Neutral beam injection(NBI)has been proven as a reliable heating and current drive method for fusion plasma.For the high-energy NBI system(particle energy>150 ke V)of large-scale fusion devices,the negative ion sou...Neutral beam injection(NBI)has been proven as a reliable heating and current drive method for fusion plasma.For the high-energy NBI system(particle energy>150 ke V)of large-scale fusion devices,the negative ion source neutral beam injection(NNBI)system is inevitable,which can obtain an acceptable neutralization efficiency(>55%).But the NNBI system is very complex and challengeable.To explore and master the key NNBI technology for future fusion reactor in China,an NNBI test facility is under development in the framework of the Comprehensive Research Facility for Fusion Technology(CRAFT).The initial goal of CRAFT NNBI facility is to achieve a 2 MW hydrogen neutral beam at the energy of 200–400 ke V for lasting 100 s.In the first operation of the CRAFT NNBI facility,a negative ion source with dual RF drivers was developed and tested.By using the 50 keV accelerator,the long-pulse and highcurrent extractions of negative hydrogen ions have been achieved and the typical values were 55.4 keV,7.3 A(~123 A/m^(2)),105 s and 55.0 keV,14.7 A(~248 A/m^(2)),30 s,respectively.By using the 200 keV accelerator,the megawatt-class negative hydrogen beam has also been achieved(135.9 keV,8.9 A,8 s).The whole process of the gas neutralization of negative ion beam,electric removal of residual ions,and beam transport have been demonstrated experimentally.展开更多
Neutral beam injection （NBI） system with two neutral beam injections will be con- structed on the Experimental Advanced Superconducting Tokamak （EAST） in two stages for high power auxiliary plasmas heating and non...Neutral beam injection （NBI） system with two neutral beam injections will be con- structed on the Experimental Advanced Superconducting Tokamak （EAST） in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2-4 MW beam power with 50-80 keV beam energy in 10-100 s pulse length. Each elements of the NBI system are presented in this contribution.展开更多
Theoretical beam intensity distribution is derived for the neutral-beam-injection ion source with a multi-slot extraction in EAST. The beam intensity profile, both along and perpendicular to the injecting direction an...Theoretical beam intensity distribution is derived for the neutral-beam-injection ion source with a multi-slot extraction in EAST. The beam intensity profile, both along and perpendicular to the injecting direction and the beam power deposition to the inner elements in the neutral beam injector （NBI） are evaluated. The results indicate that the transverse beam intensity is much higher than the longitudinal one. This study could provide information for the design of vacuum system, structure of inner elements and cooling system of the neutral beam injector in EAST.展开更多
Neutral Beam Injection (NBI) is an effective way to improve the efficiency of toka mak heating system. This article primarily introduces a work on the pressure distribution inside the tank of NBI heating system, espec...Neutral Beam Injection (NBI) is an effective way to improve the efficiency of toka mak heating system. This article primarily introduces a work on the pressure distribution inside the tank of NBI heating system, especially inside the neutralizer, which is got by selecting a proper mathematical model and constructing a series of rational calculating formulas on pressure distribution. Furthermore, we simulate the pressure distribution by the Monte Carlo method. Comparing the result of simulation with that of theoretical calculation, we find that both the results are very close each other, showing their mutual validity.展开更多
We present an experimental method to obtain neutral beam injection （NBI） power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission effi...We present an experimental method to obtain neutral beam injection （NBI） power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission efficiency, the neutralization efficiency and so on. With the empirical scaling laws, the estimating power can be obtained in every shot of experiment on time, therefore the important parameters such as the energy confinement time can be obtained precisely. The simulation results by the tokamak simulation code （TSC） show that the evolution of the plasma parameters is in good agreement with the experimental results by using the NBI power from the empirical scaling law.展开更多
