Search results for: A. Kreter

Items from 1 to 20 out of 78 results

article

First direct comparative test of single crystal rhodium and molybdenum mirrors for ITER diagnostics

A. Litnovsky, Yu. Krasikov, M. Rasinski, A. Kreter, more

Fusion Engineering and Design > 2017 > 123 > C > 674-677

All optical and laser diagnostics in ITER will use mirrors to observe the plasma radiation. In the ITER environment, mirrors may become contaminated with plasma impurities hampering the performance of corresponding diagnostics. An in-situ mirror cleaning is proposed, which relies on ion sputtering of the contaminants and the affected mirror material. Previous research demonstrated the advantages of...

article

Whole-machine material migration studies in the TEXTOR tokamak with molybdenum

A. Weckmann, P. Petersson, A. Kirschner, P. Wienhold, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 518-523

MoF₆ injection from a localised source into plasma edge in the TEXTOR tokamak was the last experiment before the final shut-down of the TEXTOR machine. During decommissioning all plasma-facing components (PFCs) became available for surface studies. Detailed mapping of Mo deposition was performed in order to determine its migration on global scale. The concentration of Mo on PFC decays exponentially...

article

The microstructure of tungsten exposed to D plasma with different impurities

M. Rasinski, A. Kreter, Y. Torikai, Ch. Linsmeier

Nuclear Materials and Energy > 2017 > 12 > Complete > 302-306

In this study the effect of impurities in deuterium plasma on the tungsten microstructure is investigated. W samples were exposed in the linear plasma generator PSI-2 at a sample temperature of 500K with an incident ion flux of about 10²²m⁻²s⁻¹, an incident ion fluence of 5×10²⁵m⁻² and an incident ion energy of 70eV. Samples were exposed to pure D+ plasma and with additional impurities of He (3%),...

article

ERO modeling of beryllium erosion by helium plasma in experiments at PISCES-B

D. Borodin, D. Nishijima, R.P. Doerner, S. Brezinsek, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1157-1162

•Be physical sputtering by He ions was characterized at PISCES-B independently by spectroscopy and mass loss and interpreted using the ERO modeling.•The influence of plasma conditions (n_e/T_e scan) and negative target biasing (sputtering ion impact energy) was investigated.•The shapes and ratios of BeI and BeII line intensity profiles were reproduced showing the feasibility of the model and ADAS’96...

article

Deuterium retention in RAFM steels after high fluence plasma exposure

Y. Martynova, S. Möller, M. Rasiński, D. Matveev, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 648-654

Deuterium retention and detrapping behavior in the ferritic-martensitic steels EUROFER’97 and P92 after exposure to plasma at high fluences ≥ 10²⁶D/m² was studied using thermal desorption spectroscopy (TDS), supported by nuclear reaction analysis. Low-temperature irradiation at 450K and fluences ≥ 10²⁶D/m² with low impact energy D⁺ / D⁺+He⁺ ions of 40eV at PSI-2 resulted in a deuterium inventory of...

article

ERO modelling of tungsten erosion in the linear plasma device PSI-2

A. Eksaeva, E. Marenkov, D. Borodin, A. Kreter, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 253-260

Series of experiments on tungsten (W) erosion and transport in Argon (Ar) plasma were conducted at the linear plasma device PSI-2. W erosion was measured with three independent methods: WΙ spectroscopy, mass loss and quartz micro-balance (QMB) deposition sensor. Consistent set of data produced in these experiments was interpreted using the 3D ERO code simulations, which have reproduced all the main...

article

Influence of the base temperature on the performance of tungsten under thermal and particle exposure

I. Steudel, A. Huber, A. Kreter, J. Linke, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1348-1351

Tungsten, the plasma facing material (PFM) for the divertor in ITER, must sustain severe, distinct loading conditions. This broad array of exposure conditions necessitates comprehensive experiments that cover most of the expected loading parameters to predict qualitative statements about the performance and as a consequence thereof the intended operation time. However, comprehensive experiments are...

article

Modelling of deposition and erosion of injected WF6 and MoF6 in TEXTOR

A. Kirschner, A. Kreter, P. Wienhold, A. Weckmann, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 564-568

Tracer injection experiments in TEXTOR with MoF₆ and WF₆ lead to local deposition of about 6% for Mo and about 1% for W relative to the injected amount of Mo and W atoms. Modelling of these experiments has been done with ERO applying updated data for physical sputtering. The dissociation of the injected molecules has been treated in a simplified manner due to the lack of dissociation rate coefficients...

