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
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
In order to obtain enhanced plasma parameters a complete new tokamak HL-2M is now under construction in Southwestern Institute of Physics. To assure the structural safety of the device for the entire operation cycle,o...In order to obtain enhanced plasma parameters a complete new tokamak HL-2M is now under construction in Southwestern Institute of Physics. To assure the structural safety of the device for the entire operation cycle,one of the most important issues is the lifetime-limiting effects due to the pulsed operation mode. Fatigue is one of the major failure modes to be considered in mechanical design,and pulsed operation imposes stress with significant alternating components on the support structure(SS). Therefore,the reliability of the whole device is strongly affected by the stress and fatigue characteristic of the SS as the interface structure. This article introduces the SS design and details the fatigue life calculation methods based on the different characteristics of the sub-structures. The fatigue life in hazardous areas of the toroidal field coils anti-torque structure(TFCs-ATs) has been determined by non-linear analysis results. And with the stresstime history data of the vacuum vessel & poloidal field coils support structure(VV&PFCs SS),the fatigue analysis of the hot spots has been completed based on rain-flow counting method and linear cumulative damage method. The calculated minimum fatigue life on TFCs-ATs and VV&PFCs SS is 4.743E+05 and 1.805E+06 cycles,respectively. And the calculated fatigue life on sub-structures can meet the required life for HL-2M tokamak:1.0E+05 cycles.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
Sets of powerful microwave diagnostic systems have been developed on the HL-2 A tokamak,including 18 subsystems with high spatial and temporal resolutions.These systems have been applied in the HL-2 A tokamak experime...Sets of powerful microwave diagnostic systems have been developed on the HL-2 A tokamak,including 18 subsystems with high spatial and temporal resolutions.These systems have been applied in the HL-2 A tokamak experiments to investigate the core plasma transport,turbulence,MHD,energetic particle physics and so on.In this paper,the microwave diagnostics and their applications are reviewed.Some new technologies,including GHz sampling digital correlation electron cyclotron emission(DCECE),multi-channel correlation reflectometers,and solid state terahertz interferometers,are also presented in the paper.展开更多
Using the trans-neut module of the BOUT++ code, we study how the fueling penetration depth of supersonic molecular beam injection(SMBI) is affected by plasma density and temperature profiles. The plasma densities and ...Using the trans-neut module of the BOUT++ code, we study how the fueling penetration depth of supersonic molecular beam injection(SMBI) is affected by plasma density and temperature profiles. The plasma densities and temperatures in L-mode are initialized to be a set of linear profiles with different core plasma densities and temperatures. The plasma profiles are relaxed to a set of steady states with different core plasma densities or temperatures. For a fixed gradient, the steady profiles are characterized by the core plasma density and temperature. The SMBI is investigated based on the final steady profiles with different core plasma densities or temperatures. The simulated results suggest that the SMB injection will be blocked by dense core plasma and high-temperature plasma. Once the core plasma density is set to be N_(i0)= 1.4N_0(N_0= 1 × 10^(19)m^(-3)) it produces a deeper penetration depth. When N_(i0) is increased from 1.4N_0 to 3.9N_0 at intervals of 0.8N_0, keeping a constant core temperature of T_(e0)= 725 eV at the radial position of ψ = 0.65, the penetration depth gradually decreases. Meanwhile, when the density is fixed at N_(i0)= 1.4N_0 and the core plasma temperature T_(e0) is set to 365 eV,the penetration depth increases. The penetration depth decreases as T_(e0) is increased from 365 eV to 2759 eV. Sufficiently large N_(i0) or T_(e0) causes most of the injected molecules to stay in the scrape-off-layer(SOL) region, lowering the fueling efficiency.展开更多
A synchronous demodulation system is proposed and deployed for CO_2 dispersion interferometer on HL-2 A,which aims at high plasma density measurements and real-time feedback control.In order to make sure that the demo...A synchronous demodulation system is proposed and deployed for CO_2 dispersion interferometer on HL-2 A,which aims at high plasma density measurements and real-time feedback control.In order to make sure that the demodulator and the interferometer signal are synchronous in phase,a phase adjustment(PA) method has been developed for the demodulation system.The method takes advantages of the field programmable gate array parallel and pipeline process capabilities to carry out high performance and low latency PA.Some experimental results presented show that the PA method is crucial to the synchronous demodulation system and reliable to follow the fast change of the electron density.The system can measure the lineintegrated density with a high precision of 2.0?×?10^(18)m^(-2).展开更多
