It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional （2D） images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmo...It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional （2D） images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmonic reconstruction method, and using the singular value decomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation. Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasiinterchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows： the magnetic surface is made up of the crescent-shaped “hot core” and the circular “cold bubble”. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.展开更多
The investigation of runaway electrons is expanded by different methods. The aim of this study is to show sawtooth oscillations of hard x-ray emission and with the help of sawtooth oscillations to obtain radial diffus...The investigation of runaway electrons is expanded by different methods. The aim of this study is to show sawtooth oscillations of hard x-ray emission and with the help of sawtooth oscillations to obtain radial diffusion coefficient and magnetic fluctuations. In the same way, the hard x-ray spectral evaluation is compared in several time intervals and it is shown that during discharge, the energy of the runaway electrons is less than 200？keV. Also, for typical plasmas, population of runaway electrons is measured at seven time intervals of 5ms and temporal evaluation of runaway electron mean energy. The sawtooth-like shape is observed in the hard x-ray range （10–1000？keV）. By the sawtooth oscillation method, the RE diffusion coefficient in radial transport in the IR-T1 plasma is Dr～0.5Dr～0.5m^2s^-1. The magnetic field fluctuation due to magnetic diffusion DmDm is given as br/Bt～10^-4.展开更多
Tomographic reconstructions of soft x-ray emissivity in the HT-7 tokamak have been obtained using 86 miniature soft-x-ray detectors. Because there are two-detector arrays which are distributed in horizontal and vertic...Tomographic reconstructions of soft x-ray emissivity in the HT-7 tokamak have been obtained using 86 miniature soft-x-ray detectors. Because there are two-detector arrays which are distributed in horizontal and vertical directions on one poloidal plane, two-dimensional images of x-ray emissivity are obtained without having resort to a rotational model. The algorithm of Fourier-Bessel expansion was employed. The data analysed so far have been used principally to study MHD instabilities, and the illustrative examples of the sawtooth crash in IBW-heated plasma are described.展开更多
A single-channel far-infrared （FIR） laser interferometer was developed to measure the line averaged electron density on the EAST tokamak. The structure of the single-channel FIR laser interferometer is described in ...A single-channel far-infrared （FIR） laser interferometer was developed to measure the line averaged electron density on the EAST tokamak. The structure of the single-channel FIR laser interferometer is described in detail. The evolution of density sawtooth oscillation was measured by means the FIR laser interferometer, and was identified by electron cyclotron emission （ECE） signals and soft X-ray intensity. The discharges with and without sawtooth were compared with each other in the Hugill diagram.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10375070 and 10305012）.
文摘It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional （2D） images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmonic reconstruction method, and using the singular value decomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation. Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasiinterchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows： the magnetic surface is made up of the crescent-shaped “hot core” and the circular “cold bubble”. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.
文摘The investigation of runaway electrons is expanded by different methods. The aim of this study is to show sawtooth oscillations of hard x-ray emission and with the help of sawtooth oscillations to obtain radial diffusion coefficient and magnetic fluctuations. In the same way, the hard x-ray spectral evaluation is compared in several time intervals and it is shown that during discharge, the energy of the runaway electrons is less than 200？keV. Also, for typical plasmas, population of runaway electrons is measured at seven time intervals of 5ms and temporal evaluation of runaway electron mean energy. The sawtooth-like shape is observed in the hard x-ray range （10–1000？keV）. By the sawtooth oscillation method, the RE diffusion coefficient in radial transport in the IR-T1 plasma is Dr～0.5Dr～0.5m^2s^-1. The magnetic field fluctuation due to magnetic diffusion DmDm is given as br/Bt～10^-4.
文摘Tomographic reconstructions of soft x-ray emissivity in the HT-7 tokamak have been obtained using 86 miniature soft-x-ray detectors. Because there are two-detector arrays which are distributed in horizontal and vertical directions on one poloidal plane, two-dimensional images of x-ray emissivity are obtained without having resort to a rotational model. The algorithm of Fourier-Bessel expansion was employed. The data analysed so far have been used principally to study MHD instabilities, and the illustrative examples of the sawtooth crash in IBW-heated plasma are described.
基金National Natural Science Foundation of China(Nos.10475078,10675127,10675126,10675124,10605028)
文摘A single-channel far-infrared （FIR） laser interferometer was developed to measure the line averaged electron density on the EAST tokamak. The structure of the single-channel FIR laser interferometer is described in detail. The evolution of density sawtooth oscillation was measured by means the FIR laser interferometer, and was identified by electron cyclotron emission （ECE） signals and soft X-ray intensity. The discharges with and without sawtooth were compared with each other in the Hugill diagram.
