The results of the last (in the thermonuclear program “Magnetic compression”) MAGO-IX experiment with a plasma chamber including a third compartment designed to compress plasma with a converging liner are presented. An X-ray pulse consisting of an intense peak of 1-μs duration, followed by a low-intensity tail with a duration of more than 10 μs, was recorded. In the MAGO-IX experiment, the neutrons were generated mainly in the third compartment. A neutron yield of 2 × 1012 was obtained. The results demonstrate that the expected compression of preheated plasma in chambers similar to MAGO-IX is promising for achieving thermonuclear ignition.

The paper presents the results of model experiments to test a new field liner driver based on the disk explosive magnetic flux compression generator, results of driver development, and revised two-dimensional magnetohydrodynamic simulations of liner implosion.

This paper describes a method and device for generating a mega-ampere quasi-trapezoidal current pulse of given amplitude and duration in a liner load. The experimental device consisting of a current source based on a helical explosive magnetic generator (HEMG) produced a current pulse in the liner load with an amplitude of ≈ 10 MA and controlled duration and current rise and decay times. The use of this source to accelerate cylindrical liners allows the study of the mechanisms of material damage in converging geometry, in which new damage effects may occur due to the multidimensional nature of the loading conditions.

The paper describes a small-size explosive current source with controllable output voltage shaping a megaampere current pulse. This energy source comprises a helical explosive magnetic generator and an explosive sectionalized current opening switch and is designed to power gas-discharge chambers of the plasma focus type. Control of the output voltage of the pulsed current source is performed in such a manner that in each of the series-connected sections of the explosive current opening switch, voltage is generated with a given time shift relative to the neighboring section.

This paper presents the results of laboratory and explosive experiments with a plasma focus discharge Mather-type chamber at a discharge current amplitude of 1.3–1.4 MA. It has been found that in laboratory experiments, the yield of a deuterium-deuterium neutrons reached 1011, and in an explosive experiment using the chamber filled with a deuterium-tritium gas mixture, the integral yield of a deuterium-tritium neutrons with an energy of 14 MeV was more than 1012 neutrons.

This paper discusses one type of power generators—a disk explosive generator with flat disk elements and metal inserts. A technique of numerical simulation of the operation of this generator is proposed. The principle of operation and the design of the disk explosive magnetic generator are described. The results of calculations and experiments are presented.

Damage initiation and evolution, failure, and recollection processes under axisymmetric convergence were studied in the Russian-Damage experimental series, a joint effort between the Los Alamos National Laboratory and the All-Russian Institute of Experimental Physics. A helical explosive magnetic generator was used to drive a cylindrical liner shell to produce shock wave loading of a concentric cylindrical target shell. Shock wave amplitude was controlled by the liner-to-target spacing and by the magnetic field amplitude. Variation of the current pulse duration produced either a single impact, to study damage initiation through failure, or a double impact, to study failure with recollection. Both full and partial recollection of the main crack was obtained. By fielding high-precision diagnostics to measure the dynamic drive conditions and material response and by employing post-shot metallographic analysis, this project produced well-characterized experimental data across a range of damage and recollection levels for the chosen material, aluminum. We present selected experimental results to illustrate the methodology and utility of this experimental technique.

To study the peculiarities of initiation, evolution and recollection of spall-type damage under axis-symmetric convergence using the impact method, the test bench with an explosive magnetic pulsed power source (EPPS) on the basis of a helical generator with an explosive opening switch and a current interrupter has been created. The EPPS allows shaping the trapezoidal current pulses with the amplitude from 4 MA to 12 MA, full base duration from 10 to 250 mu s and front rise duration similar to 2 mu s in the load (liner). The magnetic field produced by the EMG current ensures the isentropic drive of a cylindrical liner used to create a shock wave of the required characteristics in the targets. In experiments "R-Damage-8,9" representing the completion stage of the experimental series "R-Damage-0-9" realized jointly by the VNIIEF and LANL teams we used the isentropically driven liners to realize a set of processes of shock-wave compression, evolution of damage and recollection of a damaged matter under axis-symmetric convergence in the extruded aluminum. The features of these processes were recorded with the use of PDV technique due to the time dependencies of the hollow targets' inner surface velocity. The presented method allowed apparently for the first time realizing the full and incomplete recollection of the main crack as the results of metallographic analysis have showed. This result made it possible to verify the numerical models of the damaged medium recollection being developed at the present time.

