FY07 NSTX Forum

1
Experimental studies of edge turbulence and
blobs R. J. Maqueda (Nova Photonics) S. J. Zweben
(PPPL)
Experiments proposed are part of ITPAs DSOL-15
Inter-machine comparison of blob characteristics.

• Characterization of turbulence and blobs in
  H-mode discharges, providing input for theory and
  modeling.
• Theory predicts turbulence (source of blobs)
  linked to resistive ballooning instability, and
  hence to the pressure gradient.
• Relation to magnetic shape (elongation,
  triangularity, etc.) also relevant for theory.

Two Phantom 7 cameras, running at gt120000
frames/s each, to be used in NSTX beginning this
year.
2
Experimental studies on edge turbulence and
blobs Divertor region

• Although some understanding is emerging on the
  generation of the blobs from the edge pedestal
  near the midplane and away from the X-point
  regions (Myra, Lodestar Inc., et al.), very
  little is known about the evolution of these
  filaments near the X-point.
• - evolution from closed field line to open
  field lines- x-point disconnection (Ryutov et
  al.)- possibility of inducing turbulence below
  the X-point
• X-point region of NSTX shows filamentary activity
  (movie).
• Development of a divertor GPI will allow the
  turbulence and intermittent phenomena to be
  studied.

NSTX divertor view - Da No gas puff