S.A. Dan'ko

A Modernized PC-20 Facility for Studying the Characteristics of a Plasma-Opening Switch

Abstract-A modernized PC-20 facility with a plasma opening switch (POS) is described. It contains a four-module voltage pulse (Marx) generator (MXG) connected via a high-voltage feedthrough to a POS. The energy stored in the MXG is increased by a factor of 12.5 and amounts to 240 kJ at a maximum voltage of 1 MV. At such a voltage, the POS current amplitude is 320 kA and the current rise time is 2 μs. The breakdown strength of the high-voltage insulator is raised to a significant degree. The modernized facility was used in experiments in which the maximum accessible POS parameters (the obtained voltage, passed charge density, etc.) were evaluated. A voltage of up to 3.5 MV was obtained in the first experiments at a MXG voltage of 0.84 MV and a current of 300 kA.

Wire-array implosion onto a deuterated fibre at the S-300 facility

The implosion of a wire array z-pinch onto a deuterated fibre was studied on S-300 facility (4 MA, 700 kV and 100 ns; RRC Kurchatov Institute, Moscow). The peak power of soft X-rays exceeded 200 GW and the total emitted energy was 2–8 kJ. The radiation was close to the radiation of a black body with a temperature of 40 eV. The neutron yield from the D–D reaction reached 2 × 108 per shot. The mean energy of neutrons determined from time-of-flight analysis in the axial direction (downstream) was shifted from 2.45 MeV towards higher energies.

Deuterated fibre Z-pinch on the S-300 generator

Dense Z-pinch experiments were carried out on the S-300 generator (3.5 MA, 100 ns, 0.15 Omega) at the Kurchatov Institute in Moscow. The experiments were performed at a peak current of 2 MA with a rise time of about 100 ns. The Z-pinch was formed from a deuterated polyethylene fibre of 100 mu m diameter and 1 cm length. The optical emission began early in the discharge and the coronal plasma expanded with a radial velocity of about 2 x 10(6) cm s(-1). The optical and XUV emission continued for several hundreds of nanoseconds. The peak power of sub-keV radiation reached 30 GW near the maximum current. The total emitted energy exceeded 5 kJ. The neutron yield from the D-D reaction reached 2 x 10(7) per shot. The mean energy of neutrons obtained from time-of-flight analysis in the axial (downstream) direction was near 2.45 MeV.

INVESTIGATION OF THE PULSED PLASMA FLOW, GENERATED IN NON-CYLINDRICAL Z-PINCH SYSTEMS, BY ELECTRON-OPTICAL METHODS

В последнее время наблюдается значительный рост интереса к генерируемым в Z-пинчевых системах плазменным потокам. Это связано как с пониманием роли процессов, приводящих к генерации потоков, в общей физике формирования и динамики пинча, так и с все возрастающим практическим использованием этих потоков. В работе описана система щелевого электроннооптического фотографирования в видимом диапазоне, созданная для исследования динамики импульсных плазменных потоков, вызванных сжатием Z-пинча. Эксперименты проведены на установке ПФ-3, крупнейшей в мире среди представителей одной из разновидностей Z-пинчевых систем — плазменный фокус. Приведены первые результаты измерений скорости плазменных потоков при использовании различных рабочих газов (водород, неон, аргон). Показана структурированность плазменного потока. Обнаружено отсутствие существенной зависимости скорости потока от сорта рабочего газа.

A time-resolved spectroscopic diagnostic based on fast scintillator and optical fiber array for z-pinch plasmas

We report a specially designed type of temporal resolved x-ray spectroscopic diagnostic using a spherically bent quartz crystal for z-pinch plasmas. Registration of time-resolved spectra was accomplished by coupling fast plastic scintillator, an optical fiber array, an optical streak camera, and a charge coupled device as the recording medium of this diagnostic. The diagnostic has been tested in imploding wire array experiments on S-300 pulsed power facility. Time-resolved K-shell lines were successfully obtained for aluminum wire array implosion plasmas.

