Constant Of Helium Research Articles

Henry's constant of helium in liquid alkali metals

The determination of the solubility of helium in liquid lithium and in lead-lithium eutectic systems is of crucial importance for the assessment of the reliability, safety and efficiency of future nuclear reactor plants based on fusion technology. In this way, an important aspect to be considered concerns the possibility of accumulations of gas inside the so called breeding blankets of the reactors, due to the low solubility of helium, leading to potentially undesired effects. In the present work we have performed molecular dynamics simulations in order to examine the characteristics of the solubility of helium in alkali metals along a temperature interval that covers near ambient conditions up to temperatures of the order of a 1000 K. Our methodology relied on the classical Kirkwood perturbative approach, which involves the gradual coupling between the infinite diluted He atom and the solvent. Such insertion proceeds along three stages that involved a previous incorporation of a softly interacting cavity that prevented singularities due to the harshly repulsive nature of the actual He-Li potential. Simulated structure factors predicted by the force fields of the different alkali metals were found to be in excellent agreement with available experimental information. Moreover, at all thermal conditions, our results of Henry's constants predict a steady volatility reduction with increasing temperatures, in good agreement with available experimental data. Furthermore, Henry's law volatility constants increase as the sizes of the atoms of the host alkali metals become more comparable to the size of the He atom (the predicted solubility increases with the size of the alkali atoms), and are coherent with the scarce experimental data available.

Henry's law and accumulation of weak source for crust-derived helium: A case study of Weihe Basin, China

Crust-derived helium is generated from the radioactive decay of uranium, thorium and other radioactive elements in geological bodies. Compared with conventional natural gas, helium is a typical weak source gas as a result of extremely slow generation rate and absence of helium-generating peak. It is associated with methane or carbon dioxide reservoirs frequently and related to groundwater closely. Helium can meet the industry standard with 0.1% in volume fraction. In order to study the accumulation mechanism of helium, the previous research on Henry's coefficient and solubility of helium, nitrogen and methane are summarized and the key roles of Henry's Law in the helium migration, accumulation and preservation are discussed by simulating calculation taking Weihe Basin as an example. According to the Law, the gas solubility in dilute solution is controlled by the gas partial pressure and the Henry's coefficient. Compared with the carrier gases, the Henry's constant of helium is high, with striking difference at low and high temperature. In addition, the helium partial pressure is greatly different in helium source rocks and gas reservoirs, resulting in the great differences of helium solubility in the two places. The accumulation progresses are as follows. Firstly, helium can dissolve into water and migrate out of helium source rocks due to the high helium solubility, which is caused by high helium partial pressure and high temperature in source rock. Secondly, when dissolved helium is transported to the shallow gas reservoir, it is prone to be out of solution and into reservoir due to the extremely low partial pressure and low temperature. Meanwhile part of carrier gases dissolves into water, as if helium is “replaced” out. Furthermore, the low concentration funnel of dissolved helium is formed near the gas reservoir, then other dissolved helium continues to migrate towards the gas reservoir, which greatly improves the helium accumulation coefficient. Finally, after entering the gas reservoir, helium is difficult to dissolve into the water in cap layers due to its low partial pressure, resulting in the preservation of helium in reservoir. The results show that the helium enrichment mechanism in the aspects of migration, accumulation and preservation, providing theoretical basis for helium resource exploration.

Plasma modes in low-dimensional electron system over surface of liquid helium

The collective plasma modes in a quasi-two-dimensional (Q2D) electron system located over the free surface of liquid helium are studied theoretically within many-body dielectric formalism. The dispersion of modes is considered both over bulk liquid and over helium film where the essential modification of interelectron interaction occurs due to screening effects in the substrate with a large value of dielectric constant. It is shown that the plasma spectrum consists of longitudinal and transverse branches which dispersion laws depend on the values of the dielectric constant of helium and the film thickness. For the helium film covering metal, the longitudinal mode is acoustic differing of that for the surface electron (SE) system over bulk helium.

A coupled hartree-fock calculation of the paramagnetic contribution to the cotton-mouton constant of helium

Abstract The perturbation equations necessary for the evaluation of the paramagnetic part of the Cotton-Mouton constant of helium are derived as an example of coupled Hartree-Fock theory for a double perturbation and the ensuing integro-differential equations solved numerically. A comment is made on the errors in the numerical solution of such equations.