Determination of rate coefficients for fusion-relevant atoms and molecules by modelling and measurement in the boundary layer of TEXTOR

Pospieszczyk, A.; Borodin, D.; Brezinsek, S.; Huber, A.; Kirschner, A.; Mertens, Ph.; Sergienko, G.; Schweer, B.; Бейгман, И. Л.; Vaĭnshteĭn, L. A.

doi:10.1088/0953-4075/43/14/144017

Cited by 54 publications

(40 citation statements)

References 49 publications

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“…A detailed description of the method can be found in e.g. [2]. Briefly, the (spatially integrated) intensity of a spectral line Φ is characterized by an excitation rate X to the upper level of the corresponding transition, the branching ratio B of the transition, and the number of atoms in the plasma.…”

Section: Diagnostics and Methodsmentioning

confidence: 99%

“…The WI 361.7 nm line was selected on basis of its high intensity as well as strong correlation with the WI 400.9 nm line. The WII was selected for its relatively high intensity as well as for available S/XB values from modeling [2]. For the present analysis, we have not applied the calculated S/XB values because the uncertainty in the tungsten ground state temperature introduces an uncertainty in the S/XB value of an order of magnitude.…”

Section: Assessing Prompt Redeposition Via Wii Spectroscopymentioning

confidence: 99%

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Tungsten divertor erosion in all metal devices: Lessons from the ITER like wall of JET

Rooij¹,

Coenen²,

Aho-Mantila

et al. 2013

Journal of Nuclear Materials

127

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Tungsten erosion in the outer divertor of the JET ITER like wall was quantified by spectroscopy. Effective sputtering yields of typically 10 −4 were measured in L-mode at ∼ 30 eV attached divertor conditions and beryllium was identified as the main cause of sputtering. The signature of prompt redeposition was observed in the analysis of WI 400.9 nm and WII 364 nm line ratios and indicative of > 50% redeposition fractions. Inter-and intra-ELM sputtering were compared for an example of 10 Hz ELMs with 13 MW NBI heating, in which intra-ELM sputtering was found to dominate by a factor of 5. Nitrogen seeding initially increased the tungsten sputtering threefold due to higher extrinsic impurity levels and effectively reduced the tungsten sputtering when the divertor plasma temperature was decreased from the initial 25 eV down to 15 eV.

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Section: Diagnostics and Methodsmentioning

confidence: 99%

Section: Assessing Prompt Redeposition Via Wii Spectroscopymentioning

confidence: 99%

Tungsten divertor erosion in all metal devices: Lessons from the ITER like wall of JET

Rooij¹,

Coenen²,

Aho-Mantila

et al. 2013

Journal of Nuclear Materials

127

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show abstract

“…In terms of quantitative results one can now compare to high temperature erosion as describe in [8]. In both cases the amount of W releases reaches between 2.5 and 3 · 10 20 atoms/s which is, assuming a small area of about (1−4)cm 2 for the melt and interaction surface and an S/XB value of 100 [23], still orders of magnitude larger (∼ 10 24 m −2 s −1 ) than for typical high temperature erosion as deduced previously (4 · 10 21 m −2 s −1 ) [8]. This is compatible with the assumption of strong local heating and thus strong local evaporation.…”

Section: Tungsten Erosionmentioning

confidence: 96%

Analysis of tungsten melt-layer motion and splashing under tokamak conditions at TEXTOR

et al. 2011

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Behavior and characteristics of tungsten under impinging high heat-fluxes are investigated in view of the material choices for future devices such as ITER and DEMO. Experiments have been performed in the edge of the TEXTOR tokamak to study melt-layer motion, macroscopic melt layer erosion as well as the changes of the material properties. The parallel heat-flux ranges around q ∼ 45M W/m 2 allowing samples at an impact angle of 35 • to be exposed to 20 − 30M W/m 2 . Melt-layer motion perpendicular to the magnetic field is observed following a Lorentzforce originating from thermoelectric emission of the hot sample. Up to 3 g of tungsten are redistributed forming mountain like structures at the edge of the sample. The typical melt layer thickness is 1 − 1.5mm. Those hills are particularly susceptible to even higher heat-fluxes of up to the full q . Locally the temperature can reach up to 6000K, high levels of evaporation are causing significant erosion in form of continuous fine-spray (∼ 1 · 10 24 atoms m −2 s −1 ). Vaporshielding is occurring and hindering the further heating of the samples. In addition the formation of ligaments and splashes occurs several times during the melt phase ejecting droplets in the order of several 10µm up to 100µm probably caused by a Kelvin-Helmholtz instability evolving in the melt. In terms of material degradation several aspects are considered: formation of leading edges by redistributed melt, bubble formation and re-crystallization. Bubbles are occurring in sizes between µm and 200 µm while recrystallization increases the grain size up to 1.5 mm. The power handling capabilities are thus severely degraded. Melting of Tungsten in future devices is highly unfavorable and needs to be avoided especially in light of uncontrolled transients and possible unshaped PFCs

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“…This correction is of importance, however lays below uncertainties in the measurements. Moreover, their interpretation demands the knowledge of the local plasma parameters, data on surface and atomic processes, and even about chemical release of Be [6] and its further decay in plasma.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Expression for the Electric Field and Particle Tracing in Modelling of Be Erosion Experiments at the JET ITER‐like Wall

Borodkina

Borodin

Kirschner

et al. 2016

Contrib. Plasma Phys.

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A new analytical approximation for the electric potential profile in the presence of an oblique magnetic field and the analytical solution for the particle motion just before the impact with a plasma-facing surface are presented. These approximations are in good agreement with fluid solutions and the corresponding PIC simulations. These expressions were applied to provide effective physical erosion yields for Be, which have in a second step been used in ERO code simulations of spectroscopy at Be limiters of the JET ITER-like wall. These new analytical expressions lead to an increase of the effective physical sputtering yields of Be by deuteron impact up to 30% in comparison with earlier pure numerical simulations.

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Determination of rate coefficients for fusion-relevant atoms and molecules by modelling and measurement in the boundary layer of TEXTOR

Cited by 54 publications

References 49 publications

Tungsten divertor erosion in all metal devices: Lessons from the ITER like wall of JET

Tungsten divertor erosion in all metal devices: Lessons from the ITER like wall of JET

Analysis of tungsten melt-layer motion and splashing under tokamak conditions at TEXTOR

An Analytical Expression for the Electric Field and Particle Tracing in Modelling of Be Erosion Experiments at the JET ITER‐like Wall

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