9. Installation verification: testing EFIT with vacuum data

Before attempting a reconstruction of a plasma discharge, it is advisable to use EFIT on vacuum test data. The simplest test to carry out is a test in which all currents are specified a priori and EFIT predicts the flux loop and magnetic probes signals. This "predictive" test can be carried out if all the poloidal field currents are known. However, if there are some unknown currents present, for instance skin currents, then it is necessary to use a "semi-predictive" method in which measured signals are used in lieu of the unknown currents. EFIT will then predict the remaining signals and the unknown currents. In the following sections we describe in more detail the input data files required for the two cases.

9.1. EFIT in predictive mode

An example data file enabling EFIT to run in predictive mode is shown below:

$IN1
ISHOT   =       10000,
ITIME   =         300,
PLASMA  =   0. IFCURR=1
BRSP    =0.,    0.,   0., 0., 1.E6
IECURR=0     ITEK=5
ECURRT=  1.0E6
COILS= -2.0706,  -1.2706,  -1.0242,  -0.9218,  -0.8843,  -0.9473,
       -1.1096,  -1.3139,  -1.8582,  -2.5512,  -3.8053,  -6.9071,
       -5.7337,  -4.7208,  -2.7951
EXPMP2= 0.0535,  0.0351,  0.1087,  0.1313,  0.2262,  0.3294,  0.3992,
        0.4756,  0.5330,  0.6288,  0.6782,  0.5387, -0.1054, -0.0577,
      -0.0211, -0.0172,  0.0821
      -0.1954, -0.1761, -0.1613, -0.1611, -0.0951,  0.0009,  0.1081,
        0.2980,  0.3832,  0.5883,  1.0721,  1.6781,  -1.3264, -0.6617,
       -0.4070, -0.2927, -0.2202
XLIM=1
YLIM=1
LIMITR=1
$END

Note that the name of the file is unimportant as this will supplied by the user during run-time. It should also be noted that as the data is read into a namelist (IN1), the exact order of the data is unimportant. The significance of the data variables is described below:

1. ↑ ^{1.0 1.1 1.2} The following variables must be defined but are not used:

9.2. EFIT in semi-predictive mode

The data file used to run EFIT is similar to the one described in section 9.1. This time, however, the variables IFCURR=IECURR=0, and specific coils currents and signals are used according to the values set in a number of weighting arrays. The names of the relevent arrays are given in the table below. The values in the weights arrays should be set to 0 or 1 depending if the signal/current is to be predicted (weight=0) or used by EFIT (weight=1). By default, all values in FWTSI and FWTMP2 are initialized to 1, whereas all values in FWTEC and FWTFC are set to 0. All data values that are set using the arrays COILS, EXPMP2, ECURRNT, and BRSP are written out and may be used by the post-prcoessor.

      ----------------------------------------------------------
      | Variables       weights         signal          array  |
      | type            array           value           size   |
      |--------------------------------------------------------|
      |                                                        |
      | flux loops      FWTSI           COILS           NSILOP |
      |                                                        |
      | mag. detects.   FWTMP2          EXPMP2          MAGPRI |
      |                                                        |
      | e-currents      FWTEC           ECURRT          NESUM  |
      |                                                        |
      | f-currents      FWTFC           BRSP            NFCOIL |
      |                                                        |
      ----------------------------------------------------------

Table shows the names of the arrays containing weights and signals for the magnetic diagnostics and current coils.