Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-a...Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-and L-shell partially ionized ions were successfully observed with sufficient spectral intensities and resolutions for helium, lithium, boron, carbon,oxygen, neon, silicon and argon using two fast-time-response EUV spectrometers of which the spectral intensities are absolutely calibrated based on the intensity comparison method between visible and EUV bremsstrahlung continua. The wavelength is carefully calibrated using wellknown spectra. The lithium, boron and silicon are individually introduced for the wall coating of the EAST vacuum vessel to suppress mainly the hydrogen and oxygen influxes from the vacuum wall, while the carbon and oxygen intrinsically exist in the plasma. The helium is frequently used as the working gas as well as the deuterium. The neon and argon are also often used for the radiation cooling of edge plasma to reduce the heat flux onto the divertor plate. The measured spectra were analyzed mainly based on the database of National Institute of Standards and Technology. As a result, spectral lines of He Ⅱ, Li Ⅱ–Ⅲ, B Ⅳ–Ⅴ, C Ⅲ–Ⅵ, O Ⅲ–Ⅷ, Ne Ⅱ–Ⅹ,Si Ⅴ–Ⅻ, and Ar Ⅹ–XVI are identified in EAST plasmas of which the central electron temperature and chord-averaged electron density range in Te0=0.6–2.8 keV and ne=(0.5–6.0)×1019 m-3, respectively. The wavelengths and transitions of EUV lines identified here are summarized and listed in a table for each impurity species as the database for EUV spectroscopy using fusion plasmas.展开更多
The core impurity confinement properties are experimentally investigated in the Experimental Advanced Superconducting Tokamak(EAST)plasma heated by lower hybrid wave(LHW)and electron cyclotron resonance heating(ECRH)(...The core impurity confinement properties are experimentally investigated in the Experimental Advanced Superconducting Tokamak(EAST)plasma heated by lower hybrid wave(LHW)and electron cyclotron resonance heating(ECRH)(LHW+ECRH).It is shown that the impurity confinement time(τ_(imp))in the L-mode plasma jointly heated by LHW and ECRH is weakly dependent on electron density but strongly dependent on the heating power,thus it is shorter than that in LHW-only heated L-mode plasma with the similar plasma parameters.The combined heating of LHW and ECRH can reduce the collisionality and indicates a more effective heating method for coreτimp reduction and normalized poloidal beta(βP)^(im)provement.It should be emphasized that in this highβ_P operation window the small ELM regime can be accessed,and an L-mode levelτ_(imp)(40 ms-80 ms)and highβ_N(~1.7)can be obtained simultaneously.It means that this typical small ELMy H-mode regime has an advantage in avoiding the serious tungsten accumulation,and will be competitive in future long-pulse steady-state and high-performance operation with high-Z material plasma-facing components.展开更多
The first experimental investigation of the tungsten behavior in ELMy H-mode plasmas with co-/counter neutral beam injection(NBI)and unfavor-able/favorable B t was performed on EAST.Tungsten was found to accumulate ea...The first experimental investigation of the tungsten behavior in ELMy H-mode plasmas with co-/counter neutral beam injection(NBI)and unfavor-able/favorable B t was performed on EAST.Tungsten was found to accumulate easily in ELMy H-mode plasma with co-NBI heating and unfavorable B t.Thus,in this case the tungsten concentration can exceed 10^(-4),resulting in degradation of the plasma confinement and periodic H–L transitions.To reduce the tungsten concentration in steady-state type-I ELMy H-mode operation,counter-NBI is applied to modify the density and temperature and brake the plasma toroidal rotation.The applied counter-NBI decreases the PHZ+E_(r) inward pinch velocity and rever-ses the direction of neoclassical inward convection,thus decreasing the tungsten concentration from-7×10^(-5) to-2×10^(-5) in type-I ELMy H-mode plasma with favorable B_(t).A comparison of the effects of different B_(t) directions on the tungsten behavior also shows that favor-able B_(t) is beneficial for reducing the tungsten concentration in the core plasma.These results imply that counter-NBI with favorable B_(t) can effectively prevent tungsten accu-mulation and expand the operating window for exploring steady-state type-I ELMy H-mode operation of EAST.展开更多
文摘为了改进碱木质素羟甲基化的制备方法,采用水热法对碱木质素(Lig)进行羟甲基化改性,利用FT-IR半定量法测得的羟甲基含量作为参考指标,并结合产率,确定了最佳工艺条件为:反应温度100℃、反应时间2 h、m(Lig)∶m(HCHO)为6∶1,m(Lig)∶m(NaOH)为24∶1,该工艺条件下所得羟甲基化木质素(Lig—OH)的羟甲基相对含量为0.95,比改性前Lig增加了0.27,产率为98.3%。核磁共振氢谱(1 H NMR)与热失重(TGA)的分析结果表明Lig—OH的羟甲基含量和酚羟基均有所提高,且其初始降解温度(t 5%)较Lig提高了38℃,500℃下的残留量更是提高了33.6%,所得羟甲基化木质素表现出良好的热稳定性能和成炭能力,有望作为成炭剂用于膨胀型阻燃高分子材料领域。
基金supported by National Key Research and Development Program of China(Nos.2018YFE0311100,2017YFE0300402,2017YFE0301300)National Natural Science Foundation of China(Nos.Nos.11905146,11775269,U1832126,11805133)+1 种基金Hefei Science Center High-end User Development Fund Project(2019HSCUE014)Chinese Academy of Sciences President’s International Fellowship Initiative(PIFI)(2020VMA0001)。