HL-2A tokamak is the first tokamak with divertors in China. The plasma boundary and the position of the striking point on the target plates of the HL-2A closed diwrtor were simulated by the current filament code and t...HL-2A tokamak is the first tokamak with divertors in China. The plasma boundary and the position of the striking point on the target plates of the HL-2A closed diwrtor were simulated by the current filament code and they were in agreement with the diagnostic results in the divertor. Supersonic molecular beam injection （SMBI） system was first installed and tested on the HL-2A tokamak in 2004. In the present experiment low pressure SMBI fuelling on the HL-2A closed divertor was carried out. The experimental results indicate that the divertor was operated in the ＇linear regime＇ and during the period of SMB pulse injection into the HL-2A plasma the power density eonvected at the target plate surfaces was 0.4 times of that before or after the beam injection. It is a useful fuelling method for decreasing the heat load on the neutralizer plates of the divertor.展开更多
A set of data-processing middleware for a high-powered neutral beam injection（NBI） control system is presented in this paper.The middleware,based on TCP/IP and multi-threading technologies,focuses mainly on data pro...A set of data-processing middleware for a high-powered neutral beam injection（NBI） control system is presented in this paper.The middleware,based on TCP/IP and multi-threading technologies,focuses mainly on data processing and transmission.It separates the data processing and compression from data acquisition and storage.It provides universal transmitting interfaces for different software circumstances,such as WinCC,LabView and other measurement systems. The experimental data acquired on Windows,QNX and Linux platforms are processed by the middleware and sent to the monitoring applications.There are three middleware deployment models：serial processing,parallel processing and alternate serial processing.By using these models,the middleware solves real-time data-processing problems on heterogeneous environmental acquisition hardware with different operating systems and data applications.展开更多
Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply, etc. The NB...Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply, etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular. In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.展开更多
The arrangement of the neutral beam line in HL-2A tokamak is introduced. Attenuation of neutral beam injection is analyzed numerically under different plasma conditions： different plasma densities, beam energies, ele...The arrangement of the neutral beam line in HL-2A tokamak is introduced. Attenuation of neutral beam injection is analyzed numerically under different plasma conditions： different plasma densities, beam energies, electron temperatures, and impurity concentrations. Both optimized plasma density and beam energy for plasma heating are obtained.展开更多
In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular s...In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.展开更多
This research applies experimental measurements and NUBEAM,ONETWO and TRANSP modules to investigate the shine-through(ST)loss ratio and beam heating percentage of neutral beam injection on EAST.Measurements and simula...This research applies experimental measurements and NUBEAM,ONETWO and TRANSP modules to investigate the shine-through(ST)loss ratio and beam heating percentage of neutral beam injection on EAST.Measurements and simulations confirm that the ST loss ratio increases linearly with beam energy,and decreases exponentially with plasma density.Moreover,using the multi-step fitting method,we present analytical quantitative expressions of ST loss ratio and beam heating percentage,which are valuable for the high parameter long-pulse experiments of EAST.展开更多
In order to realize steady-state operation of the neutral beam injection（NBI） system with high beam energy,an accurate thermal analysis and a prediction about working conditions of heat-removal structures inside hig...In order to realize steady-state operation of the neutral beam injection（NBI） system with high beam energy,an accurate thermal analysis and a prediction about working conditions of heat-removal structures inside high-heat-flux（HHF） components in the system are key issues.In this paper,taking the HHF ion dump with swirl tubes in NBI system as an example,an accurate thermal dynamic simulation method based on computational fluid dynamics（CFD） and the finite volume method is presented to predict performance of the HHF component.In this simulation method,the Eulerian multiphase method together with some empirical corrections about the inter-phase transfer model and the wall heat flux partitioning model are considered to describe the subcooled boiling.The reliability of the proposed method is validated by an experimental example with subcooled boiling inside swirl tube.The proposed method provides an important tool for the refined thermal and flow dynamic analysis of HHF components,and can be extended to study the thermal design of other complex HHF engineering structures in a straightforward way.The simulation results also verify that the swirl tube is a promising heat removing structure for the HHF components of the NBI system.展开更多
