Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques

Jari Likonen, Sari Lehto, J. Coad, T. Renvall, T. Ahlgren, D. Hole, G. Matthews, K.-D. Zastrow, K. Lawson, Contributors to the EFDA-JET Work Programme

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

Abstract

Deposition in JET divertor tiles has been observed to be asymmetric; i.e. heavy deposition occurs in the SOL at the inner divertor whereas there is little deposition at the outer divertor. Heavy deposition at the inner divertor has lead to flaking on the water-cooled louvres and after the DTE1 tritium experiment at JET it was observed that majority of the retained tritium is in the flakes that have spallen from the louvres. Erosion/deposition issues have thus a great impact on the tritium retention and lifetime of first wall components in present and future fusion devices. The asymmetry in the deposition implies a drift in the SOL. To investigate material transport and SOL flows observed at JET, 13CH4 and SiH4 were injected into the plasma boundary in the last day of discharges prior to the JET 2001 shutdown. Methane was puffed at the top of the vessel, and the silane at the outer divertor wall. Silicon was observed spectroscopically as an impurity in the plasma. A set of special tiles was installed in the Mk IIGB divertor during the 1999 shutdown. The tiles were coated with poloidal stripes of a boron doped carbon layer on a rhenium interlayer. These tiles were removed in the 2001 shutdown, and have been analysed in 2002 to determine the erosion/deposition profile, and 13C and 28Si distribution over the entire divertor cross-section. The analysis techniques used have been Secondary Ion Mass Spectrometry (SIMS) and the Ion Beam Analysis (IBA) methods Time of Flight Elastic Recoil Detection Analysis (TOF-ERDA) and Rutherford backscattering (RBS). 13C could be found in large amounts on the surfaces of the inner divertor tiles whereas in the outer divertor it was hardly detected. Under the 13C layer a deuterium rich carbon layer was found on the inner divertor tiles. Thick deposits of beryllium were buried under the carbon layer. Also the silicon distribution was recorded. The observed 13C and Si distributions are discussed in relation to the position of strike point and the ion fluxes measured with divertor Langmuir probes. This work has been conducted under the European Fusion Development Agreement and is partly funded by EURATOM.
Original languageEnglish
Title of host publication22nd Symposium on Fusion Technology
Subtitle of host publicationBook of Abstracts
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages172-172
ISBN (Electronic)951-38-5731-X
ISBN (Print)951-38-5730-1
Publication statusPublished - 2002
Event22nd Symposium on Fusion Technology - Helsinki, Finland
Duration: 9 Sep 200213 Sep 2002
Conference number: 22

Publication series

SeriesVTT Symposium
Number220
ISSN0357-9387

Conference

Conference22nd Symposium on Fusion Technology
Abbreviated titleSOFTA
CountryFinland
CityHelsinki
Period9/09/0213/09/02

Fingerprint

tiles
secondary ion mass spectrometry
implantation
ion beams
impurities
shutdowns
tritium
louvers
erosion
carbon
fusion
flaking
flakes
rhenium
silicon
electrostatic probes
beryllium
silanes
vessels
deuterium

