upsilon transport is reduced; however, by a smaller amount than for the quasi-axisymmetric configuration.