Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium...Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent reactions.To date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational precision.In this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance.We found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H uncertainty.Currently,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He rate.From the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.展开更多
The positron lifetime spectroscopy was used to investigate the electron structures of crystal lattice and its defects in palladium samples filled galvanostatically with hydrogen and deuterium, respectively. The result...The positron lifetime spectroscopy was used to investigate the electron structures of crystal lattice and its defects in palladium samples filled galvanostatically with hydrogen and deuterium, respectively. The results have indicated that the positron lifetime were all the same between hydrogen and deuterium filled samples in which the positron lifetime τ(?) increased about 10%, corresponding to the volume expansibility after the formation of hydrides PdH or PdD phases during electrolyzing commom water or heavy water with Pd cathode; and Will not change with time in 3 weeks after stopping electrolysis; but could be recovered to 116±1ps, the value in polycrystalline pure palladium, after annealing at high temperature.展开更多
Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puf...Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes diagnostic.In boundary region, many neutral particle processes(atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-α system(d(3 p)3Πu±→ a(2 s)3Σg+), D2 emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the Q(0–0) band(d3Πu-→ a(2 s)3Σg+) in the Q branch of the Fulcher-α system were used for detailed analysis to acquire the boundary region temperature Te(below 5eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.展开更多
Large deuterium clusters are generated using a cryogenic pulse valve with a cone nozzle （21 mm long, 4° open angle）. Rayleigh scattering experiment is carried out to obtain the scaling relation between scatteri...Large deuterium clusters are generated using a cryogenic pulse valve with a cone nozzle （21 mm long, 4° open angle）. Rayleigh scattering experiment is carried out to obtain the scaling relation between scattering signal SR and backing pressure P0. A method using the Coulomb explosion model is proposed to verify that the clusters continue to grow after their leaving the nozzle. Our experiments suggest a tentatively optimized position for laser cluster interaction.展开更多
Fuel retention and recycling in plasma facing materials is a crucial issue for fusion devices, especially for the long pulse discharge devices. In this work, the deuterium retention and the surface erosion of SiC-coat...Fuel retention and recycling in plasma facing materials is a crucial issue for fusion devices, especially for the long pulse discharge devices. In this work, the deuterium retention and the surface erosion of SiC-coated graphite tiles exposed to EAST plasmas have been studied by post-mortem analyses, i.e., thermal desorption spectroscopy （TDS）, secondary ion mass spec- troscopy （SIMS） and scanning electron microscopy （SEM）. The results show that the sample cut from the high field side （HF） tile has been intensely eroded due to deuterium bombardment on plasma facing surfaces in the initial phase of discharges and trapped highest amount of deuterium. Lower deuterium retention has been found in the inner divertor sample, which is presumably due to the particular exposure history in the 2010 spring campaign.展开更多
D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy pr...D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy proton backscattering and elastic recoil detection (ERD). The measured data show that there is little diffusion of deuterium in A12O3 and the diffusion coefficient is deduced to be 1.1 ×10-17 cm2/s. The measured total concentration of implanted deuterium is 4.5×1018 at./cm2. The profile of hydrogen adsorbed on the surface of Al2O3 samples was also observed by ERD and 1H(19F, αγ)16O analysis. The distribution range of 1H in Al2O3 after deuterium implantation is much larger than that before one.展开更多
Based on our previous work(Phys.Plasmas 25 012704(2018)),a fitting formula is given for electron-ion energy partition fraction of 3.54-MeV fusion alpha particles in deuterium-tritium(DT) plasmas as a function of plasm...Based on our previous work(Phys.Plasmas 25 012704(2018)),a fitting formula is given for electron-ion energy partition fraction of 3.54-MeV fusion alpha particles in deuterium-tritium(DT) plasmas as a function of plasma mass density ρ,electron temperature T_(e),and ion temperature T_(i).The formula can be used in a huge range of the plasma state,where ρ varies between 1.0 g/cc~10.0^(3) g/cc and both T_(e) and T_(i) change from 0.1 keV to 100.0 keV.Relativistic effect for electrons is investigated including the effect of the projectile recoil in the plasmas at T_(e)≥ 50.0 keV.The partition fraction for T_(e)>T_(i) is found to be close to that for T_(e)=T_(i). The comparisons with other fitting results are made at some plasma densities when T_(e)=T_(i),and the difference is explained.The fitting result is very close to the calculated one in most cases,which is convenient for the simulation of alpha heating in hot dense DT plasmas for inertial confined fusion.展开更多
In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickne...In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickness of only several nanometers.These Cr_(2)O_(3) NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating.The effect of the Cr_(2)O_(3) NS concentration on the morphology,microstructure and deuterium permeation resistance of the coating was studied.With the addition of 1.0 g 1^(-1)Cr_(2)O_(3) NSs,compared with the Cr-Zr-O coating without NSs,the permeation reduction factor of the resultant coating was enhanced from 249℃to 575℃ at 500℃.The coating,with a thickness of nearly 193 nm,achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate.The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.展开更多
