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 systems with compression of preheated magnetized plasma (MAGO/MTF) are promising regarding the achievement of the thermonuclear fusion threshold. A version of this system has been realized in VNIIEF where a dense high temperature DT-plasma was obtained with a lifetime of few microseconds, being a source of high power neutron and X-ray pulses. For diagnostics a research method for spatial-temporal parameters in the soft X-ray generation plasma region, which is formed in the MAGO chamber, has been developed. The method is based on soft X-ray plasma image formation with the help of a pinhole camera and its consequent conversion to an optical image. Optical plasma image registration is made with the use of an electron optics multi-frame recording system. For the first time for the conditions of MAGO explosive experiments the two-dimensional plasma images for three sequential intervals of discharge, corresponding to a maximum soft X-ray yield was obtained. The position, shape and typical sizes of the plasma region are determined. The development of the method for plasma research in MAGO/MTF experiments seems possible.

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.

Describes the MAGO-MTF (magnetised target fusion) approach to fusion energy using a MHD-nozzle device as the thermonuclear target. In MAGO-MTF, thermonuclear reaction ignition has two stages: 1) heated magnetized plasma formation; and 2) adiabatic compression of the obtained plasma and the achievement of thermonuclear reaction burning conditions. The formation of plasma with definite temperature and lifetime is carried out by means of plasma acceleration up to ultrahigh velocities in the MHD Laval nozzle under the influence of quick-increasing magnetic field pressure and by means of the further plasma thermalisation. Some results of the MHD-nozzle device calculations are presented, in which one can see the character of plasma motion and the dynamics of its heating.

Recent advances in high-energy pulsed power capabilities, plasma formation techniques, plasma diagnostics, and multidimensional plasma computer codes make possible the evaluation of an unexplored approach to controlled thermonuclear fusion that is intermediate between magnetic confinement (MFE) and inertial confinement (ICF) in time and density scales. Existing capabilities appear adequate to explore the major physics issues in this area, perhaps up to and including fusion ignition, with relatively low operating costs and essentially no major capital investment.

Works on the investigation of a magnetized plasma commenced and developed in the framework of MAGO (magnetic compressuring) programme, that got its official status at VNIIEF in 1979. It was directed to the attainment of a thermonuclear ignition in dense targets (without the use of fissionable materials) by means of their compression by liners accelerated to high velocities by a magnetic field. The investigations of the magnetized plasma were focused on the production of a hot ionized low-density plasma pre-heated up to 0.2-1.5 kV and suitable for the subsequent adiabatic pressing by the liner up to thermonuclear temperatures. The development of a new type of plasma chamber has formed the basis for a new area of the works, the calculated and theoretical justification of which has been performed by the theoretical department; the experiments have been arranged and conducted at VNIIEF Electrophysical Department. This chamber has the title 'gaseous ponderomotive unit' (GPU) or gaseous PU, and the system designed for the study of dense targets has come to be known as a liner ponderomotive unit (LPU).

Results of experiments in the MAGO device are presented. Measurements of the neutron spectra of the DT and DD reactions in the MAGO plasma chamber are conducted by means of the flight-time technique. The obtained dispersion of the neutron pulse (of similar to 2 mu s duration) is found to exceed the estimate based on the assumption that the ion spectrum is Maxwellian with a temperature on the order of several keV. About 10% of the neutrons leaving the chamber along its axis in the direction of the plasma flow have a substantially higher energy than the estimated energy. The obtained results can be explained by assuming that the ion component of the plasma produced in the collisionless shock wave in the MAGO chamber has a non-Maxwellian velocity distribution characterized by an average energy on the order of several keV.

Experiments were conducted on the "CASCADE" electrophysical facility which was used as a source of impulse power for laboratory model of deuterium plasma chamber with a circular MHD nozzle (MAGO chamber). The modes of device's operations were investigated at various values of deuterium pressure in the chamber both with preliminary introduction of magnetic field in the plasma and without it. Depending on conditions of experiment the neutron radiation was generated at the front of increasing current, at its maximum or on a falling down branch of current. Though the experiments were conducted at low energies of plasma chamber powering (100-500 kJ), the stable generation of neutrons was observed. The length of neutron impulse achieved the value comparable to length of neutron radiation being obtained in experiments, in which explosive magnetic generators of multimegajoule energy scale are used (/spl sim/1 /spl mu/sec and more). It was defined the optimal deuterium pressure in the plasma chamber for the used operation modes of the device.

Studies on magnetized Plasma heating in a gas chamber.having MHD nozzle are reported in WOrK C1.23. Magnetized Plasma i s accelerated by a magnetic fields vp to velocites of 10 cmlsec and is heated, during decelerating in a shock wave. Explosive magnetic generator (EMG) serves as an energy source. Maximum neutron Yield , received in a chamber,was 4 10 neutron / Per a Pulse C21. Neutron Pulse duration was 1 to 2 p e c . The Principal way for further Plasma temperature increase UP to thermonuclear ignition is additional adiabatic compression of Plasma, heated in a shocK wave at HHD nozzle output . This tasK could be easier if it were Possible to increase hot plasma lifetime by several fold. It is assumed,that the most Probably cause of m i c K Plasma cooling in d hot area of a chamber decelerdtlon section, giving rise to neutron Pulse durdtion of * Zpsec., is a delivery of insulator vapours into this area from a deceleration section. Insulator vapours and gas, located near the insulator, are frozen into a higher magnetic field , as they are located at a small radins . This PdPt of gas dPtPrminPs now neutron Yield out of the chamber, 3s 1 t obtains the most velocity ,and the neutron Pulse duration is determined by the Presence of insulutor vapours. 8

IN THE MAGNETIC IMPLOSION SYSTEM MAGO A. M. Buyko, V. K. Chernyshev, V. A. Demidov, Yu. N. Dolin, S. F. Garanin, V. A. Ivanov, V. P. Korchagin, M. V. Lartsev, V. I. Mamyshev, A . P. Mochalov, V. N. Mokhov, I. V. Morozov, N. N. Moskvichev, E. S. Pavlovsky, S. V. Pak, S. V. Trusillo, G. I. Volkov, V. B. Yakubov, V. V. Zmushko All-Russian Institute of Experimental Physics 607200, Arzamas-16, Nizhny Novgorod Region, Russia