Details

Autor(en) / Beteiligte

• LaBombard, B.
• Rice, J. E.
• Hubbard, A. E.
• Hughes, J. W.
• Greenwald, M.
• Granetz, R. S.
• Irby, J. H.
• Lin, Y.
• Lipschultz, B.
• Marmar, E. S.
• Marr, K.
• Mossessian, D.
• Parker, R.
• Rowan, W.
• Smick, N.
• Snipes, J. A.
• Terry, J. L.
• Wolfe, S. M.
• Wukitch, S. J.

Titel

Transport-driven scrape-off layer flows and the x -point dependence of the L - H power threshold in Alcator C-Mod

Ist Teil von

• Physics of plasmas, 2005-05, Vol.12 (5), p.056111-056111-10

Ort / Verlag

United States: American Institute of Physics

Erscheinungsjahr

2005

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Factor of ∼ 2 higher power thresholds for low- to high-confinement mode transitions ( L - H ) with unfavorable x -point topologies in Alcator C-Mod [ Phys. Plasmas 1 , 1511 ( 1994 ) ] are linked to flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives flow along magnetic field lines from low- to high-field regions with toroidal direction dependent on upper/lower x -point balance; the toroidal rotation of the confined plasma responds, exhibiting a strong counter-current rotation when B × ∇ B points away from the x point. Increased auxiliary heating power (rf, no momentum input) leads to an L - H transition at approximately twice the edge electron pressure gradient when B × ∇ B points away. As gradients rise prior to the transition, toroidal rotation ramps toward the co-current direction; the H mode is seen when the counter-current rotation imposed by the SOL flow becomes compensated. Remarkably, L - H thresholds in lower-limited discharges are identical to lower x -point discharges; SOL flows are also found similar, suggesting a connection.