In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics （MD） method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble...In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics （MD） method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals.展开更多
Although the deuterium and helium have almost the same mass,a Penning Optical Gas Analyzer（POGA） system on the basis of the spectroscopic method and Penning discharging has been designed on EAST,since 2014.The POGA ...Although the deuterium and helium have almost the same mass,a Penning Optical Gas Analyzer（POGA） system on the basis of the spectroscopic method and Penning discharging has been designed on EAST,since 2014.The POGA system was developed successfully in 2015,it was the first time that EAST could detect helium partial pressure in deuterium plasma（wall conditioning and plasma operation scenario）.With dedicated calibration and proper adjustment of the parameters,the minimum concentration of helium in deuterium gas can be measured as about 0.5% instead of 1% on the other tokamak devices.Moreover,the He and D2 partial pressures are measured simultaneously.At present,the measurable range of deuterium partial pressure is 1×10^-7 mbar to 1×10^-5mbar,meanwhile the range of helium is 1×10^-8 mbar to 1×10^-5 mbar.The measurable range can be modified by means of the adjustment of POGA system＇s parameters.It is possible to detect the interesting part of the gas with a time resolution of less than 5 ms（the 200 ms because of conductance of transfer pipe at present）.The POGA system was routinely employed to wall conditioning and helium enrichment investigation in2015.Last but not the least,the low temperature plasma of POGA is generated by normal penning gauge Pfeiffer IKR gauge instead of Alcatel CF2 P,which has been suspended for a few years and was used for almost all the POGA systems in the world.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10775101)National Magnetic Confinement Fusion Program of China (Grant No. 2009GB106004)
文摘In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics （MD） method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals.
基金funded by National Magnetic Confinement Fusion Science Program of China under Contract No.2013GB114004,No.2014GB106005 & No.2015GB101000National Nature Science Foundation of China under Contract No.11625524,No.11321092 and No.11405210partly supported by the Japan Society for the Promotion of ScienceNational Research Foundation of Korea-National Science Foundation of China(JSPS-NRF-NSFC) A3 Foresight Program in the field of Plasma Physics(NSFC No.11261140328)
文摘Although the deuterium and helium have almost the same mass,a Penning Optical Gas Analyzer（POGA） system on the basis of the spectroscopic method and Penning discharging has been designed on EAST,since 2014.The POGA system was developed successfully in 2015,it was the first time that EAST could detect helium partial pressure in deuterium plasma（wall conditioning and plasma operation scenario）.With dedicated calibration and proper adjustment of the parameters,the minimum concentration of helium in deuterium gas can be measured as about 0.5% instead of 1% on the other tokamak devices.Moreover,the He and D2 partial pressures are measured simultaneously.At present,the measurable range of deuterium partial pressure is 1×10^-7 mbar to 1×10^-5mbar,meanwhile the range of helium is 1×10^-8 mbar to 1×10^-5 mbar.The measurable range can be modified by means of the adjustment of POGA system＇s parameters.It is possible to detect the interesting part of the gas with a time resolution of less than 5 ms（the 200 ms because of conductance of transfer pipe at present）.The POGA system was routinely employed to wall conditioning and helium enrichment investigation in2015.Last but not the least,the low temperature plasma of POGA is generated by normal penning gauge Pfeiffer IKR gauge instead of Alcatel CF2 P,which has been suspended for a few years and was used for almost all the POGA systems in the world.