Study of the Multiwire X‐Pinch as a Load for Mega‐Ampere‐Range Pulsed Power Generators

We present the results of experimental study of the dynamics of plasma formations originated from the high‐current multiwire X‐pinch (the current value up to 2.3 MA) based on the wires of different thicknesses made of different materials

Energy transformation in Z-pinch and plasma focus discharges with wire and wire-in-liner loads

The results of the study of the Z-pinch and plasma-focus plasmas at presence of the axial C, Al, or Cu wires of sufficient high diameter are discused in this paper. The wire was positioned on the top of the inner electrode of the PF 1000 plasma focus (1.8 MA, IPPLM Warsaw), or at the axis with or without the tungsten or alumine wire array load at the S-300 facility (3 MA, RRC Kurchatov Institute, Moscow), and at the axis of the small Z-pinch Z-150 (50 kA, CTU Prague). The plasma corona around the wire was generated both by the current going through the wires and by the implosion of the wire array or of the current sheath. The experiments showed interesting results often observed in some shots of Z-pinch type discharges - existence of helical structures, two relatively long and stable pinch phases, oscillation of pinch diameter, and back return of the plasma exploding from the pinch. All these observed phenomena can be evolved by spontaneous self-generation and transformation of the axial magnetic field in the pinch during the plasma implosion and explosion. A configuration of axial and azimuthal magnetic field confines the plasma and later transforms or dissipates during a few tens or hundreds ns. A fast transformation of internal magnetic fields can induce a sufficiently high electric field for generation of keV particles and radiation.

Dense Z-pinch neck development dynamics investigation on S-300 generator

The experimental investigations of neck development dynamics in the Z-pinch with 0.1 g/cm/sup 3/ density were carried out on an 8-module pulsed power generator, the S-300 (4 MA, 100 ns). The objective of these experiments was a study for the possibility of obtaining plasmas with extra-high parameters in the Z-pinch neck region, corresponding to the fusion ignition conditions.

Behavior specificities of the plasma in the REB - polymeric anode interactions.

To study Relativistic Electron Beam (REB) interaction with a set of polymeric targets we have made experiments for the investigation of the plasma dynamics in high-voltage diode of high-current generator. It is necessary for applied goals, such as correction of mathematical models of high power density deposition in the matter, for testing materials reaction under the powerful impulse of ionizing radiation, etc. An electron-optical streak camera (EOC) was used to measure the velocity of the visible light border of the plasma glowing. It was estimated to be from 10 to 35 km/s at the energy-release density in range of 200 - 800 J/cm2. In a few of experiments, besides regular motion of contrast border in the direction from electrodes to the middle of the diode, the motion from the middle to the periphery of the high-voltage diode with velocity up to 500 km/s was observed. It was by an order of magnitude greater than regular one.

Experimental Modeling on the Recyclable Magnetically Insulated Transporting Lines Aimed at the IFE Reactor

At the Kurchatov Institute, the series of IFE experiments is carried out on the S-300 high-current generator (3 MA, 100 ns, 0.15 Ohm). In this talk, the experimental results on the S-300 machine are presented, related to the study of operation of co-axial magnetically self-insulated transporting line, by the linear current flow density on the inner electrode surface up to j ≈ 7 MA/cm. The specific parameters of this current-carrying line fairly correspond to those of the Sandia Laboratories’ conceptual project of IFE reactor based on the fast Z-pinch [1]. The near-electrode plasma dynamics and its effect on the current transport were studied. The cathode material effect, as well as that of gases and oil layer absorbed by its surface, on the near-electrode plasma dynamics and the current pulse transport along the short MITL segment ware studied too. With respect to the whole project, our conclusion is quite optimistic, to wit, we have found the idea of Recyclable Transporting Lines being adequate to the IFE reactor requirements.