G. E. Remnev

High-power ion beam sources for industrial application

Abstract Two sources of high-power ion beams of nanosecond duration are described, a MUK and a TEMP unit They generated ions with energies of up to 150 and 300 keV, respectively, and the pulse duration was 20–200 and 50 ns, respectively. For the MUK unit, beam parameters for heavy ion implantation (Al n+ , Mg n+ , Fe n+ , W n+ , etc.) were as follows: current density ranging from 1 to 10 A cm −2 and total ion flux energy up to 20 J. For the TEMP unit, the following beam parameters were used for H + and C n+ ions: current density 40–200 A cm −2 and total ion flux energy 0.3–0.5 kJ. The sources are powered by various diode systems and can be applied in material science for scientific research and technology.

Intense pulsed ion beam sources for industrial applications

The different kinds of intense pulsed ion beam (IPIB) sources and their applications to surface modification of materials, e.g., IPIB technology, are reviewed. Intense pulsed energy effects on the surface microstructure as well as properties of 45# steel have been experimentally investigated in this work with different pulse parameters of the IPIB, such as current density and pulse duration. It is shown that ion beams with power density (106–108 W/cm2) are very promising ones, but the modification result is affected significantly by the pulsed ion beam parameters. New requirements to the IPIB sources for the industrial applications are discussed.

Pulse Plasma-Chemical Synthesis of Ultradispersed Powders of Titanium and Silicon Oxide

This paper is devoted to studying the plasma-chemical synthesis of nanosized SiO2 and TiO2 powders and to the analysis of their major characteristics. The nanosized powder was synthesized in the plasma-chemical reactor using a pulse electron beam to generate low-temperature plasma. The synthesized powders were studied by the transmission electron microscopy to determine the morphology and the size of the nanosized powder with respect to by-products of the reaction. The elemental composition was studied using the Oxford ED2000 X-ray fluorescent spectrometer. To determine the crystal structure of the nanosized powder, we used the standard technology of X-ray phase analysis. The reaction products were processed using Shimadzu XRD-6000/7000. The substances included in the composition of the nanosized powder were identified using Nicolet 5700 Fourier transform infrared spectrometer.

The Astra repetitive-pulse electron accelerator

The description and results of tests of the Astra pulsed electron accelerator are presented. A high-voltage pulse transformer with a pseudospark gap that serves as a switch of a capacitive storage is directly loaded into a vacuum planar diode, which is based on a metal-ceramic cathode with a long delay time of the electron explosive emission. The generated electron beam is injected into the atmosphere at a frequency of 50 Hz. The full width at half maximum (FWHM) duration of the injected beam current is 60 ns for an accelerating voltage of 370 ± 10 kV. The electron-beam energy is 19 J, when the accelerator operates into an internal target, and 4.5 J, when the electron beam is injected into the atmosphere and the low-energy fraction of beam electrons is cut off by a separating foil.

Formation of silicon carbide and diamond nanoparticles in the surface layer of a silicon target during short-pulse carbon ion implantation

Synthesis of silicon carbide and diamond nanoparticles is studied during short-pulse implantation of carbon ions and protons into a silicon target. The experiments are carried out using a TEMP source of pulsed powerful ion beams based on a magnetically insulated diode with radial magnetic field Br. The beam parameters are as follows: the ion energy is 300 keV, the pulse duration is 80 ns, the beam consists of carbon ions and protons, and the ion current density is 30 A/cm2. Single-crystal silicon wafers serve as a target. SiC nanoparticles and nanodiamonds form in the surface layer of silicon subjected to more than 100 pulses. The average coherent domain sizes in the SiC particles and nanodiamonds are 12–16 and 8–9 nm, respectively.

