一般边界条件下球形压力容器钢壁中氚和氦-3的浓度变化规律研究

为了认识储氚高压容器壁材料的力学性能变化及其导致的容器承载能力变化, 必须研究储氚期间, 容器壁中氚和氦-3浓度的空间分布和随时间的变化. 针对容器外表面为一般传质边界条件和容器内部氚为范德瓦尔斯气体的情况, 同时考虑容器腔内和容器壁中氚的衰变和扩散, 建立求解储氚高压容器壁中氚和氦-3浓度的解析理论模型, 导出了氚和氦-3浓度的理论公式. 通过解析计算给出了器壁中氚和氦-3浓度随外表面传质系数的变化曲线和浓度的时空变化曲线, 提出了氦-3浓度的2β ₁ + β ₂ / 2倍定律, 即处于开放空间的储氚球形高压容器, 器壁中氦-3的浓度呈内高外低的分布, 时间越长, 浓度沿径向的梯度越大, 在时间足够长时, 各处浓度逼近时间无限长时的最终值, 也就是各处的最大值, 内表面处的最大值是该处氚初始时刻浓度的2β ₁ + β ₂ / 2倍, 这里β ₁ 和β ₂ 为与氚的范德瓦尔斯常数相关的参数. 研究结果为储氚高压容器的强度安全性评估提供了前提.     

实验包层氚增殖区提氚气体换热研究

描述了提氚气体(氦气)进入氚增值区后被正硅酸锂(Li4SiO4)小球加热的过程。通过现有实验包层(TBM)设计参数完成的提氚气体温升理论计算和三维数值模拟验证计算得到提氚气体经过球床时温度可以很快从20℃升到500℃。因此,在进行提氚系统设计优化时,中国设计的实验包层模块不需要增加额外设备对提氚气体进行预热。     

Positron and deuteron depth profiling in helium-3-implanted electrum-like alloy

In spite of previous extensive studies, the helium behavior in metals still remains an issue in microelectronics as well as in nuclear technology. A gold-silver solid solution (Au₆₀Ag₄₀: synthetic gold-rich electrum) was chosen as a relevant model to study helium irradiation of heavy metals. After helium-3 ion implantation at an energy ranging from 4.2 to 5.6 MeV, nuclear reaction analysis (NRA) based on the ³He(d,p)⁴He reaction, was performed in order to study the thermal diffusion of helium atoms. At room temperature, NRA data reveal that a single Gaussian can fit the He-distribution, which remains unchanged after annealing at temperatures below 0.45 of the melting point. Slow positron implantation spectroscopy, used to monitor the fluence dependence of induced defects unveils a positron saturation trapping, which occurs for He contents of the order of 50-100 appm, whereas concentrations larger than 500 appm seem to favor an increase in the S-parameter of Doppler broadening. Moreover, at high temperature, NRA results clearly show that helium long range diffusion occurs, though, without following a simple Fick law.     

Decrease in the probability of tritium decay in an external electric field

The probability of tritium beta decay is shown to decrease under the effect of a constant uniform external electric field on the atom. For the tritium atom, the effect is due first to the reduction of the beta-decay endpoint energy and second to the reduction of the density of vacant bound electron states at the nucleus. Both of these factors reduce the beta-decay probability: the first reduces the probability of decay to continuum electron states, while the second reduces the probability of decay to a bound state.     

Experimental detection and investigation of muon catalyzed fusion of deuterium and tritium

Measurement of the neutron yield of the reaction $\text{dt}\text{μ →}{}^4\text{He}\text{+ μ}{}^{\mathrm{?}}\text{+ 17.6}\text{MeV}$, induced by negative muons in a mixture of gaseous D₂ and T₂, has shown that the rate of muon transfer from deuterium to tritium is λ_dt = (2.7 ± 0.9) × 10⁸s^?1 and that the lower limit of the formation rate of dt_μ molecules is λ_dtμ > 10⁸s^?1.     

Discovery of temperature-dependent phenomena of muon-catalyzed fusion in solid deuterium and tritium mixtures

A systematic experimental study on muon-catalyzed fusion was conducted using a series of solid deuterium and tritium mixtures. A variety of conditions were investigated, i.e., tritium concentrations from 20% to 70%, and temperatures from 5 to 16 K. With decreasing temperature, we observed an unexpected decrease in the muon cycling rate (lambda(c)) and an increase in the muon loss probability (W). The origins of these observed changes were interpreted by the temperature-dependence in the dt mu formation process for lambda(c) and that in the muon reactivation process after muon-to-alpha sticking for W.     

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通过对聚变堆设计包层进行先后的一维、三维氚增殖比计算与分析,确定合适的模块材料、明确的模块划分以及相应的模块厚度,最终找到了合适的满足氚自持(TBR=1.3162)的熔盐设计包层.     

熔盐包层设计与氚增殖比的计算

通过对聚变堆设计包层进行先后的一维、三维氚增殖比计算与分析,确定合适的模块材料、明确的模块划分以及相应的模块厚度,最终找到了合适的满足氚自持(TBR=1.3162)的熔盐设计包层。     

X-ray diffraction study of thermal vacancies in solid helium-3

Thermal vacancy concentrations in solid ³He have been directly measured by x-rays over a wide range of molar volumes in the bcc phase and one molar volume in the hcp phase. Values of the vacancy free energies and free volumes of formation have been obtained, and comparison with NMR and ultrasonic studies yields information about vacancy motion in the two phases of the solid.     

