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Studies of plasma interactions with tungsten targets in PF-1000U facility

Ladygina M. S., Skladnik-Sadowska E., Zaloga D. R., Sadowski M. J., Kubkowska M., Kowalska-Strzeciwilk E., Krawczyk N., Paduch M., Miklaszewski R., Garkusha I. E.

Nukleonika

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2016

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Vol. 61, No. 2

149--153

EN

This paper presents results of experimental studies of tungsten samples of 99.95% purity, which were irradiated by intense plasma-ion streams. The behaviour of tungsten, and particularly its structural change induced by high plasma loads, is of great importance for fusion technology. The reported measurements were performed within a modifi ed PF-1000U plasma-focus facility operated at the IFPiLM in Warsaw, Poland. The working gas was pure deuterium. In order to determine the main plasma parameters and to study the behaviour of impurities at different instants of the plasma discharge, the optical emission spectroscopy was used. The dependence of plasma parameters on the initial charging voltage (16, 19 and 21 kV) was studied. Detailed optical measurements were performed during interactions of a plasma stream with the tungsten samples placed at the z-axis of the facility, at a distance of 6 cm from the electrode outlets. The recorded spectra showed distinct WI and WII spectral lines. Investigation of a target surface morphology, after its irradiation by intense plasma streams, was performed by means of an optical microscope. The observations revealed that some amounts of the electrodes material (mainly copper) were deposited upon the irradiated sample surface. In all the cases, melted zones were observed upon the irradiated target surface, and in experiments performed at the highest charging voltage there were formed some cracks.

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Progress in stellarator research at IPP-Kharkov

Moiseenko V. E., Lozin O. V., Shapoval A. M., Dreval M. B., Kulyk Y. S., Mironov Y. K., Romanov V. S., Pashnev V. K., Sorokovoy E. L., Petrushenya A. A., Ozherel’ev F. I., Kozulya M. M., Konovalov V. G., Maznichenko S. M., Garkusha I. E.

Nukleonika

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2016

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Vol. 61, No. 2

91--97

EN

A new antenna of ‘crankshaft’ type has been installed in the Uragan-2M device in order to increase the plasma density and heating below the ion cyclotron frequency. Antenna operation is modelled by 1D code, which solves boundary problem for time-harmonic Maxwell’s equations in radially non-uniform plasma cylinder. In recent experiments with this antenna, the SXR, CV, OV and OII emission measurements indicate that the light impurity radiation barrier is overcame at this device. Plasma with a temperature of ~50 eV exists during a short period of a few milliseconds. Then the radiation collapse comes owing to strong infl ux of impurities to the plasma column. A new magnetic diagnostics has been installed at Uragan-3M. Using it the poloidal magnetic fi eld is measured and the shift of toroidal current in major radius is registered. A miniature pinhole camera array for spatially and temporally resolved measurements of soft X-ray (SXR) plasma emission has been recently installed on the U-3M. Different shapes of the SXR emission profi le has been observed in different discharge conditions.

3

Non-self-sustained discharge with hollow anode for plasma-based surface treatment

Misiruk I. O., Timoshenko O. I., Taran V. S., Garkusha I. E.

Nukleonika

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2016

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Vol. 61, No. 2

195--199

EN

The paper discusses plasma methods for surface modification using the non-self-sustained glow discharge with a hollow anode. This discharge is characterised by low voltage and high values of electron and ion currents. It can be easily excited in vacuum-arc installations that are widely used for coatings deposition. It is shown that such type of discharge may be effectively used for ion pumping, film deposition, ion etching, diffusion saturation of metallic materials, fusion and brazing of metals, and for combined application of above mentioned technologies in a single vacuum cycle.

4

Study of tungsten surface interaction with plasma streams at DPF-1000U

Ladygina M. S., Skladnik-Sadowska E., Zaloga D. R., Malinowski K., Sadowski M. J., Kubkowska M., Kowalska-Strzeciwilk E., Paduch M., Zielinska E., Miklaszewski R., Garkusha I. E., Gribkov V. A.