During the operation of a high-power neutral beam injection (NBI) system on theHL-1M tokamak, an optical diagnostic means using CCD camera was developed to characterize theNBI performance. The vacuum valve opening pro...During the operation of a high-power neutral beam injection (NBI) system on theHL-1M tokamak, an optical diagnostic means using CCD camera was developed to characterize theNBI performance. The vacuum valve opening process and NBI period in the HL-1M experimentwere displayed by a lot of photos taken with this means. Thus, the Hα emission profiles of theneutral beam (NB) and its interaction with plasma were given. Finally, the reason possible forplasma breakdown during NBI mode Ⅱ discharge was investigated. Therefore, this in-situ diagnosiscan provide more information of the NBI.展开更多
HL-2A tokamak, the first tokamak with divertor in China, has been constructed and put into operation in 2002. The main parameters are R=1.65 m, a=0.4 m, BT=2.8 T, Ip = 0. 48 MA. The divertor of HL-2A is unique, becaus...HL-2A tokamak, the first tokamak with divertor in China, has been constructed and put into operation in 2002. The main parameters are R=1.65 m, a=0.4 m, BT=2.8 T, Ip = 0. 48 MA. The divertor of HL-2A is unique, because it is characterized with a large closed divertor chamber. The device has double divertor chamber, but now it is operating with lower single null configuration to study the physics of divertor for the next step design of a divertor. Supersonic molecular beam injection （SMBI） system with LN2 cooling trap was first installed and demonstrated on the HL-2A tokamak in 2004. The first results of SMBI into HL-2A plasma are to demonstrate the function of the HL-2A divertor and to observe the cold pulse propagation during multi-pulse SMBI on HL-2A Tokamak.展开更多
Negative-ion-based neutral beam injection(NNBI)at high energy is still a potential heating and current drive method for future large-scale fusion reactors.One feature of the negative ion source is that the electrons a...Negative-ion-based neutral beam injection(NNBI)at high energy is still a potential heating and current drive method for future large-scale fusion reactors.One feature of the negative ion source is that the electrons are also accelerated with the negative ions in the accelerator.In addition to the electrons co-extracted from the source plasma,electrons are inevitably generated in the main acceleration stage due to the stripping loss of negative ions or the ionization of background gas.Many of these accelerated electrons can be ejected by the negative ion source,which poses a risk for the downstream components in the beamline of the NNBI system,especially the thermosensitive cryopumps.To prevent the ejected electrons from impacting the cryopumps,electron dumps have been designed for the beamline of the China Fusion Engineering Test Reactor(CFETR)advance neutral beam equipment(CANBE).Using a selfconsistent model of the negative ion accelerator,the generation and motion of the ejected electrons were simulated for different negative ion sources to be tested on the CANBE.Based on the orbits of the ejected electrons,a set of fixed and movable electron dumps was designed to be placed in front of the neutralizer inside the CANBE beamline.The effects of the electron dumps were quantitatively analyzed.展开更多
Supervisory control and protection system of the neutral beam injector （NBI） in the HL-2A tokamak is presented. The system is used for a safe coordination of all the main NBI subsystems. Because the system is based ...Supervisory control and protection system of the neutral beam injector （NBI） in the HL-2A tokamak is presented. The system is used for a safe coordination of all the main NBI subsystems. Because the system is based on computer networks with its transmission medium of optical fiber, its advantages in high operational stability, reliability, security and flexible functional expandability are clearly shown during the NBI commissioning and heating experiment in HL-2A.展开更多