A 20 cm focal length normal incidence vacuum ultraviolet(VUV_20 cm) monochromator with a fast time response has been developed for measuring edge impurity line emission in the wavelength range of 300–2000 ? on an HL-...A 20 cm focal length normal incidence vacuum ultraviolet(VUV_20 cm) monochromator with a fast time response has been developed for measuring edge impurity line emission in the wavelength range of 300–2000 ? on an HL-2A tokamak. An aberration corrected concave holographic grating with 1200 grooves/mm is adopted in the monochromator, which provides a wavelength dispersion of 40 ? mm^(-1). The aperture is f/4.5. A channel electron multiplier is used as a detector. The time resolution of the system is 17 μs. Wavelength calibration of the system has been done by using a hollow cathode light source in the laboratory with helium and argon gases. The obtained signals of helium and argon spectra are very strong since the inner surface of the monochromator vacuum chamber is blackened and the stray light level is then significantly reduced. The optical property of the system has been examined by scanning the width of the entrance and exit slits. The system is then installed at the mid-port of the HL-2A tokamak and typical line emissions from the HL-2A plasma are measured. Time behaviors of edge impurity line emissions are observed with the fast time response system in different plasma confinement regimes, especially in the H-mode discharges. The result shows that the VUV_20 cm system works very well to measure the edge impurity line emissions in the edge localized modes phase of H-mode discharges.展开更多
Real-time equilibrium reconstruction is crucially important for plasma shape control in the process of tokamak plasma discharge.However,as the reconstruction algorithm is computationally intensive,it is very difficult...Real-time equilibrium reconstruction is crucially important for plasma shape control in the process of tokamak plasma discharge.However,as the reconstruction algorithm is computationally intensive,it is very difficult to improve its accuracy and reduce the computation time,and some optimizations need to be done.This article describes the three most important aspects of this optimization:(1) compiler optimization;(2) some optimization for middle-scale matrix multiplication on the graphic processing unit and an algorithm which can solve the block tri-diagonal linear system efficiently in parallel;(3) a new algorithm to locate the X&O point on the central processing unit.A static test proves the correctness and a dynamic test proves the feasibility of using the new code for real-time reconstruction with 129?×?129 grids;it can complete one iteration around 575 μs for each equilibrium reconstruction.The plasma displacements from real-time equilibrium reconstruction are compared with the experimental measurements,and the calculated results are consistent with the measured ones,which can be used as a reference for the real-time control of HL-2 A discharge.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
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supported by National Magnetic Confinement Fusion Science Program of China(No.2013GB113001)
文摘In order to obtain enhanced plasma parameters a complete new tokamak HL-2M is now under construction in Southwestern Institute of Physics. To assure the structural safety of the device for the entire operation cycle,one of the most important issues is the lifetime-limiting effects due to the pulsed operation mode. Fatigue is one of the major failure modes to be considered in mechanical design,and pulsed operation imposes stress with significant alternating components on the support structure(SS). Therefore,the reliability of the whole device is strongly affected by the stress and fatigue characteristic of the SS as the interface structure. This article introduces the SS design and details the fatigue life calculation methods based on the different characteristics of the sub-structures. The fatigue life in hazardous areas of the toroidal field coils anti-torque structure(TFCs-ATs) has been determined by non-linear analysis results. And with the stresstime history data of the vacuum vessel & poloidal field coils support structure(VV&PFCs SS),the fatigue analysis of the hot spots has been completed based on rain-flow counting method and linear cumulative damage method. The calculated minimum fatigue life on TFCs-ATs and VV&PFCs SS is 4.743E+05 and 1.805E+06 cycles,respectively. And the calculated fatigue life on sub-structures can meet the required life for HL-2M tokamak:1.0E+05 cycles.
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 Magnetic Confinement Fusion Science Program of China(Grant Nos.2014GB107001,2014GB108002,2013GB104000,2013GB-107002,2017YFE0301680 and 2017YFE0300500)Sichuan Science and Technology Program(Grant No.2018RZ0123)National Natural Science Foundation of China(Grant Nos.11475057,11705049,11705051,11775070,11305053 and 11261140326)
文摘Sets of powerful microwave diagnostic systems have been developed on the HL-2 A tokamak,including 18 subsystems with high spatial and temporal resolutions.These systems have been applied in the HL-2 A tokamak experiments to investigate the core plasma transport,turbulence,MHD,energetic particle physics and so on.In this paper,the microwave diagnostics and their applications are reviewed.Some new technologies,including GHz sampling digital correlation electron cyclotron emission(DCECE),multi-channel correlation reflectometers,and solid state terahertz interferometers,are also presented in the paper.
