Ion heat transport in electron cyclotron resonance heated L-mode plasma on the T-10 tokamak

Abstract

Abstract Anomalous ion heat transport is analyzed in the T-10 tokamak plasma heated with electron cyclotron resonance heating (ECRH) on second harmonic extra-ordinary mode. Predictive modeling with empirical scaling for Ohmical heat conductivity shows that in ECRH plasmas the calculated ion temperature could be overestimated, so the increase of anomalous ion heat transport is required. To study this effect two scans are presented: over the EC resonance position and over the ECRH power. EC resonance position varies from high field side to low field side by variation of toroidal magnetic field. Scan over the heating power is presented with on-axis and mixed ECRH regimes. Discharges with high anomalous ion heat transport are obtained in all considered regimes. In these discharges power balance ion heat conductivity exceeds neoclassical level up to 10 times. High ion heat transport regimes are distinguished by three parameters: T e /T i ratio, normalized electron density gradient R/L n e , and ion-ion collisionality ν ii ∗ . Combination of high T e /T i , high ν ii ∗ , and R/L n e =6-10 results in values of normalized anomalous ion heat fluxes up to 10 times higher than in low transport scenario.