article

Damage and deuterium retention of re-solidified tungsten following vertical displacement event-like heat load

Y. Hamaji, H.T. Lee, A. Kreter, S. Möller, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1303-1307

Surface morphology and hydrogen isotope retention of W specimen melted with vertical displacement event-like heat load and subsequent deuterium (D) plasma exposure were studied. Applied heat loads using electron beam without raster scanning were about 190 and 230 MW/m² in heat flux and 0.08, 0.12 and 0.16s in duration. After the heat load application, specimens showed apparent melting spots with grain...

article

In-situ mass-spectrometer of magnetized plasmas

I.A. Sorokin, I.V. Vizgalov, V.A. Kurnaev, C. Brandt, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1243-1247

Modified mass-spectrometer of magnetized plasmas (MSMP-03) was installed on the linear plasma device PSI-2 in support of plasma-material interaction studies. MSMP-03 was adapted for in-situ mass-spectrum measurements in high-power discharge regimes and equipped with advanced measurements system consisting of a double-collector system allowing to decrease both the secondary electron emission signal...

article

Design and development of a LIBS system on linear plasma device PSI-2 for in situ real-time diagnostics of plasma-facing materials

X. Jiang, G. Sergienko, B. Schweer, N. Gierse, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1224-1230

Laser induced breakdown spectroscopy (LIBS) is a strong candidate for detecting and monitoring the H/D/T content on the surface of plasma facing components (PFCs) due to its capability of fast direct in situ measurement in extreme environment (e.g., vacuum, magnetic field, long distance, complex geometry). To study the feasibilities and encounter the challenges of LIBS on plasma devices, a LIBS system...

article

Smart alloys for a future fusion power plant: First studies under stationary plasma load and in accidental conditions

A. Litnovsky, T. Wegener, F. Klein, Ch. Linsmeier, more

Nuclear Materials and Energy > 2017 > 12 > Complete > 1363-1367

In case of an accident in the future fusion power plant like DEMO, the loss-of-coolant may happen simultaneously with air ingress into the vacuum vessel. The radioactive tungsten and its isotopes from the first wall may become oxidized and vaporized into the environment. The so-called “smart” alloys are under development to suppress the mobilization of oxidized tungsten. Smart alloys are aimed at...

article

Melt-layer formation on PFMs and the consequences for the material performance

I. Steudel, A. Huber, A. Kreter, J. Linke, more

Nuclear Materials and Energy > 2016 > 9 > Complete > 153-156

One of the numerous challenges of the demonstration power plant DEMO is the selection of appropriate plasma facing materials (PFMs) and this task is ultimately important to the success for DEMO. Low-activation stainless steel (e.g. EUROFER, P92), which is already intended as structural material, could also become a possible plasma facing material, e.g. for the first wall (FW). Therefore, the ferritic...

article

Influence of helium induced nanostructures on the thermal shock performance of tungsten

M. Wirtz, M. Berger, A. Huber, A. Kreter, more

Nuclear Materials and Energy > 2016 > 9 > Complete > 177-180

Experiments were performed in the linear plasma device PSI-2 in order to investigate the synergistic effects of combined steady-state He-plasma and thermal shock exposure. Tungsten produced according to the ITER material specifications by Plansee SE, Austria, was loaded sequentially and simultaneously by steady-state He plasma and transient thermal loads induced by a laser beam. All tungsten samples...

article

Deuterium retention in tungsten under combined high cycle ELM-like heat loads and steady-state plasma exposure

A. Huber, G. Sergienko, M. Wirtz, I. Steudel, more

Nuclear Materials and Energy > 2016 > 9 > Complete > 157-164

To investigate the synergistic effects of fuel retention in tungsten, experiments were performed in the linear plasma device PSI-2 where the transient heat loads were applied by a high energy laser during the steady-state plasma operation. The impact on the deuterium (D) retention of simultaneous and sequential exposures to laser and plasma has been investigated. A significant increase of D retention,...

article

Characterisation of surface layers formed on plasma-facing components in controlled fusion devices: Role of heavy ion elastic recoil detection

P. Ström, P. Petersson, M. Rubel, A. Weckmann, more

Vacuum > 2015 > 122 > Part B > 260-267

Wall components retrieved from the TEXTOR tokamak after tracer experiments with nitrogen-15 and molybdenum hexafluoride (MoF₆) injection were studied to determine deposition patterns and, by this, to conclude on material migration. Toroidal limiter tiles made of carbon fibre composites and fine grain graphite were examined using time-of-flight heavy ion elastic recoil detection analysis. Molybdenum...

