Plasma heating and confinement in the GOL-3 multiple mirror trap

Experiments on plasma confinement in a multiple mirror configuration are carried out at GOL-3 facility in Novosibirsk. Feature of experiments at this facility is high plasma density (up to 5⋅10²¹ m⁻³ ). High ion temperature (up to 2 keV) essentially differs the regime with multimirror configuration from previously studied plasma heating by the Ebeam in a uniform magnetic field. Physical mechanism of effective heating of plasma ions, substantially dependent on corrugation of the magnetic field is discussed. In this paper the new experimental data from the GOL-3 facility are presented and the main attention to a stage of ion heating is addressed.Експерименти по нагріванню й утриманню плазми в багатопробковій пастці проводяться на установці ГОЛ- 3 у Новосибірську. Особливістю плазми в цій пастці є її відносно висока (до 5⋅10²¹ м⁻³ ) густина. Нагрівання плазми релятивістським електронним пучком у багатопробковій пастці істотно відрізняється від нагрівання в простому соленоїді тим, що спостерігається збільшення іонної температури аж до 2 кэВ. У роботі обговорюється механізм швидкого нагрівання іонів і представляються нові експериментальні результати, отримані на установці ГОЛ-3.Эксперименты по нагреву и удержанию плазмы в многопробочной ловушке проводятся на установке ГОЛ-3 в Новосибирске. Особенностью плазмы в этой ловушке является ее относительно высокая (до 5⋅10²¹ м⁻³ ) плотность. Нагрев плазмы релятивистским электронным пучком в многопробочной ловушке существенно отличается от нагрева в простом соленоиде тем, что наблюдается увеличение ионной температуры вплоть до 2 кэВ. В работе обсуждается механизм быстрого нагрева ионов и представляются новые экспериментальные результаты, полученные на установке ГОЛ-3

Plasma heating and confinementat the GOL-3-II facility

Results of experiments on plasma heating and confinement in multimirror open trap GOL-3-II are presented. This facility is intended for heating and confinement of a relatively dense (10¹⁵-10¹⁷ cm⁻³) plasma in axially-symmetrical magnetic system. The plasma heating is provided by a high-power electron beam (1 MeV, 30 kA, 8 µs, 200 kJ). Results of the experiments with multimirror configuration of the device indicate that the confinement time of the plasma with ne ~ (0,5÷5).10¹⁵ cm⁻³ and Te ~1 keV increases more than order of magnitude in comparison with single mirror device

Observation of dust particles ejected from the tungsten surface by transient heat flux with small-angle scattering of cw laser light

A new test facility for experimental simulation of transient heat load expected in the ITER divertor during unmitigated events is developed. Application of a long-pulse (0.1–0.3ms) wide-aperture (up to 2cm2) electron beam as a heating device provides powerful energy loads at a tungsten target with FHF> 250MJm−2s−0.5. Dynamics of tungsten particles in the ablation plume is investigated with a novel for PSI experiments small-angle laser light scattering technique. The threshold of intense droplet generation and dynamics of particles sizes are estimated

In-situ imaging of tungsten surface modification under ITER-like transient heat loads

Experimental research on behavior of rolled tungsten plates under intense transient heat loads generated by a powerful (a total power of up to 7 MW) long-pulse (0.1–0.3ms) electron beam with full irradiation area of 2 cm2 was carried out. Imaging of the sample by the fast CCD cameras in the NIR range and with illumination by the 532nm continuous-wave laser was applied for in-situ surface diagnostics during exposure. In these experiments tungsten plates were exposed to heat loads 0.5–1MJ/m2 with a heat flux factor (Fhf) close to and above the melting threshold of tungsten at initial room temperature. Crack formation and crack propagation under the surface layer were observed during multiple exposures. Overheated areas with excessive temperature over surrounding surface of about 500K were found on severely damaged samples more than 5ms after beam ending. The application of laser illumination enables to detect areas of intense tungsten melting near crack edges and crack intersections

Blistering of the selected materials irradiated by intense 200keV proton beam

Formation of blisters on the surfaces of metal targets made of the selected materials was studied. The targets were irradiated by 100-200 keV, 1-2 mA proton beam up to the doses above 10/sup 24/ m/sup -2/. Real-time monitoring of the target surface was performed with a set of in situ optical surface diagnostics that allows detection of the moment of blisters appearance. The overview of experimental setup and the results of testing of different materials are presented. The number and the size of blisters gradually increase during the irradiation. Critical fluence of blistering strongly depends on the target temperature, proton energy and surface machining method. The features of blistering under the proton beam irradiation and the effects of hydrogen diffusion and interaction with the target lattice are discussed. [All rights reserved Elsevier].Anglai