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Title: Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers

Abstract

The results on laser heating and ablation of graphite tiles of thermonuclear tokamaks are presented. Two pulsed Nd-YAG lasers (20 Hz repetition rate, 5 ns pulse duration and 10 kHz repetition rate, 100 ns pulse duration) were applied for ablation measurements. The ablation thresholds (1.0{+-}0.5 J/cm{sup 2} for 5 ns and 2.5{+-}0.5 J/cm{sup 2} for 100 ns laser pulses) were determined for the Tore Supra tokamak graphite tiles (backside) nonexposed to plasma. The high repetition rate Nd-YAG laser (10 kHz, 100 ns pulse duration) and the developed pyrometer system were applied for graphite heating measurements. Some unexpected features of laser heating of the graphite surface were observed. They were explained by the presence of a thin surface layer with the properties different from those of the bulk graphite. The theoretical models of laser heating and near-threshold ablation of graphite with imperfectly adhered layer were developed to interpret the experimental results.

Authors:
; ; ; ; ;  [1];  [2]
  1. CEA Saclay, DEN/DPC/SCP/LILM, Batiment 467, 91191 Gif sur Yvette (France)
  2. (France)
Publication Date:
OSTI Identifier:
20982837
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 8; Other Information: DOI: 10.1063/1.2721750; (c) 2007 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; ABLATION; GRAPHITE; KHZ RANGE 01-100; LASER-RADIATION HEATING; LAYERS; NEODYMIUM LASERS; PLASMA; PLASMA CONFINEMENT; PLASMA DIAGNOSTICS; PULSES; PYROMETERS; TORE SUPRA TOKAMAK; WALL EFFECTS

Citation Formats

Semerok, A., Fomichev, S. V., Weulersse, J.-M., Brygo, F., Thro, P.-Y., Grisolia, C., and CEA Cadarache, DSM/DRFC, Batiment 506, 13108 Saint Paul Lez Durance. Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers. United States: N. p., 2007. Web. doi:10.1063/1.2721750.
Semerok, A., Fomichev, S. V., Weulersse, J.-M., Brygo, F., Thro, P.-Y., Grisolia, C., & CEA Cadarache, DSM/DRFC, Batiment 506, 13108 Saint Paul Lez Durance. Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers. United States. doi:10.1063/1.2721750.
Semerok, A., Fomichev, S. V., Weulersse, J.-M., Brygo, F., Thro, P.-Y., Grisolia, C., and CEA Cadarache, DSM/DRFC, Batiment 506, 13108 Saint Paul Lez Durance. Sun . "Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers". United States. doi:10.1063/1.2721750.
@article{osti_20982837,
title = {Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers},
author = {Semerok, A. and Fomichev, S. V. and Weulersse, J.-M. and Brygo, F. and Thro, P.-Y. and Grisolia, C. and CEA Cadarache, DSM/DRFC, Batiment 506, 13108 Saint Paul Lez Durance},
abstractNote = {The results on laser heating and ablation of graphite tiles of thermonuclear tokamaks are presented. Two pulsed Nd-YAG lasers (20 Hz repetition rate, 5 ns pulse duration and 10 kHz repetition rate, 100 ns pulse duration) were applied for ablation measurements. The ablation thresholds (1.0{+-}0.5 J/cm{sup 2} for 5 ns and 2.5{+-}0.5 J/cm{sup 2} for 100 ns laser pulses) were determined for the Tore Supra tokamak graphite tiles (backside) nonexposed to plasma. The high repetition rate Nd-YAG laser (10 kHz, 100 ns pulse duration) and the developed pyrometer system were applied for graphite heating measurements. Some unexpected features of laser heating of the graphite surface were observed. They were explained by the presence of a thin surface layer with the properties different from those of the bulk graphite. The theoretical models of laser heating and near-threshold ablation of graphite with imperfectly adhered layer were developed to interpret the experimental results.},
doi = {10.1063/1.2721750},
journal = {Journal of Applied Physics},
number = 8,
volume = 101,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}