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Title: Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50

Abstract

The paper presents energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and the main features of plasma interaction with tungsten surfaces in dependence on plasma heat loads. The samples of pure sintered tungsten of EU trademark have been exposed to hydrogen plasma streams. The experiments were performed with up to 450 pulses (pulse duration of 0.25 ms) and the surface heat loads in the range of (0.45 - 1.2) MJ/m2. A threshold character of morphological changes on the melt tungsten surface with the pulses number is demonstrated. The number of initial exposures without formation of corrugations and pits is about 200, which does not depend on the target heat load magnitude. Further increase of the exposures results in the corrugation structures becoming dominant. The melt layer disintegrates into a set of droplets remaining at the surface. Such evolution seems to be driven by the surface tension forces within the fine cells of crack network. Finally a stabilization of the surface pattern occurs. The onset of intensive evaporation at molten tungsten surface under the repetitive heat loads has also been studied. The evaporation can result in enhanced mass losses: increase of the heat load from 0.75more » to 1.1 MJ/m2 rises mass losses for one order of magnitude and causes bubble structures at the surface. Due to evaporation, the erosion crater grows with the rate of 0.04 {mu}m/pulse. It was obtained, that for ELM-like repetitive loads the melt motion driven by plasma pressure gradient did not contribute significantly to the erosion profile.« less

Authors:
; ; ; ; ; ; ;  [1];  [2]
  1. Institute of Plasma Physics of the NSC KIPT, Kharkov, 61108 (Ukraine)
  2. Forschungszentrum Karlsruhe, IHM, 76021 Karlsruhe (Germany)
Publication Date:
OSTI Identifier:
20797882
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 812; Journal Issue: 1; Conference: PLASMA 2005: International conference on research and applications of plasmas; 3. German-Polish conference on plasma diagnostics for fusion and applications; 5. French-Polish seminar on thermal plasma in space and laboratory, Opole-Turawa (Poland), 6-9 Sep 2005; Other Information: DOI: 10.1063/1.2168807; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; EDGE LOCALIZED MODES; EROSION; EVAPORATION; HEATING LOAD; HYDROGEN; ITER TOKAMAK; MORPHOLOGICAL CHANGES; PLASMA; PLASMA GUNS; PLASMA PRESSURE; PLASMA SIMULATION; PULSES; STEADY-STATE CONDITIONS; SURFACE TENSION; SURFACES; TUNGSTEN; WALL EFFECTS

Citation Formats

Tereshin, V. I., Bandura, A. N., Byrka, O. V., Chebotarev, V. V., Garkusha, I. E., Makhlaj, V. A., Solyakov, D. G., Tsarenko, A. V., and Landman, I. Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50. United States: N. p., 2006. Web. doi:10.1063/1.2168807.
Tereshin, V. I., Bandura, A. N., Byrka, O. V., Chebotarev, V. V., Garkusha, I. E., Makhlaj, V. A., Solyakov, D. G., Tsarenko, A. V., & Landman, I. Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50. United States. doi:10.1063/1.2168807.
Tereshin, V. I., Bandura, A. N., Byrka, O. V., Chebotarev, V. V., Garkusha, I. E., Makhlaj, V. A., Solyakov, D. G., Tsarenko, A. V., and Landman, I. Sun . "Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50". United States. doi:10.1063/1.2168807.
@article{osti_20797882,
title = {Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50},
author = {Tereshin, V. I. and Bandura, A. N. and Byrka, O. V. and Chebotarev, V. V. and Garkusha, I. E. and Makhlaj, V. A. and Solyakov, D. G. and Tsarenko, A. V. and Landman, I.},
abstractNote = {The paper presents energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and the main features of plasma interaction with tungsten surfaces in dependence on plasma heat loads. The samples of pure sintered tungsten of EU trademark have been exposed to hydrogen plasma streams. The experiments were performed with up to 450 pulses (pulse duration of 0.25 ms) and the surface heat loads in the range of (0.45 - 1.2) MJ/m2. A threshold character of morphological changes on the melt tungsten surface with the pulses number is demonstrated. The number of initial exposures without formation of corrugations and pits is about 200, which does not depend on the target heat load magnitude. Further increase of the exposures results in the corrugation structures becoming dominant. The melt layer disintegrates into a set of droplets remaining at the surface. Such evolution seems to be driven by the surface tension forces within the fine cells of crack network. Finally a stabilization of the surface pattern occurs. The onset of intensive evaporation at molten tungsten surface under the repetitive heat loads has also been studied. The evaporation can result in enhanced mass losses: increase of the heat load from 0.75 to 1.1 MJ/m2 rises mass losses for one order of magnitude and causes bubble structures at the surface. Due to evaporation, the erosion crater grows with the rate of 0.04 {mu}m/pulse. It was obtained, that for ELM-like repetitive loads the melt motion driven by plasma pressure gradient did not contribute significantly to the erosion profile.},
doi = {10.1063/1.2168807},
journal = {AIP Conference Proceedings},
number = 1,
volume = 812,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}