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
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
The structures of three operating regions in HT-6B Tokamak have been studied by soft X-ray tomo-graphic system with high sensibility and high time-space resolution. One of the requisites for forming sawtooth discharge...The structures of three operating regions in HT-6B Tokamak have been studied by soft X-ray tomo-graphic system with high sensibility and high time-space resolution. One of the requisites for forming sawtooth discharge is the effective heating action in the central region. In the sawtooth region there are five evolutional phases and five types of magnetic surface structures correspondingly; that is, the concentric, the eccentric, the double-core, the 'MHD-type' and the 'ultra-MHD type' magnetic surface structures. In the MHD oscillation region, there is a stable 'MHD-type' magnetic surface structure. It consists of a crescent 'hot core' and a circular 'cold bubble' and rotates in the diamagnetic direction of electrons. In the resonant region, the resonant helical field improves the heating status and suppresses the MHD disturbances; therefore the single 'MHD-type' magnetic surface changes into a sawtooth type one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
随着电子产品性能日益增强,在生产与技术研究中对其电源系统的性能要求也愈来愈高,如DC/DC开关电源的PWM控制电路中,锯齿波振荡电路起着关键性的作用。以电压比较器为核心电路,引入了恒流源充放电、低电源抑制比的基准电压源,设计了一...随着电子产品性能日益增强,在生产与技术研究中对其电源系统的性能要求也愈来愈高,如DC/DC开关电源的PWM控制电路中,锯齿波振荡电路起着关键性的作用。以电压比较器为核心电路,引入了恒流源充放电、低电源抑制比的基准电压源,设计了一种基于0.33μm互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)工艺的锯齿波振荡电路,并运用Cadence Spectres仿真工具对其进行设计验证。结果表明,该锯齿波振荡电路在一定的电源电压和温度范围内,工作性能较好,频率稳定,可广泛应用于PWM控制电路。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.
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.
文摘The structures of three operating regions in HT-6B Tokamak have been studied by soft X-ray tomo-graphic system with high sensibility and high time-space resolution. One of the requisites for forming sawtooth discharge is the effective heating action in the central region. In the sawtooth region there are five evolutional phases and five types of magnetic surface structures correspondingly; that is, the concentric, the eccentric, the double-core, the 'MHD-type' and the 'ultra-MHD type' magnetic surface structures. In the MHD oscillation region, there is a stable 'MHD-type' magnetic surface structure. It consists of a crescent 'hot core' and a circular 'cold bubble' and rotates in the diamagnetic direction of electrons. In the resonant region, the resonant helical field improves the heating status and suppresses the MHD disturbances; therefore the single 'MHD-type' magnetic surface changes into a sawtooth type one
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.
文摘随着电子产品性能日益增强,在生产与技术研究中对其电源系统的性能要求也愈来愈高,如DC/DC开关电源的PWM控制电路中,锯齿波振荡电路起着关键性的作用。以电压比较器为核心电路,引入了恒流源充放电、低电源抑制比的基准电压源,设计了一种基于0.33μm互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)工艺的锯齿波振荡电路,并运用Cadence Spectres仿真工具对其进行设计验证。结果表明,该锯齿波振荡电路在一定的电源电压和温度范围内,工作性能较好,频率稳定,可广泛应用于PWM控制电路。
