A new bipartition neutral transport model has been developed for simulation of the hydrogenic neutral particle transport in the vicinity of HL-2A divertor target plate.The numerical calculation results on the basis of...A new bipartition neutral transport model has been developed for simulation of the hydrogenic neutral particle transport in the vicinity of HL-2A divertor target plate.The numerical calculation results on the basis of this model are fairly consistent with the results obtained with the "multi-generation method". One possible application of this model is to provide a source term originating from neutral transport calculation for any other edge plasma transport code, for instance, B-2 code, which has been used to simulate edge plasma transport of the HL-2A divertor configuration. Especially it can be utilized to quickly classify the plasma in divertor region as high or low recycling regime.展开更多
In order to avoid destroying the vessel wall and poisoning the plasma, at the same time to efficiently extract the waste product of the fusion process from the system, divertors were adopted in some machines just at t...In order to avoid destroying the vessel wall and poisoning the plasma, at the same time to efficiently extract the waste product of the fusion process from the system, divertors were adopted in some machines just at the beginning of dealing with this problems. Up to now, the remarkable progress has been made in this respect field . In order to understand the physics behind divertors, HL-2A tokamak with two closed divertors was successfully built in 2002. Its parameters are as follows：展开更多
Tungsten(W)accumulation in the core,depending on W generation and transport in the edge region,is a severe issue in fusion reactors.Compared to standard divertors(SDs),snowflake divertors(SFDs)can effectively suppress...Tungsten(W)accumulation in the core,depending on W generation and transport in the edge region,is a severe issue in fusion reactors.Compared to standard divertors(SDs),snowflake divertors(SFDs)can effectively suppress the heat flux,while the impact of magnetic configurations on W core accumulation remains unclear.In this study,the kinetic code DIVIMP combined with the SOLPS-ITER code is applied to investigate the effects of divertor magnetic configurations(SD versus SFD)on W accumulation during neon injection in HL-3.It is found that the W concentration in the core of the SFD is significantly higher than that of the SD with similar total W erosion flux.The reasons for this are:(1)W impurities in the core of the SFD mainly originate from the inner divertor,which has a short leg,and the source is close to the divertor entrance and upstream separatrix.Furthermore,the W ionization source(S_(W0))is much stronger,especially near the divertor entrance.(2)The region overlap of S_(W0)and F_(W,TOT)pointing upstream promote W accumulation in the core.Moreover,the influence of W source locations at the inner target on W transport in the SFD is investigated.Tungsten impurity in the core is mainly contributed by target erosion in the common flux region(CFR)away from the strike point.This is attributed to the fact that the W source at this location enhances the ionization source above the W ion stagnation point,which sequentially increases W penetration.Therefore,the suppression of far SOL inner target erosion can effectively prevent W impurities from accumulating in the core.展开更多
The plasma optical boundary reconstruction technique based on Hommen's theory is promising for future tokamaks with high parameters. In this work, we conduct detailed analysis and simulation verification to estima...The plasma optical boundary reconstruction technique based on Hommen's theory is promising for future tokamaks with high parameters. In this work, we conduct detailed analysis and simulation verification to estimate the ‘logic loophole' of this technique. The finite-width effect and unpredictable errors reduce the technique's reliability, which leads to this loophole. Based on imaging theory, the photos of a virtual camera are simulated by integrating the assumed luminous intensity of plasma. Based on Hommen's theory, the plasma optical boundary is reconstructed from the photos. Comparing the reconstructed boundary with the one assumed, the logic loophole and its two effects are quantitatively estimated. The finite-width effect is related to the equivalent thickness of the luminous layer, which is generally about 2-4 cm but sometimes larger. The level of unpredictable errors is around 0.65 cm. The technique based on Hommen's theory is generally reliable, but finite-width effect and unpredictable errors have to be taken into consideration in some scenarios. The parameters of HL-2M are applied in this work.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
