Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod

B. Lipschultz; Y. Lin; E.S. Marmar; S. Wukitch; I.H. Hutchinson; J. Irby; B. LaBombard; M.L. Reinke; J.L. Terry; D.G. Whyte; G. Wright

doi:10.1016/j.jnucmat.2007.01.227

Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod

B. Lipschultz, Y. Lin, E.S. Marmar, S. Wukitch, I.H. Hutchinson, J. Irby, B. LaBombard, M.L. Reinke, J.L. Terry, D.G. Whyte, G. Wright

Physics

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

Abstract

We report the results of operation of Alcator C-Mod with all high-Z molybdenum plasma facing component (PFC) surfaces. Without boron-coated PFCs energy confinement was poor (H ∼ 1) due to high core molybdenum (n/n ≤ 0.1%) and radiation. After applying boron coatings, n/n was reduced by a factor of 10-20 with H approaching 2. Results of between-discharge boronization, localized at various major radii, point towards important molybdenum source regions being small, outside the divertor, and due to RF-sheath-rectification. Boronization also has a significant effect on the plasma startup phase lowering Z, radiation, and lowering the runaway electron damage. The requirement of low-Z coatings over at least a fraction of the Mo PFCs in C-Mod for best performance together with the larger than expected D retention in Mo, give impetus for further high-Z PFC investigations to better predict the performance of un-coated tungsten surfaces in ITER and beyond.

Original language	English
Pages (from-to)	1110-1118
Number of pages	9
Journal	Journal of Nuclear Materials
Volume	363-365
Issue number	1-3
DOIs	https://doi.org/10.1016/j.jnucmat.2007.01.227
Publication status	Published - 15 Jun 2007

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title = "Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod",

abstract = "We report the results of operation of Alcator C-Mod with all high-Z molybdenum plasma facing component (PFC) surfaces. Without boron-coated PFCs energy confinement was poor (H ∼ 1) due to high core molybdenum (n/n ≤ 0.1%) and radiation. After applying boron coatings, n/n was reduced by a factor of 10-20 with H approaching 2. Results of between-discharge boronization, localized at various major radii, point towards important molybdenum source regions being small, outside the divertor, and due to RF-sheath-rectification. Boronization also has a significant effect on the plasma startup phase lowering Z, radiation, and lowering the runaway electron damage. The requirement of low-Z coatings over at least a fraction of the Mo PFCs in C-Mod for best performance together with the larger than expected D retention in Mo, give impetus for further high-Z PFC investigations to better predict the performance of un-coated tungsten surfaces in ITER and beyond.",

author = "B. Lipschultz and Y. Lin and E.S. Marmar and S. Wukitch and I.H. Hutchinson and J. Irby and B. LaBombard and M.L. Reinke and J.L. Terry and D.G. Whyte and G. Wright",

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doi = "10.1016/j.jnucmat.2007.01.227",

language = "English",

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T1 - Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod

AU - Lipschultz, B.

AU - Lin, Y.

AU - Marmar, E.S.

AU - Wukitch, S.

AU - Hutchinson, I.H.

AU - Irby, J.

AU - LaBombard, B.

AU - Reinke, M.L.

AU - Terry, J.L.

AU - Whyte, D.G.

AU - Wright, G.

PY - 2007/6/15

Y1 - 2007/6/15

N2 - We report the results of operation of Alcator C-Mod with all high-Z molybdenum plasma facing component (PFC) surfaces. Without boron-coated PFCs energy confinement was poor (H ∼ 1) due to high core molybdenum (n/n ≤ 0.1%) and radiation. After applying boron coatings, n/n was reduced by a factor of 10-20 with H approaching 2. Results of between-discharge boronization, localized at various major radii, point towards important molybdenum source regions being small, outside the divertor, and due to RF-sheath-rectification. Boronization also has a significant effect on the plasma startup phase lowering Z, radiation, and lowering the runaway electron damage. The requirement of low-Z coatings over at least a fraction of the Mo PFCs in C-Mod for best performance together with the larger than expected D retention in Mo, give impetus for further high-Z PFC investigations to better predict the performance of un-coated tungsten surfaces in ITER and beyond.

AB - We report the results of operation of Alcator C-Mod with all high-Z molybdenum plasma facing component (PFC) surfaces. Without boron-coated PFCs energy confinement was poor (H ∼ 1) due to high core molybdenum (n/n ≤ 0.1%) and radiation. After applying boron coatings, n/n was reduced by a factor of 10-20 with H approaching 2. Results of between-discharge boronization, localized at various major radii, point towards important molybdenum source regions being small, outside the divertor, and due to RF-sheath-rectification. Boronization also has a significant effect on the plasma startup phase lowering Z, radiation, and lowering the runaway electron damage. The requirement of low-Z coatings over at least a fraction of the Mo PFCs in C-Mod for best performance together with the larger than expected D retention in Mo, give impetus for further high-Z PFC investigations to better predict the performance of un-coated tungsten surfaces in ITER and beyond.

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ER -

Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod

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