A refined reciprocating probe system was installed on the midplane of HL-2A tokamak. The system is developed in collaboration with the Institute of Scientific Instrument, Chinese Academy of Science in Shenyang.The sys...A refined reciprocating probe system was installed on the midplane of HL-2A tokamak. The system is developed in collaboration with the Institute of Scientific Instrument, Chinese Academy of Science in Shenyang.The system has been used to measure edge density, temperature, potential and their fluctuation profiles with 8 cm scan from scrapeoff layer to plasma boundary. The velocity of the reciprocating stroke is designed by 1 m ·s^-1.展开更多
Fast reciprocating probe systems （ FRPS ） are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these syste...Fast reciprocating probe systems （ FRPS ） are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these systems. The FRPS on HL-2A is developed, which is composed of transmission bar, digital grating displacement system, electromagnetic valves, stepping motor and so on. The high-pressure gas from the electromagnetic valves controlled by trigger signals provides the power to drive the transmission bar forward or backward. Reciprocating distance is 8 cm with the maximum speed of 1.5 m·s^-1.展开更多
As the basic of a deeper investigation on the turbulent transport, the fluctuation property in the boundary of the newly-reconstructed Joint Texas Experimental Tokamak （J- TEXT） is studied experimentally using the r...As the basic of a deeper investigation on the turbulent transport, the fluctuation property in the boundary of the newly-reconstructed Joint Texas Experimental Tokamak （J- TEXT） is studied experimentally using the reciprocating Langmuir four-tip probe, which has been built and operated as the primary diagnostic tool in the boundary of J-TEXT tokamak. In this paper, spatial profiles of the plasma-edge parameters are obtained, such as electron temperature, plasma density, plasma potential, poloidal electric field and their fluctuations. The results indicate the existence of a Er ×BT shear layer at the vicinity of last closed flux surface （LCFS）, with the fluctuations suppressed in varying degrees. The turbulence-induced particle and energy fluxes can be calculated by the local plasma parameters above. Convection dominates the cross-field turbulent transport in boundary plasma. Electrostatic fluctuations properties are also studied in detail with the help of numerical analysis. Statistical analysis on density fluctuation shows that, the intermittency can affect the turbulence in the scrape-off layer （SOL）.展开更多
As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the ...As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive （LHCD） wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron tempel：ature Te in the scrape-off layer （SOL） were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave （LHW） reflection. It was found that the power loss Ploss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Da emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential （Vf） had negative spikes corresponding with the Da signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.展开更多
文摘A refined reciprocating probe system was installed on the midplane of HL-2A tokamak. The system is developed in collaboration with the Institute of Scientific Instrument, Chinese Academy of Science in Shenyang.The system has been used to measure edge density, temperature, potential and their fluctuation profiles with 8 cm scan from scrapeoff layer to plasma boundary. The velocity of the reciprocating stroke is designed by 1 m ·s^-1.
文摘Fast reciprocating probe systems （ FRPS ） are widely used in some tokamaks, such as JT- 60 U, TEXT and DIlI-D. The parameters with high temporal-spatial resolution are measured for boundary plasmas using these systems. The FRPS on HL-2A is developed, which is composed of transmission bar, digital grating displacement system, electromagnetic valves, stepping motor and so on. The high-pressure gas from the electromagnetic valves controlled by trigger signals provides the power to drive the transmission bar forward or backward. Reciprocating distance is 8 cm with the maximum speed of 1.5 m·s^-1.
基金supported by Open Research Program from Key Laboratory of Geospace Environment, Chinese Academy of Sciences
文摘As the basic of a deeper investigation on the turbulent transport, the fluctuation property in the boundary of the newly-reconstructed Joint Texas Experimental Tokamak （J- TEXT） is studied experimentally using the reciprocating Langmuir four-tip probe, which has been built and operated as the primary diagnostic tool in the boundary of J-TEXT tokamak. In this paper, spatial profiles of the plasma-edge parameters are obtained, such as electron temperature, plasma density, plasma potential, poloidal electric field and their fluctuations. The results indicate the existence of a Er ×BT shear layer at the vicinity of last closed flux surface （LCFS）, with the fluctuations suppressed in varying degrees. The turbulence-induced particle and energy fluxes can be calculated by the local plasma parameters above. Convection dominates the cross-field turbulent transport in boundary plasma. Electrostatic fluctuations properties are also studied in detail with the help of numerical analysis. Statistical analysis on density fluctuation shows that, the intermittency can affect the turbulence in the scrape-off layer （SOL）.
基金supported by the National Magnetic Confinement Fusion Science Program of China (No. 2011GB107001)National Natural Science Foundation of China (Nos. 11075181, 10725523, 10721505, 10990212, 10605028)the ITER project of China (No. 2010GB104001)
文摘As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive （LHCD） wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron tempel：ature Te in the scrape-off layer （SOL） were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave （LHW） reflection. It was found that the power loss Ploss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Da emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential （Vf） had negative spikes corresponding with the Da signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.
