ELM heat flux in the ITER divertor

Conference · Wed Jul 01 00:00:00 EDT 1998

OSTI ID:638247

Leonard, A W; Osborne, T H ^[1]; Hermann, A; Suttrop, W ^[2]; Itami, K ^[3]; Lingertat, J ^[4]; Loarte, A ^[5]

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1. General Atomics, San Diego, CA (United States)
2. Max Planck Inst. fuer Plasmaphysics (Germany)
3. Japan Atomic Energy Research Inst. (Japan)
4. JET Joint Undertaking, Abingdon (United Kingdom)
5. Next European Torus, Garching (Germany)

Edge-Localized-Modes (ELMs) have the potential to produce unacceptable levels of erosion of the ITER divertor. Ablation of the carbon divertor target will occur if the surface temperature rises above about 2,500 C. Because a large number of ELMs, {ge}1000, are expected in each discharge it is important that the surface temperature rise due to an individual ELM remain below this threshold. Calculations that have been carried out for the ITER carbon divertor target indicate ablation will occur for ELM energy {ge}0.5MJ/m{sup 2} if it is deposited in 0.1 ms, or 1.2 MJ/m{sup 2} if the deposition time is 1.0 ms. Since {Delta}T{proportional_to}Q{Delta}t{sup {minus}1/2}, an ablation threshold can be estimated at Q{Delta}t{sup {minus}1/2}{approx}45 MJm{sup {minus}2} s{sup {minus}1/2} where Q is the divertor ELM energy density in J-m{sup {minus}2} and {Delta}t is the time in seconds for that deposition. If a significant fraction of ELMs exceed this threshold then an unacceptable level of erosion may take place. The ablation parameter in ITER can be determined by scaling four factors from present experiments: the ELM energy loss from the core plasma, the fraction of ELM energy deposited on the divertor target, the area of the ELM profile onto the target, and the time for the ELM deposition. ELM data from JET, ASDEX-Upgrade, JT-60U, DIII-D and Compass-D have been assembled by the ITER Divertor Modeling and Database expert group into a database for the purpose of predicting these factors for ELMs in the ITER divertor.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114
• OSTI ID: 638247
• Report Number(s): GA--A22899; CONF-980678--; ON: DE98007256
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABLATION
DIVERTORS
EDGE LOCALIZED MODES
ENERGY ABSORPTION
ENERGY LOSSES
HEAT FLUX
ITER TOKAMAK
SCALING LAWS