Никита Вадимович Мамедов

A systematic experimental study of ion fluxes extracted from a DC magnetron discharge is presented for the development of ion sources for implantation applications. A planar circular magnetron with a closed anode configuration was operated with aluminum and boron targets in Ar and Ar/N₂ gas mixtures. Ion composition, discharge characteristics, and current densities were measured as functions of gas flow, discharge power, and nitrogen admixture.Stable generation of Al⁺, Ar⁺, N⁺, and B⁺ ion fluxes was demonstrated. In argon discharge with an aluminum target, Al⁺ current densities up to ~3 mA/cm² were achieved. The ion composition is shown to be strongly influenced by charge-exchange processes during transport. The addition of nitrogen enabled efficient generation of N⁺ ions with fractions exceeding 50% while maintaining stable discharge at limited N₂/Ar ratios. For boron targets, B⁺ ion generation was achieved with current densities up to ~0.5 mA/cm².The closed anode configuration significantly enhances ion flux compared to conventional geometries due to improved plasma confinement. The results indicate that magnetron-based ion sources provide a simple, stable, and versatile approach for generating metal and gaseous ion beams without toxic precursors, making them promising for ion implantation systems.

The basis of the neutron generator is a miniature linear accelerator, which allows us to obtain a specific size of the generating region of neutron radiation with specified parameters of the neutron flux. Numerical modeling can help solve the problem of creating an accelerator with a strictly specified ion beam size on a target. Based on the simulation result, it will be possible to select the appropriate optimal physical and geometric characteristics of the Penning ion source and the ion-optical system. The initial data for the simulation are the spatial and energy distributions of ions emitted from the ion source. The purpose of the study was to experimentally determine these characteristics. The energy spectra and spatial distributions of ions are given for various discharge combustion modes as functions of the working gas pressure and the voltage at the anode. The relationship between the discharge VAC and the sagging potential inside the discharge, as well as their effect on the plasma emission boundary, is shown. Data on the width of ion beams and energy spectra at half-height are presented. The maximum value of the energy spectra is two and more times less than the corresponding value of the voltage applied to the anode. The gas pressure had little effect on the shape of the energy spectra. The profiles of the ion beams differed during probe diagnostics of the ion source in two perpendicular planes.

This paper studies full-scale gas neutron tube modeling, including the following processes: gas discharge combustion in a Penning ion source, particle motion in an ion optical system, and modeling the in-target processes, such as sputtering, diffusion, thermal desorption of hydrogen isotopes, and nuclear reactions. Plasma modeling in quadrupole electric and axial magnetic fields was based on the electrostatic particle-in-cell method with molecular kinetic processes. The TechX Vsim software package was used. The neutron tube element sputtering by ions was simulated using SRIM/TRIM software based on Monte–Carlo methods. The OpenFOAM, as an open integrated platform for numerical simulation in continuum mechanics, was used to calculate the hydrogen thermal desorption activated by ion irradiation. The time-dependent neutron yield modeling was performed using the Geant4 software based on Monte–Carlo methods with CHIPS-TPT VNIIA-developed library. In addition, an experimental study of a gas neutron tube with a Penning ion source was conducted here as well. Details are given on the experiment and measurement technique used in this study. The operating characteristics for the gas neutron tube, including amplitude-time characteristics of current flashes (discharge and extraction currents), were determined. The neutron flux dependencies on the discharge current at various accelerating voltages were also obtained. Finally, a comparison between the experimental and calculated results is presented.

В данной работе проведено экспериментальное исследование миниатюрного линейного ускорителя (МЛУ) с пеннинговским ионным источником. Определены рабочие характеристики МЛУ – измерены амплитудно-временные характеристики токовых вспышек (разрядного и вытягиваемого токов). Получены зависимости нейтронного потока и вытягиваемого токов от тока разряда при различных ускоряющих напряжениях. Также в работе рассматривается сквозное моделирование МЛУ методом PIC (Particle-In-Cell) и MCC (Monte-Carlo Calculation), реализованном в программном пакете Tech-X VSim 9.0. Отдельно происходит моделирование горения газового разряда в источнике Пеннинга и выход его на квазистационарный режим. После чего расчет движения заряженных частиц в ионно-оптической системе (ИОС) МЛУ с учетом кинетических процессов, распыление элементов МЛУ, расчет нагревания мишени и термодессорбции ионов водорода под воздействием ионного облучения. Конечным итогом моделирования является получение зависимости выхода нейтронов от времени и нейтронного потока от тока на мишень, а также валидация с экспериментальными данными.

Magnetic field configuration for a miniature pulse Penning ion source was designed in this work. The amplitude-time characteristics of discharge and extracted currents were investigated as a function of gas pressure for various magnetic field magnitude and configuration An effect of magnetic field configuration on the Penning’s discharge modes and characteristics of the extraction current impulse were experimentally shown. Stable operation modes of the ion source were found in this work. Also the appropriate ranges of working gas pressure and magnetic field configuration were demonstrated, at which the current pulse of the extracted ions had a quasi-rectangular form. For better understanding real magnetic fields distributions of within the discharge cell magnetic field have been calculated in COMSOL software.

In the present work, the results of the experimental and particle in cell (PIC) simulation studies of the discharge combustion modes in a miniature Penning ion source (PIS) under the pulse-periodic power supply conditions are presented. Dynamics of discharge ignition and discharge operation mode at a pulsed anode voltage supply are investigated for different values of anode voltage and gas pressure in various magnetic field configurations. Typical examples of current pulse waveforms are shown. Also, numerical simulations of the PIS were performed using 3D PIC combined with Monte Carlo collisions in the code VSim. Temporal dependencies of electron, ion, and potential distributions in the Penning cell are simulated. Differences between the numerical and experimental results are discussed.

The results of investigation of discharge characteristics of the Penning plasma source are presented. Volt-ampere characteristics (VAC), energy distribution, and mass-charge composition of ions...

The optimization of hydrogen Penning sources used, in particular, in plasma chemical processing of materials and DLC deposition, is still very important. Investigations of mass-charge composition of these ion source emitted beams are particular relevant for miniature linear accelerators (neutron flux generators) nowadays. The Penning ion source energy and mass-charge ion distributions are presented. The relation between the discharge current abrupt jumps with increasing plasma density in the discharge center and increasing potential whipping (up to 50% of the anode voltage) is shown. Also the energy spectra in the discharge different modes as the pressure and anode potential functions are presented. It has been revealed that the atomic hydrogen ion concentration is about 5-10%, and it weakly depends on the pressure and the discharge current (in the investigated range from 1 to 10 mTorr and from 50 to 1000 μA) and increases with the anode voltage (up 1 to 3,5 kV).