Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak

• 来源期刊: 中国物理（英文版）
• 关键词: soft x-ray tomography magnetohydrodynamic oscillation singular value decomposition
• 年，卷（期）: 2006,（3）
• 页码范围: 593-599
• 页数: 7页
• 语种: 英文

摘要

Multi-channel soft x-ray (SX) detectors are applied to generate images of magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data from SX cameras are analysed by using the Fourier Bessel harmonic reconstruction method and the singular value decomposition. The image reconstruction of SX emissivity is obtained on the assumption of plasma rigid rotation. One of the important phenomena in the HT-7 discharge is the transition from the sawtooth oscillations to the MHD oscillations when the plasma density grows higher. The MHD structure observed in the SX tomography is featured as follows: the magnetic surface of MHD structure is made up of the crescent-shaped "hot core" and the circular "cold bubble" . The structure of the magnetic surface is relatively stable. It rotates in the direction of the electron diamagnetic drift at a frequency being the oscillation frequency of the MHD oscillations.