Electromagnetic implosion of the cylindrical condensed liners is of great interest for the studies of high energy density physics, and in particular for getting pressures of terapascal range and for measuring the Hugoniots of materials under such pressures. The pulsed power systems on the basis of disk explosive magnetic generators (DEMG) provide the highest currents in the liner loads. A device on the basis of a 15-element DEMG Ø 0.4 m with a foil current opening switch and an explosive closing switch connecting the load is being developed to explore a possibility of driving the aluminum liner to a velocity of ~ 20 km/s and using it as an impactor. It is planned to check the operability of this device in the joint VNIIEF-LANL experiment ALT-3. To test the key systems of the ALT-3 assembly, a series of model experiments has been conducted. The model units will be described, the setup of the experiments testing the operability of the explosive current closing switch able to commute the currents of 60 - 70 MA and the system of high-voltage insulation of the line delivering the energy to the liner and able to withstand high voltages will be discussed. The experiment with the system modeling the ALT-3 device to check the scheme of operation of the pulsed power source' elements and the operability of disk elements under the explosive magnetic regime at the initial feeding current of 7.0 - 7.5 MA will be considered.

The paper presents the current status of MAGO research and the basic results of the latest explosive experiments. The program of activities aimed at preparation and conduct of experiments on finish compression of high-temperature plasma generated in the thermonuclear compartment of the electric-discharge chamber will be described.

A computational model of explosive opening switches, in which the conductor is broken by a ribbed barrier or by dielectric jets, is presented. The setup and results of TIM-2D hydrodynamic simulations with elastoplasticity, magnetic diffusion and electric circuit effects are discussed. The numerical simulations were done in Lagrange variables on unstructured grids. The results of the MHD opening switch simulations are compared with experiment.

The paper describes a transportable neutron generator made on the basis of electric-discharge chamber with plasma focus powered by an explosive current source. The electric-discharge chamber of Meiser type, the explosive current source consisting of a small-size helical explosive magnetic generator and the current opening switch are used. The explosive source of current can shape the current pulse with the amplitude of 3...4 MA and a microsecond front in the inductive load of 30... 40 nil. The current opening switch is made in the form of several series-connected sections that makes it possible to vary the amplitude and the duration of the voltage pulse applied to the load. The electric-discharge chamber is connected to the current source through a solid switch which helps to shape rather a steep front (< 100 ns) of the voltage pulse on the electrodes of the chamber. It is planned to conduct several series of explosive experiments. The first series of experiments with tire maximum current on the level of 1.5... 2 MA will study the operation of the neutron generator at the integral yield of DT-neutrons of > 10 12 n/pulse. The developed explosive current source will also allow conducting the experiments of tire next series at the maximum current o f 2... 3 MA in the discharge chamber.

The design and the results of testing of an explosive device forming a current pulse of quasi-trapezoidal shape with the given amplitude and duration in the liner load are presented. A need for such devices was caused by a necessity to compare the experimental data obtained on the gas guns with the results of the experiments with a magnetic drive of the liners under the effect of current flowing through the liner. The results of the experiments in which the formed current pulse in the driven liner had the amplitude of 5 MA, the base duration of 10 ¿s, and the duration of the leading and trailing edges of 2 ¿s are presented.

In some experiments conducted on the powerful capacitor facilities it is necessary to keep the electromagnetic energy in the load as long as possible, i.e. to support the current in the load during a longer period of time. This can be realized by installing a fast-operating closing switch (in literature called "crowbar") at the capacitors output or at the load input. Herewith, the closing switch should have a low self-inductance and an active resistance in the process of operation as compared with a discharge circuit of a pulsed source. The paper describes the design and presents the results of the experiments with an explosive cumulative current closing switch having a minimum amount of HE that allows using it both at the test sites and on the laboratory facilities. In the experiments conducted the amplitude of current in a discharge circuit reached 50 kA, the contact keeping time was no more than 100 mus, and the magnitude of contact resistance was within the range 0,1...0,2 mOhm. When the powerful pulsed sources of current are used, a necessity arises in a number of cases to close some parts of the electric circuit of the source. For example, often the load circuit is separated from the source circuit with the help of a special closing switch at a required time moment to limit the effect of the pulsed current source on the load. The fast-operating closing switches for the electric circuits of powerful pulsed sources of current are called crowbars.

The paper presents the results of application of the explosive magnetic pulsed power source (EMPPS), in the first experiments studying the spallation mechanisms of the solid substances damage under conditions of converging axisymmetric geometry of loading of samples by the impact of the cylindrical liner driven to a velocity of 0,2-1 km/s.