Electron Heat Diffusivity in the HT-7 Tokamak with Si-Coating Wall

Electron heat diffusivity inferred from the electron power balance was studied in the ohmically heated plasma on an HT-7 tokamak. The results obtained before and after siliconization were compared and it is found that the diffusivity is reduced obviously in the half of the outer region (r/a > 0.5) after siliconization, which was the reason why energy confinement was improved after siliconization.