This paper presents the characteristics of L-mode detachment,together with the behavior of edge turbulent transport and plasma confinement on the HL-2A tokamak.Partially detached and pronounced detached states have be...This paper presents the characteristics of L-mode detachment,together with the behavior of edge turbulent transport and plasma confinement on the HL-2A tokamak.Partially detached and pronounced detached states have been achieved in L-mode plasma.Stored energy was maintained before and after detachment.Edge turbulence and its transport have increased obviously in the partially detached state.In the pronounced detached state,redistribution of the density and temperature profiles due to detachment leads to low amplitude of electron temperature and pressure,as well as very weak edge turbulence and transport.Despite strong plasma radiation in the pronounced detached state,reduced edge turbulent transport contributes to maintaining stored energy in detached L-mode plasma in HL-2A.Different detachment states play an important role in the redistribution of density and temperature profiles,which requires further study.展开更多
A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically ...A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically through the plasma region and the polarization is parallel to the toroidal magnetic field.A special designed Galileo-type telescope with long Rayleigh length is applied to focus the laser size and ensure collimation.A group of doubleGaussian collection lenses image the 600 mm vertical scattered region onto rectangular fiber arrays with a spatial resolution of 10 mm.The 2.20 mm × 2.86 mm fiber optic bundle consists of 130 low hydroxyl(OH) 200/220 μm(core/cladding) diameter fibers with numerical aperture NA=0.22,carrying the light to remotely located multi-channel polychromators.Effect of oblique incidence on narrow band filter has been analyzed.The designed electron temperatures range from 5 to 1000 eV and electron densities from 5 × 10^(18) to 1×10^(20) m^(-3).展开更多
A newly designed divertor Langmuir probe diagnostic system has been installed in a rare closed divertor of the HL-2A tokamak and steadily operated for the study of divertor physics involved edge-localized mode mitigat...A newly designed divertor Langmuir probe diagnostic system has been installed in a rare closed divertor of the HL-2A tokamak and steadily operated for the study of divertor physics involved edge-localized mode mitigation,detachment and redistribution of heat flux,etc.Two sets of probe arrays including 274 probe tips were placed at two ports(approximately 180°separated toroidally),and the spatial and temporal resolutions of this measurement system could reach6 mm and 1μs,respectively.A novel design of the ceramic isolation ring can ensure reliable electrical insulation property between the graphite tip and the copper substrate plate where plasma impurities and the dust are deposited into the gaps for a long experimental time.Meanwhile,the condition monitoring and mode conversion between single and triple probe of the probe system could be conveniently implemented via a remote-control station.The preliminary experimental result shows that the divertor Langmuir probe system is capable of measuring the high spatiotemporal parameters involved the plasma density,electron temperature,particle flux as well as heat flux during the ELMy H-mode discharges.展开更多
Acceleration of a dust particle in the SOL （scrape-off layer）/divertor plasma of HL- 2A with a single-null configuration is studied. A simplest model of the dust dynamics is applied, namely spherical shape of a dust...Acceleration of a dust particle in the SOL （scrape-off layer）/divertor plasma of HL- 2A with a single-null configuration is studied. A simplest model of the dust dynamics is applied, namely spherical shape of a dust, ion drag force due to Coulomb scattering as a dominant force, and spontaneous charging of a dust particle to the equilibrium charge. In the outer region near the plasma-facing wall the poloidal plasma flow pushes the dust particle to the divertor plates. It is clarified that the dust particle with a radius of 1 μm from the top of the SOL/divertor region is accelerated up to around 100 m/s at the divertor plates along the poloidal direction .展开更多
1 Introduction In the last two years＇ campaigns of the HL-2A experiments, single null （SN） divertor plasma was achieved. During the 2004 experiment, the supersonic molecular beam injection （SMB） and strong hydro...1 Introduction In the last two years＇ campaigns of the HL-2A experiments, single null （SN） divertor plasma was achieved. During the 2004 experiment, the supersonic molecular beam injection （SMB） and strong hydrogen gas puffing were used for gas fuelling, some unique phenomena have been observed. The plasma parameters achieved are： Ip=320 kA, ne=4.4× 10^19 m^ 3, By=2.2 T, plasma duration t=1580 ms.展开更多
文摘A new bipartition neutral transport model has been developed for simulation of the hydrogenic neutral particle transport in the vicinity of HL-2A divertor target plate.The numerical calculation results on the basis of this model are fairly consistent with the results obtained with the "multi-generation method". One possible application of this model is to provide a source term originating from neutral transport calculation for any other edge plasma transport code, for instance, B-2 code, which has been used to simulate edge plasma transport of the HL-2A divertor configuration. Especially it can be utilized to quickly classify the plasma in divertor region as high or low recycling regime.