Nukleonika

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2015

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Vol. 60, No. 2

293--296

EN

In this note experimental studies of tungsten (W) samples irradiated by intense plasma-ion streams are reported. Measurements were performed using the modified plasma focus device DPF-1000U equipped with an axial gas-puffing system. The main diagnostic tool was a Mechelle®900 optical spectrometer. The electron density of a freely propagating plasma stream (i.e., the plasma stream observed without any target inside the vacuum chamber) was estimated on the basis of the half-width of the Dβ spectral line, taking into account the linear Stark effect. For a freely propagating plasma stream the maximum electron density amounted to about 1.3 × 1017 cm–3 and was reached during the maximum plasma compression. The plasma electron density depends on the initial conditions of the experiments. It was thus important to determine first the plasma flow characteristics before attempting any target irradiation. These data were needed for comparison with plasma characteristics after an irradiation of the investigated target. In fact, spectroscopic measurements performed during interactions of plasma streams with the investigated W samples showed many WI and WII spectral lines. The surface erosion was determined from mass losses of the irradiated samples. Changes on the surfaces of the irradiated samples were also investigated with an optical microscope and some sputtering and melting zones were observed.

5

Transient plasma loads to the ITER divertor surfaces : simulation experiments with QSPA Kh - 50

Garkusha I. E., Aksenov N. N., Chuvilo A. A., Landman I. S., Makhlaj V. A., Malykhin S. V., Pugachev A. T., Sadowski M. J., Skladnik-Sadowska E.

Nukleonika

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2012

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Vol. 57, No. 2

167-170

EN

Experimental simulations of International Thermonuclear Experimental Reactor (ITER) transient events with relevant heat load and particle load parameters have been performed with a quasi-stationary plasma accelerator QSPA Kh-50. Pulsed plasma guns PPA and IBIS were also used for comparative studies of surface damages appearing under varying plasma parameters and sorts of plasma ions. Particular attention is paid to the material erosion due to particles ejection from the tungsten surfaces both in the form of droplets and solid dust. Generation mechanisms of the dust in the course of ELM-like plasma impacts to the tungsten surfaces are discussed

6

Time - and space - resolved measurements of high - energy ion beams emitted from PF - type discharges

Kwiatkowski R., Sadowski M. J., Skladnik-Sadowska E., Zebrowski J., Malinowski K., Czaus K., Garkusha I. E.

Nukleonika

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2012

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Vol. 57, No. 2

211-214

EN

The paper presents experimental studies of the spatial-microstructure and temporal-characteristics of fast ion beams, which are emitted from high-current plasma-focus (PF) discharges performed within the PF-360 facility at National Centre for Nuclear Research (NCBJ) at Otwock/Świerk, Poland. The spatial structure of the ion beams was investigated by means of pinhole cameras equipped with solid-state nuclear track detectors shielded by absorption filters made of Al-foils of different thickness. In order to perform time-resolved measurements there were applied miniature scintillation detectors placed at different points of the ion-image plane.

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Research on spatial and energetic characteristics of the ion beams emitted in the PF - 360 discharges

Kwiatkowski R., Skladnik-Sadowska E., Malinowski K., Sadowski M. J., Czaus K., Zebrowski J., Garkusha I. E.

Nukleonika

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2012

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Vol. 57, No. 1

67-74

EN

Experimental results are presented on the spatial structure and energetic characteristics of the fast ion beams produced by high-current discharges in a PF-360 device operated at the National Centre for Nuclear Research (NCBJ, Otwock/Świerk, Poland). The 105 kJ discharges were initiated at the initial deuterium pressure around p0 = 6 hPa and were powered from a 234 miF capacitor bank charged up to 30 kV. The spatial structure of the ion beams was recorded using pinhole cameras equipped with the solid-state nuclear track detectors of the PM-355 type, placed at two different angles (0 centigrade, 45 centigrade) relative to the discharge axis. The detectors were shielded by thin absorption filters made of pure Al foils of various thickness, which made it possible to record only ions with energies exceeding a chosen threshold value. Similarly as in other plasma focus (PF) experiments, energies of the emitted ions ranged from about 30 keV to about 3 MeV, i.e. they were much higher than the voltage applied to the electrodes. The recorded ion images showed a complex spatial structure of the fast ion beams, which consisted of many micro-beams of different energies. It is possible that these beams were emitted by various local micro-sources (e.g. plasma micro-diodes) the were formed inside the PF pinch column.

8

Recent developments of plasma - based technologies for medicine and industry

Taran V. S., Garkusha I. E., Krasnyj V. V.

