The high magnetic field helicon experiment system is a helicon wave plasma（HWP）source device in a high axial magnetic field（B0）developed for plasma–wall interactions studies for fusion reactors.This HWP was reali...The high magnetic field helicon experiment system is a helicon wave plasma（HWP）source device in a high axial magnetic field（B0）developed for plasma–wall interactions studies for fusion reactors.This HWP was realized at low pressure（5×10^-3-10 Pa）and a RF（radio frequency,13.56 MHz）power（maximum power of 2 k W）using an internal right helical antenna（5 cm in diameter by 18 cm long）with a maximum B0of 6300 G.Ar HWP with electron density～10^18–10^20m^-3 and electron temperature～4–7 e V was produced at high B0 of 5100 G,with an RF power of 1500 W.Maximum Ar^＋ion flux of 7.8×10^23m^-2s^-1 with a bright blue core plasma was obtained at a high B0 of 2700 G and an RF power of 1500 W without bias.Plasma energy and mass spectrometer studies indicate that Ar^＋ ion-beams of 40.1 eV are formed,which are supersonic（～3.1cs）.The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry.And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1×10^24N2/m^2 h.展开更多
The divertor configuration was successfully formed and the siliconization as a wall conditioning was first achieved on HL-2A tokamak experimentally in 2004. The divertor configuration is reconstructed by the use of th...The divertor configuration was successfully formed and the siliconization as a wall conditioning was first achieved on HL-2A tokamak experimentally in 2004. The divertor configuration is reconstructed by the use of the CFC code. Impurity as an important issue is investigated in the experiments with divertor configuration and wall conditioning. Impurities dramatically decrease after both the divertor configuration is formed and silicon is coated on the surface of the vacuum vessel.展开更多
HL-2A tokamak with two close divertors has been operated since 2003. In the experimental campaign of 2004 the divertor configuration has been successfully formed and the sillconization as a wall conditioning has been ...HL-2A tokamak with two close divertors has been operated since 2003. In the experimental campaign of 2004 the divertor configuration has been successfully formed and the sillconization as a wall conditioning has been firstly done in this device. The divertor configuration can be reconstructed by the CFc code. Impurity behavior has been investigated during the experiment with divertor configuration and wall conditioning. The reduction of impurity is clear under both conditions of divertor configuration and siliconization.展开更多
Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an incre...Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ~100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal （up to ~40% to 50%） and a 20% to 30% decrease of Ha signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Zeff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.展开更多
As the startup phase of HL-2A operation and the first divertor tokamak device in China, it is important to identify the species of impurity, estimate the concentration of impurities and compare the different behaviors...As the startup phase of HL-2A operation and the first divertor tokamak device in China, it is important to identify the species of impurity, estimate the concentration of impurities and compare the different behaviors of radiation in limiter and divertor configurationt. In startup phase of HL-2A, glowing discharge cleaning （GDC） is used as a conventional wall conditioning technology and titanium gettering is used occasionally in closed divertor chamber during SN configuration discharges phase.展开更多
The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is a...The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is also concluded that the W sputtering yield becomes more with increasing carbon(C)content in the main deuterium(D)plasma.In EAST,the integrated use of discharge cleanings and lithium(Li)coating has positive effects on the suppression of W sputtering source.In the plasma recovery experiments,it is suggested that the W intensity is reduced by approximately 60%with the help of~35 h Ion Cyclotron Radio Frequency Discharge Cleaning(ICRF-DC)and~40 g Li coating after vacuum failure.The first wall covered by Li film could be relieved from the bombardment of energetic particles,and the impurity in the vessel would be removed through the particle induced desorption and isotope exchange during the discharge cleanings.In general,the sputtering yield of W would decrease from the source,on the bias of the improvement of wall condition and the mitigation of plasmawall interaction process.It lays important base of the achievement of high-parameter and longpulse plasma operation in EAST.The experiences also would be constructive for us to promote the understanding of relevant physics and basis towards the ITER-like condition.展开更多
