Behavior of graphite under heat load and in contact with a hydrogen plasma

Bohdansky, J.; Croessmann, C.D.; Linke, J.; McDonald, J.M.; Morse, D.H.; Pontau, A.E.; Watson, R.D.; Whitley, J.B.; Goebel, Dan M.; Hirooka, Y.; Leung, K. N.; Conn, R.W.; Roth, J.; Ottenberger, W.; Kotzlowski, H.

doi:10.1016/0168-583x(87)90481-2

Cited by 22 publications

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“…The total erosion yield at room temperature is found to be independent of incident ion energy over this range. This result has also been observed in ion beam experiments [16]. The maximum yield obtained Values for physical sputtering yields extrapolated from the PISCES data and calculated by a semi-empirical relation [18] are given for temperatures above 900°C where chemical erosion is suppressed.…”

Section: Poco Graphite Erosionsupporting

confidence: 74%

“…The sputtering yield at this energy increases by about a factor of three for both species as the temperature is raised above room temperature, with the maximum yield found for a temperature of about 500°C. This behaviour corresponds to the chemical production of methane, as observed in ion beam experiments at these low energies [16]. The yield decreases strongly at temperatures above 700 °C as the chemical production of hydrocarbons is suppressed.…”

Section: Poco Graphite Erosionsupporting

confidence: 60%

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Erosion of graphite by high flux hydrogen plasma bombardment

Goebel

Bohdansky²,

Conn

et al. 1988

Nucl. Fusion

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The total erosion yields of several types of graphites have been measured during high ion flux exposure in the PISCES plasma facility. Hydrogen and deuterium plasmas have been used to bombard Poco, ATJ, pyrolytic, and C-SiC-coated graphites, and a ‘4-D’ C-C composite weave. Erosion experiments with ion fluxes of up to 2 × 1018 cm−2 · s−1, at ion energies of 50 to 200 eV and sample temperatures of 50 to 950°C, are reported. In the absence of redeposition, the erosion rates of all the graphites tested is essentially the same. The C-C composite weave material showed equal or lower erosion yields compared to the other graphites over the range of temperatures tested. The maximum total carbon erosion yield at 600°C increased by a factor of two for 50 eV ion bombardment and by a factor of five for 200 eV ion bombardment, compared to the reference values found for room temperature samples. At temperatures above 800°C, the chemical erosion is suppressed and the erosion yield reaches values expected for physical sputtering. A direct comparison with two ion beam experiments with an ion flux three orders of magnitude lower than used in PISCES showed total erosion rates within a factor of two, indicating that chemical sputtering is not significantly suppressed by high ion fluxes. The results show that the chemical sputtering of graphite limiters or divertor plates in tokamaks will vary by a factor of only two to three over a limiter temperature range of 0 to 800°C if the incident ion energy is less than 100 eV as is observed in tokamak experiments. The net erosion is also strongly reduced by reionization in the plasma and redeposition of both hydrocarbons and physically sputtered carbon.

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Section: Poco Graphite Erosionsupporting

confidence: 74%

Section: Poco Graphite Erosionsupporting

confidence: 60%