A distributed control system of Neutral Beam Injector （NBI） on the Experimental Advanced Superconducting Tokamak （EAST-NBI） is briefly presented in this paper. The control system is developed in accordance with th...A distributed control system of Neutral Beam Injector （NBI） on the Experimental Advanced Superconducting Tokamak （EAST-NBI） is briefly presented in this paper. The control system is developed in accordance with the experimental operational characteristics of the EAST- NBI. The NBI control system （NBICS）, which is based on the computer network technologies and classified according to the control levels, consists of three levels： a remote monitoring layer, a server control layer, and a field control layer. The 3-layer architecture is capable of extending the system functions and upgrading devices. The timing system provides the reference clock of the synchronization and interlock for the EAST-NBI system. An interlock system ensures the safety of the experiment operators and field devices. Both of the ion sources of the beamline are designed to operate independently. This lays an important foundation for developing a control system for the second beamline on EAST. Experimental results demonstrate that the NBICS meets functional requirements of the EAST-NBI control, and makes experimental operations visual and automatic.展开更多
In order to support the design, manufacture and commissioning of the negative- ion-based neutral beam injection （NBI） system for the Chinese Fusion Engineering Test Reactor （CFETR）, the Hefei utility negative ion ...In order to support the design, manufacture and commissioning of the negative- ion-based neutral beam injection （NBI） system for the Chinese Fusion Engineering Test Reactor （CFETR）, the Hefei utility negative ion test equipment with RF source （HUNTER） was proposed at ASIPP. A prototype negative ion source will be developed at first. The main bodies of plasma source and accelerator of the prototype negative ion source are similar to that of the ion source for EAST-NBI. But instead of the filament-arc driver, an RF driver is adopted for the prototype negative ion source to fulfill the requirement of long pulse operation. A cesium seeding system and a magnetic filter are added for enhancing the negative ion density near the plasma grid and minimizing co-extracted electrons. Besides, an ITER-like extraction system is applied inside the accelerator, where the negative ion beam is extracted and accelerated up to 50 kV.展开更多
Predictions on the ripple loss of neutral beam fast ions on EAST are investigated with a guiding center code, including both ripple and collisional effects. A 6% to 16% loss of neutral beam ions is predicted for typic...Predictions on the ripple loss of neutral beam fast ions on EAST are investigated with a guiding center code, including both ripple and collisional effects. A 6% to 16% loss of neutral beam ions is predicted for typical EAST experiments, and a synergistic enhancement of fast ion loss is found for toroidal field （TF） ripples with collisions. The lost ions are strongly localized and will cause a maximum heat load of - 0.05 MW/m^2 on the first wall.展开更多
In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Ga...In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×10^(17)m^(-3)in the case without the magnetic shield,and the value increases to 9.4×10^(17)m^(-3)when the magnetic shield is introduced.展开更多
基金supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)。
文摘Neutral beam injection(NBI)has been proven as a reliable heating and current drive method for fusion plasma.For the high-energy NBI system(particle energy>150 ke V)of large-scale fusion devices,the negative ion source neutral beam injection(NNBI)system is inevitable,which can obtain an acceptable neutralization efficiency(>55%).But the NNBI system is very complex and challengeable.To explore and master the key NNBI technology for future fusion reactor in China,an NNBI test facility is under development in the framework of the Comprehensive Research Facility for Fusion Technology(CRAFT).The initial goal of CRAFT NNBI facility is to achieve a 2 MW hydrogen neutral beam at the energy of 200–400 ke V for lasting 100 s.In the first operation of the CRAFT NNBI facility,a negative ion source with dual RF drivers was developed and tested.By using the 50 keV accelerator,the long-pulse and highcurrent extractions of negative hydrogen ions have been achieved and the typical values were 55.4 keV,7.3 A(~123 A/m^(2)),105 s and 55.0 keV,14.7 A(~248 A/m^(2)),30 s,respectively.By using the 200 keV accelerator,the megawatt-class negative hydrogen beam has also been achieved(135.9 keV,8.9 A,8 s).The whole process of the gas neutralization of negative ion beam,electric removal of residual ions,and beam transport have been demonstrated experimentally.
