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
The arc regulation method is applied to the high-current ion source for high-power hydrogen ion beam extraction for the first time. The characteristics of the arc and beam, including the probe ion saturation current, ...The arc regulation method is applied to the high-current ion source for high-power hydrogen ion beam extraction for the first time. The characteristics of the arc and beam, including the probe ion saturation current, the arc power and the beam current, are studied with feedback control. The results show that the arc regulation method can be successfully applied to ion beam extraction. This lays a sound foundation for the testing of a new ion source and the operation of a conditioned ion source for neutral beam injector devices.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
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
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 new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such a...A new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such as high mirror magnetic field, large plasma volume, and biased probe. 140uA of O^7+, 185uA of Ar^11+ and 50uA of Xe^26+ could be produced with a RF power of 800 W. The intense beams of highly charged metallic ions are produced by means of the method of a metal evaporation oven and volatile compound through axial access. The test results are 130uA of Ca^11+, 70uA of Ca^12+ and 65uA of Fe^lo+. The ion source has been put into operation for the cyclotron at the institute of Modern Physics (IMP).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 large-area high-power radio-frequency(RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute(KAERI). The RF ion source consists of a dr...A large-area high-power radio-frequency(RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute(KAERI). The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.展开更多
Long pulse operation of high power ion source is the requirement of fusion science research on neutral beam injector. A breakdown of accelerator column is drastically increased when operating with high beam energy and...Long pulse operation of high power ion source is the requirement of fusion science research on neutral beam injector. A breakdown of accelerator column is drastically increased when operating with high beam energy and long beam duration. To extend the pulse length, which was stopped with every breakdown so far, the beam re-starting technology was developed and utilized. As a result, the voltage drop of every power supply due to breakdown was recovered within a time of 90 ms and beam pulse length was extended much longer than the case before this improvement. The details of the beam re-starting technology and the preliminary results were presented in this manuscript.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
The operating principles of the two duoplasmatron ion sources and the PIG source available for the Van de Graaff accelerator have been determined qualitatively, mainly by studying the extensive literature on ion sourc...The operating principles of the two duoplasmatron ion sources and the PIG source available for the Van de Graaff accelerator have been determined qualitatively, mainly by studying the extensive literature on ion sources. The main characteristics of the three sources have therefore been determined experimentally on an ion source test bench. Important parameters of the sources such as the pressure and temperature in different regions of the sources not measured, because of space limitations. However, in spite of these limitations in quantitative understanding of the sources, sufficient information to continue with the study of the beam transport through the Van de Graaff accelerator and its beamlines could be obtained from these measurements. With regard to beam intensity, lifetime and gas consumption the measurements showed that the hotcathode duoplasmatron is at present by far the most suitable source for the van de Graaff accelerator. The emittance of the ion source was measured with two slits, 90 mm apart, and a Faraday cup in the ion source test bench at an arc voltage of 83 V, an arc current of 1 Amp, a filament voltage of 24 V and an extraction voltage of 5 kV. The measured emittance for 90% of the beam intensity is 48π mm mrad. This figure will be used to calculate the beam transmission through the Van de Graaf accelerator. Different computer programs have been used for these calculations from the ion source through the terminal section, the accelerator and beam line up to the Nuclear Microprobe (NMP) for beam quality.展开更多
A practical 2.45-GHz microwave-driven Cs-free H^- source was improved based on the experimental H^- source at Peking University(PKU). Several structural improvements were implemented to meet the practical requiremen...A practical 2.45-GHz microwave-driven Cs-free H^- source was improved based on the experimental H^- source at Peking University(PKU). Several structural improvements were implemented to meet the practical requirements of Xi'an Proton Application Facility(XiPaf). Firstly, the plasma chamber size was optimized to enhance the plasma intensity and stability. Secondly, the filter magnetic field and electron deflecting magnetic field were enhanced to reduce co-extracted electrons. Thirdly, a new two-electrode extraction system with farther electrode gap and enhanced water cooling ability to diminish spark and sputter during beam extraction was applied. At last, the direct H^- current measuring method was adopted by the arrangement of a new pair of bending magnets before Faraday cup(FC) to remove residual electrons. With these improvements, electron cyclotron resonance(ECR) magnetic field optimization experiments and operation parameter variation experiments were carried out on the H^- ion source and a maximum 8.5-mA pure H^- beam was extracted at 50 kV with the time structure of 100 Hz/0.3 ms. The root-mean-square(RMS) emittance of the beam is 0.25 Π·mm·mrad. This improved H^- source and extraction system were maintenance-free for more than 200 hours in operation.展开更多
A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamb...A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave(CW) mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.展开更多
