Transport of runaway electrons in sawtooth active plasmas in the HT-7 tokamak

The magnetic fluctuation level is an important parameter in lower hybrid current-drive (LHCD) plasmas because LHCD has been used to improve plasma performance extensively in the HT-7 tokamak. We investigate the transport of runaway electrons in LHCD plasmas with strong sawteeth in the HT-7 tokamak. A delay time was found to exist between the peak of the soft X-ray sawteeth and the peak of the hard X-ray flux. Based on the delay time, we obtained the transport coefficient of the runaway electrons and the averaged magnetic fluctuation level in sawtooth activity of the plasmas. We found that the diffusion coefficient of the runaway electrons was on the order of D (r) similar to 1 m(2)s(-1) and that the magnetic fluctuation level was on the order of bI integral similar to 10(-6).