Fourier analysis of sawtooth heat pulse propagation in the HL-1 tokamak plasma

A recently proposed method for Fourier analysis of sawtooth heat pulse propagation is applied to the HL-1 data. Not only can the method be used to calculate the incremental heat diffusivity, but also to obtain information on the amplitude and the phase of harmonics involved. A comparison with other method shows good agreement between the heat diffusivity determined by the arrival time of peak and estimated by using energy confinement scaling. An isotope effect of improving confinement in the HL-1 tokamak has also been observed