The long-term stability of deuterated thin titanium films

Using neutron reflectometry, we investigated the deuterium desorption of Pd-covered Ti films that have been deuterated at 1 bar deuterium at room temperature and then exposed to air. The deuterium content was monitored continuously for the first two days. Thereafter, measurements were conducted periodically, spanning a period of up to 2 years. The films were in the thickness range of 10–300 nm and the desorption behaviour showed a strong dependence on the film thickness. The smaller the Ti film thickness the faster the Ti films desorbed the stored deuterium.     

“PROCESS”: A systems code for fusion power plants—Part 1: Physics

PROCESS is a reactor systems code – it assesses the engineering and economic viability of a hypothetical fusion power station using simple models of all parts of a reactor system, from the basic plasma physics to the generation of electricity. It has been used for many years, but details of its operation have not been previously published. This paper describes some of its capabilities. PROCESS is usually used in optimisation mode, in which it finds a set of parameters that maximise (or minimise) a figure of merit chosen by the user, while being consistent with the inputs and the specified constraints. Because the user can apply all the physically relevant constraints, while allowing a large number of parameters to vary, it is in principle only necessary to run the code once to produce a self-consistent, physically plausible reactor model. The scope of PROCESS is very wide and goes well beyond reactor physics, including conversion of heat to electricity, buildings, and costs, but this paper describes only the plasma physics and magnetic field calculations.The capabilities of PROCESS in plasma physics are limited, as its main aim is to combine engineering, physics and economics. A model is described which shows the main plasma features of an inductive ITER scenario. Significant differences between the PROCESS results and the published scenario include the bootstrap current and loop voltage. The PROCESS models for these are being revised. Two new models for DEMO have been obtained. The first, DEMO A, is intended to be “conservative” in that it might be possible to build it using the technology of the near future. For example, since current drive technologies are not yet mature, only 12% of the current is assumed to be due to current drive. Consequently it is a pulsed machine, able to burn for only 1.65 hours at a time. Despite the comparatively large size (major radius is 9 m), the fusion power is only 1.95 GW. The assumed gross thermal efficiency is 33%, giving just 465 MW net electric power. The second, DEMO B, is intended to be “advanced” in that more optimistic assumptions are made. Comparison of DEMO A and B with a reference ITER scenario shows that current drive and bootstrap fraction need the most extrapolation from the perspective of plasma physics.     

Temperature dependence of calcium and magnesium induced caseinate precipitation in H2O and D2O

Casein is a well-known and highly studied protein present in milk found in the form of large colloidal particles called casein micelles. Here we assessed the influence of two solvents, H₂O and D₂O, on the precipitation temperatures of sodium caseinate induced by calcium and magnesium ions. The intrinsic fluorescence of casein was correlated with the suspended and precipitated protein fractions in order to extrapolate the precipitation temperature. The precipitation temperature values were determined for several calcium and magnesium concentrations in H₂O, demonstrating the strong differences in the association behaviour induced by the two divalent cations. The precipitation temperatures of caseinate, in the presence of calcium induced by heating the samples in D₂O, were significantly lower compared with the one performed in H₂O. On the contrary, the precipitation temperatures of casein in the presence of magnesium were very close to those obtained in the samples tested in H₂O. Thus, calcium interaction with the protein depends on temperature and solvents, two parameters that modify the accessibility of the binding site of the cation. Conversely, the interaction of the divalent magnesium ion with casein was shown to depend only upon the temperature. Remarkably, this evidence indicates that the two ions have different binding sites on the protein, suggesting that the D₂O solvent plays an important role in the detection of the different binding sites for calcium and magnesium. Additionally, the results obtained with the simultaneous presence of both cations suggest the existence of a cooperative mechanism between the two ions, in which the presence of calcium makes more sites available for the binding of magnesium.     

高分辨四极质谱计在HL-2A装置上的应用

将具有分辨氦(He)和氘(D2)能力的高分辨四极质谱计安装到HL-2A托卡马克装置上,同时送入氦气和氘气,得到了质谱计可分辨的最小He+/D2+峰值比.分别对真空室在辉光放电清洗前后、不同等离子体放电次数的氢同位素和氦进行测量,观察到四种工况下质谱峰m/q=4的主要成分为D2+,He+只在辉光放电清洗中作为工作气体引入.向真空室送入氘气后,比较了由分子泵和低温泵抽气的质谱情况.分压强的测量结果表明低温泵对氘气的抽速大于分子泵约18％.实验结果初步验证了高分辨四极质谱计应用于托卡马克装置可靠真空检漏和残余气体成分精确分析的可行性,并为托卡马克装置抽气泵的选型提供了依据.     

