Mixtures Of Hydrogen Isotopes Research Articles

A Computerized Monitoring and Control System for the Gas-Mixture Preparation Complex for Experiments on Muon-Catalyzed Fusion

A computerized system for monitoring and controlling the gas-mixture preparation complex of the TRITON installation is described. The installation is designed for experimental investigations of muon-catalyzed fusion in triple mixtures of hydrogen isotopes H/D/T over wide ranges of temperature and pressure. The system is used to control the entire complex of gas-mixture preparation, the target parameters, and the gas-mixture composition, as well as to carry out radiation monitoring. Good performance characteristics, the high reliability of the system, and the possibility of its rapid adaptation to new tasks have been demonstrated in physics experiments.

Gas-Chromatographic Analysis of Mixtures of Hydrogen Isotopes

A simple method is proposed for the gas-chromatographic analysis of complex gas mixtures containing hydrogen isotopes; the method is based on the substantial difference in the thermal conductivity of these isotopes. The total peak of the isotopes is recorded in a chromatogram, and the calibration is performed by pure reference gases. The concentrations of impurity gases in the analyzed mixture and in reference samples for each of the hydrogen isotopes are determined simultaneously. The fractional concentrations of protium and deuterium are calculated by the equations involving the heights of the unresolved peaks of hydrogen isotopes in chromatograms and concentrations of impurity components.

Measurement and Control Systems for Investigations with Mixtures of Hydrogen Isotopes

Measurement and control systems of two instrumentation complexes for experimental studies using hydrogen isotopes are described. The first of these, the complex that prepares the gas mixture of the Triton facility, is designed for studying the muonic catalysis of nuclear fusion reactions in triple mixtures of H/D/T hydrogen isotopes over wide ranges of temperature and pressure. The second, the Prometheus complex, is designed for studying the phenomena of tritium accumulation and transmission by metals and other structural materials.

Raman spectra of solid isotopic hydrogen mixtures

Rotational and vibrational Raman spectra are investigated for mixtures of hydrogen isotopes in the solid phase. The ${\mathrm{S}}_{0}(0)$ rotational Raman transitions are asymmetrically broadened in energy for each isotope in the mixture compared to their respective pure component transitions. The isotopic energy shift of ${\mathrm{S}}_{0}(0)$ breaks the lattice symmetry and limits the roton hopping responsible for the well defined ${\mathrm{S}}_{0}(0)$ triplet found in the pure component. The ${\mathrm{S}}_{0}(0)$ line shapes of tritiated and nontritiated mixtures are nearly identical, and shows there is little effect from radiation damage. The vibrational ${\mathrm{Q}}_{1}(J)$ lines are shifted to higher energy, and the ${\mathrm{Q}}_{1}(1)/{\mathrm{Q}}_{1}(0)$ intensity ratio is decreased in the mixtures relative to the pure component. Both effects are due to a localization of the vibrons in mixtures.

Simulation of the Startup Period of the Operation of Rectification Columns for Separating Isotopic Mixtures of Hydrogen

A method for calculating the accumulation time of a column for cryogenic rectification of multicomponent mixtures of hydrogen isotopes is presented. Relations which do not use the theoretical separation step approximation and which are exclusively based on information about the physicochemical properties of the components of the mixture to be separated are used to simulate the process. A system of differential equations for nonstationary mass transfer is solved numerically to obtain the concentration profile of the components along the height of the column at a fixed time. The calculation of the startup period is illustrated by an example in which the dependence of the accumulation time on the feed-material load is obtained.

Investigation of the Parameters of Muon-Catalyzed Fusion in Double D/T Mixture at High Temperature and Density

Experiments on the study of the muon catalyzed fusion (μCF) process in a double D/T mixture of hydrogen isotopes in the temperature range 300–800 K at densities 0.3–0.5 LHD are performed at the JINR phasotron. The values of the effective μCF parameters (cycling rate λ c , neutron yield Y n , muon losses w) are obtained. Tentative dtμ-molecule formation rates on D2 and DT molecules (λ dtμ−d and λ dtμ−t ) are obtained for different mixture temperatures and densities. The results obtained show that λ dtμ−t increases with temperature, but its value is smaller than theoretical predictions.