article

Calculation of cracking under pulsed heat loads in tungsten manufactured according to ITER specifications

A.S. Arakcheev, D.I. Skovorodin, A.V. Burdakov, A.A. Shoshin, more

Journal of Nuclear Materials > 2015 > 467 > P1 > 165-171

A mathematical model of surface cracking under pulsed heat load was developed. The model correctly describes a smooth brittle–ductile transition. The elastic deformation is described in a thin-heated-layer approximation. The plastic deformation is described with the Hollomon equation. The time dependence of the deformation and stresses is described for one heating–cooling cycle for a material without...

article

Nitrogen removal from plasma-facing components by ion cyclotron wall conditioning in TEXTOR

A.G. Carrasco, T. Wauters, P. Petersson, A. Drenik, more

Journal of Nuclear Materials > 2015 > 463 > C > 688-692

The efficiency of ion cyclotron wall conditioning (ICWC) in the removal of nitrogen from plasma-facing components in TEXTOR was assessed. In two experiments the wall was loaded with nitrogen and subsequently cleaned by ICWC in deuterium and helium. The retention and removal of nitrogen was studied in-situ by means of mass spectrometry, and ex-situ by surface analysis of a set of graphite, tungsten...

article

Tracer techniques for the assessment of material migration and surface modification of plasma-facing components

M. Rubel, A. Weckmann, P. Ström, P. Petersson, more

Journal of Nuclear Materials > 2015 > 463 > C > 280-284

Tracer techniques were used in the TEXTOR tokamak to determine high-Z metal migration and the deposition of species used for plasma edge cooling or wall conditioning under different types of operation conditions. Volatile molybdenum hexa-fluoride, nitrogen-15 and oxygen-18 were used as markers in tokamak or ion cyclotron wall conditioning discharges (ICWC). The objective was to obtain qualitative...

article

Influence of tungsten microstructure and ion flux on deuterium plasma-induced surface modifications and deuterium retention

L. Buzi, G. De Temmerman, B. Unterberg, M. Reinhart, more

Journal of Nuclear Materials > 2015 > 463 > C > 320-324

The influence of surface temperature, particle flux density and material microstructure on the surface morphology and deuterium retention was studied by exposing tungsten targets (20μm and 40μm grain size) to deuterium plasma at the same particle fluence (10²⁶m⁻²) and incident ion energy (40eV) to two different ion fluxes (low flux: 10²²m⁻²s⁻¹, high flux: 10²⁴m⁻²s⁻¹). The maximum of deuterium retention...

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Search results for: A. Kreter

First direct comparative test of single crystal rhodium and molybdenum mirrors for ITER diagnostics

Whole-machine material migration studies in the TEXTOR tokamak with molybdenum

The microstructure of tungsten exposed to D plasma with different impurities

ERO modeling of beryllium erosion by helium plasma in experiments at PISCES-B

Deuterium retention in RAFM steels after high fluence plasma exposure

ERO modelling of tungsten erosion in the linear plasma device PSI-2

Influence of the base temperature on the performance of tungsten under thermal and particle exposure

Modelling of deposition and erosion of injected WF6 and MoF6 in TEXTOR

Damage and deuterium retention of re-solidified tungsten following vertical displacement event-like heat load

In-situ mass-spectrometer of magnetized plasmas

Design and development of a LIBS system on linear plasma device PSI-2 for in situ real-time diagnostics of plasma-facing materials

Smart alloys for a future fusion power plant: First studies under stationary plasma load and in accidental conditions

Melt-layer formation on PFMs and the consequences for the material performance

Influence of helium induced nanostructures on the thermal shock performance of tungsten

Deuterium retention in tungsten under combined high cycle ELM-like heat loads and steady-state plasma exposure

Characterisation of surface layers formed on plasma-facing components in controlled fusion devices: Role of heavy ion elastic recoil detection

Calculation of cracking under pulsed heat loads in tungsten manufactured according to ITER specifications

Nitrogen removal from plasma-facing components by ion cyclotron wall conditioning in TEXTOR

Tracer techniques for the assessment of material migration and surface modification of plasma-facing components

Influence of tungsten microstructure and ion flux on deuterium plasma-induced surface modifications and deuterium retention

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