m / n = 1 / 1 mode behavior during sawtooth activity in LHCD plasmas on the HT-7 tokamak

• Published in: Physics letters. A Vol. 361; no. 1; pp. 136 - 140
• Main Authors: Ma, T.P., Hu, L.Q., Wan, B.N., Sun, Y.W., Chen, K.Y.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 22.01.2007
• Subjects: [formula omitted] mode; Grow rate of magnetic island; Soft X-ray tomography; 52.55.Fa; Soft X-ray tomography; Grow rate of magnetic island; 52.35.Py; 52.70.La; m / n = 1 / 1 mode; 52.55.Tn
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2006.09.097

Different types of m / n = 1 / 1 mode during the central relaxation oscillations are observed in lower hybrid current drive (LHCD) plasma on the HT-7 tokamak. In this Letter, the difference of the mid-mode and the precursor on the sawtooth oscillation are reported using two-dimensional tomography of soft X-ray signal. It is shown that the growth rate of magnetic island of the mid-oscillation is smaller than that of the precursor oscillation, and the hot core in the mid-oscillation case does not move outward to the vicinity of the q = 1 surface. However, in the precursor oscillation case, the colder plasma develops a magnetic island on the former magnetic axis after the hot core expulsion, from the contour map of the soft X-ray emissivity.