[en] Main results of researches on plasma heating and confinement of dense plasma in the multimirror trap GOL-3 are presented.Recently magnetic system of the facility was converted into completely multimirror one. This results in further improvement of energy confinement time of plasma with ion temperature ∼1 keV. Collective plasma heating by ∼120 kJ (∼8 ωs) relativistic electron beam results in T_e ∼ 2 keV at ∼10²¹ m^-3 density. High T_e exists for ∼10 μs. To this time T_i reaches ∼2 keV. Ion temperature keeps at the high level during ∼1 ms. The energy confinement time sufficiently increases and a value of nτ_E = (1.5-3).10¹⁸ m^-3s

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[en] At present, in the Budker Institute of Nuclear Physics there is in operation the most complete set of modern mirror machines based on different principles of plasma confinement. This set includes the multi-mirror system GOL-3 for confinement of dense plasma heated by relativistic electron beam, the gas dynamic trap (GDT) for confinement of collisional plasma and anisotropic fast ions, and the ambipolar trap AMBAL-M.Mirrors have a number of advantages in comparison with the closed magnetic systems like tokamak, stellarator, etc. The most important are the following. The effects of disruptions are not appeared in mirrors. There are no divertor problems in them. Plasma pressure in a mirror device can be comparable with magnetic field pressure. As to the multi-mirror system, in this case, the β value can be even significantly higher than unity (the so called << wall confinement>>). At last, mirrors are convenient for direct conversion of energy of charged particles leaving out the ends. This circumstance can turn out to be especially important in future << low neutron>> schemes of fusion reactors.In principle, mirrors are very attractive from the engineering point of view, if the plasma confined in axisymmetric magnetic systems would be MHD stable. At present, the problem of MHD stability has already been solved for all axisymmetric traps designed in Novosibirsk. At least, the value β [approximately or equal to] 0.4 was obtained in these traps without any indications of macroscopic instability development.Some important results were obtained recently in the GOL-3 experiments. A specific mechanism of reduction of longitudinal electron thermal conductivity was detected. Recently, the magnetic system of the GOL-3 device was reconstructed into multi-mirror configuration. In this configuration, a new mechanism of fast ion heating was observed. As a result, the ion temperature was increased from a few eV up to 1 keV and the confinement time significantly increased (up to 1ms). These results were obtained for plasma density of 10²¹m^-3.The experiments on the GDT device are directed to the solution of the problem of creation of a 14 MeV high power neutron source. At present, new powerful neutral beam injectors for this device are under construction. After installing these neutral beams at GDT, the electron temperature of plasma should increase up to 300 eV. It means that calculated neutron flux for the case of D-T reaction will be about 0.5 MW/m². If this value will be obtained, it will be immediately possible to begin the design of final stage of high power neutron source.In the paper, the status of all mirror traps in Novosibirsk is presented and description of the main experiments is given

[en] Experimental results of the investigation of the return current dynamics induced by the powerful relativistic electron beam injection in magnetized plasma are given. (Auth.)

[en] Thomson scattering system for measurements of radial profile of plasma density (range 0.5-5x10²¹ m^-3) with temperature up to 2 keV was developed at the GOL-3 facility. First harmonics (λ=1.06 μm) of Nd glass laser is used. Scattered light from different points of plasma cross-section is imaged to a set of quartz optical fibers and detected by avalanche photodiodes.During the first 10 μs after start of the relativistic electron beam injection the intense light emission from plasma is observed. Single powerful laser pulse is used for providing of good signal-noise ratio in this period. Later the plasma radiation intensity decreases and the less powerful laser oscillator operated in multiple-pulsed regime is used.Description of the diagnostics, methodical aspects of operation, and results of the density dynamics measurements are presented in the paper