This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deu...This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deuterium-loaded titanium foil samples and powder sample. Detection of charged particle was carried out using a low-level charged particle spectrometer. An A1 foil was used as an energy absorber for identification of charged particle. Although the counting rate is very low in the experiment, the emission of energetic particle from the sample is observed and the particle is identified as a proton having energy about 2.8 MeV after exiting the titanium sample. This work provides a positive result for the emission of charged particle in the deuterium-loaded titanium foil samples at low temperature, but a negative result for the deuterium-loaded titanium powder sample. The average reaction yield is deduced to be （0.46±0.08） protons/h for the foil samples. With the suggestion that the proton originates from d-d reaction, we calculate the reaction rate for d-d reaction, and the obtained result is 1.4×10^-24 fusion/d-d.sec. The negative result of the deuterium-loaded titanium powder sample suggests that the reaction yield might be correlated with the density or microscopic variables of deuterium-loaded titanium materials. The negative result also indicates that d-d reaction catalysed by μ-meson from cosmic ray can be excluded in the samples in this experiment.展开更多
Tungsten has been chosen as one of the most promising candidates as the plasma-facing material in future fusion reactors. Although tungsten has numerous advantages compared with other materials, issues including dust ...Tungsten has been chosen as one of the most promising candidates as the plasma-facing material in future fusion reactors. Although tungsten has numerous advantages compared with other materials, issues including dust are rather difficult to deal with. Dust is produced in fusion devices by energetic plasma-surface interaction. The re-deposition of dust particles could cause the retention of fuel atoms. In this work, tungsten is deposited with deuterium plasma by hollow cathode discharge to simulate the dust production in a tokamak. The morphology of the deposited tungsten can be described as a film with spherical particles on it. Thermal desorption spectra of the deposited tungsten show extremely high desorption of the peak positions. It is also found that there is a maximum retention of deuterium in the deposited tungsten samples due to the dynamic equilibrium of the deposition and sputtering process on the substrates.展开更多
基金supported by the National Key R&D Program of China(No.2022YFA1602401)by the National Natural Science Foundation of China(No.11825504)。
文摘Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent reactions.To date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational precision.In this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance.We found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H uncertainty.Currently,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He rate.From the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.
文摘The positron lifetime spectroscopy was used to investigate the electron structures of crystal lattice and its defects in palladium samples filled galvanostatically with hydrogen and deuterium, respectively. The results have indicated that the positron lifetime were all the same between hydrogen and deuterium filled samples in which the positron lifetime τ(?) increased about 10%, corresponding to the volume expansibility after the formation of hydrides PdH or PdD phases during electrolyzing commom water or heavy water with Pd cathode; and Will not change with time in 3 weeks after stopping electrolysis; but could be recovered to 116±1ps, the value in polycrystalline pure palladium, after annealing at high temperature.
基金Project supported by the National Natural Science Foundation of China(Grant No.11805234)
文摘Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes diagnostic.In boundary region, many neutral particle processes(atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-α system(d(3 p)3Πu±→ a(2 s)3Σg+), D2 emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the Q(0–0) band(d3Πu-→ a(2 s)3Σg+) in the Q branch of the Fulcher-α system were used for detailed analysis to acquire the boundary region temperature Te(below 5eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975121)the Foundation of National Key Laboratory of Laser Plasma
文摘Large deuterium clusters are generated using a cryogenic pulse valve with a cone nozzle （21 mm long, 4° open angle）. Rayleigh scattering experiment is carried out to obtain the scaling relation between scattering signal SR and backing pressure P0. A method using the Coulomb explosion model is proposed to verify that the clusters continue to grow after their leaving the nozzle. Our experiments suggest a tentatively optimized position for laser cluster interaction.
基金supported partially by National Natural Science Foundation of China(Nos.10905070,10875148 and 10728510)the Knowledge Innovation Program of the Chinese Academy of Sciences,the National Magnetic Confinement Fusion Science Program of China(No.2009GB106005)
文摘Fuel retention and recycling in plasma facing materials is a crucial issue for fusion devices, especially for the long pulse discharge devices. In this work, the deuterium retention and the surface erosion of SiC-coated graphite tiles exposed to EAST plasmas have been studied by post-mortem analyses, i.e., thermal desorption spectroscopy （TDS）, secondary ion mass spec- troscopy （SIMS） and scanning electron microscopy （SEM）. The results show that the sample cut from the high field side （HF） tile has been intensely eroded due to deuterium bombardment on plasma facing surfaces in the initial phase of discharges and trapped highest amount of deuterium. Lower deuterium retention has been found in the inner divertor sample, which is presumably due to the particular exposure history in the 2010 spring campaign.