Simulation of cryogenic rectification of tritium-containing isotopic hydrogen mixtures

A method is presented for calculating the basic technological parameters of rectification systems for separating tritium-containing mixtures of hydrogen isotopes with intermediate homomolecular isotopic exchange stages. The method of independent determination of the concentrations was used in simulating the rectification process. The liquid-vapor equilibrium problem was solved with a correction for the nonideality of the mixtures. Heat release due to tritium decay is taken into account in the heat balance equations. The quantum-statistical method was used to calculate the equilibrium constants for simulating the homomolecular isotopic exchange. The CRYDIST computer code implementing this method is used to determine the optimal parameters of the apparatus for separative processing of two isotopic mixtures with different composition and including two low-temperature rectification columns and two homomolecular isotopic exchange units.

Experimental Results on Muon Catalyzed dt Fusion in H/D/T Mixture

Experimental study on muon catalyzed dt fusion in a triple mixture of hydrogen isotopes (H/D/T) was carried out at the JINR phasotron. The measurements have been performed at various temperatures and densities with liquid and gaseous H/D/T mixtures. Results are presented for the main characteristics of the dtμ cycle. A reduction of the number of dt fusions is observed when hydrogen is added to the D/T mixture, This is mainly due to muon loss to the pt and pd cycles, which have a high sticking probability. We also observe an increase of the cycle rate when the temperature of the H/D/T mixture rises. This confirms the theoretical prediction.

Hydrogen isotope cell and its application to hydrogen isotope sensing

The EMFs of hydrogen isotope cells with H 2–D 2 gas mixtures against H 2 and D 2 reference gases were measured at 700°C using CaZr 0.90In 0.10O 3− α as a proton-conducting solid electrolyte. Steady electromotive forces (EMFs) with quick response were obtained. The EMFs were almost linear functions of the gas composition of the H 2–D 2 mixtures and were consistent with those theoretically estimated. Such defined EMFs can be used to monitor H 2/D 2 ratios in hydrogen isotope mixtures.

Empirical Correlation of Equilibrium Separation Factors in the Pd−H2/D2 System with Temperature and Composition

The range of available data on separation factors (α) in the palladium−hydrogen/deuterium system has been extended in this study using a thermal conductivity detector. The thermal conductivity detector employed a matched pair of glass-coated bead thermistors to measure the gas-phase composition of hydrogen isotope mixtures. Separation factors (α) were measured in the β-phase, over the temperature (T) and hydrogen mole fraction (xH) ranges T = 175 K to 389 K and xH = 0.195 to 0.785, respectively. These data were correlated with temperature (T) and hydrogen mole fraction in the palladium (xH) by α = exp[−0.27 + B(xH)(1000/T)0.75] and B(xH) = 0.5155 − 0.0569xH − 0.12xH2, where B(xH) is an empirical function relating the dependence of the separation factor on composition.

Operational experience with the JET AGHS cryodistillation system during and after DTE1

The JET Active Gas Handing (AGH) Cryodistillation system (CD) was designed to separate a mixture of hydrogen isotopes into individual isotopic components, discharging low activity protium gas directly to stack, and storing the deuterium and tritium product for re-use. Following successful trace tritium commissioning the system became fully operational for the JET DTE1 experimental campaign which commenced in 1997. This paper describes the operating performance of the CD system during and after this period. This includes an assessment of the total amount of gas processed and the operating conditions which were implemented to achieve optimum process conditions. Note that the original design specification of the system assumed a large proportion of process gas would be protium from the fast pellet injection system. This system was not used during the campaign and consequently the feed gas was mainly a deuterium mix requiring the discharge of large amounts of detritiated deuterium to stack. Hence operating parameters had to be changed to suit these new conditions, which led to a need to keep the tritium inventory in the system to a minimum. Despite this, the overall tritium enrichment in the system with a feed of low activity hydrogen input was up to 35% thus providing an effective pre-enrichment level for introduction to the preparative Gas Chromatograph (GC) hydrogen isotope separation system used in the AGHS. In this respect even though the operational requirements of CD had changed from the original design specification, the system was successfully adapted to its revised role, providing an important contribution in the tritium reprocessing cycle during the DTE1 campaign.

The change of surface topography of plasma facing components in controlled fusion devices

Surface microstructure and composition of plasma facing components from the TEXTOR tokamak are described. Surfaces of such components are drastically modified by the impact of plasma ions. This interaction results in the formation of thick co-deposited/co-implanted layers containing a mixture of hydrogen isotopes and plasma impurity species. The emphasis is on the characterisation of changes occurring on the graphite surface exposed for a few hours to a hot deuterium plasma and, afterwards, following the exposure either to air or annealing in vacuum at elevated temperatures. The investigation carried out by means of electron microscopy, energy dispersive X-ray spectroscopy, ion beam analysis methods and laser profilometry gives evidence on the conditions under which the deuterium is released due to the oxidation or desorption from the plasma eroded surfaces. It is also demonstrated that the oxygen-assisted removal of deuterium at 300°C has rather small impact on the decomposition of thick co-deposits.

