Neoclassical Aspects of Transport in ITER Plasmas with High Axial Safety Factors

The neoclassical bootstrap current, parallel electrical resistivity and radial particle and heat transport properties are examined for a reference ITER low current plasma with elevated axial safety factor, q(0), and reverse shear, q′ < 0. The results are compared with two other reference cases at full current and differing plasma profiles. In each of the cases it is found that higher Z impurities are fairly robustly expelled from the core by ion temperature gradient screening, although the screening is weaker in the high q(0) plasma because of its lower collisionality. The bootstrap current is strongly enhanced in the high q(0) case as expected. Potato orbits do not significantly modify the results.