Particle and Energy Transport in the SOL of DIII-D and NSTX
The far scrape-off layer (SOL) radial transport and plasma-wall contact is mediated by intermittent and ELM-driven transport. Experiments to characterize the intermittent transport and ELMs have been performed in both DIII-D and NSTX under similar conditions. Both intermittent transport and ELMs are comprised of filaments of hot, dense plasma (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}, T{sub e} {approx} 400 eV) originating at the edge, transport both particles and heat into the SOL by convection, increasing wall interaction and causing sputtering and impurity release. Both intermittent filaments and ELMs leave the pedestal region at speeds of {approx}0.5-3 km/s, losing heat and particles by parallel transport as they travel through the SOL. The intermittency shows many similarities in NSTX and DIII-D, featuring similar size (2-5 cm), large convective radial velocity, ''holes'' inside and peaks outside the LCFS which quickly decay and slow down with radius. Whereas in DIII-D the intermittency decays in both intensity and frequency in H-mode, it chiefly decays in frequency in NSTX. In the low collisionality (v* = {pi}R{sub q{sub 95}}/{lambda}C) (v* {approx} 0.1, N{sub G} {approx} 0.3) case, the ELMs impact the walls quite directly and account for {approx}90% of the wall particle flux, decreasing to {approx}30% at (v* {approx} 1.0, N{sub G} > 0.6).
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 897947
- Report Number(s):
- UCRL-CONF-225190; TRN: US200706%%142
- Resource Relation:
- Conference: Presented at: 21st IAEA Fusion Energy Conference, Chengdu, China, Oct 16 - Oct 22, 2006
- Country of Publication:
- United States
- Language:
- English
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