文摘D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy proton backscattering and elastic recoil detection (ERD). The measured data show that there is little diffusion of deuterium in A12O3 and the diffusion coefficient is deduced to be 1.1 ×10-17 cm2/s. The measured total concentration of implanted deuterium is 4.5×1018 at./cm2. The profile of hydrogen adsorbed on the surface of Al2O3 samples was also observed by ERD and 1H(19F, αγ)16O analysis. The distribution range of 1H in Al2O3 after deuterium implantation is much larger than that before one.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0402300 and 2017YFA0403200)the National Natural Science Foundation of China(Grant No.11574034)+1 种基金the Innovation Development Foundation of China Academy of Engineering Physics(CAEP)(Grant No.CX20200029)the Science Challenge Project(Grant Nos.JCKY201612A501)。
文摘Based on our previous work(Phys.Plasmas 25 012704(2018)),a fitting formula is given for electron-ion energy partition fraction of 3.54-MeV fusion alpha particles in deuterium-tritium(DT) plasmas as a function of plasma mass density ρ,electron temperature T_(e),and ion temperature T_(i).The formula can be used in a huge range of the plasma state,where ρ varies between 1.0 g/cc~10.0^(3) g/cc and both T_(e) and T_(i) change from 0.1 keV to 100.0 keV.Relativistic effect for electrons is investigated including the effect of the projectile recoil in the plasmas at T_(e)≥ 50.0 keV.The partition fraction for T_(e)>T_(i) is found to be close to that for T_(e)=T_(i). The comparisons with other fitting results are made at some plasma densities when T_(e)=T_(i),and the difference is explained.The fitting result is very close to the calculated one in most cases,which is convenient for the simulation of alpha heating in hot dense DT plasmas for inertial confined fusion.
基金supported by the National MCF Energy R&D Program of China(No.2018YFE0313300)National Natural Science Foundation of China(Nos.52273224,51402116)the Fundamental Research Funds for the Central Universities(Nos.2018KFYYXJJ028,2019KFYXMBZ045)
文摘In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickness of only several nanometers.These Cr_(2)O_(3) NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating.The effect of the Cr_(2)O_(3) NS concentration on the morphology,microstructure and deuterium permeation resistance of the coating was studied.With the addition of 1.0 g 1^(-1)Cr_(2)O_(3) NSs,compared with the Cr-Zr-O coating without NSs,the permeation reduction factor of the resultant coating was enhanced from 249℃to 575℃ at 500℃.The coating,with a thickness of nearly 193 nm,achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate.The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.
基金Project supported by President Foundation of China Institute of Atomic Energy (Grant No YZ0714)
文摘This paper reports on an experiment for testing natural nuclear fusion at low temperature searching for evidence of the origin of 3He from natural nuclear fusion in deep Earth. The experiment was carried out using deuterium-loaded titanium foil samples and powder sample. Detection of charged particle was carried out using a low-level charged particle spectrometer. An A1 foil was used as an energy absorber for identification of charged particle. Although the counting rate is very low in the experiment, the emission of energetic particle from the sample is observed and the particle is identified as a proton having energy about 2.8 MeV after exiting the titanium sample. This work provides a positive result for the emission of charged particle in the deuterium-loaded titanium foil samples at low temperature, but a negative result for the deuterium-loaded titanium powder sample. The average reaction yield is deduced to be （0.46±0.08） protons/h for the foil samples. With the suggestion that the proton originates from d-d reaction, we calculate the reaction rate for d-d reaction, and the obtained result is 1.4×10^-24 fusion/d-d.sec. The negative result of the deuterium-loaded titanium powder sample suggests that the reaction yield might be correlated with the density or microscopic variables of deuterium-loaded titanium materials. The negative result also indicates that d-d reaction catalysed by μ-meson from cosmic ray can be excluded in the samples in this experiment.
基金Supported by the National Magnetic Confinement Fusion Program under Grant No 2015GB109003the National Natural Science Foundation of China under Grant No 11675010
文摘Tungsten has been chosen as one of the most promising candidates as the plasma-facing material in future fusion reactors. Although tungsten has numerous advantages compared with other materials, issues including dust are rather difficult to deal with. Dust is produced in fusion devices by energetic plasma-surface interaction. The re-deposition of dust particles could cause the retention of fuel atoms. In this work, tungsten is deposited with deuterium plasma by hollow cathode discharge to simulate the dust production in a tokamak. The morphology of the deposited tungsten can be described as a film with spherical particles on it. Thermal desorption spectra of the deposited tungsten show extremely high desorption of the peak positions. It is also found that there is a maximum retention of deuterium in the deposited tungsten samples due to the dynamic equilibrium of the deposition and sputtering process on the substrates.