基金supported by National Natural Science Foundation of China (No. 11075188)the Chinese Academy of Sciences Knowledge Innovation Project: the study of neutral beam steady-state operation of the key technical and physical problems
文摘Neutral beam injection （NBI） system with two neutral beam injections will be con- structed on the Experimental Advanced Superconducting Tokamak （EAST） in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2-4 MW beam power with 50-80 keV beam energy in 10-100 s pulse length. Each elements of the NBI system are presented in this contribution.
基金supported by National Natural Science Foundation of China(No.10875146)the Knowledge Innovation Project of the Chinese Academy of Sciences in the Study of the Key Technical and Physical Problems for a Steady-state Operated Neutral Beam
文摘Theoretical beam intensity distribution is derived for the neutral-beam-injection ion source with a multi-slot extraction in EAST. The beam intensity profile, both along and perpendicular to the injecting direction and the beam power deposition to the inner elements in the neutral beam injector （NBI） are evaluated. The results indicate that the transverse beam intensity is much higher than the longitudinal one. This study could provide information for the design of vacuum system, structure of inner elements and cooling system of the neutral beam injector in EAST.
基金The project supported by the Canada Research Chair Program and Natural Sciences and Engineering Research Council of Canada
文摘Neutral Beam Injection (NBI) is an effective way to improve the efficiency of toka mak heating system. This article primarily introduces a work on the pressure distribution inside the tank of NBI heating system, especially inside the neutralizer, which is got by selecting a proper mathematical model and constructing a series of rational calculating formulas on pressure distribution. Furthermore, we simulate the pressure distribution by the Monte Carlo method. Comparing the result of simulation with that of theoretical calculation, we find that both the results are very close each other, showing their mutual validity.
文摘We present an experimental method to obtain neutral beam injection （NBI） power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission efficiency, the neutralization efficiency and so on. With the empirical scaling laws, the estimating power can be obtained in every shot of experiment on time, therefore the important parameters such as the energy confinement time can be obtained precisely. The simulation results by the tokamak simulation code （TSC） show that the evolution of the plasma parameters is in good agreement with the experimental results by using the NBI power from the empirical scaling law.
基金Project supported by the National Science Foundation of China （Grant Nos 19775011, 10075016 and 10475024）.The authors wish to thank the HL-2A team members for their hard work.
文摘HL-2A tokamak is the first tokamak with divertors in China. The plasma boundary and the position of the striking point on the target plates of the HL-2A closed diwrtor were simulated by the current filament code and they were in agreement with the diagnostic results in the divertor. Supersonic molecular beam injection （SMBI） system was first installed and tested on the HL-2A tokamak in 2004. In the present experiment low pressure SMBI fuelling on the HL-2A closed divertor was carried out. The experimental results indicate that the divertor was operated in the ＇linear regime＇ and during the period of SMB pulse injection into the HL-2A plasma the power density eonvected at the target plate surfaces was 0.4 times of that before or after the beam injection. It is a useful fuelling method for decreasing the heat load on the neutralizer plates of the divertor.
基金supported by National Natural Science Foundation of China(No.10875146)
文摘A set of data-processing middleware for a high-powered neutral beam injection（NBI） control system is presented in this paper.The middleware,based on TCP/IP and multi-threading technologies,focuses mainly on data processing and transmission.It separates the data processing and compression from data acquisition and storage.It provides universal transmitting interfaces for different software circumstances,such as WinCC,LabView and other measurement systems. The experimental data acquired on Windows,QNX and Linux platforms are processed by the middleware and sent to the monitoring applications.There are three middleware deployment models：serial processing,parallel processing and alternate serial processing.By using these models,the middleware solves real-time data-processing problems on heterogeneous environmental acquisition hardware with different operating systems and data applications.
基金The project supported by the Meg-science Engineering Project of the Chinese Academy of Sciences
文摘Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply, etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular. In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.
文摘The arrangement of the neutral beam line in HL-2A tokamak is introduced. Attenuation of neutral beam injection is analyzed numerically under different plasma conditions： different plasma densities, beam energies, electron temperatures, and impurity concentrations. Both optimized plasma density and beam energy for plasma heating are obtained.