Dynamics of muonic atom cascade in hydrogen-helium mixtures

The deexcitation of excited muonic protium and deuterium in the mixture of hydrogen and helium isotopes is considered. Methods of experimental determination of the probability of direct atomic muon capture by hydrogen and muon transfer rates from excited muonic hydrogen to helium are proposed. Theoretical results for the population of the muonic atoms in the ground state, , are compared with the existing experimental data. Results obtained for mixtures are of interest for investigation of nuclear fusion in muonic molecules.

A CRYOGENIC TARGET TO STUDY CHARGE NONSYMMETRIC MUONIC MOLECULES

An experimental setup, including a cryogenic gas target with temperature control and gas filling systems, has been developed to study muon catalyzed fusion in gas mixtures of hydrogen and helium isotopes.

Measurement of the fusion rate in μd 3 He

Many atomic and molecular processes may occur after a muon has been stopped in a mixture of hydrogen and helium isotopes. In particular, the muonic molecule μd3He can be formed. This molecule either decays or undergoes muon catalyzed fusion. Theory predicts a fusion rate much lower than the decay rate; moreover, the various theoretical predictions differ from each other by several orders of magnitude.

First measurements of dtμ cycle characteristics in liquid H/D/T mixture

Muon catalyzed fusion in a dense triple mixture of hydrogen isotopes was investigated for the first time. The experimental method is based on the registration of neutrons from dtμ fusion by a full absorption detector in 4π geometry. The measurements were performed in H/D/T mixture at T=21 K and φ≃ 1.1 LHD using four sets of isotope concentrations. The basic parameters of the dtμ cycle (neutron yield, cycling rate and total sticking) in H/D/T mixtures obtained from neutron time distributions are presented and discussed.

Liquid tritium target

The concentration dependence study of the formation rate of the muon molecules dtμ in equilibrium double D/T and triple H/D/T liquid mixtures of hydrogen isotopes requires an installation consisting of a target of volume 30 cm3 with helium cooling and a thermostabilization system. The temperature of the target, close to 22 K is fixed with an accuracy of 0.1 K.

Temperature and density dependence of μ-catalysis cycling rate in dense D/T and H/D/T gas mixtures

Muon catalyzed dt fusion in dense D/T and H/D/T gas mixtures of hydrogen isotopes is studied by the MCF collaboration at JINR. The measurements were carried out with a high pressure target at the JINR phasotron in the temperature range 300-800 K at mixture densities \( \simeq 0.4{\text{ and }} \simeq {\text{0}}{\text{.8 LHD}}\). Tentative experimental results obtained by several analysis methods are presented.

Demonstration of the Integrated Fusion Fuel Loop at the Tritium Process Laboratory of the Japan Atomic Energy Research Institute

An integrated fusion fuel loop was constructed. A palladium diffuser first treated a simulated plasma exhaust gas, that is a mixture of hydrogen isotopes and impurities such as helium and methane. A pure hydrogen isotopes stream was sent to a cascade of cryogenic distillation columns. The impurities were processed with a unit of an electrolytic reactor and a palladium diffuser. The integrated fusion fuel loop was thus demonstrated. A major result was that the electrolytic reactor processed methane successfully in a gas phase without using the catalysts. A laser Raman analysis system installed into the cryogenic distillation columns gave a set of analysis results with no time delay and no sampling gas exhaust. It was demonstrated that the laser Raman was a promising analysis system for the control of the fusion fuel loop.

New target cryostat for experiments with negative muons

An experimental setup, including a cryostat with temperature control and gas supply systems has been developed to study muon catalyzed fusion in mixtures of hydrogen and helium isotopes. The target body is made of aluminum with five Kapton windows 55–135 μm thick. The working temperature range of the target is 21–300 K, and the pressure is 0–10 atm. The coolant is either liquid helium or liquid nitrogen, according to the experimental conditions. The average consumption of liquid helium at a target temperature of 32 K is 0.6 l/h, providing a 0.45 W cooling power. The temperature control system ensures an accuracy of ±0.05 K in the temperature range 21–70 K. Hydrogen isotopes are purified by molecular sieves (CaA), and helium isotopes by the intermetallic compound ZrCrFe.