Laboratory simulation is an effective tool for studying astrophysical processes. The paper considers a scheme for simulating jets from young stellar objects by means of a plasma-focus device with application of an external poloidal magnetic field. The mechanisms of amplification of the poloidal magnetic field in the region where the plasma flow is formed by the conductive plasma sheath upon its compression toward the axis of the system up to values of ~100 kG are discussed. Magnetic probe measurements have shown that the value of the B z component of the field also increases significantly in the plasma flow itself, while the direction of the field captured by the flow corresponds to the direction of the external applied field. An increase in the toroidal component of the magnetic field is also observed. It is concluded that this experiment quite accurately simulates the processes in young stellar objects, including accretion and the operation of the “central engine.”

The paper is devoted to the study of the plasma flows generated in the plasma focus discharge at the PF-3 facility at its propagation in the ambient medium up to distances of ~100 cm and, in particular, the study of the dynamics of such important parameters as velocity, total energy, and momentum. Momentum and energy measurements were made using a ballistic pendulum, which could be used simultaneously in the calorimeter mode. Optical collimators are used to measure the flow velocity. It is shown that, in experiments with argon at a distance of 65 cm, the energy density of the incident flow of ≥10 J/cm 2 is observed. The total number of particles in the flow and the total mass of the flow are calculated.

Results are presented from laboratory simulations of plasma jets emitted by young stellar objects carried out at the plasma focus facilities. The experiments were performed at three facilities: the PF-3, PF-1000U and KPF-4. The operation modes were realized enabling the formation of narrow plasma jets which can propagate over long distances. The main parameters of plasma jets and background plasma were determined. In order to control the ratio of a jet density to that of background plasma, some special operation modes with pulsed injection of the working gas were used.

The results of laboratory simulations of astrophysical jets are presented. Plasma flows generated in the PF-3 plasma-focus installation of the NRC “Kurchatov Institute” and propagating to distances substantially exceeding their transverse dimensions are studied. It is shown usingmagnetic probes that the plasma flow propagates with a frozen-in magnetic field. The resulting radial distribution of the azimuthal magnetic field corresponds well to the distribution created by a longitudinal current of ~10 kA flowing in a region with a radius of 1–2 cm near the axis. Structures associated with return currents are observed at the periphery of the flow. The magnetic field decays rapidly as the flow propagates along the axis. Nevertheless, the leading lobe of the plasma flow is preserved to substantial distances in a neon discharge, possibly due to radiative cooling of the plasma.

The shape of the plasma current sheath (PCS) in the final stage of its radial compression, the dynamics of pinching, and the subsequent pinch decay in plasma focus (PF) discharges in different gases are studied using an improved multichannel system of electron-optical plasma photography and a newly elaborated synchronization system. The PCS structure in discharges in heavy gases (Ne, Ar) is found to differ significantly from that in discharges in hydrogen and deuterium. The influence of a heavy gas (Хе) additive to hydrogen and deuterium on the structure and compression dynamics of the PCS is investigated.

Studies of thin film materials (TFM) as coatings of tips of pacemaker electrodes implanted into the human heart have been performed. TFM coatings were deposited in vacuum by arc magnetron discharge plasma, by pulsed discharge of “Plasma Focus”, and by electron beam evaporation. Simulation of electric charge transfer to the heart in physiological blood- imitator solution and determination of electrochemical properties of the coatings were carried out. TFM of highly developed surface of contact with tissue was produced by argon plasma spraying of titanium powder with subsequent coating by titanium nitride in vacuum arc assisted by Ti ion implantation. The TFM coatings of pacemaker electrode have passed necessary clinical tests and were used in medical practice. They provide low voltage myocardium stimulation thresholds within the required operating time.