A 16 kV/20 A power supply was developed for the extraction grid of prototype radio frequency(RF) ion source of neutral beam injector. To acquire the state signals of extraction grid power supply(EGPS) and control ...A 16 kV/20 A power supply was developed for the extraction grid of prototype radio frequency(RF) ion source of neutral beam injector. To acquire the state signals of extraction grid power supply(EGPS) and control the operation of the EGPS, a data acquisition and control system has been developed. This system mainly consists of interlock protection circuit board, photoelectric conversion circuit, optical fibers, industrial compact peripheral component interconnect(CPCI) computer and host computer. The human machine interface of host computer delivers commands and data to program of the CPCI computer, as well as offers a convenient client for setting parameters and displaying EGPS status. The CPCI computer acquires the status of the power supply. The system can turn-off the EGPS quickly when the faults of EGPS occur. The system has been applied to the EGPS of prototype RF ion source. Test results show that the data acquisition and control system for the EGPS can meet the requirements of the operation of prototype RF ion source.展开更多
The neutral beam injector (NBI) system was designed and developed mainly for the plasma heating on the Experimental Advanced Superconducting Tokamak (EAST). The high power ion source is the key part of the NBI. A ...The neutral beam injector (NBI) system was designed and developed mainly for the plasma heating on the Experimental Advanced Superconducting Tokamak (EAST). The high power ion source is the key part of the NBI. A hot cathode ion source was used on the EAST-NBI. The ion source was conditioned on the ion source test bed with hydrogen gas and achieved the designed parameters. The deuterium gas was used when it moved to the EAST-NBI. The main performance of the ion source on EAST is presented in this paper. The highest beam power of 4.5 MW in NBI-1 and 2.75 MW in NBI-2 was achieved. The total neutral beam power is about 4.5 MW. The long pulse beam of 100 s is injected into the EAST plasma too.展开更多
In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The ne...In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand (NBTS) at the Korea Atomic Energy Research Institute (KAERI) in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.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
Huazhong University of Science and Technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions f...Huazhong University of Science and Technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions for neutral beam injection in nuclear fusion reactors.The main design parameters of the ion source are:RF power ≤40 kW;extraction voltage ≤10kV;accelerator voltage ≤20 kV.This paper gives an overview of the progress of the ion source with particular emphasis on some issues.The RF driver and source plasma are analyzed and optimized in terms of impedance matching,plasma characteristics and power coupling.In regard to the simulation analysis,a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion source.Furthermore,a collisional radiative model of H and H2is built for plasma optical diagnosis.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
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 Magnetic Confinement Fusion Science Program of China(No.2013GB101000)partly supported by National Natural Science Foundation of China(No.11075183)the Knowledge Innovation Program of the Chinese Academy of Sciences(Study of the physical characteristics of arc power feedback control for the high current ion source)
文摘The arc regulation method is applied to the high-current ion source for high-power hydrogen ion beam extraction for the first time. The characteristics of the arc and beam, including the probe ion saturation current, the arc power and the beam current, are studied with feedback control. The results show that the arc regulation method can be successfully applied to ion beam extraction. This lays a sound foundation for the testing of a new ion source and the operation of a conditioned ion source for neutral beam injector devices.
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 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(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Equipment Upgrading Fund and '9.5' Fund for Fundamental Research from the Chinese Academy of Sciences
文摘A new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such as high mirror magnetic field, large plasma volume, and biased probe. 140uA of O^7+, 185uA of Ar^11+ and 50uA of Xe^26+ could be produced with a RF power of 800 W. The intense beams of highly charged metallic ions are produced by means of the method of a metal evaporation oven and volatile compound through axial access. The test results are 130uA of Ca^11+, 70uA of Ca^12+ and 65uA of Fe^lo+. The ion source has been put into operation for the cyclotron at the institute of Modern Physics (IMP).
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.
基金supported by the Ministry of Science,ICT and Future Planning of the Republic of Korea under the ITER Technology R&D ProgramNational R&D Program Through the National Research Foundation of Korea(NRF)Funded by the Ministry of Science,ICT&Future Planning(NRF-2014M1A7A1A03045372)
文摘A large-area high-power radio-frequency(RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute(KAERI). The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.
基金supported by National Natural Science Foundation of China(Nos.11675215,11575240)the Key Program of Research and Development of Hefei Science Center,CAS(No.2016HSC-KPRD002)the National Key R&D Program of China(No.2017YFE300101)
文摘Long pulse operation of high power ion source is the requirement of fusion science research on neutral beam injector. A breakdown of accelerator column is drastically increased when operating with high beam energy and long beam duration. To extend the pulse length, which was stopped with every breakdown so far, the beam re-starting technology was developed and utilized. As a result, the voltage drop of every power supply due to breakdown was recovered within a time of 90 ms and beam pulse length was extended much longer than the case before this improvement. The details of the beam re-starting technology and the preliminary results were presented in this manuscript.
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.
