Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade

Vl Bobkov; F. Braun; R. Dux; L. Giannone; A. Herrmann; A. Kallenbach; H. W. Müller; R. Neu; J. M. Noterdaeme; Th Pütterich; V. Rohde

doi:10.1016/j.jnucmat.2009.01.231

Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade

Vl Bobkov, F. Braun, R. Dux, L. Giannone, A. Herrmann, A. Kallenbach, H. W. Müller, R. Neu, J. M. Noterdaeme, Th Pütterich, V. Rohde

Max Planck Institute for Plasma Physics

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (> 5 × 10²¹ s^{- 1}) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90° can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.

Original language	English
Pages (from-to)	900-903
Number of pages	4
Journal	Journal of Nuclear Materials
Volume	390-391
Issue number	1
DOIs	https://doi.org/10.1016/j.jnucmat.2009.01.231
State	Published - 15 Jun 2009
Externally published	Yes

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title = "Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade",

abstract = "In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (> 5 × 1021 s- 1) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90° can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.",

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doi = "10.1016/j.jnucmat.2009.01.231",

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T1 - Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade

AU - Bobkov, Vl

AU - Braun, F.

AU - Dux, R.

AU - Giannone, L.

AU - Herrmann, A.

AU - Kallenbach, A.

AU - Müller, H. W.

AU - Neu, R.

AU - Noterdaeme, J. M.

AU - Pütterich, Th

AU - Rohde, V.

PY - 2009/6/15

Y1 - 2009/6/15

N2 - In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (> 5 × 1021 s- 1) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90° can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.

AB - In the 2007 and early part of 2008 experimental campaigns, ASDEX Upgrade operated with full tungsten (W) wall without boronization. Use of ICRF power results in a significant increase of W source. Low temperature conditions at the plasma facing components, achieved by a large clearance between the separatrix and the antenna (>6 cm) and by elevated gas puff rates (> 5 × 1021 s- 1) help to lower W sputtering yield during ICRF. Operation of neighboring ICRF antennas at the phase difference close to -90° can lead to a reduction in the W source. However, a reduction of parallel near-fields by antenna design is needed to further minimize the W source. A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment. The shapes of the measured vertical profile of effective sputtering yields and the calculated sheath driving voltages show a qualitative agreement. This confirms that the existing tools are a good basis to design an improved antenna.

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VL - 390-391

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JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

IS - 1

ER -

Operation of ICRF antennas in a full tungsten environment in ASDEX Upgrade

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