Profile Arrays

For each profile set, SNAP generates several new arrays, in addition to those passed in from SNAPIN:

1. A smoothed array (if the processed array from SNAPIN was already smoothed, then no further smoothing is done, and this array will be identical to the processed array).
2. An array of the smoothed data which has been mapped to minor radius, e.g., T_e(r). The radius grid is always on an array of zone centers.
3. An array of the minor radius array (e.g., T_e(r)) mapped back to a major radius grid, using SNAP's calculation of magnetic surface geometry. The major radius grid is a major radius array on the horizontal midplane of the zone centers, , where R₀ is the center of the outermost flux surface, r_j is the minor radius of the jth zone center and s(r_j) is SNAP's calculation of the Shafranov shift at that radius.
4. For ECE T_e(R) profiles only: The ECE diagnostics measure T_e as a function of frequency, not as a function of major radius. SNAP computes the total magnetic field strength as a function of major radius, including the paramagnetic and diamagnetic terms, to define the proper mapping of frequency to major radius. An array of major radii corresponding to the ECE frequencies is saved in the SNAP archives for every ECE profile.

In addition to creating these new arrays for each set of input profiles, SNAP also constructs an entirely new set of profile arrays known as the used profiles. These are simply copies of the active arrays that SNAP actually used in its analyses. The used profile set has the full complement of arrays, including raw arrays, error bar arrays, and processed arrays. Although the used arrays simply duplicate information that is available elsewhere, they are useful in that one can easily ask for plots of the various profiles (e.g., T_e(r)) used in SNAP's internal calculations without having to know in advance which diagnostic they come from. This proves to be a handy feature when preparing command procedures for CUPLOT.

All of these arrays are written into the SNAP archives when SNAP completes its work.

• Each array has a name and an integer identifier. These are listed in MASTER_INC:SNAP_CHANNEL_DESC.TXT.
• As described in section 5.1, you can ask CUPLOT\ to list the available names.
• The names follow, more or less, a standard template. This is described below.
• Each profile is also assigned a short curve title, which will appear at the top of the graph when plotted in CUPLOT. If several profiles are plotted, CUPLOT concatenates the individual curve titles to generate a graph title.

  This puts a severe constraint on the allowed length of a short curve title: 8 characters. The curve titles also follow a standard template, which is similar to, but slightly compressed from, the corresponding array name.