Nukleonika

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2012

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Vol. 57, No. 2

277-282

EN

The paper presents an overview of experimental results of various plasma applications based on atmospheric and vacuum discharges. A multifunctional low-temperature ozone sterilizer with a ultrasonic cavitation and dielectric barrier discharge generated at atmospheric pressure as well as ozonators with a diaphragm for water treatment and disinfection of medical tools have been developed. Particular attention is paid to the investigation of arc, high-frequency and non-self maintained discharges generated in vacuum for coatings application. Some aspects of pulsed plasma treatment, surface modification and hardening due to nitriding, oxidation and carburization are discussed.

9

Optical emission spectroscopy of plasma produced from tungsten target irradiated within RPI - IBIS facility

Skladnik-Sadowska E., Malinowski K., Sadowski M. J., Nowakowska-Langier K., Ladygina M. S., Garkusha I. E.

Nukleonika

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2012

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Vol. 57, No. 2

193-196

EN

The paper presents recent research on characteristics of deuterium plasma streams generated within an RPI-IBIS (multi-rod plasma injector) facility, and optical spectra of plasma produced during the interaction of these streams with a tungsten target placed at a distance of 20 cm from the electrode outlets. Distinct WI- and WII-lines were recorded and the noticeable erosion of the W-target was observed for shots delivering more than 4 J/cm2 on the target surface.

10

Characterization of dense plasma streams generated by MPC and their interaction with material surfaces

Makhlaj V. A., Chebotarev V. V., Chuvilo A. A., Garkusha I. E., Ladygina M. S., Marchenko A. K., Petrov Y. V., Solyakov D. G.

Nukleonika

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2012

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Vol. 57, No. 2

197-200

EN

Comparative studies of the parameters both pure helium and helium-xenon plasma have been fulfilled in a magneto-plasma compressor (MPC). The current-voltage characteristics of MPC accelerating channel and the maximum plasma velocity of (6-8) x 106 cm/s changed negligibly under local xenon injection to compression zone. Nevertheless, the xenon addition causes a growth of maximal plasma pressure up to of 2.3 MPa, an increase of plasma radiation from the compression zone. The plasma density achieved 1018 cm.

11

Calorimetric studies of the energy deposition on a material surface by plasma jets generated with QSPA and MPC devices

Chuvilo A. A., Garkusha I. E., Makhlaj V. A., Petrov Y. V.

Nukleonika

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2012

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Vol. 57, No. 1

49-53

EN

Studies of the energy deposition by plasma jets incident on a material surface are of topical interest for both the fusion and plasma technology applications. In this paper the results are reported of a comparative study of plasma energy deposition on different material surfaces exposed to plasma jets of various duration and energy density, generated using the QSPA Kh-50 and the MPC devices. The spatial distribution of plasma energy density and the heat load on the surface were measured with a movable calorimeter. The measurements demonstrate that in the case of an exposure to QSPA plasma jets the absorbed heat load is approximately equal to 55-60% of the energy in the incident plasma jet. In the case of plasma jets generated using the MPC device the heat load on the target surface and was practically the same as for the QSPA jets, and additional shielding effects were found to be negligible due to the short duration of plasma jets.

12

Measurements of electron and ion beams emitted from the PF-1000 device in the upstream and downstream direction

Kwiatkowski R., Skladnik-Sadowska E., Malinowski K., Sadowski M. J., Czaus K., Zebrowski J., Karpinski L., Paduch M., Scholz M., Garkusha I. E., Kubeš P.

Nukleonika

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2011

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Vol. 56, No. 2

119-123

EN

In this paper we report on measurements of the energy spectra and other properties of the electron and fast ion beams emitted in the upstream and downstream direction along the z-axis of a large plasma focus device PF-1000, that was operated at 21-27 kV, delivering 290–480 kJ pulse. Measurements of the electron beam (EB) properties were performed using a magnetic analyzer. Properties of the ion beams were measured by means of pinhole cameras equipped with PM-355 nuclear track detectors and placed at various angles (0, 60 and 180 centigrade) to the discharge axis. Measurements revealed a complex spatial structure of the fast ion beams. The ion measurements behind the PF-1000 collector proved that some fast deuterons are emitted also in the upstream direction. Measurements of the EBs emitted in the upstream and downstream direction revealed electron energies in the range from approximately 40 keV to approximately 800 keV. These spectra confirm that in localized regions within the PF-1000 plasma column there appear strong fields accelerating charged particles in different directions along the discharge axis.