基金Supported by the National Natural Science Foundation of China （ 10475022 ）The authors would like to thank all of our colleagues working on HL-2A, particularly LU J., LU E, FU B. Z. and LU0 C. W. for their assistance in the experiment on HL-2A.
文摘In order to avoid destroying the vessel wall and poisoning the plasma, at the same time to efficiently extract the waste product of the fusion process from the system, divertors were adopted in some machines just at the beginning of dealing with this problems. Up to now, the remarkable progress has been made in this respect field . In order to understand the physics behind divertors, HL-2A tokamak with two closed divertors was successfully built in 2002. Its parameters are as follows：
基金supported by National Natural Science Foundation of China(Nos.12235002 and 12122503)National Key R&D Program of China(No.2018YFE0301101)+1 种基金Dalian Science&Technology Talents Program(No.2022RJ11)Xingliao Talent Project(No.XLYC2203182)。
文摘Tungsten(W)accumulation in the core,depending on W generation and transport in the edge region,is a severe issue in fusion reactors.Compared to standard divertors(SDs),snowflake divertors(SFDs)can effectively suppress the heat flux,while the impact of magnetic configurations on W core accumulation remains unclear.In this study,the kinetic code DIVIMP combined with the SOLPS-ITER code is applied to investigate the effects of divertor magnetic configurations(SD versus SFD)on W accumulation during neon injection in HL-3.It is found that the W concentration in the core of the SFD is significantly higher than that of the SD with similar total W erosion flux.The reasons for this are:(1)W impurities in the core of the SFD mainly originate from the inner divertor,which has a short leg,and the source is close to the divertor entrance and upstream separatrix.Furthermore,the W ionization source(S_(W0))is much stronger,especially near the divertor entrance.(2)The region overlap of S_(W0)and F_(W,TOT)pointing upstream promote W accumulation in the core.Moreover,the influence of W source locations at the inner target on W transport in the SFD is investigated.Tungsten impurity in the core is mainly contributed by target erosion in the common flux region(CFR)away from the strike point.This is attributed to the fact that the W source at this location enhances the ionization source above the W ion stagnation point,which sequentially increases W penetration.Therefore,the suppression of far SOL inner target erosion can effectively prevent W impurities from accumulating in the core.
基金supported by the Tsinghua University 2021 Doctoral Summer Projectsupported by the National Key R&D Program of China (No. 2018YFE0301102)National Natural Science Foundation of China (Nos. 11875020 and 11875023)。
文摘The plasma optical boundary reconstruction technique based on Hommen's theory is promising for future tokamaks with high parameters. In this work, we conduct detailed analysis and simulation verification to estimate the ‘logic loophole' of this technique. The finite-width effect and unpredictable errors reduce the technique's reliability, which leads to this loophole. Based on imaging theory, the photos of a virtual camera are simulated by integrating the assumed luminous intensity of plasma. Based on Hommen's theory, the plasma optical boundary is reconstructed from the photos. Comparing the reconstructed boundary with the one assumed, the logic loophole and its two effects are quantitatively estimated. The finite-width effect is related to the equivalent thickness of the luminous layer, which is generally about 2-4 cm but sometimes larger. The level of unpredictable errors is around 0.65 cm. The technique based on Hommen's theory is generally reliable, but finite-width effect and unpredictable errors have to be taken into consideration in some scenarios. The parameters of HL-2M are applied in this work.
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National Key Research and Development Program of China(Nos.2018YFE0303102,2018YFE0309103,2017YFE0300405 and 2017YFE0301203)National Natural Science Foundation of China(Nos.U1867222,11875124,11905051,11805055 and 11875020)Sichuan Youth Science and Technology Innovation Team Project(No.2020JDTD0030)。
文摘This paper presents the characteristics of L-mode detachment,together with the behavior of edge turbulent transport and plasma confinement on the HL-2A tokamak.Partially detached and pronounced detached states have been achieved in L-mode plasma.Stored energy was maintained before and after detachment.Edge turbulence and its transport have increased obviously in the partially detached state.In the pronounced detached state,redistribution of the density and temperature profiles due to detachment leads to low amplitude of electron temperature and pressure,as well as very weak edge turbulence and transport.Despite strong plasma radiation in the pronounced detached state,reduced edge turbulent transport contributes to maintaining stored energy in detached L-mode plasma in HL-2A.Different detachment states play an important role in the redistribution of density and temperature profiles,which requires further study.
