Determination of electron and ion thermal conductivities by analysis of Alcator-A profile data

Profile data from the Alcator-A tokamak are analyzed using the onetwo transport code to study thermal conductivities and power balance. It is found that the observed central ion temperatures can be explained by assuming an ion thermal conductivity equal to the neoclassical value as calculated recently by Bolton and Ware. For low density, n̄=1×1014 cm−3, the possible anomaly in the ion conductivity is small: ±30% of the Bolton–Ware value. The anomalous electron thermal conductivity as deduced from the profile data is 〈Kexpe〉=〈nχexpe〉 ≂2.5(±1.5)×1017 cm−1 sec−1. The power balance study shows that at low densities, electron energy losses from radiation and thermal conduction are equally important, and both are larger than the exchanges loss to the ions. At higher densities, n̄≥2×1014 cm−3, electron energy losses by thermal conduction and exchange are equally important, and both are larger than the radiation loss. Convective losses, as calculated from measured particle confinement times, are negligible for all densities analyzed.