Features of Studying Atomic Hydrogen – Metal Systems

All the main areas of energy development suggest or are already implementing the use of metal-hydrogen systems. For nuclear energy, this is associated with the creation of thermostable moderators and special-purpose construction materials, for thermonuclear energy, with the behavior of the so-called first wall of fusion reactors, for hydrogen energy — storage, transportation and extraction of hydrogen. Hydrogen is the most effective moderator of fast and thermal neutrons, especially at high volumetric concentrations of hydrogen atoms in the material, i.e. at a high value of the ratio of the number of hydrogen atoms to the number of metal atoms, taking into account the heat resistance of the hydride. This paper discusses the modern methods of experimental studies of heterogeneous reactions, the topochemistry of metal – hydrogen reactions, the dependence of the interaction rate on pressure and temperature, models of surface processes occurring during the interaction of hydrogen with metal. Methods for determining the probability of adsorption of hydrogen on a metal surface, methods for measuring the activation energy of dissociation of a hydrogen molecule on a surface are also discussed. The paper describes the fea-tures of the preparation of the reactor, experimental samples and the method of their study in the study of atomic hydrogen-metal systems, the method of plasma-chemical thermogravimetry used to study heterogeneous reactions occurring in a hydrogen plasma electrodeless discharge. In order to study the mechanism of interaction of hydrogen with hydride-forming metals, a kinetic method of research is proposed. The essence of the kinetic method is that the elimination of the limiting influence of surface and diffusion processes on the rate of hydride formation using atomic hydrogen and metal foil makes it possible to directly record the formation of the corresponding phases using hydro-gen-metal kinetic curves, and also study the effect of various parameters on the rate of interaction and the formation of hydride phases.

A Loss-Free Resistor-Based Versatile Ballast for Discharge Lamps

This paper presents a versatile ballast for discharge lamps, whose operation is based on the notion of a loss-free resistor (LFR). The ballast consists of two stages: (1) a boost converter operating in continuous conduction mode (CCM) and exhibiting an LFR behavior imposed by sliding-mode control; and (2) a resonant inverter supplying the discharge lamp at high frequencies. Thanks to this mode of operation, the power transferred to the lamp is regulated by the LFR input resistance, allowing successful ignition, warm-up, nominal, and dimming operation of a range of discharge lamps, with no need for complex regulation schemes based on lamp models. The versatility of the ballast has been experimentally proven for both conventional and electrodeless discharge lamps. Tests include induction electrodeless fluorescent (IEFL), high-pressure sodium (HPS) vapor, and metal-halide lamps.

The induction pumping of Coaxial Lasers on Self-Terminating Transitions

The paper presents the results of the numerical simulations of pumping a copper vapour laser by a repetitively pulsed induction (electrodeless) discharge. We have investigated the version of the laser with an annular discharge volume formed by two coaxial cylinders. Such coaxial chamber is shown to be more appropriate for the induction pumping than the conventional cylindrical chamber. In the first case, higher coupling factors in the transformercoupled circuit of the induction discharge as well as rather high curl electric field are achieved. Moreover, from the ecological point of view, the coaxial chamber appears to be safer for the surrounding personnel in terms of their exposure to electromagnetic radiation. The present work briefly presents the physical model of the laser which describes the dynamics of the plasma parameters, the kinetics of the inverse population of the working levels for the laser on self terminating transitions as well as the development of the induction radiation. The paper also presents the electrical equations describing the simplest source of electrical pump pulses. The thermal characteristics of the working medium are estimated and the design calculations of the chamber are performed. The numerical experiments have found that, in contrast to the case of a conventional copper vapour laser with aperiodic discharge, in the regarded versions of the copper vapour laser the pump pulse is realized as a train of high-frequency damped oscillations. The analysis of the physical processes occurring in the plasma of the high-frequency discharge is carried out. The pulsed behaviour of the Joule heat power is shown to release results in pronounced pulsations of the electron temperature. This fact, however, does not significantly affect the operation of the laser on self-terminating transitions. In the optimal pumping regimes, subtle oscillations are merely observed for the inverse population of the copper atom working levels and for the intensity in the radiation pulse. High output laser characteristics achieved in the numerical simulations demonstrate the potential for efficient pumping of the copper vapour laser using the inductive method which is new for such lasers.