Response of bootstrap current and electron thermal conductivity to shaping in an ECRH plasma in the CHS heliotron/torsatron

The bootstrap current and electron thermal conductivity have been investigated in ECRH plasmas on the CHS heliotron/torsatron. The neoclassical transport coefficients have been externally controlled over a wide range by changing the ellipticity of the plasma cross-section. While local thermal conductivity, as well as global confinement, have shown inconsistency with the neoclassical predictions, the observed toroidal net current has been successfully explained by considering the three dimensional geometry with the available neoclassical theory. The present experimental results indicate that the transport parallel to the magnetic field lines (bootstrap current) is likely to be neoclassical but that the perpendicular transport (thermal conductivity) is anomalous, which is common in current less plasmas as well as tokamaks.