A magnetic field produced by a current flowing through the plasma grid(PG) is one of the solutions to reduce the collisional loss of negative ions in a negative ion source, which reduces the electron temperature in fr...A magnetic field produced by a current flowing through the plasma grid(PG) is one of the solutions to reduce the collisional loss of negative ions in a negative ion source, which reduces the electron temperature in front of the PG. However, the magnetic field diffused into the driver has some influence on the plasma outflowing. In order to investigate the effect of changing this magnetic field on the outflowing of plasma from the driver, a circular ring(absorber) of high permeability iron has been introduced at the driver exit, which can reduce the magnetic field around it and improve plasma outflowing. With the application of the absorber, the electron density is increased by about 35%, and the extraction current measured from the extraction grid is increased from 1.02 A to 1.29 A. The results of the extraction experiment with cesium injection show that both the extraction grid(EG) current and H-current are increased when the absorber is introduced.展开更多
Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion expe...Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion experiments to heat the plasma.The collisions between the fast negative ions and neutral background gas result in a significant number of high-energy positive ions being produced in the acceleration area,and for the high-power long-pulse operation of NBI systems,this acceleration of positive ions back to the ion source creates heat load and material sputtering on the source backplate.This difficulty cannot be ignored,with the neutral gas density in the acceleration region having a significant impact on the flux density of the backstreaming positive ions.In the work reported here,the pressure gradient in the acceleration region was estimated using an ionization gauge and a straightforward 1D computation,and it was found that once gas traveled through the acceleration region,the pressure dropped by nearly one order of magnitude,with the largest pressure drop occurring at the plasma grid.The computation also revealed that the pressure drop in the grid gaps was substantially smaller than that in the grid apertures.展开更多
Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheatin...Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheating, a data acquisition and over-current protection system based on the PXI(PCI e Xtensions for Instrumentation) platform has been developed. The system consists of a current sensor, data acquisition module and over-current protection module. In the data acquisition module,the acquired data of one shot will be transferred in isolation and saved in a data-storage server in a txt file. It can also be recalled using NBWave for future analysis. The over-current protection module contains two modes: remote and local. This gives it the function of setting a threshold voltage remotely and locally, and the forbidden time of over-current protection also can be set by a host PC in remote mode. Experimental results demonstrate that the data acquisition and overcurrent protection system has the advantages of setting forbidden time and isolation transmission.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
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
A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source...A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source for a neutral beam injector in China,an RF ion source test facility was developed at the Institute of Plasma Physics,Chinese Academy of Sciences.In this paper,a two-dimensional fluid model is used to simulate the fundamental physical characteristics of RF plasma discharge.Simulation results show the relationship of the characteristics of plasma(such as electron density and electron temperature)and RF power and gas pressure.In order to verify the effectiveness of the model,the characteristics of the plasma are investigated using a Langmuir probe.In this paper,experimental and simulation results are presented,and the possible reasons for the discrepancies between them are given.This paper can help us understand the characteristics of RF plasma discharge,and give a basis for further R&D for an RF ion source.展开更多
A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current...A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current drive of EAST plasmas. The first long pulse ion source (LPIS-1) has been installed in the neutral beam test bed (NBTB) system, and the performance is being tested in the NBTB. The LPIS-1 consists of a magnetic bucket plasma generator with multipole cusp-fields and a set of tetrode accelerators with slit-type apertures (a transparency of 60%). The ion beam trajectories of the accelerator column are estimated for the LPIS-1, including an original structure, with the change of slit aperture distance, plasma grid shape, grid gap distance, and voltage ratio between a plasma grid and a gradient grid using the IGUN code. This kind of calculation for the ion beam trajectory may be useful for the estimation of beam extraction characteristics and the direction of accelerator upgrade or modification, prior to the experiments of ion beam extraction.展开更多
