Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET

J.W. Coenen, M. Sertoli, S. Brezinsek, I. Coffey, R. Dux, C. Giroud, M. Groth, A. Huber, D. Ivanova, K. Krieger, K. Lawson, S. Marsen, A. Meigs, R. Neu, T. Puetterich, G.J. van Rooij, M.F. Stamp

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Abstract

This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172–6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20% while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.
LanguageEnglish
JournalNuclear Fusion
Volume53
Issue number7
DOIs
StatePublished - Jul 2013
Externally publishedYes

Cite this

Coenen, J. W., Sertoli, M., Brezinsek, S., Coffey, I., Dux, R., Giroud, C., ... Stamp, M. F. (2013). Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET. Nuclear Fusion, 53(7). DOI: 10.1088/0029-5515/53/7/073043
Coenen, J.W. ; Sertoli, M. ; Brezinsek, S. ; Coffey, I. ; Dux, R. ; Giroud, C. ; Groth, M. ; Huber, A. ; Ivanova, D. ; Krieger, K. ; Lawson, K. ; Marsen, S. ; Meigs, A. ; Neu, R. ; Puetterich, T. ; van Rooij, G.J. ; Stamp, M.F./ Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET. In: Nuclear Fusion. 2013 ; Vol. 53, No. 7.
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title = "Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET",
abstract = "This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172–6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20{\%} while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.",
author = "J.W. Coenen and M. Sertoli and S. Brezinsek and I. Coffey and R. Dux and C. Giroud and M. Groth and A. Huber and D. Ivanova and K. Krieger and K. Lawson and S. Marsen and A. Meigs and R. Neu and T. Puetterich and {van Rooij}, G.J. and M.F. Stamp",
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Coenen, JW, Sertoli, M, Brezinsek, S, Coffey, I, Dux, R, Giroud, C, Groth, M, Huber, A, Ivanova, D, Krieger, K, Lawson, K, Marsen, S, Meigs, A, Neu, R, Puetterich, T, van Rooij, GJ & Stamp, MF 2013, 'Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET' Nuclear Fusion, vol. 53, no. 7. DOI: 10.1088/0029-5515/53/7/073043

Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET. / Coenen, J.W.; Sertoli, M.; Brezinsek, S.; Coffey, I.; Dux, R.; Giroud, C.; Groth, M.; Huber, A.; Ivanova, D.; Krieger, K.; Lawson, K.; Marsen, S.; Meigs, A.; Neu, R.; Puetterich, T.; van Rooij, G.J.; Stamp, M.F.

In: Nuclear Fusion, Vol. 53, No. 7, 07.2013.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET

AU - Coenen,J.W.

AU - Sertoli,M.

AU - Brezinsek,S.

AU - Coffey,I.

AU - Dux,R.

AU - Giroud,C.

AU - Groth,M.

AU - Huber,A.

AU - Ivanova,D.

AU - Krieger,K.

AU - Lawson,K.

AU - Marsen,S.

AU - Meigs,A.

AU - Neu,R.

AU - Puetterich,T.

AU - van Rooij,G.J.

AU - Stamp,M.F.

PY - 2013/7

Y1 - 2013/7

N2 - This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172–6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20% while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.

AB - This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172–6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20% while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.

U2 - 10.1088/0029-5515/53/7/073043

DO - 10.1088/0029-5515/53/7/073043

M3 - Article

VL - 53

JO - Nuclear Fusion

T2 - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 7

ER -

Coenen JW, Sertoli M, Brezinsek S, Coffey I, Dux R, Giroud C et al. Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET. Nuclear Fusion. 2013 Jul;53(7). Available from, DOI: 10.1088/0029-5515/53/7/073043