Experimental constraints on transport from dimensionless parameter scaling studies
Conference
·
OSTI ID:578724
- General Atomics, San Diego, CA (United States); and others
The scalings of heat transport with safety factor (q), normalized collisionality (v), plasma beta ({beta}), and relative gyroradius ({rho}*) have been measured on the DIII-D tokamak. The measured {rho}* {beta} and v scalings of heat transport indicate that E x B transport from drive wave turbulence is a plausible basis for anomalous transport. For high confinement (H) mode plasmas where the safety factor was varied at fixed magnetic shear, the effective (or one-fluid) thermal diffusivity was found to scale like {chi}{sub eff} {proportional_to} q{sup 2.3{+-}0.64}, with the ion and electron fluids having the same q scaling to within the experimental errors except near the plasma edge. The scaling of the thermal confinement time with safety factor was in good agreement with this local transport dependence, {tau}{sub th} {proportional_to} q{sup {minus}2.42{+-}0.31}; however, when the magnetic shear was allowed to vary to keep q{sub 0} fixed during the (edge) safety factor scan, a weaker global dependence was observed, {tau}{sub th} {proportional_to} q{sub 95}{sup {minus}1.43{+-}0.23}. This weaker dependence was mainly due to the change in the local value of q between the two types of scans. The combined {rho}*, {beta}, v and q scalings of heat transport for H-mode plasmas on DIII-D reproduce the empirical confinement scaling using physical (dimensionless) parameters with the exception of weaker power degradation.
- Research Organization:
- General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab., CA (United States); Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; W-7405-ENG-48; AC05-96OR22464
- OSTI ID:
- 578724
- Report Number(s):
- GA--A22788; CONF-971103--; ON: DE98003184
- Country of Publication:
- United States
- Language:
- English
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