Select the Shot and Time of Analysis

This section allows you to change the shot number, the SNAP analysis time, and smoothing time for time-averaged data. The smoothing time that you specify is the half-width, i.e., data vs time is averaged over the interval Whenever data is averaged, the percentage error in the averaging is shown in the menus.

After entering the shot, SNAPIN displays the current comments from the SNAP.DAT file. It also shows a table of diagnostics and times of interest for profile waveforms that are available for that shot.

   <0=MO> Option for SHOT 58505 @ 3.400 s? <Sh>:  ,

   <1> New shot? <58505>:    ,
   Old Comments -----------------------------------------------------
   repeat of try 1 but use VB for Zeff.  Earlier cases bombed
   But try 58505/01 indicated that the zeff from vb would be 3.88.
   This case may bomb due to negative thermal ion density
   ------------------------------------------------------------------

       TS  3.406
       TV  _____
       YS  1)_____  2)_____  3)_____  4)_____  5)_____
       YM  1)1.000  2)2.500  3)3.400  4)3.400  5)5.000
       FM  1)1.000  2)2.500  3)3.400  4)3.400  5)5.000
       BRV 1)1.018  2)2.490  3)3.410  4)3.410  5)5.020
       BRT 1)1.018  2)2.490  3)3.410  4)3.410  5)5.020

   \* Options are:

    1) Time of SNAP analysis ......... < 3.400>
    2) TOi .................. 1)1.000  2)2.500  **3)3.400  4)3.400  5)5.000
    3) Dt half-width for smoothing ... < 0.040>
    4) TOKamak  ...................... <TFTR>

Your responses in this section affect how SNAPIN will function hence-forth.

• If you change the shot number, SNAP analysis time, or the smoothing time, then SNAPIN assumes that most of the diagnostic data that it obtained from its last read of a SNAP.DAT file is invalid. For this reason, SNAPIN will force you to visit each of the menu items in order, reading in new profiles, etc., in order to create a new set of consistent diagnostic input. Note: The diagnostic data is read upon entering the menu that lets you change that data. Generally menus should be visited in order because of dependencies between the menu items. For example, the ECE conversion of frequencies to radii uses I_TF which is read in the magnetics menu.
• If you make no changes to the shot number, SNAP time, or dt, then SNAPIN assumes that all of the diagnostic data is still valid, so you can directly go to whatever menu item you desire to change. You could, for example, type Ti to proceed to the ion temperature menu in order to read in a new T_i profile or to change the switches which control the treatment of the T_i profile (e.g., its mapping to minor radius, etc.).

Only the diagnostic data needed by SNAP for its analysis is forced to be reread if a menu item is labelled invalid. User-defined switch settings do not need to be re-entered. For example, since you typically want to use the same physics assumptions (regarding plasma composition, current profile modeling, etc.) for most snap-tries, SNAPIN does not force you to re-enter these values even if the shot number is changed, i.e., the value from the most recently read SNAP.DAT file or shot-try file is retained.

Whenever SNAPIN fails to read a value (for example, if the file doesn't exist) it will write an error message. If a profile read fails, then that profile is deleted. If a non-profile data read fails, then the value of that parameter is set to zero and ZERO is displayed in the source column of the menu. When SNAPIN\ reads a time-averaged value, like R_major, it reads the entire signal vs time and adds an option in that menu to plot that signal.

After visiting the physics sections, select the Comments menu and enter your comments for this shot-try. You must have at least one line of comment.

Finally, select the Write SNAP Input File option and write the new file with the default name of SNAP.DAT. SNAPIN warns you if you are about to write a file with any invalid menu items. This feature tries to prevent you from creating files which have unintentional mixtures of data from different shots.