Academic literature on the topic 'Meta-stable helium'

A convenient thulium fiber laser source is described with 3 W of output power operating at a wavelength of 2059 nm with a slope efficiency of 49% with respect to input pump power and 60% with respect to absorbed pump power. The laser was applied in an atomic helium spectroscopy experiment to quench 3He (2058.63 nm) and 4He (2058.69 nm) meta-stable singlets (21S0), allowing for further investigation of the helium fine structure. The customized laser effectively eliminates the singlet counts to well below a background level (1%). A simplified analysis describes the basic laser performance with fitted constants in reasonable agreement with previous work.

Purpose. Investigation of the peculiarities of the electric field energy conversion by an anisotropic meta-medium with a negative value of the dielectric constant in one of the selected main crystallographic directions. Methodology. Research was carried out using methods of physical and mathematical modeling of anisotropic metadielectric converter; using methods to optimize the function of the dependence of the conversion factor m, anisotropic metadielectric converter, on the angle α between one of the crystallographic axes and the edge of the platinum a, at fixed anisotropy coefficients of metadielectric material. Findings. For the first time, the peculiarities of the electric field transformation by an anisotropic meta-medium with a negative value of the dielectric constant in one of the selected main crystallographic directions were studied. It is established that at the moment of application to the upper and lower faces of the anisotropic metadielectric plate, which is the basis of the anisotropic metadielectric converter, some potential difference leads to polarization of its volume and the emergence of both longitudinal and transverse components of the vortex electric field. This situation leads to axial folding of its internal field, which in turn causes the appearance of micro-vortices of the electric field, given by the expression , where - the circular time of rotation of the micro-vortex, and signs "+" and "-" - indicate the direction of its rotation. Such axial electric micro vortices are an efficient mechanism that pumps energy between the physical vacuum and, in our case, the anisotropic metadielectric plate of the transducer. The dependence of the transformation coefficient m of this medium on the value of anisotropy is analyzed. Studies have shown that in the interval the value of m is characterized by a negative value, and in the interval – positive, this allowed us to determine the areas of stable existence of different types of energy. The use of metadielectric material in comparison with the classical one is characterized by values of m>1. Note that in some cases there is an abnormal increase in the coefficient. Originality. Using the representations of vortex electrodynamics, the mechanism of energy interaction between the vortex electric field of an anisotropic metaenvironment and the physical vacuum is proposed. Practical value. A model of the original design of an anisotropic metadielectric converter is proposed. Areas of its practical use in the form of generators of electricity, heat and cold are determined, calculated expressions for their efficiency are in the range η = 0.5 ÷ 0.98, and the cooling temperature can reach the temperature of liquid helium.

ABSTRACTWe report the properties of MgO:Si film as a protective cathode material on the electrical discharge, and the electronic state of the outer-most surface on MgO:Si film characterized by helium Meta-stable De-excitation Spectroscopy (MDS) and that of several nanometer region from the surface evaluated by X-ray Photoelectron Spectroscopy (XPS). Both of the spectra are discussed focusing on the dependence upon the amount of Si in the MgO film for understanding discharge phenomena. The analyses of the experimental data imply that the discharge properties are not improved due to surface degradation with the increase of Si in MgO films. However, an in-situ discharge experiment, in which MgO:Si films are not exposed for the atmosphere after its deposition, shows that the introduction of Si up to about 1 atomic% has the potential to enhance the secondary electron emission coefficient.

We report contributions made towards achievement of Bose-Einstein condensation of metastable helium, with the common theme of enabling the achievement of a magneto-optical trap. The primary contribution of this thesis is the characterisation of a sigma-minus Zeeman slower, capable of slowing metastable helium atoms to approximately 70 m/s, allowing the loading of a magneto-optical trap.