Variation of power crossing the separatrix in SOLT code simulations for various levels of mean flow imposed in the core. The mean flow control parameter is (see text). Inset: typical radial profile of the mean flow which is proportional to the negative of the radial electric field, . Note the well.
NSTX experimental heat flux, mapped to the outboard midplane for shots 135009 (gray ) and 135038 (red/black ). Data from the IRTV are shown as dots, exponential fits are shown as solid lines.
SOLT simulation of the midplane parallel heat flux for shot 135009 (solid) and exponential fit (dashed).
Heat-flux width for simulated power scans for shots 135009 and 135038. The code inputs for these shots are nearly the same, so they are essentially indistinguishable in the plot. The solid line is a linear fit to the code data for both shots. Gray ellipses mark the actual experimental power levels for these two shots. Reprinted from Ref. 24 , J. R. Myra, D. A. Russell, D. A. D’Ippolito, J.-W. Ahn, R. Maingi, R. J. Maqueda, D. P. Lundberg, D. P. Stotler, S. J. Zweben, and M. Umansky, J. Nucl. Mater. (in press), with permission from Elsevier.
Midplane plasma profiles in the SOL for shot 135009. Points indicate experimental data, solid lines are the time and zonally averaged simulation results.
Measured and simulated fluctuation levels at the midplane vs radial distance from the separatrix for shot 135009.
Mechanism for setting of the near-SOL width by intermittent separatrix-spanning convection. Shown is a snapshot of the turbulent fields of density (logarithmic color palette, which is truncated to white for ) and potential (contours shown are for , 0.8, 0.9, and 1.0). The arrow points to a downward-sheared finger structure (see text).
Snapshots from SOLT simulations using synthetic GPI. Emission of a blob (circled) occurs in frames at (a) , (b) , and (c) . Times are relative to frame (a) and the blob emission is triggered by the initial transient. Frame (d) is typical of the quasisteady-state after 1.5 ms of simulation. The palette denotes synthetic GPI intensity.
Snapshots from NSTX GPI data for shot 135009. Frame (a) shows a trapped structure (circled) that is never emitted as a blob. Frame (b) is quiescent and typical of most frames. Frames (c) and (d) show a rare blob emission event. The time between frames (c) and (d) is .
NSTX experimental heat flux, mapped to the outboard midplane for shots 128013 (upper panel, 0.8 MA) and 128797 (lower panel, 1.2 MA). Data from the IRTV at different times are shown as dots, exponential fits are shown as solid lines. Note the difference in x-axis scaling. The insets show the complete profiles, including the private SOL, , on the same scale.
Heat-flux width for simulated power scans for shots 128013 (0.8 MA) and 128797 (1.2 MA). The solid lines are linear fits. Thin gray ellipses mark the actual experimental power levels for these two shots. The open symbols near 6 MW for shot 128797 are convergence study runs. Reprinted from Ref. 24 , J. R. Myra, D. A. Russell, D. A. D’Ippolito, J.-W. Ahn, R. Maingi, R. J. Maqueda, D. P. Lundberg, D. P. Stotler, S. J. Zweben, and M. Umansky, J. Nucl. Mater. (in press), with permission from Elsevier.
Snapshot of the turbulent density fields from SOLT for simulations of shot 128013, (left) and shot 128797, (right). The figure shows the separatrix marked by a dashed line. The low case at the left emits blobs while the high case has convective cells trapped near the separatrix and the shear layer.
Radial structure of the normalized GPI fluctuation level for NSTX data (upper) and SOLT synthetic GPI (lower). Only the region is relevant to the heat-flux width.
Test case comparison of the DEGAS 2 neutral puff profile with the smoothed fit.
Power scaling of the SOL width for low power ELM-free H-modes. The first six columns, described in the text, are from the experiment. The last column is the midplane SOL width from the SOLT simulations.
Scaling of the SOL width for the current scan. The first five columns, described in the text, are from the NSTX experiment. The last column is the midplane heat-flux width from the SOLT simulations. The ratio of the various quantities for the two shots is also given.
Coefficients for the fit given by Eq. (B2) .
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