A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection. A real-time feedback control system (RFCS) is designed to control...A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection. A real-time feedback control system (RFCS) is designed to control the gas supply for ion source based on the control model and the discrete-time control algorithm. The experimental results have proved that RFCS could regulate the gas supply smoothly, suppress the arc's abrupt over-current at the end of the ion source discharging, prolong the discharge pulse and stabilize the ion concentration. With RFCS, the ion source for neutral beam injection has reached its longest pulse with a length of 4.5 seconds in a stable status.展开更多
Optical emission spectroscopy(OES)using the trace rare gases of Ar and Xe have been carried out in a radio frequency(RF)driven negative ion source at Institute of Plasma Physics,Chinese Academy of Science(ASIPP),in or...Optical emission spectroscopy(OES)using the trace rare gases of Ar and Xe have been carried out in a radio frequency(RF)driven negative ion source at Institute of Plasma Physics,Chinese Academy of Science(ASIPP),in order to determine the electron temperature and density of the hydrogen plasma.The line-ratio methods based on population models are applied to describe the radiation process of the excited state particles and establish their relations with the plasma parameters.The spectral lines from the argon and xenon excited state atoms with the wavelength of 750.4 and 828.0 nm are used to calculate the electron temperature based on the corona model.The argon ions emission lines with the wavelength of 480 and 488 nm are selected to calculate the electron density based on the collisional radiative model.OES has given the preliminary results of the electron temperature and density by varying the discharge gas pressure and RF power.According to the experimental results,the typical plasma parameters isTe2≈2-4 eV and ne≈1 x 1017-8 x 1017 m^-3 in front of plasma grid.展开更多
In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma ...In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP). Its negative ion source can be equipped with single or double RF drivers. There is a plasma expansion chamber with depth of 19 mm and an enhanced filter field. A three electrodes negative ion accelerator was employed to extract and accelerate the negative ions, which are plasma grid,extraction grid and ground grid. And there are several diagnostic tools for the plasma and beam parameters measurement. The characteristics of plasma generation, negative ion production and extraction were studied on the test equipment. The negative ion beam was extracted from the RF driven negative ion source for the first time. The detailed structure and main results are presented in this article.展开更多
This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc d...This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.展开更多
基于直接等离子体注入(Direct Plasma Injection Scheme,DPIS)的方法,设计并建造了一台低能段离子加速装置;目前实验上利用该方法成功地加速了峰值流强为11.28 m A,能量为593 ke V/u的C6+脉冲束流。考虑到激光离子源产生的束流为脉冲束...基于直接等离子体注入(Direct Plasma Injection Scheme,DPIS)的方法,设计并建造了一台低能段离子加速装置;目前实验上利用该方法成功地加速了峰值流强为11.28 m A,能量为593 ke V/u的C6+脉冲束流。考虑到激光离子源产生的束流为脉冲束,且具有能散大,强度高等特点,给低能传输线(LEBT)的设计带来很大的困难,而DPIS方法则简单易行,可有效地提高注入效率;因此该装置将激光离子源与RFQ直接连接在一起,将离子源产生的等离子体直接注入到RFQ,并没有采用传统的LEBT。并采用IGUN程序对该注入方法进行了模拟,计算确定了离子源引出的强流脉冲束的参数以及注入效率,模拟的结果与实验的测量值一致。展开更多
The neutral beam injection (NBI) system was developed on the Experimental Ad- vanced Superconducting Tokamak (EAST) for plasma heating and current driving. This paper presents the brief history, design, developmen...The neutral beam injection (NBI) system was developed on the Experimental Ad- vanced Superconducting Tokamak (EAST) for plasma heating and current driving. This paper presents the brief history, design, development, and the main experimental results of the R&D of neutral beam injector on the test bed and on EAST. In particular, it will describe: (1) how the two beamlines with a total beam power of 8 MW were developed; (2) the design of the EAST-NBI system including the high power ion source, main vacuum chamber, inner components, beam diag- nostic system and sub-system; (3) the experimental results of beamline-1 on the summer campaign of EAST in 2014 and, (4) the status of beamline-2 and the future plan of EAST-NBIs.展开更多
基金supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)National Natural Science Foundation of China(No.11975264)。
文摘A magnetic field produced by a current flowing through the plasma grid(PG) is one of the solutions to reduce the collisional loss of negative ions in a negative ion source, which reduces the electron temperature in front of the PG. However, the magnetic field diffused into the driver has some influence on the plasma outflowing. In order to investigate the effect of changing this magnetic field on the outflowing of plasma from the driver, a circular ring(absorber) of high permeability iron has been introduced at the driver exit, which can reduce the magnetic field around it and improve plasma outflowing. With the application of the absorber, the electron density is increased by about 35%, and the extraction current measured from the extraction grid is increased from 1.02 A to 1.29 A. The results of the extraction experiment with cesium injection show that both the extraction grid(EG) current and H-current are increased when the absorber is introduced.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2202700).
