Edge and SOL turbulence and blob variations over a large database in NSTX

摘要

This paper describes the range of variations in edge and SOL turbulence observed using a gas puff imaging (GPI) diagnostic in NSTX discharges. The database consists of 140 shots including Ohmic, L-mode, and H-mode plasmas measured during steady-state conditions (e.g. without ELMs). Turbulence quantities were evaluated using both cross-correlation analysis and blob tracking. Relative fluctuation levels varied from δⅠ/Ⅰ ～ 0.15-1.0, correlation times were τ_(auto) ～ 15-40 μs, correlation lengths were L_(pol) ～ L)(rad) ～5-10 cm, and turbulence velocities were V_(pol) ～ 2 ± 1 km s~(-1) and V_(rad) ～ 0.5 ± 0.5 km s~(-1) outwards. These variations were evaluated with respect to both the global and local edge plasma parameters, and compared with simplified theoretical models.