Parametric scaling studies of radiofrequency and neutral beam heated currentless Heliotron E plasmas have been performed. The parametric local electron transport analyses show that the electron energy transport in electron cyclotron heating (ECH) plasmas is nearly of the same magnitude as the neoclassically predicted transport inside the 2/3 radius, while neutral beam injection (NBI) plasmas and plasmas in the ion cyclotron range of frequencies (ICRF) are dominated by anomalous electron transport in the entire region. Scaling studies on the global energy confinement time reveal that ECH, NBI and ICRF plasmas obey approximately identical scalings that are characterized by continuous power degradation and favourable positive density dependence. The global energy confinement time is thought to be affected by the anomalous transport in the peripheral plasma regions in the same way for ECH, NBI and ICRF plasmas although the core plasma properties – such as local electron transport – seem to be different for the individual plasmas.
Thermal energy confinement scaling in PDX limiter discharges