Cite this

Likonen, J., Lehto, S., Coad, J., Renvall, T., Ahlgren, T., Hole, D., ... Programme, C. T. T. EFDA-JET. W. (2002). Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques. In 22nd Symposium on Fusion Technology: Book of Abstracts (pp. 172-172). [BO-4] Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 220
Likonen, Jari ; Lehto, Sari ; Coad, J. ; Renvall, T. ; Ahlgren, T. ; Hole, D. ; Matthews, G. ; Zastrow, K.-D. ; Lawson, K. ; Programme, Contributors to the EFDA-JET Work. / Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques. 22nd Symposium on Fusion Technology: Book of Abstracts. Espoo : VTT Technical Research Centre of Finland, 2002. pp. 172-172 (VTT Symposium; No. 220).
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abstract = "Deposition in JET divertor tiles has been observed to be asymmetric; i.e. heavy deposition occurs in the SOL at the inner divertor whereas there is little deposition at the outer divertor. Heavy deposition at the inner divertor has lead to flaking on the water-cooled louvres and after the DTE1 tritium experiment at JET it was observed that majority of the retained tritium is in the flakes that have spallen from the louvres. Erosion/deposition issues have thus a great impact on the tritium retention and lifetime of first wall components in present and future fusion devices. The asymmetry in the deposition implies a drift in the SOL. To investigate material transport and SOL flows observed at JET, 13CH4 and SiH4 were injected into the plasma boundary in the last day of discharges prior to the JET 2001 shutdown. Methane was puffed at the top of the vessel, and the silane at the outer divertor wall. Silicon was observed spectroscopically as an impurity in the plasma. A set of special tiles was installed in the Mk IIGB divertor during the 1999 shutdown. The tiles were coated with poloidal stripes of a boron doped carbon layer on a rhenium interlayer. These tiles were removed in the 2001 shutdown, and have been analysed in 2002 to determine the erosion/deposition profile, and 13C and 28Si distribution over the entire divertor cross-section. The analysis techniques used have been Secondary Ion Mass Spectrometry (SIMS) and the Ion Beam Analysis (IBA) methods Time of Flight Elastic Recoil Detection Analysis (TOF-ERDA) and Rutherford backscattering (RBS). 13C could be found in large amounts on the surfaces of the inner divertor tiles whereas in the outer divertor it was hardly detected. Under the 13C layer a deuterium rich carbon layer was found on the inner divertor tiles. Thick deposits of beryllium were buried under the carbon layer. Also the silicon distribution was recorded. The observed 13C and Si distributions are discussed in relation to the position of strike point and the ion fluxes measured with divertor Langmuir probes. This work has been conducted under the European Fusion Development Agreement and is partly funded by EURATOM.",
author = "Jari Likonen and Sari Lehto and J. Coad and T. Renvall and T. Ahlgren and D. Hole and G. Matthews and K.-D. Zastrow and K. Lawson and Programme, {Contributors to the EFDA-JET Work}",
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language = "English",
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Likonen, J, Lehto, S, Coad, J, Renvall, T, Ahlgren, T, Hole, D, Matthews, G, Zastrow, K-D, Lawson, K & Programme, CTTEFDA-JETW 2002, Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques. in 22nd Symposium on Fusion Technology: Book of Abstracts., BO-4, VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 220, pp. 172-172, 22nd Symposium on Fusion Technology, Helsinki, Finland, 9/09/02.

Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques. / Likonen, Jari; Lehto, Sari; Coad, J.; Renvall, T.; Ahlgren, T.; Hole, D.; Matthews, G.; Zastrow, K.-D.; Lawson, K.; Programme, Contributors to the EFDA-JET Work.

22nd Symposium on Fusion Technology: Book of Abstracts. Espoo : VTT Technical Research Centre of Finland, 2002. p. 172-172 BO-4 (VTT Symposium; No. 220).

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

TY - CHAP

T1 - Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques

AU - Likonen, Jari

AU - Lehto, Sari

AU - Coad, J.

AU - Renvall, T.

AU - Ahlgren, T.

AU - Hole, D.

AU - Matthews, G.

AU - Zastrow, K.-D.

AU - Lawson, K.