[en] Plasma-facing materials (PFM's) of a fusion reactor will be affected by high heatflux, fast particles and 14 MeV-neutron irradiation. All these factors are crucial for the lifetime of the reactor components. Fast neutrons produce a high level of radiation damage in materials during long operation of the fusion reactor (estimated value is up to hundred dpa). At the same time, PFM's will suffer from erosion induced by the plasma. While important data on the plasma erosion have been collected for non-irradiated materials, it is difficult to qualify PFM's at present taking into account radiation damage effect. This paper is devoted to the experimental results on radiation damage effect on erosion of materials under plasma impact. To obtain a high level of radiation damage, we simulated neutron irradiation by fast ions with energies of 1-60 MeV accelerated on the cyclotron at Kurchatov Institute. Using this method we can accumulate the radiation damage equivalent to fast neutron effect at the dose of up to 10²⁶ neutron/m² in a few days operation of the cyclotron. Both carbon materials and tungsten were taken for the study as the targets: MPG-8 (Russian graphite), SEP NB-31 (ITER PFM candidate) and W (99.95% wt). Irradiation of these materials on the cyclotron has been performed with 5 MeV carbon ions (for carbon materials) and alpha particles 3.4 MeV for tungsten. The experiments have been performed on the materials having accumulated 0.1-10 dpa of radiation damage. Plasma erosion was studied on the linear plasma simulator LENTA. Irradiated samples were exposed to steady-state deuterium plasma at 100 eV (deuterium ions) to dose of up to 10²⁵ ion/m². The microstructure modification was observed and comparison was made of damaged and non-irradiated materials. Enhancement of the erosion process was detected for the radiation-damaged materials. New experimental approach developed in this work to explore the plasma-facing materials for accounting of neutron effect and the results obtained appear to be important for the further studies of the combined plasma and neutron effect on fusion PFM's. (author)

[en] Recent results on heating and confinement of plasma at the multimirror trap GOL-3 are presented. This facility is open trap for confinement of hot (0.1-1 keV) dense (10¹⁵ - 10¹⁶ 1/cm³) plasma. The plasma heating is provided by high-power electron beam (1 MeV, 30 kA, 8 μs) with energy content of up to 200 kJ. The upgrade to full-scale corrugation of a magnetic field was completed during last two years at the facility. In the 12-meter solenoid the multimirror sections of 4-meter-length were made at both ends of the solenoid (B_max=B_min = 5.2 / 3.2 T, cell length is 22 cm). The modified source of preliminary plasma was put in operation for improvement of macroscopically stable beam transport through the plasma column. Search of optimal conditions for confinement of plasma with ∼10¹⁵ 1/cm³ density and high ion temperature, and also for macroscopically stable system 'electron beam - plasma' was carried out in the new configuration of facility. As a result of the experiments the plasma with density of (1-2)x10¹⁵ 1/cm³, n(e)T(e)+n(i)T(i)=(0.5-2)x10¹⁵ keV/cm³ and confinement time of 100-200 μs in a multimirror trap is obtained. Dynamics of electron and ion temperatures is discussed. (author)

[en] Results related to physics of collective interaction of a high-power relativistic electron beam with a magnetized plasma are presented. The main regularities of this process are given. The observed peculiarities of hot plasma producing by E-beam heating on the GOL-3 device are discussed. Some results on study of strong Langmuir turbulence by laser scattering method on GOL-M device are presented. copyright 1996 American Institute of Physics

[en] A system of creation of 12-meter-long column of low temperature hydrogen plasma for GOL-3-2 facility is discussed. The plasma of ∼ 10¹⁵ cm^-3 density is created by a linear discharge. Major features of this system is high enough longitudinal magnetic field (5 T on full length, 10 T in end mirrors) and conductive vacuum chamber. Characteristics of the plasma and mechanism of the discharge are discussed

[en] Mirrors ave a number of advantages in comparison with the closed magnetic systems like tokamak, stellarator, etc. In principle, mirrors are very attractive from the engineering point of view, if the plasma confined in axisymmetric magnetic systems would be MHD stable. At present, the MHD stabile confinement has already been demonstrated for all axisymmetric traps designed in Novosibirsk for the value of β value as high as 0.4. Some important results were obtained recently in the GOL-3 and GDT experiments. In the paper, the status of two mirror traps in Novosibirsk is presented and description of the main experiments is given