The main stages of the plasma current sheath (PCS) dynamics on two plasma focus (PF) facilities with different geometries of the electrode system, PF-3 (Filippov type) and PF-1000 (Mather type), were studied by analyzing the results of the current and voltage measurements. Some dynamic characteristics, such as the PCS velocity in the acceleration phase in the Mather-type facility (PF-1000), the moment at which the PCS reaches the anode end, and the plasma velocity in the radial stage of plasma compression in the PF-3 Filippov-type facility, were determined from the time dependence of the inductance of the discharge circuit with a dynamic plasma load. The energy characteristics of the discharge circuit of the compressing PCS were studied for different working gases (deuterium, argon, and neon) at initial pressures of 1.5–3 Torr in discharges with energies of 0.3–0.6 MJ. In experiments with deuterium, correlation between the neutron yield and the electromagnetic energy deposited directly in the compressed PCS was investigated.

Results of measurements of soft X-ray emission with photon energies of <1 keV under conditions of a plasma focus (PF) experiment are presented. The experiments were carried out at the world’s largest PF device—the PF-3 Filippov-type facility ( I ⩽ 3 MA, T/4 ≈ 15–20 µs, W 0 ⩽ 3 MJ). X-ray emission from both a discharge in pure neon and with a tungsten wire array placed on the axis of the discharge chamber was detected. The wire array imploded under the action of the electric current intercepted from the plasma current sheath of the PF discharge in neon. The measured soft X-ray powers from a conventional PF discharge in gas and a PF discharge in the presence of a wire array were compared for the first time.

Представлены результаты экспериментов по сжатию вольфрамовых многопроволочных сборок токово-плазменной оболочкой установки ПФ-3 при уровне тока до 2 МА. Проведено исследование эффективности транспортировки тока в область проволочной сборки и переключение на нее разрядного тока. Информация о проникновении магнитного поля внутрь проволочной сборки, полученная при помощи микрозондов, позволила провести сравнение с результатами измерений магнитных полей, выполненных в последние годы на других мощных электрофизических установках. Сделана оценка интенсивности производства плазмы с вольфрамовых проволок при воздействии оболочки плазменного фокуса. Проведено сравнение результатов экспериментов с существующими моделями имплозии проволочных сборок с затянутым плазмообразованием.

Results of experiments on the compression of tungsten wire arrays by the plasma current sheath (PCS) of the PF-3 facility at currents of up to 2 MA are presented. The efficiency of current transportation to the wire array and switching-over of the discharge current to the array were studied. Information on the penetration of the magnetic field into the wire array obtained using microprobes made it possible to compare the obtained experimental data with the results of magnetic field measurements carried out at other high-power electrophysical devices. The intensity of plasma production from tungsten wires under the action of the plasma focus PCS is estimated. The experimental results are tested against the existing models of wire array implosion with prolonged plasma production.

This paper presents new results from studies of plasma focus (PF) systems at the Kurchatov Institute (Moscow, Russia). High efficiency of the discharge current transport into the axial region of the system was demonstrated at the PF-3 PF facility, where the experiments on implosion of wire arrays by the current carrying plasma sheath of the PF discharge were performed. The efficiency of the sheath current switching over to the wire array and penetration of the plasma with the magnetic field inside the wire array was studied. The emission parameters of the new small-sized PF facility with W-max = 600 J were studied. When operating at frequencies of up to 10 Hz, neutron fluxes of about similar to 10(8) neutrons s(-1) were obtained. The first results in the new field of research associated with the use of the PF facilities in the laboratory simulations of astrophysical processes, such as astrophysics jets, are presented.

Работа посвящена разработке компактного импульсного источника нейтронного излучения на базе плазмофокусного разряда. Основной задачей являлось исследование физических закономерностей развития ПФ-разряда в субкилоджоулевом диапазоне энергии разряда в частотном режиме работы установки. Разработана и создана установка с энергией источника питания до 600 Дж, работающая с частотой следования импульсов до 10 Гц. Исследованы экспериментальные зависимости нейтронного выхода от частоты следования импульсов. Получен нейтронный поток 108 нейтр/с при работе в пакетном режиме длительностью 3 с с частотой 10 Гц (разрядный ток 80–90 кА).