AU - Programme, Contributors to the EFDA-JET Work

PY - 2002

Y1 - 2002

N2 - Deposition in JET divertor tiles has been observed to be asymmetric; i.e. heavy deposition occurs in the SOL at the inner divertor whereas there is little deposition at the outer divertor. Heavy deposition at the inner divertor has lead to flaking on the water-cooled louvres and after the DTE1 tritium experiment at JET it was observed that majority of the retained tritium is in the flakes that have spallen from the louvres. Erosion/deposition issues have thus a great impact on the tritium retention and lifetime of first wall components in present and future fusion devices. The asymmetry in the deposition implies a drift in the SOL. To investigate material transport and SOL flows observed at JET, 13CH4 and SiH4 were injected into the plasma boundary in the last day of discharges prior to the JET 2001 shutdown. Methane was puffed at the top of the vessel, and the silane at the outer divertor wall. Silicon was observed spectroscopically as an impurity in the plasma. A set of special tiles was installed in the Mk IIGB divertor during the 1999 shutdown. The tiles were coated with poloidal stripes of a boron doped carbon layer on a rhenium interlayer. These tiles were removed in the 2001 shutdown, and have been analysed in 2002 to determine the erosion/deposition profile, and 13C and 28Si distribution over the entire divertor cross-section. The analysis techniques used have been Secondary Ion Mass Spectrometry (SIMS) and the Ion Beam Analysis (IBA) methods Time of Flight Elastic Recoil Detection Analysis (TOF-ERDA) and Rutherford backscattering (RBS). 13C could be found in large amounts on the surfaces of the inner divertor tiles whereas in the outer divertor it was hardly detected. Under the 13C layer a deuterium rich carbon layer was found on the inner divertor tiles. Thick deposits of beryllium were buried under the carbon layer. Also the silicon distribution was recorded. The observed 13C and Si distributions are discussed in relation to the position of strike point and the ion fluxes measured with divertor Langmuir probes. This work has been conducted under the European Fusion Development Agreement and is partly funded by EURATOM.

AB - Deposition in JET divertor tiles has been observed to be asymmetric; i.e. heavy deposition occurs in the SOL at the inner divertor whereas there is little deposition at the outer divertor. Heavy deposition at the inner divertor has lead to flaking on the water-cooled louvres and after the DTE1 tritium experiment at JET it was observed that majority of the retained tritium is in the flakes that have spallen from the louvres. Erosion/deposition issues have thus a great impact on the tritium retention and lifetime of first wall components in present and future fusion devices. The asymmetry in the deposition implies a drift in the SOL. To investigate material transport and SOL flows observed at JET, 13CH4 and SiH4 were injected into the plasma boundary in the last day of discharges prior to the JET 2001 shutdown. Methane was puffed at the top of the vessel, and the silane at the outer divertor wall. Silicon was observed spectroscopically as an impurity in the plasma. A set of special tiles was installed in the Mk IIGB divertor during the 1999 shutdown. The tiles were coated with poloidal stripes of a boron doped carbon layer on a rhenium interlayer. These tiles were removed in the 2001 shutdown, and have been analysed in 2002 to determine the erosion/deposition profile, and 13C and 28Si distribution over the entire divertor cross-section. The analysis techniques used have been Secondary Ion Mass Spectrometry (SIMS) and the Ion Beam Analysis (IBA) methods Time of Flight Elastic Recoil Detection Analysis (TOF-ERDA) and Rutherford backscattering (RBS). 13C could be found in large amounts on the surfaces of the inner divertor tiles whereas in the outer divertor it was hardly detected. Under the 13C layer a deuterium rich carbon layer was found on the inner divertor tiles. Thick deposits of beryllium were buried under the carbon layer. Also the silicon distribution was recorded. The observed 13C and Si distributions are discussed in relation to the position of strike point and the ion fluxes measured with divertor Langmuir probes. This work has been conducted under the European Fusion Development Agreement and is partly funded by EURATOM.

M3 - Conference abstract in proceedings

SN - 951-38-5730-1

T3 - VTT Symposium

SP - 172

EP - 172

BT - 22nd Symposium on Fusion Technology

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Likonen J, Lehto S, Coad J, Renvall T, Ahlgren T, Hole D et al. Studies of impurity deposition/implantation in JET divertor tiles using SIMS and ion beam techniques. In 22nd Symposium on Fusion Technology: Book of Abstracts. Espoo: VTT Technical Research Centre of Finland. 2002. p. 172-172. BO-4. (VTT Symposium; No. 220).