An impurity powder dropper was installed in the 21 st campaign of the Large Helical Device experiment(Oct.2019–Feb.2020)under a collaboration between the National Institute for Fusion Science and the Princeton Plasma...An impurity powder dropper was installed in the 21 st campaign of the Large Helical Device experiment(Oct.2019–Feb.2020)under a collaboration between the National Institute for Fusion Science and the Princeton Plasma Physics Laboratory for the purposes of real-time wall conditioning and edge plasma control.In order to assess the effective injection of the impurity powders,spectroscopic diagnostics were applied to observe line emission from the injected impurity.Thus,extreme-ultraviolet(EUV)and vacuum-ultraviolet(VUV)emission spectra were analyzed to summarize observable impurity lines with B and BN powder injection.Emission lines released from B and N ions were identified in the EUV wavelength range of 5–300Ameasured using two grazing incidence flat-field EUV spectrometers and in the VUV wavelength range of 300–2400Ameasured using three normal incidence 20 cm VUV spectrometers.BI–BV and NIII–NVII emission lines were identified in the discharges with the B and BN powder injection,respectively.Useful B and N emission lines which have large intensities and are isolated from other lines were successfully identified as follows:BI(1825.89,1826.40)A(blended),BII 1362.46A,BIII(677.00,677.14,677.16)A(blended),BIV 60.31A,BV 48.59A,NIII(989.79,991.51,991.58)A(blended),NIV765.15A,NV(209.27,209.31)A(blended),NVI 1896.80A,and NVII 24.78A.Applications of the line identifications to the advanced spectroscopic diagnostics were demonstrated,such as the vertical profile measurements for the BV and NVII lines using a space-resolved EUV spectrometer and the ion temperature measurement for the BII line using a normal incidence 3 m VUV spectrometer.展开更多
基金supported by the National Magnetic Confinement Fusion Science Program of China(Grant Nos.2014GB106005 and 2010GB106000)National Natural Science Foundation of China(Nos.11505123 11435009 11375126)a Project funded by China Postdoctoral Science Foundation(No.156455)
文摘The high magnetic field helicon experiment system is a helicon wave plasma（HWP）source device in a high axial magnetic field（B0）developed for plasma–wall interactions studies for fusion reactors.This HWP was realized at low pressure（5×10^-3-10 Pa）and a RF（radio frequency,13.56 MHz）power（maximum power of 2 k W）using an internal right helical antenna（5 cm in diameter by 18 cm long）with a maximum B0of 6300 G.Ar HWP with electron density～10^18–10^20m^-3 and electron temperature～4–7 e V was produced at high B0 of 5100 G,with an RF power of 1500 W.Maximum Ar^＋ion flux of 7.8×10^23m^-2s^-1 with a bright blue core plasma was obtained at a high B0 of 2700 G and an RF power of 1500 W without bias.Plasma energy and mass spectrometer studies indicate that Ar^＋ ion-beams of 40.1 eV are formed,which are supersonic（～3.1cs）.The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry.And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1×10^24N2/m^2 h.
基金Project supported by the National Natural Science Foundation of China （Grant No 10475022）.Acknowledgment The aut, hors would like to thank all of our colleagues working on HL-2A, particularly LU J, LU P, FU B Z and LU0 C W for their assistance in the experiment on HL-2A.
文摘The divertor configuration was successfully formed and the siliconization as a wall conditioning was first achieved on HL-2A tokamak experimentally in 2004. The divertor configuration is reconstructed by the use of the CFC code. Impurity as an important issue is investigated in the experiments with divertor configuration and wall conditioning. Impurities dramatically decrease after both the divertor configuration is formed and silicon is coated on the surface of the vacuum vessel.
基金supported by the National Natural Science foundation of china(No.10475022)supported in part by the JSPS-CAS Core University Program in the Field of Plasma and Nuclear Fusion
文摘HL-2A tokamak with two close divertors has been operated since 2003. In the experimental campaign of 2004 the divertor configuration has been successfully formed and the sillconization as a wall conditioning has been firstly done in this device. The divertor configuration can be reconstructed by the CFc code. Impurity behavior has been investigated during the experiment with divertor configuration and wall conditioning. The reduction of impurity is clear under both conditions of divertor configuration and siliconization.
