In this paper, we describe the behavior of impurity transport in the HL-2A electron cyclotron resonance heating （ECRH） L-mode plasma. The neon as a trace impurity is injected by the supersonic molecular beam injecti...In this paper, we describe the behavior of impurity transport in the HL-2A electron cyclotron resonance heating （ECRH） L-mode plasma. The neon as a trace impurity is injected by the supersonic molecular beam injection （SMBI） technique, which is used for the first time to study the impurity transport in HL-2A. The progression of neon ions is monitored by the soft X-ray camera and bolometer arrays with good temporal and spatial resolutions. The convection and diffusion process of the neon ions are investigated with the one-dimensional impurity transport code STRAHL. The results show that the diffusion coefficient D of neon ions is a factor of four larger than the neoclassical value in the central region. The value of D is larger in the outer region of the plasma （ρ 〉 0.6） than in the central region of the plasma （ρ 〈 0.6）. The convective velocity directs inwards with a value of ～-1.0 m/s in the Ohmic discharge, but it reverses to direct outwards with a value of ～ 8.0 m/s in the outer region of the plasma when ECRH is applied. The result indicates that the impurity transport is strongly enhanced with ECRH.展开更多
Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical（GO） ray tubes,they are very inefficient in many practical applications.An improved ray model scheme for a ...Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical（GO） ray tubes,they are very inefficient in many practical applications.An improved ray model scheme for a complex source beam（CSB） tracking technique is proposed in this paper.The source field can be expressed by a superposition of CSBs,then every CSB basis function has a Gaussian-type amplitude distribution and is suitable for replacing a GO ray tube in the ray tracing approach.The complex phase matching technique is adopted to find the reflected beam in the reflection point where local approximation is used to represent the curved surface in its neighborhood.A new solution to multiple reflections using the conventional right-handed reflected system is used to track the field easily.Numerical results show the accuracy of the proposed method.展开更多
Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illumi...Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illuminated charge-coupled device （CCD） and a laser light source for optical alignment. Spectral lines in wavelength region of 20-500 A observed from HL-2A plasmas were analyzed to study the impurity behavior. Spectral and temporal resolutions used for the analysis were 0.19A at CV （2×33.73 ,h,） and 6 ms, respectively. It was found that carbon, oxygen and iron impurities were usually dominant in the HL-2A plasma. They almost disappeared when the siliconization was carried out. Although the EUV spectra were entirely replaced by the silicon emissions just after the siliconization, the emissions were considerably decreased with accumulation of discharges. Aluminum and neon were externally introduced into the HL-2A plasma based on laser blow-off （LBO） and supersonic molecular beam injection （SMBI） techniques for a trial of the impurity transport study, respectively. The preliminary result is presented for time behavior of EUV spectral lines.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10975048,11175061,and 10975049)
文摘In this paper, we describe the behavior of impurity transport in the HL-2A electron cyclotron resonance heating （ECRH） L-mode plasma. The neon as a trace impurity is injected by the supersonic molecular beam injection （SMBI） technique, which is used for the first time to study the impurity transport in HL-2A. The progression of neon ions is monitored by the soft X-ray camera and bolometer arrays with good temporal and spatial resolutions. The convection and diffusion process of the neon ions are investigated with the one-dimensional impurity transport code STRAHL. The results show that the diffusion coefficient D of neon ions is a factor of four larger than the neoclassical value in the central region. The value of D is larger in the outer region of the plasma （ρ 〉 0.6） than in the central region of the plasma （ρ 〈 0.6）. The convective velocity directs inwards with a value of ～-1.0 m/s in the Ohmic discharge, but it reverses to direct outwards with a value of ～ 8.0 m/s in the outer region of the plasma when ECRH is applied. The result indicates that the impurity transport is strongly enhanced with ECRH.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61301056 and 61231001)the Fundamental Research Funds for the Central Universities,China(Grant No.ZYGX2014J012)+2 种基金the Fok Ying Tung Education Foundation,China(Grant No.141062)the Aero-Science Fund,China(Grant No.20142580012)the"111"Project(Grant No.B07046)
文摘Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical（GO） ray tubes,they are very inefficient in many practical applications.An improved ray model scheme for a complex source beam（CSB） tracking technique is proposed in this paper.The source field can be expressed by a superposition of CSBs,then every CSB basis function has a Gaussian-type amplitude distribution and is suitable for replacing a GO ray tube in the ray tracing approach.The complex phase matching technique is adopted to find the reflected beam in the reflection point where local approximation is used to represent the curved surface in its neighborhood.A new solution to multiple reflections using the conventional right-handed reflected system is used to track the field easily.Numerical results show the accuracy of the proposed method.
基金supported partially by National Natural Science Foundation of China(Nos.11175061 and 11375057)the JSPS-NRF-NSFC A3Foresight Program in the field of Plasma Physics(NSFC:No.11261140328)
文摘Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illuminated charge-coupled device （CCD） and a laser light source for optical alignment. Spectral lines in wavelength region of 20-500 A observed from HL-2A plasmas were analyzed to study the impurity behavior. Spectral and temporal resolutions used for the analysis were 0.19A at CV （2×33.73 ,h,） and 6 ms, respectively. It was found that carbon, oxygen and iron impurities were usually dominant in the HL-2A plasma. They almost disappeared when the siliconization was carried out. Although the EUV spectra were entirely replaced by the silicon emissions just after the siliconization, the emissions were considerably decreased with accumulation of discharges. Aluminum and neon were externally introduced into the HL-2A plasma based on laser blow-off （LBO） and supersonic molecular beam injection （SMBI） techniques for a trial of the impurity transport study, respectively. The preliminary result is presented for time behavior of EUV spectral lines.