基金supported by the National Key Research and Development Program of China (Nos. 2019YFE0302002, 2017YFE0301203 and 2017YFE0301202)National Natural Science Foundation of China (No. 12175055)。
文摘A vertical edge Thomson scattering(ETS) diagnostic system on HL-2M tokamak has been designed.The ETS system collects the scattered light from Nd:YAG laser(1064 nm,2 J,30 Hz,15 ns).The laser beam propagates vertically through the plasma region and the polarization is parallel to the toroidal magnetic field.A special designed Galileo-type telescope with long Rayleigh length is applied to focus the laser size and ensure collimation.A group of doubleGaussian collection lenses image the 600 mm vertical scattered region onto rectangular fiber arrays with a spatial resolution of 10 mm.The 2.20 mm × 2.86 mm fiber optic bundle consists of 130 low hydroxyl(OH) 200/220 μm(core/cladding) diameter fibers with numerical aperture NA=0.22,carrying the light to remotely located multi-channel polychromators.Effect of oblique incidence on narrow band filter has been analyzed.The designed electron temperatures range from 5 to 1000 eV and electron densities from 5 × 10^(18) to 1×10^(20) m^(-3).
基金partially supported by National Natural Science Foundation of China(Nos.11875017,11875020,12175186 and 11905052)the National Magnetic Confinement Fusion Science Program of China(Nos.2019YFE03030002,2017YFE0301203 and 2018YFE0310100)the Sichuan Outstanding Youth Science Foundation(No.2020JDJQ0019)。
文摘A newly designed divertor Langmuir probe diagnostic system has been installed in a rare closed divertor of the HL-2A tokamak and steadily operated for the study of divertor physics involved edge-localized mode mitigation,detachment and redistribution of heat flux,etc.Two sets of probe arrays including 274 probe tips were placed at two ports(approximately 180°separated toroidally),and the spatial and temporal resolutions of this measurement system could reach6 mm and 1μs,respectively.A novel design of the ceramic isolation ring can ensure reliable electrical insulation property between the graphite tip and the copper substrate plate where plasma impurities and the dust are deposited into the gaps for a long experimental time.Meanwhile,the condition monitoring and mode conversion between single and triple probe of the probe system could be conveniently implemented via a remote-control station.The preliminary experimental result shows that the divertor Langmuir probe system is capable of measuring the high spatiotemporal parameters involved the plasma density,electron temperature,particle flux as well as heat flux during the ELMy H-mode discharges.
基金the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusiona Grant-in-Aid for scientific research from Ministry of Education,Science and Culture of Japan (No.19055005)the program of the Formation of the International Joint Research Base Network in the National Institute for Fusion Science.
文摘Acceleration of a dust particle in the SOL （scrape-off layer）/divertor plasma of HL- 2A with a single-null configuration is studied. A simplest model of the dust dynamics is applied, namely spherical shape of a dust, ion drag force due to Coulomb scattering as a dominant force, and spontaneous charging of a dust particle to the equilibrium charge. In the outer region near the plasma-facing wall the poloidal plasma flow pushes the dust particle to the divertor plates. It is clarified that the dust particle with a radius of 1 μm from the top of the SOL/divertor region is accelerated up to around 100 m/s at the divertor plates along the poloidal direction .
文摘1 Introduction In the last two years＇ campaigns of the HL-2A experiments, single null （SN） divertor plasma was achieved. During the 2004 experiment, the supersonic molecular beam injection （SMB） and strong hydrogen gas puffing were used for gas fuelling, some unique phenomena have been observed. The plasma parameters achieved are： Ip=320 kA, ne=4.4× 10^19 m^ 3, By=2.2 T, plasma duration t=1580 ms.