A study on microstructure and service property of Ni3Al base alloy irradiated by intense pulsed ion beams

Abstract Ni 3 Al base alloy samples, a kind of high temperature material, were irradiated with intense pulsed ion beams (IPIB) at the beam parameters of 250 KV acceleration voltage, 100–200 A/cm 2 current density and 60 ns pulse duration. The surface morphology and the cross-section microstructures of the samples were observed with Scanning Electron Microscope (SEM); X-ray Diffraction (XRD) method was used to determine the phase and structural changes that occurred in the near surface region of the samples after IPIB irradiation. Craters with different diameters ranging from a few microns to 30 microns appeared and spread all over the irradiated surfaces. The near surface region of irradiated samples had been melted or even evaporated and then was quickly resolidified; moreover a new structural layer of approximately 4–5 μm thick was formed at 200 A/cm 2 IPIB irradiation. Both the wear resistance and the oxidation resistance property at high temperature environment were improved in general at the near surface region of irradiated samples. The relations between the microstructural transformations and the service property changes were reasonably discussed.

A high-repetition rate pulsed electron accelerator

A new electron beam accelerator with the beam ejection into the atmosphere has been recently developed for radiation technology application. A high-voltage nanosecond pulse generator of the accelerator is based on a low-inductance pulse transformer. The energy stored in the high voltage capacitor bank is transferred through a step-up pulse transformer to a vacuum electron diode at triggering of a cold cathode thyratron. The electron diode consists of a metal-ceramic explosive emission cathode, which provides a high delay time in the plasma formation. The electron beam current pulse duration at half height is 75 ns. The kinetic energy of the electron beam is 450 keV with the energy of extracted electron beam of up to 10 Joules/pulse. The accelerator is capable of operating in a long-term repetition rated system, producing up to 40 pulses per second, which is possible due to the use of both a built-in system of regeneration and cooling of the transformer oil and an additional cooling system of an exit window foil. The results of shot-to-shot variation of the beam parameters in the frequency mode are presented.

Optical properties of GaAs films deposited via pulsed ion ablation

Optical reflectance and absorbance of gallium arsenide films formed on polycrystalline corundum, quartz glass, and copper foil are investigated in the energy interval of 1.1–6.2 eV. The films have been deposited from ablation plasma induced by a high-power ion beam. The exponential and interband absorbance spectra of the material of films are determined by defects in the GaAs crystalline lattice and the intricate composition of the material with predominance of nanocrystalline inclusions in the amorphous phase. Films deposited on polycor at the plasma flame center with the use of a low-resistance target have optimal properties for application in devices of optoelectronics and solar power engineering. Thermal vacuum treatment at 300–850 K modifies the optical properties of films owing to annealing of defects and changing of the structural-phase composition of a material.

Dynamic processes in metal nanoparticles under irradiation

Dynamic processes occurring in a nanoscale metal object during the implantation of high-energy ions are studied in detail. It is shown that the elastic and thermoelastic lattice responses to irradiation form force factors considerably affecting the evolution of the defect-impurity system, which, in turn, leads to a decrease in the number of structural defects. Quantitative estimates of the spatial redistribution of defects resulting in their emergence on the surface are obtained. Such self-organization of nanoparticles under ionizing radiation forms a basis for the production of nanostructured radiation-resistant materials capable of sustaining a long-term intense radiation load.

Modification of the T15K6 hard alloy with high-power pulsed ion beams and compression plasma fluxes

The change in the morphology, phase composition, hardness of surface layers, microstructure, and elemental composition of the inner layers of an alloy under the effect of high-power pulsed ion beams (HIBs) and compression plasma streams (CPSs) is investigated. It is found that the thickness of the molten surface layer increases to 3–4 μm after the HIB effect: 300 pulses 9 × 10−2 μm long with a summary energy density of 430 J/cm2. The features of the CPF treatment are a larger time of pulse effect (100 μs) and the preferential convection agitation of the molten layer. As a result, a thicker layer of the (W, Ti)C solid solution with uniform elemental distribution over the depth and high hardness (30 GPa) is formed.