基金financially supported by the Science Foundation for International Cooperation of Sichuan Province (2014HH0016)the Fundamental Research Funds for the Central Universities (SWJTU2014: A0920502051113-10000)National Magnetic Confinement Fusion Science Program (2011GB112001)
文摘In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.
基金Supported by the Collaborative Innovation Program of Hefei Science Center,CAS (Grant No.2019HSC-CIP015)the National Natural Science Foundation of China (Grant Nos.11875290,1170529,11875253,and 11975276)+2 种基金the Fundamental Research Funds for the Central Universities (Grant No.WK3420000004)the Anhui Provincial Natural Science Foundation (Grant No.2008085J04)the National Key Research and Development Program of China (Grant No.2019YFE03020004)。
文摘This research applies experimental measurements and NUBEAM,ONETWO and TRANSP modules to investigate the shine-through(ST)loss ratio and beam heating percentage of neutral beam injection on EAST.Measurements and simulations confirm that the ST loss ratio increases linearly with beam energy,and decreases exponentially with plasma density.Moreover,using the multi-step fitting method,we present analytical quantitative expressions of ST loss ratio and beam heating percentage,which are valuable for the high parameter long-pulse experiments of EAST.
基金supported by the Special Program of ITER(International Thermonuclear Experimental Reactor)in China(No.2013GB101002)
文摘In order to realize steady-state operation of the neutral beam injection（NBI） system with high beam energy,an accurate thermal analysis and a prediction about working conditions of heat-removal structures inside high-heat-flux（HHF） components in the system are key issues.In this paper,taking the HHF ion dump with swirl tubes in NBI system as an example,an accurate thermal dynamic simulation method based on computational fluid dynamics（CFD） and the finite volume method is presented to predict performance of the HHF component.In this simulation method,the Eulerian multiphase method together with some empirical corrections about the inter-phase transfer model and the wall heat flux partitioning model are considered to describe the subcooled boiling.The reliability of the proposed method is validated by an experimental example with subcooled boiling inside swirl tube.The proposed method provides an important tool for the refined thermal and flow dynamic analysis of HHF components,and can be extended to study the thermal design of other complex HHF engineering structures in a straightforward way.The simulation results also verify that the swirl tube is a promising heat removing structure for the HHF components of the NBI system.
文摘During the operation of a high-power neutral beam injection (NBI) system on theHL-1M tokamak, an optical diagnostic means using CCD camera was developed to characterize theNBI performance. The vacuum valve opening process and NBI period in the HL-1M experimentwere displayed by a lot of photos taken with this means. Thus, the Hα emission profiles of theneutral beam (NB) and its interaction with plasma were given. Finally, the reason possible forplasma breakdown during NBI mode Ⅱ discharge was investigated. Therefore, this in-situ diagnosiscan provide more information of the NBI.
文摘HL-2A tokamak, the first tokamak with divertor in China, has been constructed and put into operation in 2002. The main parameters are R=1.65 m, a=0.4 m, BT=2.8 T, Ip = 0. 48 MA. The divertor of HL-2A is unique, because it is characterized with a large closed divertor chamber. The device has double divertor chamber, but now it is operating with lower single null configuration to study the physics of divertor for the next step design of a divertor. Supersonic molecular beam injection （SMBI） system with LN2 cooling trap was first installed and demonstrated on the HL-2A tokamak in 2004. The first results of SMBI into HL-2A plasma are to demonstrate the function of the HL-2A divertor and to observe the cold pulse propagation during multi-pulse SMBI on HL-2A Tokamak.