文摘Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion experiments to heat the plasma.The collisions between the fast negative ions and neutral background gas result in a significant number of high-energy positive ions being produced in the acceleration area,and for the high-power long-pulse operation of NBI systems,this acceleration of positive ions back to the ion source creates heat load and material sputtering on the source backplate.This difficulty cannot be ignored,with the neutral gas density in the acceleration region having a significant impact on the flux density of the backstreaming positive ions.In the work reported here,the pressure gradient in the acceleration region was estimated using an ionization gauge and a straightforward 1D computation,and it was found that once gas traveled through the acceleration region,the pressure dropped by nearly one order of magnitude,with the largest pressure drop occurring at the plasma grid.The computation also revealed that the pressure drop in the grid gaps was substantially smaller than that in the grid apertures.
基金supported by National Natural Science Foundation of China(No.11575240)Key Program of Research and Development of Hefei Science Center,CAS(grant 2016HSC-KPRD002)
文摘Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheating, a data acquisition and over-current protection system based on the PXI(PCI e Xtensions for Instrumentation) platform has been developed. The system consists of a current sensor, data acquisition module and over-current protection module. In the data acquisition module,the acquired data of one shot will be transferred in isolation and saved in a data-storage server in a txt file. It can also be recalled using NBWave for future analysis. The over-current protection module contains two modes: remote and local. This gives it the function of setting a threshold voltage remotely and locally, and the forbidden time of over-current protection also can be set by a host PC in remote mode. Experimental results demonstrate that the data acquisition and overcurrent protection system has the advantages of setting forbidden time and isolation transmission.
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 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.
基金National Natural Science Foundation of China(Nos.11675216,11905248,11975261,11975262,11975263,and 11975264)the Key Program of Research and Development of Hefei Science Center,CAS(Contract No.2016HSC-KPRD002)the National Key R&D Program of China(Nos.2017YFE0300101,2017YFE0300103,and 2017YFE0300503).
文摘A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source for a neutral beam injector in China,an RF ion source test facility was developed at the Institute of Plasma Physics,Chinese Academy of Sciences.In this paper,a two-dimensional fluid model is used to simulate the fundamental physical characteristics of RF plasma discharge.Simulation results show the relationship of the characteristics of plasma(such as electron density and electron temperature)and RF power and gas pressure.In order to verify the effectiveness of the model,the characteristics of the plasma are investigated using a Langmuir probe.In this paper,experimental and simulation results are presented,and the possible reasons for the discrepancies between them are given.This paper can help us understand the characteristics of RF plasma discharge,and give a basis for further R&D for an RF ion source.
文摘A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current drive of EAST plasmas. The first long pulse ion source (LPIS-1) has been installed in the neutral beam test bed (NBTB) system, and the performance is being tested in the NBTB. The LPIS-1 consists of a magnetic bucket plasma generator with multipole cusp-fields and a set of tetrode accelerators with slit-type apertures (a transparency of 60%). The ion beam trajectories of the accelerator column are estimated for the LPIS-1, including an original structure, with the change of slit aperture distance, plasma grid shape, grid gap distance, and voltage ratio between a plasma grid and a gradient grid using the IGUN code. This kind of calculation for the ion beam trajectory may be useful for the estimation of beam extraction characteristics and the direction of accelerator upgrade or modification, prior to the experiments of ion beam extraction.