First gamma-ray measurements of fusion alpha particles in JET trace tritium experiments

Gamma-ray spectra from nuclear reactions between fusion-born alpha (alpha) particles and Be impurities were measured for the first time in deuterium-tritium plasmas in the Joint European Torus. The time dependence of the measured spectra allowed the determination of the density evolution of fast alpha particles. Correlation between the decay time of the gamma-ray emission and the plasma parameters in different plasma scenarios was established. Results are consistent with classical slowing down of the alpha particles in discharges with high plasma currents and monotonic q-profiles. In low plasma current discharges and in the discharges with large on-axis current holes (extreme reversal central magnetic shear), the gamma-ray emission decay times are shorter than the classical slowing down times, indicating an alpha-particle confinement degradation in such discharges in line with theoretical predictions.     

Measurement of helium-3 and deuterium stopping power ratio for negative muons

The measurement method and results measuring of the stopping power ratio of helium-3 and deuterium atoms for muons slowed down in the D/³He mixture are presented. Measurements were performed at four values of pure ³He gas target densities, ϕ_He = 0.0337, 0.0355, 0.0359, 0.0363 (normalized to the liquid hydrogen density) and at a density 0.0585 of the D/³He mixture. The experiment was carried out at PSI muon beam μE4 with the momentum Pμ= 34.0 MeV/c. The measured value of the mean stopping ratio S$_{3^He/D}$ is 1.66±0.04.     

Additional production of deuterium and helium-3 by high-energy protons and antiprotons in the early Universe

The results of calculations of ³He, ³H, and D production as a result of the disintegration of primordial ⁴He by high-energy protons and anti-protons in the early Universe are reported. It is shown that for primary particle energies E _p , _p ^t- <0.2 GeV the main role in ³He, ³H, and D production is played by the secondary proton cascade that develops in the cosmological plasma and which destroys ⁴He most intensively at E~75 MeV. At the current state of the experimental data one can calculate the number of nuclei produced to within 10%, and investigation of the inelastic p ⁴He interaction channels at E~75 MeV will make it possible to improve substantially the accuracy of calculations of the additional production of light elements. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 9, 609–613 (May 1999)     

μ− meson catalysis of nuclear fusion in a mixture of deuterium and tritium

Due to the existence of a weakly bound state of the mesic molecule dt μ^? meson in a mixture of deuterium and tritium can catalyze ～ 10² of the fusion reactions dt μ →⁴He + n + μ^? + 17.6 MeV and release ～ 2 GeV of energy.     

Simultaneous self-focusing of two laser beams in a subthreshold coherent population trapping regime

The propagation of two-component laser radiation in a medium consisting of atoms with a Λ level scheme is investigated. The simultaneous self-focusing of two beams is considered. The main features of this phenomenon are: 1) lowering of the self-focusing threshold by several orders of magnitude in comparison with the known case of saturation of a transition in a two-level atom; 2) a strong dependence of the character of the propagation of the radiation on the difference between the detunings of the two frequency components of the field from resonance, which is associated with fulfillment of the two-photon resonance condition. Zh. Tekh. Fiz. 67, 126–129 (July 1997)     

Plasma and surface tension model for explaining the surface effect of tritium generation at cold fusion

Summary For explaining the surface mechanism of deuterium reactions in palladium and titanium (clod fusion or neutron swapping) leading to strong tritium production and isotope shifts in palladium, the mechanism of an exotic deuterium plasma with possible short nuclear distance by thermal motion was introduced. Using a new model of the surface tension of metals, resulting in a ?swimming electron layer?, the increase of the concentration of deuterons and the decrease of their distance cause a higher cold fusion in the surface layer by orders of magnitudes compared with the bulk material. The work of one of the authors (H. Hora) was supported by the Wilhelm-Heinrich and Else Heraeus Foundation, Hanau, while being on leave at the University of Giessen, Germany.     

Chemical interaction in peroxide-metal systems in the regime of combustion in an external electric field

The effect of a contactless electric field on the interactions involved in the combustion of the BaO₂-Fe and MnO₂-Fe systems is studied. The results are indicative of the possibility of increasing the extent of chemical conversion during the combustion of oxide systems by applying an external electric field. A possible mechanism of the influence of an electric field on the redox processes occurring during the combustion of oxide systems composed of a metal fuel and a solid oxidizer is described.     

Epithermal effects in muon catalyzed fusion in H/D/T mixtures at low deuterium and tritium concentrations

The results of a Monte Carlo simulation of muon catalyzed fusion in H/D/T mixtures at low deuterium and tritium concentrations are presented, and the kinetics of the dt branch of the CF cycle is discussed. It is shown that the epithermal effects in the dt cycle produce a multicomponent structure in the time spectra of dt fusion, in agreement with the recent experimental results obtained by the CF collaboration at PSI. The importance of further studies of the CF reactions in triple mixtures is emphasized.