基金supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)。
文摘Negative-ion-based neutral beam injection(NNBI)at high energy is still a potential heating and current drive method for future large-scale fusion reactors.One feature of the negative ion source is that the electrons are also accelerated with the negative ions in the accelerator.In addition to the electrons co-extracted from the source plasma,electrons are inevitably generated in the main acceleration stage due to the stripping loss of negative ions or the ionization of background gas.Many of these accelerated electrons can be ejected by the negative ion source,which poses a risk for the downstream components in the beamline of the NNBI system,especially the thermosensitive cryopumps.To prevent the ejected electrons from impacting the cryopumps,electron dumps have been designed for the beamline of the China Fusion Engineering Test Reactor(CFETR)advance neutral beam equipment(CANBE).Using a selfconsistent model of the negative ion accelerator,the generation and motion of the ejected electrons were simulated for different negative ion sources to be tested on the CANBE.Based on the orbits of the ejected electrons,a set of fixed and movable electron dumps was designed to be placed in front of the neutralizer inside the CANBE beamline.The effects of the electron dumps were quantitatively analyzed.
文摘Supervisory control and protection system of the neutral beam injector （NBI） in the HL-2A tokamak is presented. The system is used for a safe coordination of all the main NBI subsystems. Because the system is based on computer networks with its transmission medium of optical fiber, its advantages in high operational stability, reliability, security and flexible functional expandability are clearly shown during the NBI commissioning and heating experiment in HL-2A.
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2013GB101001)
文摘A distributed control system of Neutral Beam Injector （NBI） on the Experimental Advanced Superconducting Tokamak （EAST-NBI） is briefly presented in this paper. The control system is developed in accordance with the experimental operational characteristics of the EAST- NBI. The NBI control system （NBICS）, which is based on the computer network technologies and classified according to the control levels, consists of three levels： a remote monitoring layer, a server control layer, and a field control layer. The 3-layer architecture is capable of extending the system functions and upgrading devices. The timing system provides the reference clock of the synchronization and interlock for the EAST-NBI system. An interlock system ensures the safety of the experiment operators and field devices. Both of the ion sources of the beamline are designed to operate independently. This lays an important foundation for developing a control system for the second beamline on EAST. Experimental results demonstrate that the NBICS meets functional requirements of the EAST-NBI control, and makes experimental operations visual and automatic.
基金supported by National Natural Science Foundation of China(Nos.11505224,11575240,11405207)the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB101001,2013GB101002,2013GB101003)+1 种基金International Science and Technology Cooperation Program of China(No.2014DFG61950)Foundation of ASIPP(No.DSJJ-14-JC07)
文摘In order to support the design, manufacture and commissioning of the negative- ion-based neutral beam injection （NBI） system for the Chinese Fusion Engineering Test Reactor （CFETR）, the Hefei utility negative ion test equipment with RF source （HUNTER） was proposed at ASIPP. A prototype negative ion source will be developed at first. The main bodies of plasma source and accelerator of the prototype negative ion source are similar to that of the ion source for EAST-NBI. But instead of the filament-arc driver, an RF driver is adopted for the prototype negative ion source to fulfill the requirement of long pulse operation. A cesium seeding system and a magnetic filter are added for enhancing the negative ion density near the plasma grid and minimizing co-extracted electrons. Besides, an ITER-like extraction system is applied inside the accelerator, where the negative ion beam is extracted and accelerated up to 50 kV.
基金supported by National Natural Science Foundation of China (Nos.10975160,11175211)
文摘Predictions on the ripple loss of neutral beam fast ions on EAST are investigated with a guiding center code, including both ripple and collisional effects. A 6% to 16% loss of neutral beam ions is predicted for typical EAST experiments, and a synergistic enhancement of fast ion loss is found for toroidal field （TF） ripples with collisions. The lost ions are strongly localized and will cause a maximum heat load of - 0.05 MW/m^2 on the first wall.
基金supported by the National Key R&D Program of China(No.2017YFE0300106)National Natural Science Foundation of China(No.12075049)the Fundamental Research Funds for the Central Universities(Nos.DUT20LAB201 and DUT21LAB110)。
文摘In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×10^(17)m^(-3)in the case without the magnetic shield,and the value increases to 9.4×10^(17)m^(-3)when the magnetic shield is introduced.
