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.

Magnitnoe Obzhatie (MAGO)/magnetized target fusion (MTF) thermonuclear experiments executed with a goal of producing the target plasma heated up to temperatures of hundreds of electronvolts, intended for subsequent compression by an imploding liner accelerated by explosion products, are reviewed. In MAGO/MTF experiments, plasma chambers were used consisting of two or three compartments connected by narrow nozzles: acceleration cylinder compartment and deceleration/fusion compartments (cylindrical or hemispherical). A technology of plasma chamber laboratory conditioning is described. Neutron and soft X-ray pulses are presented and obtained in experiments with chambers powered by an explosive magnetic generator. Irrespective of the chamber geometry and number of compartments, the X-ray pulse consists of a highly intensive peak with a duration of 1μs and more than a 10-μs-long low-intensity tail. The neutron pulse is time coincident with the X-ray peak. Yields up to 10 13 neutrons were detected in experiments with two-compartment chambers. Three-compartment chambers with an intermediate compartment are believed to be more promising for the compression. The results are described of the latter MAGO-IX experiment, the only successful experiment with the three-compartment chamber, in which the yield of 2 × 10 12 neutrons was detected in the third compartment and the yield in the middle compartment was many times lower.

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.

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.

When solving some physical problems, in particular, when studing the dynamic characteristics of solid liners accelerated by magnetic field, highpower magnetic energy sources with controlled time of current rising in the load are needed. The helical explosive-magnetic generators equipped with explosive opening switches are commonly used in our experiments. Such sources produce the energy of tens megajoules (1) and transmit it to the load in a matter of microseconds.

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.

The paper considers the design of the sectionalized explosive current opening switch which allows increasing the power of the current pulse in the load. The results of testing of the sectionalized opening switch operation on plane models are presented. The results of the experiment with the pulsed source of current on the basis of HEMG and 10-section cylindrical current opening switch are described.

The facilities for pulsed compression of materials are necessary to study the phase transformations and the dynamic parameters of substances. The acceleration of the solid liners with the help of magnetic field of the explosive magnetic generator (EMG) with subsequent deceleration on a specimen allows carrying out the pulsed compression. The paper describes a powerful pulsed source of current on the basis of helical EMG Oslash240 mm and explosive current opening switch Oslash 300 mm that makes it possible to shape the current pulse with the amplitude 15 MA with rise time adjustable from 3 mus to 10 mus in the liner load.

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.

This paper studied the process of implosion of the solid quasi-spherical liner driven by the axial magnetic field generated by the pulsed power source. In the experiment the pulsed power source comprising the helical EMG, the current opening switch and the transmission line provided the current pulse of 13 MA with the rise time of ~10 mus in the liner load. Two radiographic images of the quasi-spherical liner collapsing to the central axis under the effect of the magnetic field forces were obtained at different time moments. The velocity of the inner surface of the quasi-spherical liner at the moment of focusing was ~ 9 km/s. The parameters of the pulsed power source and the image of the imploding quasi-spherical liner obtained experimentally agree well with the calculated values.

Summary form only given. One of the tasks in the area of high energy density physics is to drive magnetically the cylindrical quasi-spherical solid and wire liners as one of the ways to generate soft X-radiation. The parameters required for the liner systems feeding can be provided by means of using the helical explosive magnetic generators (HHMG) developed at VNHEF and equipped with the explosive current opening switches. The paper describes the design and the operation principle of the energy source on the basis of helical EMG O240 mm with the explosive current opening switch O300 mm making it possible to obtain the current pulse w ith the amplitude of ~20 MA and rise time of 1-1.5 mus in the liner load of 15 nH. The paper presents the results of calculations demonstrating a possibility to apply this source in the research of stabilization of high-speed implosion of the liner both in condensed and plasma state. It is supposed that the methods of stabilization of the liner flight with the application of special operations on the shell surface preparation will be developed and tested experimentally.

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.

The paper presents the technique and results of 2-D computations for inductance and mutual inductance of coaxial helical coils As well as in the paper [1], the equation ΔA =-J is solved. The inductances are computed as the ratio of the flux linkage with coil turns to the current in the helix, giving rise to this flux generation. Accordingly, proper L and mutual M of inductance are possible. The computations were performed for a helical EMG with flux input into the main helix from the coupling coil. The computed L(t) and M(t) are used to solve the system of differential equations describing the EMG operation starting from the discharge of the capacitor bank onto the coupling coil to the operation of the opening switch transferring the current into the load from the main coil loop.

Summary form only given. High matter velocities level (several tens of km/s) can be achieved by means of magnetic implosion, using explosive magnetic generators. Helical+Potok type generators developed by Russian Federal Institute of Research in Experimental Physics (VNIIEF) can provide 30 MJ inductive storage and, after fast explosive opening switch operation, current law in the range 15 MA within a few microseconds. This allows high velocity jet generation, due to conical aluminium liner implosion and focalization on axis. VNIIEF and the Commissariat l'Energie Atomique (CEA, France) used this principle to realize a joint experiment in Sarov by June, 30th, 1999. Electrical power supply was provided by VNIIEF, target with diagnostics by CEA. This experiment was a challenge, with regards to several points: unusual current level range, poor data available about such a device, very short duration for radiographic observation of main phenomena: liner focalization and subsequent fast matter emission along axis. Both radiographic flashes were realized at required times. Pictures show expected density gradients in liner when collapsing on axis. Moreover, liner external face structure exhibits machining defect growth under magnetic Rayleigh Taylor instability effect: this feature already appeared in previous liner flight experiments. The present experiment clearly shows magnetocumulative generator ability for high velocities purpose, machining precision effects under high current values, radiographic observation pertinency, and prediction calculation capacity to be close to experimental results.

Rayleigh-Taylor instability (RTI) in imploding devices is to be studied if to define ICF targets. Direct use of explosive as a propellant was tested by the past to analyse RTI effects. Drawbacks of corresponding devices are well known: side effects, high areal masses inducing accuracy limitation in transverse radiographic observation, no simple way for pressure level modulation. They can be avoided by the use of magnetic driver and relevant device design, hereafter described. This paper presents results of a joint CEA/VNIIEF experiment dedicated to this topic. Potok type EMG with FOS was used to provide 7-8 MA current law within a few microseconds. Electrical power supply was provided by VNIIEF, target with diagnostics by CEA.

This paper considers the scheme to supply the MAGO chamber with the help of all inductive shunt. In this scheme the time of flow of the preliminary supply current is reduced as compared with the scheme using the explosive closing switch. When supplying the plasma chamber by the helical EMG. the current of preliminary supply is commutated by the closing switch. In the circuit with the closing switch the current flows in the chamber without changing the amplitude till the end of helical generator operation, thus producing a destroying effect on the chamber elements.