Determination of the Mn/Fe Ratio in Ferromanganese Nodules Using Calibration-Free Laser-Induced Breakdown Spectroscopy

Optics and Spectroscopy - The Mn/Fe ratio in ferromanganese nodules is determined by calibration-free laser-induced breakdown spectroscopy based on the use of only the plasma temperature and...     

Calibration-Free Libs for Determination of the Mn/Fe Ratio in Ferromanganese Nodules with a Portable Diode-Pumped Solid-State Laser

Journal of Applied Spectroscopy - The Mn/Fe ratio, which serves as a marker of the contents of rare-earth and platinum-group elements in ferromanganese nodules, was determined in samples taken...     

Technique for the visualization and determination of the surface-erosion profile caused by ion bombardment

A technique for the experimental high-precision measurement of the surface-material erosion profile caused by ion bombardment is proposed. It is based on the preliminary deposition of a coating consisting of submicron layers of different materials with different colors. The erosion profile is determined using multilayer copper and aluminum coatings. An important advantage of the proposed procedure is that the erosion profile of the surface treated with an ion beam can be estimated preliminarily without using complex measuring instruments.     

Numerical simulation of a high-perveance ion-extraction system with a plasma emitter

The cell of a multiaperture three-electrode ion-extraction system (IES) with a plasma ion emitter is numerically simulated within the range of ion current density and accelerating potentials corresponding to gas-discharge ion sources used in technological and space applications (ion thrusters). The formation of the primary ion beam and the configuration of the secondary (charge-exchange) ion flux impinging on the IES electrodes from both the beam volume and the beam-transport (neutralization) region are investigated for different IES geometries. The erosion of the accelerating electrode is estimated.     

The optimality of the velocity-gradient method in the problem of controlling the escape from a potential well

The problem of controlling the escape of a particle from a potential well for a nonlinear system with friction is considered. The velocity-gradient method [Polushin IG, Fradkov AL, Hill, D. Passivity and passivation in non-linear systems. Avtomatika i Telemekhanika 2000;3:3–37] is proved to be optimal in the sense that if it does not guarantee escape from the well, then this is also impossible with any other control law. Nonlinear Duffing and Helmholtz oscillators with one degree of freedom and negative stiffness are considered. For each of them a curve is constructed separating the parameter plane of the problem into two parts: one where escape is feasible and one where it is not. An estimate is obtained for the inclination angle of the tangent to that curve near the origin.