Analysis of isotopic ratios for the detection of illegal watering of beverages

The applications of the stable isotope ratio analyses (D/H, ¹³C and ¹⁸O) in the assessment of watering in beverages such as wine and fruit juices are discussed in this study. The measurement of ¹⁸O/¹⁶O ratio in combination with D/H and ¹³C/¹²C ratio is mainly focused and the international official methods implementing stable isotope techniques will be mentioned. Furthermore, the ongoing study on a possible use of ¹³C/¹²C ratio of CO₂ to detect the addition of technical produced CO₂ in mineral sparkling waters is also presented.     

Numerical model for separation of H-D gas mixture in batch-type concentric-tube thermal diffusion columns

The modeling simulation for the separation of H-D gas mixture in batch-type concentric-tube thermal diffusion columns have been analyzed from the transport equation coupled with the application of mass balance. The most important assumption is that the concentrations of H₂, HD and D₂ are locally equilibrium at every points in the column as H₂ + D₂ ↔ 2HD. The concentration distribution equation was derived and the concentration difference between the bottom and top ends of the column could be estimated. The degree of separation and separation factor for recovery of deuterium from H-D gas mixture in the batch-type cryogenic-wall thermal diffusion column were estimated.     

Heterolytic activation of hydrogen gas: New evidence for Spencer–Yu hypothesis!

Hydrogenolysis or deuterogenolysis of organolithium compounds is described for the first time under heterogeneous catalysis. This work establishes that the carbon–lithium bond can undergo a facile reduction reaction when catalyzed by palladium or platinum catalysts and provides strong evidence for the existence of Pd^δ−–H^δ+ species.     

Cross-section for D(p,p)D elastic scattering from 1.8 to 3.2 MeV at the laboratory angles of 155° and 165°

The D(p,p)D cross-sections for elastic scattering of proton on deuterium over incident proton energy range from 1.8 to 3.2 MeV at both laboratory angles of 155° and 165° were measured. A thin solid state target Ni/TiD_x/Ta/Al used for cross-section measurement was fabricated by firstly depositing layers of Ta, Ti and Ni film on the Al foil substrate of about 7 μm in turn using magnetron sputtering and then deuterating under the deuterium atmosphere. The areal density of metal element in each layer of film was measured with RBS analysis by using a 4.0 MeV ⁴He ion beam, while the areal density of the deuterium absorbed in the Ti film was measured with ERD analysis by using a 6.0 MeV ¹⁶O ion beam. The results show that the cross-sections of p-D scattering under this experimental circumstance were much enhanced over the Rutherford cross-section value. It was found that the enhancement increases linearly as the energy of the incident beam increases. The total uncertainty in the measurements was less than 7.5%.     

Modeling of monothermal ammonia-hydrogen chemical exchange column using a non-equilibrium model

The monothermal NH₃-H₂ chemical exchange process, operating at low temperature and high pressures, is simulated by considering non-ideal behavior of both phases and multicomponent mass transfer at the gas-liquid interface. The hydrodynamics of special ejector tube tray is incorporated in the simulation and validated against actual operating plant data. The column operation is simulated with respect to process parameters to determine the optimum operating window for the column. A higher temperature operation near 270 K has been suggested for better performance of the column. The multicomponent effect is not prominent in the first tower operated at 248 K and 20 MPa but is significant in the second tower operated at 270 K and 10 MPa. In the overall operation, the multicomponent effect cannot be neglected.     

Neutron powder diffraction and solid-state deuterium NMR studies of Ca2RuD6 and the stability of transition metal hexahydride salts

The crystal structure of Ca₂RuD₆ has been determined by neutron powder diffraction: space group Fm3m, K₂PtCl₆ structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340 K and 50 K. The deuterium nuclear quadrupole coupling constant, 54.7 kHz, leads to an ionic character of the Ru–D bond of 76%. The known trends in the behaviour of A₂MH₆ salts are interpreted in terms of the ionization energies of the cation and the central metal atom.