Sputtering flux measurements in the ASDEX divertor

Fußmann, G.; Hofmann, J.; Janeschitz, G.; Yang, H.R.

doi:10.1088/0029-5515/30/11/009

Cited by 25 publications

(52 citation statements)

References 14 publications

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“…The antenna protection tiles and Faraday screen are located .5 and 1.0 cm further away from the core plasma. formalism [15]. The n e and T e in the SOL and at the plate needed for determination of inverse photon efficiencies are measured by Langmuir probes [20].…”

Section: Experiments and Techniquementioning

confidence: 99%

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Molybdenum sources and transport in Alcator C-Mod

Lipschultz

Pappas

LaBombard

et al. 2001

Journal of Nuclear Materials

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We present a characterization of molybdenum sources, Γ Mo , core Mo density, n Mo , and their dependencies on Alcator C-Mod operational regimes. This includes sources from the divertor, the inner wall and the ICRF antenna limiters. We also present information characterizing the penetration of these impurities into the core plasma under different conditions based on penetration factors, PF=n Mo /Γ Mo (seconds). In general the inner wall Mo source is large (~10 18 /sec) but is found to be relatively uncorrelated with the core Mo level in diverted plasmas.The outer divertor source is of similar order to that from the inner wall and has a penetration factor in the range 10 -5 -2x10 -3 seconds depending on density and confinement mode. The antenna limiter Mo sources are typically smaller, but with higher penetration factors -10 -3 -2x10 -2 seconds. The behavior of the antenna limiter sources is consistent with physical sputtering due to the influence of RF sheath rectification.

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Section: Experiments and Techniquementioning

confidence: 99%

“…The issue of impurity penetration to the core has often been separately addressed through examination of recycling [10][11][12][13] and nonrecycling elements [11,12,[14][15][16][17][18]. The experience with high-Z materials has not been as prevalent as that with carbon, particularly in the presence of RF heating.…”

Section: Introductionmentioning

confidence: 99%

Molybdenum sources and transport in Alcator C-Mod

Lipschultz

Pappas

LaBombard

et al. 2001

Journal of Nuclear Materials

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“…S is the ionization rate, X is the excitation rate, B the branching ratio. For a description of this technique see Field [2] and Fussmann [3].…”

Section: Experiments and Techniquementioning

confidence: 99%

“…The study of high-Z materials with this method is somewhat limited [3,4]. Source rate calculations have also been routinely made, especially in tokamaks with low-Z plasma interaction surfaces [5,6].…”

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confidence: 99%

Molybdenum sources and transport in the Alcator C-Mod tokamak

Pappas

Lipschultz

LaBombard

et al. 1999

Journal of Nuclear Materials

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Atomic molybdenum influxes in the Alcator C-Mod tokamak have been monitored using visible spectroscopy. Measured source rates from the outer divertor, the largest source location, are compared to rates calculated from a standard physical sputtering model utilizing divertor Langmuir probe data. Comparison of the sputtering model with the measured molybdenum source rate shows good agreement during the Ohmic phase of the discharges examined. During the rf phase, the sputtering model consistently underestimates the molybdenum source rate. Analysis of a number of discharges shows no strong dependence of the divertor source on the plasma density for both L-modes and H-modes. The same source rates can be used to follow the screening of Mo from the core plasma. The penetration factor, PF ≡ N core /Φ, i.e. the ratio of the total number of Mo ions in the plasma core to the particle source rate, is higher for limited than diverted portions of discharges. The PF for Mo is found to be lower than another non-recycling impurity, nitrogen, during L-mode diverted plasmas.

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“…The geometry of the views of different first-wall surfaces are further detailed in reference [12]. The inverse photon efficiency for the Mo-I line, also known as S/XB, is utilized to convert the Mo-I photon brightness to influx (per unit area) based on a standard formalism [5,26]. The specific Mo-I S/XB required for this study are provided in reference [27].…”

Section: Introductionmentioning

confidence: 99%