文摘Extreme ultraviolet(EUV) spectra emitted from low-Z impurity ions in the wavelength range of10–500Å were observed in Experimental Advanced Superconducting Tokamak(EAST)discharges. Several spectral lines from K-and L-shell partially ionized ions were successfully observed with sufficient spectral intensities and resolutions for helium, lithium, boron, carbon,oxygen, neon, silicon and argon using two fast-time-response EUV spectrometers of which the spectral intensities are absolutely calibrated based on the intensity comparison method between visible and EUV bremsstrahlung continua. The wavelength is carefully calibrated using wellknown spectra. The lithium, boron and silicon are individually introduced for the wall coating of the EAST vacuum vessel to suppress mainly the hydrogen and oxygen influxes from the vacuum wall, while the carbon and oxygen intrinsically exist in the plasma. The helium is frequently used as the working gas as well as the deuterium. The neon and argon are also often used for the radiation cooling of edge plasma to reduce the heat flux onto the divertor plate. The measured spectra were analyzed mainly based on the database of National Institute of Standards and Technology. As a result, spectral lines of He Ⅱ, Li Ⅱ–Ⅲ, B Ⅳ–Ⅴ, C Ⅲ–Ⅵ, O Ⅲ–Ⅷ, Ne Ⅱ–Ⅹ,Si Ⅴ–Ⅻ, and Ar Ⅹ–XVI are identified in EAST plasmas of which the central electron temperature and chord-averaged electron density range in Te0=0.6–2.8 keV and ne=(0.5–6.0)×1019 m-3, respectively. The wavelengths and transitions of EUV lines identified here are summarized and listed in a table for each impurity species as the database for EUV spectroscopy using fusion plasmas.
基金the National Key Research and Development Program of China(Grant Nos.2018YFE031110 and 2017YFE0301205)the National Natural Science Foundation of China(Grant Nos.11905146,11775269,and 11805113)+1 种基金the Users with Excellence Program of Hefei Science Center,Chinese Academy of Sciences(Grant No.2019HSC-UE014)the Fund from the Shenzhen Clean Energy Research Institute,China。
文摘The core impurity confinement properties are experimentally investigated in the Experimental Advanced Superconducting Tokamak(EAST)plasma heated by lower hybrid wave(LHW)and electron cyclotron resonance heating(ECRH)(LHW+ECRH).It is shown that the impurity confinement time(τ_(imp))in the L-mode plasma jointly heated by LHW and ECRH is weakly dependent on electron density but strongly dependent on the heating power,thus it is shorter than that in LHW-only heated L-mode plasma with the similar plasma parameters.The combined heating of LHW and ECRH can reduce the collisionality and indicates a more effective heating method for coreτimp reduction and normalized poloidal beta(βP)^(im)provement.It should be emphasized that in this highβ_P operation window the small ELM regime can be accessed,and an L-mode levelτ_(imp)(40 ms-80 ms)and highβ_N(~1.7)can be obtained simultaneously.It means that this typical small ELMy H-mode regime has an advantage in avoiding the serious tungsten accumulation,and will be competitive in future long-pulse steady-state and high-performance operation with high-Z material plasma-facing components.
基金supported by the National Key R&D Program of China(Nos.2018YFE0311100 and 2017YFE0301205)National Natural Science Foundation of China(Nos.11905146,11775269,11575244,11575249,11575235,11422546,11805133,and U19A20113)+4 种基金Users with Excellence Program of Hefei Science Center,CAS(No.2019HSC-UE014)National Magnetic Confinement Fusion Science Program of China(Nos.2015GB110005,2015GB103003,2015GB101002,and 2015GB103000)Key Research Program of Frontier Sciences,CAS(No.QYZDB-SSWSLH001)CASHIPS Director’s Fund(No.BJPY2019A01)Shenzhen Clean Energy Research Institute.
文摘The first experimental investigation of the tungsten behavior in ELMy H-mode plasmas with co-/counter neutral beam injection(NBI)and unfavor-able/favorable B t was performed on EAST.Tungsten was found to accumulate easily in ELMy H-mode plasma with co-NBI heating and unfavorable B t.Thus,in this case the tungsten concentration can exceed 10^(-4),resulting in degradation of the plasma confinement and periodic H–L transitions.To reduce the tungsten concentration in steady-state type-I ELMy H-mode operation,counter-NBI is applied to modify the density and temperature and brake the plasma toroidal rotation.The applied counter-NBI decreases the PHZ+E_(r) inward pinch velocity and rever-ses the direction of neoclassical inward convection,thus decreasing the tungsten concentration from-7×10^(-5) to-2×10^(-5) in type-I ELMy H-mode plasma with favorable B_(t).A comparison of the effects of different B_(t) directions on the tungsten behavior also shows that favor-able B_(t) is beneficial for reducing the tungsten concentration in the core plasma.These results imply that counter-NBI with favorable B_(t) can effectively prevent tungsten accu-mulation and expand the operating window for exploring steady-state type-I ELMy H-mode operation of EAST.