Perturbative experiments on electron heat transport have been successfully conducted on the HL-2A tokamak.The pulse propagation of the electron temperature is induced by the supersonic molecular beam injection (SMBI),which has characteristics of good localization and deep deposition.A model based on the electron heat transport in cylindrical geometry has been applied to reconstruct the measured amplitude and phase profiles of the electron temperature perturbation.The results show that the heat transport is significantly reduced near the pedestal region of the H-mode plasma.In the "profile stiffness/resilience" region,similar heat diffusivities have been observed in L-mode and H-mode plasmas,which verifies the gradient-driven transport physics in tokamaks.