基金National Natural Science Foundation of China(No.10575105)
文摘A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection. A real-time feedback control system (RFCS) is designed to control the gas supply for ion source based on the control model and the discrete-time control algorithm. The experimental results have proved that RFCS could regulate the gas supply smoothly, suppress the arc's abrupt over-current at the end of the ion source discharging, prolong the discharge pulse and stabilize the ion concentration. With RFCS, the ion source for neutral beam injection has reached its longest pulse with a length of 4.5 seconds in a stable status.
文摘Optical emission spectroscopy(OES)using the trace rare gases of Ar and Xe have been carried out in a radio frequency(RF)driven negative ion source at Institute of Plasma Physics,Chinese Academy of Science(ASIPP),in order to determine the electron temperature and density of the hydrogen plasma.The line-ratio methods based on population models are applied to describe the radiation process of the excited state particles and establish their relations with the plasma parameters.The spectral lines from the argon and xenon excited state atoms with the wavelength of 750.4 and 828.0 nm are used to calculate the electron temperature based on the corona model.The argon ions emission lines with the wavelength of 480 and 488 nm are selected to calculate the electron density based on the collisional radiative model.OES has given the preliminary results of the electron temperature and density by varying the discharge gas pressure and RF power.According to the experimental results,the typical plasma parameters isTe2≈2-4 eV and ne≈1 x 1017-8 x 1017 m^-3 in front of plasma grid.
基金supported by the Key Program of Research and Development of Hefei Science Center,CAS(No.2016HSCKPRD002)National Natural Science Foundation of China(Nos.11505224,11505225,11575240,11675215,11675216)
文摘In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP). Its negative ion source can be equipped with single or double RF drivers. There is a plasma expansion chamber with depth of 19 mm and an enhanced filter field. A three electrodes negative ion accelerator was employed to extract and accelerate the negative ions, which are plasma grid,extraction grid and ground grid. And there are several diagnostic tools for the plasma and beam parameters measurement. The characteristics of plasma generation, negative ion production and extraction were studied on the test equipment. The negative ion beam was extracted from the RF driven negative ion source for the first time. The detailed structure and main results are presented in this article.
文摘This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.
文摘基于直接等离子体注入(Direct Plasma Injection Scheme,DPIS)的方法,设计并建造了一台低能段离子加速装置;目前实验上利用该方法成功地加速了峰值流强为11.28 m A,能量为593 ke V/u的C6+脉冲束流。考虑到激光离子源产生的束流为脉冲束,且具有能散大,强度高等特点,给低能传输线(LEBT)的设计带来很大的困难,而DPIS方法则简单易行,可有效地提高注入效率;因此该装置将激光离子源与RFQ直接连接在一起,将离子源产生的等离子体直接注入到RFQ,并没有采用传统的LEBT。并采用IGUN程序对该注入方法进行了模拟,计算确定了离子源引出的强流脉冲束的参数以及注入效率,模拟的结果与实验的测量值一致。
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2013GB101000,Sub-Contract No.2013GB101001)National Natural Science Foundation of China(No.11405207)the International Science&Technology Cooperation Program of China(No.2014DFG61950)
文摘The neutral beam injection (NBI) system was developed on the Experimental Ad- vanced Superconducting Tokamak (EAST) for plasma heating and current driving. This paper presents the brief history, design, development, and the main experimental results of the R&D of neutral beam injector on the test bed and on EAST. In particular, it will describe: (1) how the two beamlines with a total beam power of 8 MW were developed; (2) the design of the EAST-NBI system including the high power ion source, main vacuum chamber, inner components, beam diag- nostic system and sub-system; (3) the experimental results of beamline-1 on the summer campaign of EAST in 2014 and, (4) the status of beamline-2 and the future plan of EAST-NBIs.