文摘The operating principles of the two duoplasmatron ion sources and the PIG source available for the Van de Graaff accelerator have been determined qualitatively, mainly by studying the extensive literature on ion sources. The main characteristics of the three sources have therefore been determined experimentally on an ion source test bench. Important parameters of the sources such as the pressure and temperature in different regions of the sources not measured, because of space limitations. However, in spite of these limitations in quantitative understanding of the sources, sufficient information to continue with the study of the beam transport through the Van de Graaff accelerator and its beamlines could be obtained from these measurements. With regard to beam intensity, lifetime and gas consumption the measurements showed that the hotcathode duoplasmatron is at present by far the most suitable source for the van de Graaff accelerator. The emittance of the ion source was measured with two slits, 90 mm apart, and a Faraday cup in the ion source test bench at an arc voltage of 83 V, an arc current of 1 Amp, a filament voltage of 24 V and an extraction voltage of 5 kV. The measured emittance for 90% of the beam intensity is 48π mm mrad. This figure will be used to calculate the beam transmission through the Van de Graaf accelerator. Different computer programs have been used for these calculations from the ion source through the terminal section, the accelerator and beam line up to the Nuclear Microprobe (NMP) for beam quality.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775007 and 11575013)
文摘A practical 2.45-GHz microwave-driven Cs-free H^- source was improved based on the experimental H^- source at Peking University(PKU). Several structural improvements were implemented to meet the practical requirements of Xi'an Proton Application Facility(XiPaf). Firstly, the plasma chamber size was optimized to enhance the plasma intensity and stability. Secondly, the filter magnetic field and electron deflecting magnetic field were enhanced to reduce co-extracted electrons. Thirdly, a new two-electrode extraction system with farther electrode gap and enhanced water cooling ability to diminish spark and sputter during beam extraction was applied. At last, the direct H^- current measuring method was adopted by the arrangement of a new pair of bending magnets before Faraday cup(FC) to remove residual electrons. With these improvements, electron cyclotron resonance(ECR) magnetic field optimization experiments and operation parameter variation experiments were carried out on the H^- ion source and a maximum 8.5-mA pure H^- beam was extracted at 50 kV with the time structure of 100 Hz/0.3 ms. The root-mean-square(RMS) emittance of the beam is 0.25 Π·mm·mrad. This improved H^- source and extraction system were maintenance-free for more than 200 hours in operation.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB845502)the National Natural Science Foundation of China(Grant No.11575013)
文摘A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance(PMECR) ion source, which has the ability of producing a tens-m A H+beam, has been built and tested at Peking University(PKU). Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave(CW) mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.
基金supported by National Natural Science Foundation of China(Contract Nos.11505225&11675216)Foundation of ASIPP(Contract No.DSJJ-15-GC03)the Key Program of Research and Development of Hefei Science Center,CAS(2016HSC-KPRD002)
文摘A 16 kV/20 A power supply was developed for the extraction grid of prototype radio frequency(RF) ion source of neutral beam injector. To acquire the state signals of extraction grid power supply(EGPS) and control the operation of the EGPS, a data acquisition and control system has been developed. This system mainly consists of interlock protection circuit board, photoelectric conversion circuit, optical fibers, industrial compact peripheral component interconnect(CPCI) computer and host computer. The human machine interface of host computer delivers commands and data to program of the CPCI computer, as well as offers a convenient client for setting parameters and displaying EGPS status. The CPCI computer acquires the status of the power supply. The system can turn-off the EGPS quickly when the faults of EGPS occur. The system has been applied to the EGPS of prototype RF ion source. Test results show that the data acquisition and control system for the EGPS can meet the requirements of the operation of prototype RF ion source.
基金supported by National Natural Science Foundation of China (NNSFC) (Contract Nos. 11405207, 11507215 and 11675215)
文摘The neutral beam injector (NBI) system was designed and developed mainly for the plasma heating on the Experimental Advanced Superconducting Tokamak (EAST). The high power ion source is the key part of the NBI. A hot cathode ion source was used on the EAST-NBI. The ion source was conditioned on the ion source test bed with hydrogen gas and achieved the designed parameters. The deuterium gas was used when it moved to the EAST-NBI. The main performance of the ion source on EAST is presented in this paper. The highest beam power of 4.5 MW in NBI-1 and 2.75 MW in NBI-2 was achieved. The total neutral beam power is about 4.5 MW. The long pulse beam of 100 s is injected into the EAST plasma too.
文摘In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand (NBTS) at the Korea Atomic Energy Research Institute (KAERI) in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.
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.
基金supported by the National Key R&D Program of China(No.2017YFE0300105)National Natural Science Foundation of China(Nos.11775088 and 12005074)the Fundamental Research Funds for the Central Universities,HUST(No.2021XXJS013)
文摘Huazhong University of Science and Technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions for neutral beam injection in nuclear fusion reactors.The main design parameters of the ion source are:RF power ≤40 kW;extraction voltage ≤10kV;accelerator voltage ≤20 kV.This paper gives an overview of the progress of the ion source with particular emphasis on some issues.The RF driver and source plasma are analyzed and optimized in terms of impedance matching,plasma characteristics and power coupling.In regard to the simulation analysis,a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion source.Furthermore,a collisional radiative model of H and H2is built for plasma optical diagnosis.
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.