Evolution of turbulence and transport in EAST H-mode plasmas with Te/Ti~1

The enhanced heat transport in ion channel is observed as the temperature ratio T e /T i increased from 1.0 to 2.2 in Experimental Advanced Superconducting Tokamak (EAST) H-mode plasmas. Electron cyclotron resonance heating (ECRH) was applied to modulate T e /T i within the range T e /T i ≥1 expected for ITER where electron heating is dominant. The ONETWO code presents increased ion thermal diffusivity. Trapped-Gyro–Landau-Fluid (TGLF) and Numerical Lie Transform (NLT) simulations imply the development of TEM together with the reduction of ITG as T e /T i increases. The reduction of ITG driven turbulence was supported by weakened density fluctuations measured by the poloidal correlation reflectometer (PCR). Conversely, after the removal of ECRH power, the behavior of turbulence also reverses. When T e /T i reduces following the removal of ECRH power, PCR shows enhanced density fluctuations. The results from upgraded Thomson scattering diagnostics (CTS) shows simultaneously enhanced low-k (k~5cm -1 ) fluctuations and weakened intermediate-k (k~20cm -1 ) fluctuations as T e /T i decreases. This study broadens the comprehension of evolution of turbulence and ion heat transport within the temperature ratio range T e /T i ≥1, which is likely to occur in future tokamak like ITER.