文摘Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ~100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal （up to ~40% to 50%） and a 20% to 30% decrease of Ha signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Zeff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.
文摘As the startup phase of HL-2A operation and the first divertor tokamak device in China, it is important to identify the species of impurity, estimate the concentration of impurities and compare the different behaviors of radiation in limiter and divertor configurationt. In startup phase of HL-2A, glowing discharge cleaning （GDC） is used as a conventional wall conditioning technology and titanium gettering is used occasionally in closed divertor chamber during SN configuration discharges phase.
基金supported by the National Key Research and Development Program of China(Nos.2017YFE0301100 and 2017YFA0402500)National Natural Science Foundation of China(No.11605237)the Users with Excellence Program of Hefei Science Center CAS(2020HSC-UE010)。
文摘The steady fusion plasma operation is constrained by tungsten(W)material sputtering issue in the EAST tokamak.In this work,the suppression of W sputtering source has been studied by advanced wall conditionings.It is also concluded that the W sputtering yield becomes more with increasing carbon(C)content in the main deuterium(D)plasma.In EAST,the integrated use of discharge cleanings and lithium(Li)coating has positive effects on the suppression of W sputtering source.In the plasma recovery experiments,it is suggested that the W intensity is reduced by approximately 60%with the help of~35 h Ion Cyclotron Radio Frequency Discharge Cleaning(ICRF-DC)and~40 g Li coating after vacuum failure.The first wall covered by Li film could be relieved from the bombardment of energetic particles,and the impurity in the vessel would be removed through the particle induced desorption and isotope exchange during the discharge cleanings.In general,the sputtering yield of W would decrease from the source,on the bias of the improvement of wall condition and the mitigation of plasmawall interaction process.It lays important base of the achievement of high-parameter and longpulse plasma operation in EAST.The experiences also would be constructive for us to promote the understanding of relevant physics and basis towards the ITER-like condition.
基金supported by the Post-CUP programJSPSCAS Bilateral Joint Research Projects,‘Control of wall recycling on metallic plasma facing materials in fusionreactor,’2019–2022,(No.GJHZ201984)+2 种基金US Department of Energy(No.DE-AC02-09CH11466)with Princeton Universitythe LHD project financial support(Nos.ULPP010,ULFF022)JSPS KAKENHI(Nos.17K14426,20K03896)。
文摘An impurity powder dropper was installed in the 21 st campaign of the Large Helical Device experiment(Oct.2019–Feb.2020)under a collaboration between the National Institute for Fusion Science and the Princeton Plasma Physics Laboratory for the purposes of real-time wall conditioning and edge plasma control.In order to assess the effective injection of the impurity powders,spectroscopic diagnostics were applied to observe line emission from the injected impurity.Thus,extreme-ultraviolet(EUV)and vacuum-ultraviolet(VUV)emission spectra were analyzed to summarize observable impurity lines with B and BN powder injection.Emission lines released from B and N ions were identified in the EUV wavelength range of 5–300Ameasured using two grazing incidence flat-field EUV spectrometers and in the VUV wavelength range of 300–2400Ameasured using three normal incidence 20 cm VUV spectrometers.BI–BV and NIII–NVII emission lines were identified in the discharges with the B and BN powder injection,respectively.Useful B and N emission lines which have large intensities and are isolated from other lines were successfully identified as follows:BI(1825.89,1826.40)A(blended),BII 1362.46A,BIII(677.00,677.14,677.16)A(blended),BIV 60.31A,BV 48.59A,NIII(989.79,991.51,991.58)A(blended),NIV765.15A,NV(209.27,209.31)A(blended),NVI 1896.80A,and NVII 24.78A.Applications of the line identifications to the advanced spectroscopic diagnostics were demonstrated,such as the vertical profile measurements for the BV and NVII lines using a space-resolved EUV spectrometer and the ion temperature measurement for the BII line using a normal incidence 3 m VUV spectrometer.
