АНАЛІЗ ОСОБЛИВОСТЕЙ РОБОТИ НАДПРОВІДНОГО ІНДУКТИВНОГО ОБМЕЖУВАЧА СТРУМУ З ДОДАТКОВИМ НАДПРОВІДНИМ ЕКРАНОМ

Purpose. The inductances of magnetic system of a current limiter for the nominal operating mode were determined. The aspects of functioning and a design of a superconducting short-circuit current limiter of inductive type with a superconductive main and additional screens, and superconductive winding, which are placed in a general cryostat on a ferromagnetic core, which ensures an improvement of magnetic field dissipation and in energy efficiency are observed. Methodology. The analysis of distribution of magnetic field of the short-circuit current limiter of inductive type with superconducting high-temperature coil and superconducting main and additional screens, using mathematical modeling by the finite element method in math software package FEMM for different modes of operation is carried out. Results. The calculations of magnetic field dissipation in operational modes are carried out. Originality. The investigations aimed to analyze the influence of distribution of the magnetic field in inductive short-circuit current limiter with superconducting additional screen on its operation modes. First calculation of the distribution of magnetic fields in different modes of operation for the short-circuit current limiter in the area between high-temperature superconducting screens. Practical value. The advantage of additional screen of superconducting short-circuit current limiter is to improve screening from dissipation of the magnetic fields of the magnetic system and reducing the power losses at nominal mode. Using the proposed methodology will identify options acceptable to the current limiter mode of operation.Проведено аналіз режимів роботи та конструктивної схеми надпровідного обмежувача струму короткого замикання індуктивного типу з додатковим надпровідним екраном. Проведено математичне моделювання магнітної системи обмежувача струму методом скінченних елементів у програмному середовищі FEMM. Проведено розрахунок розподілу магнітних полів у різних режимах спрацювання обмежувача струму короткого замикання на ділянці між основним і додатковим екранами, що дозволяє визначити параметри обмежувача струму

АНАЛІЗ ОСОБЛИВОСТЕЙ РОБОТИ НАДПРОВІДНОГО ІНДУКТИВНОГО ОБМЕЖУВАЧА СТРУМУ З ДОДАТКОВИМ НАДПРОВІДНИМ ЕКРАНОМ

Purpose. The inductances of magnetic system of a current limiter for the nominal operating mode were determined. The aspects of functioning and a design of a superconducting short-circuit current limiter of inductive type with a superconductive main and additional screens, and superconductive winding, which are placed in a general cryostat on a ferromagnetic core, which ensures an improvement of magnetic field dissipation and in energy efficiency are observed. Methodology. The analysis of distribution of magnetic field of the short-circuit current limiter of inductive type with superconducting high-temperature coil and superconducting main and additional screens, using mathematical modeling by the finite element method in math software package FEMM for different modes of operation is carried out. Results. The calculations of magnetic field dissipation in operational modes are carried out. Originality. The investigations aimed to analyze the influence of distribution of the magnetic field in inductive short-circuit current limiter with superconducting additional screen on its operation modes. First calculation of the distribution of magnetic fields in different modes of operation for the short-circuit current limiter in the area between high-temperature superconducting screens. Practical value. The advantage of additional screen of superconducting short-circuit current limiter is to improve screening from dissipation of the magnetic fields of the magnetic system and reducing the power losses at nominal mode. Using the proposed methodology will identify options acceptable to the current limiter mode of operation.Проведено аналіз режимів роботи та конструктивної схеми надпровідного обмежувача струму короткого замикання індуктивного типу з додатковим надпровідним екраном. Проведено математичне моделювання магнітної системи обмежувача струму методом скінченних елементів у програмному середовищі FEMM. Проведено розрахунок розподілу магнітних полів у різних режимах спрацювання обмежувача струму короткого замикання на ділянці між основним і додатковим екранами, що дозволяє визначити параметри обмежувача струму

Multilayered ZnO Films of Improved Quality Deposited by Magnetron Sputtering

Multilayered ZnO films were deposited by rf magnetron sputtering on silicon and sapphire substrates. The aim of this work is to improve structural quality of ZnO thin films grown on just listed substrates. Presented X-ray diffraction data testify to remarkable relaxation of compressive stress in two- and three-layered ZnO films in comparison with single-layer one

Neutron emission parameters from the collapse of the condensed Z-pinch

The parameters of neutron emission from the neck of the condensed Z-pinch, were measured at an S-300 installation (2 MA, 100 ns). Profiled loads with central parts made from microporous deuterated polyethylene (with a density of 100 mg/cm3) were used in the experiments. Neutron emission parameters were measured by the time-of-flight (TOF) method. Neutrons were registered using four flight bases with 10 scintillation detectors which were placed at two axial and two radial directions. It was found that the mean neutron energy, determined by the TOF method, turned out to be anisotropic. The average energy of neutrons emitted along the axis towards the cathode, was shifted to higher energy (2.6-2.8 MeV) and the average energy of neutrons emitted towards the anode, was shifted to lower energy (2.1-2.3 MeV) compared to the d-d reaction neutron energy 2.45 MeV. The average energy of neutrons, emitted in two opposite radial directions, was close to 2.45 MeV. The half-width of the energy distributions reconstructed for all directions was 400-500 keV. The analysis of the experimental results demonstrated that the found phenomena could be explained by a slowly decaying high energy tail in the energy distribution of colliding deuterons. The maximal neutron yield was of 6 x 109

Measuring of spatio-temporal characteristics Z-pinch from deuterated polyethylene

On the S-300 installation at currents up to 2 MA with rise time 100 ns, the investigation of the formation process of high-temperature plasma in fast Z-pinch was carried out. The central part of the loads was made from agar-agar and represented a deuterated polyethylene cylinder with small density 50 and 75 mg/sm3 and 1–2 mm diameter. On the ICT images, obtained in optical and soft X-ray range of a spectrum with 3–5 ns exposition, it is visible that on the axis of the polyethylene cylinder at the current`s rise time a cord is formed and it is separated into bright formations. They were observed on a background of a luminous area which occupied the initial neck volume. On time-integrated pinhole pictures obtained in SXR range (E > 1–4 keV), hot points with minimal size of 50 microns were registered. From the chronograms results, obtained by means of the optical high-speed-streak camera mount along the neck axis with time resolution 1 keV with short duration of 2–4 ns. Simultaneously with X-ray radiation neutrons with the maximal yield of 4.5×109 were registered. The average energy measured in 4 directions under angles with an axis of: 0○ (above the anode), 90○, 180○ (under the cathode) and 270○, were accordingly: 2.4±0.2, 2.5±0.1, 2.5±0.1, 2.5±0.1 MeV