基金supported by the National Natural Science Foundation for Young Scientists of China(Grant No.11605143)the Undergraduate Training Programs for Innovation and Entrepreneurship of Sichuan Province,China(Grant No.05020732)+4 种基金the National Natural Science Foundation of China(Grant No.11575055)the Fund from the Department of Education in Sichuan Province of China(Grant No.15ZB0129)the China National Magnetic Confinement Fusion Science Program(Grant No.2013GB107001)the National ITER Program of China(Contract No.2014GB113000)the Funds of the Youth Innovation Team of Science and Technology in Sichuan Province of China(Grant No.2014TD0023)
文摘Using the trans-neut module of the BOUT++ code, we study how the fueling penetration depth of supersonic molecular beam injection(SMBI) is affected by plasma density and temperature profiles. The plasma densities and temperatures in L-mode are initialized to be a set of linear profiles with different core plasma densities and temperatures. The plasma profiles are relaxed to a set of steady states with different core plasma densities or temperatures. For a fixed gradient, the steady profiles are characterized by the core plasma density and temperature. The SMBI is investigated based on the final steady profiles with different core plasma densities or temperatures. The simulated results suggest that the SMB injection will be blocked by dense core plasma and high-temperature plasma. Once the core plasma density is set to be N_(i0)= 1.4N_0(N_0= 1 × 10^(19)m^(-3)) it produces a deeper penetration depth. When N_(i0) is increased from 1.4N_0 to 3.9N_0 at intervals of 0.8N_0, keeping a constant core temperature of T_(e0)= 725 eV at the radial position of ψ = 0.65, the penetration depth gradually decreases. Meanwhile, when the density is fixed at N_(i0)= 1.4N_0 and the core plasma temperature T_(e0) is set to 365 eV,the penetration depth increases. The penetration depth decreases as T_(e0) is increased from 365 eV to 2759 eV. Sufficiently large N_(i0) or T_(e0) causes most of the injected molecules to stay in the scrape-off-layer(SOL) region, lowering the fueling efficiency.
基金supported by the National Magnetic Confinement Fusion Science Program of China (Nos.2014GB109001 and 2013GB104003)National Natural Science Foundation of China (Grant Nos.11375195,11505053,and 11575184)
文摘A synchronous demodulation system is proposed and deployed for CO_2 dispersion interferometer on HL-2 A,which aims at high plasma density measurements and real-time feedback control.In order to make sure that the demodulator and the interferometer signal are synchronous in phase,a phase adjustment(PA) method has been developed for the demodulation system.The method takes advantages of the field programmable gate array parallel and pipeline process capabilities to carry out high performance and low latency PA.Some experimental results presented show that the PA method is crucial to the synchronous demodulation system and reliable to follow the fast change of the electron density.The system can measure the lineintegrated density with a high precision of 2.0?×?10^(18)m^(-2).
基金partly supported by National Natural Science Foundation of China (Nos. 11375057 and 11505051)the National Magnetic Confinement Fusion Program of China (Nos. 2014GB108003 and 2015GB104003)
文摘A 20 cm focal length normal incidence vacuum ultraviolet(VUV_20 cm) monochromator with a fast time response has been developed for measuring edge impurity line emission in the wavelength range of 300–2000 ? on an HL-2A tokamak. An aberration corrected concave holographic grating with 1200 grooves/mm is adopted in the monochromator, which provides a wavelength dispersion of 40 ? mm^(-1). The aperture is f/4.5. A channel electron multiplier is used as a detector. The time resolution of the system is 17 μs. Wavelength calibration of the system has been done by using a hollow cathode light source in the laboratory with helium and argon gases. The obtained signals of helium and argon spectra are very strong since the inner surface of the monochromator vacuum chamber is blackened and the stray light level is then significantly reduced. The optical property of the system has been examined by scanning the width of the entrance and exit slits. The system is then installed at the mid-port of the HL-2A tokamak and typical line emissions from the HL-2A plasma are measured. Time behaviors of edge impurity line emissions are observed with the fast time response system in different plasma confinement regimes, especially in the H-mode discharges. The result shows that the VUV_20 cm system works very well to measure the edge impurity line emissions in the edge localized modes phase of H-mode discharges.
基金supported in part by National Natural Science Foundation of China under Grant Nos.11505050 and 11775071the ITER-CN under Grant No.2014GB107003
文摘Real-time equilibrium reconstruction is crucially important for plasma shape control in the process of tokamak plasma discharge.However,as the reconstruction algorithm is computationally intensive,it is very difficult to improve its accuracy and reduce the computation time,and some optimizations need to be done.This article describes the three most important aspects of this optimization:(1) compiler optimization;(2) some optimization for middle-scale matrix multiplication on the graphic processing unit and an algorithm which can solve the block tri-diagonal linear system efficiently in parallel;(3) a new algorithm to locate the X&O point on the central processing unit.A static test proves the correctness and a dynamic test proves the feasibility of using the new code for real-time reconstruction with 129?×?129 grids;it can complete one iteration around 575 μs for each equilibrium reconstruction.The plasma displacements from real-time equilibrium reconstruction are compared with the experimental measurements,and the calculated results are consistent with the measured ones,which can be used as a reference for the real-time control of HL-2 A discharge.
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.