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The paper describes a method of negative hydrogen ions separation from axial flow of charged particles extracted from Penning discharge with a metal hydride cathode. For this purpose, an electromagnetic filter has been designed basing on numerical solution of motion equations of charged particles in the filter. The optimal parameters of the filter operation were determined for the effective registration of negative hydrogen ions extracted in axial direction. Performed calculations together with experimental verification shows that there are not more than 10% electrons in the registered H– current. This model could be applied for the interpretation of any experiments with H– ions separation from an axial flow of charged particles extracted from a source with cylindrical geometry.

Relevance. Vacuum-plasma methods of applying functional coatings are widely used to increase the reliability and durability of machine and mechanism parts, cutting tools, and technological equipment, as well as in modern micro- and nanoelectronics for applying conductive and dielectric layers of various thicknesses. The study presents a method of thermionic coating that combines in one technological cycle the processes of surface cleaning by a stream of low-energy ions and plasma electron beam evaporation of a substance under conditions of thermionic plasma formation. Aim. The research aims to determine the possibility of using the presented methodology to create and process functional coatings without radiation damage to the substrate surface. Methodology. The experimental studies were carried out in a plasma electron beam system with a primary plasma source based on an arc discharge with a filament cathode. The samples were diagnosed using a scanning electron microscope. Results. The ion current density from the primary plasma was investigated to determine the efficiency of the surface cleaning mechanism by ion bombardment. The dependences of the ionic current density on the initial parameters of the experiment were determined. The results of the treatment of the (TiZr/TiSi) N sample surface with a plasma ion stream are presented. The obtained scanning electron microscope images showed that such treatment leads to the cleaning of the surface layer from various contaminants without damage and creates a substrate for further thermionic deposition of a coating with a high degree of adhesion. The mechanism of thermionic deposition of a titanium monolayer on a stainless-steel substrate previously cleaned by ion bombardment was studied. The revealed order of magnitude higher values of the ionic current to the substrate during the formation of thermionic plasma indicate a significant increase in the rate of the deposition process and contribute to the formation of a high-quality ion-plasma coating. Conclusions. The scanning electron microscope images of the sample surface showed that the titanium coating during thermionic deposition was uniformly distributed over the substrate surface, without any droplet phase, which indicates the suitability of this technique for applying functional coatings without radiation damage to the substrate surface

The enhancement of negative ion production in a volume Penning based source could be performed by the application of metal hydride cathode. Hydrogen isotopes are stored there in a chemically bound atomic state and desorbed from the metal hydride under the discharge current impact. Highly vibrationally / rotationally excited molecules H2* are formed by recombination of H-atoms at the metallic surface, which then can be easily converted to H– by dissociative electron attachment without the pre-excitation of a H2 molecule in plasma. Changing the discharge properties opens the way of source design simplification by negative ions extraction along the external magnetic field in comparison with traditional volume sources, where the extraction is performed perpendicular to magnetic field. The separation of negative ions from the extracted in longitudinal direction flux of charged particles was performed by an electromagnetic filter basing on numerical calculations of particles trajectories. The dependence of electron temperature and plasma density on the bias potential is carried out by Langmuir probe method. The measurement of electron energy was performed by an electrostatic energy analyzer. It was shown that the yield of H– ions depends on the electrical bias on the metal hydride cathode with strong dependences on the plasma electrons temperature. The estimation of the bias potential versus Te was performed under the assumption of electron Boltzmann distribution near the cathode. The presence of additional groups of electrons with higher energies distorts the behavior of H– current, but generally the experimental results are in good agreement with estimation based on the physics behind the Boltzmann distribution. The optimum for the effective extraction of H– ions was revealed, when the metal hydride cathode had been electrically biased at -20V and higher, and plasma density reaches the maximum value to 2×109 cm-3.