Poloidal field null, delete pfjalw, fix temp margin

In GitLab by @mkovari on Feb 25, 2015, 10:50

1 Diagnostic for poloidal field null

PROCESS calculates the PF coil currents required to create a poloidal field null on the midplane for plasma initiation. This is a complicated calculation and happens suspiciously quickly! I have added an output to OUT.DAT of the field at all the points on the midplane where it is supposed to be null, active when verbose = 1.

The code is in pfcoil.f90, following ! Find currents for plasma initiation to null field across plasma.
This sets the field to zero at the 32 test points, and calls subroutine efc to determine the currents.

I put the actual fields calculated in subroutine rsid in module-level arrays br_actual and bz_actual. When the null is calculated these are copied to null_br and null_bz, and these are only output if verbose = 1. I have put the output of the "smoothing parameter" in the same section, and commented out the printing of the very unhelpful normalised sum of squares.

I have run one test file, and have reasonable results:

 Residual fields at equi-spaced points on midplane during null for plasma initiation [T] (radial, vertical):
 
  2.8E-17 -5.6E-17 -8.3E-17  5.6E-17 -2.8E-17  0.0E+00 -2.8E-17  0.0E+00 -8.3E-17 -2.8E-17 -2.8E-17  0.0E+00 -2.8E-17 -5.6E-17  0.0E+00 -2.8E-17 -2.8E-17  0.0E+00 -2.8E-17 -5.6E-17 -2.8E-17 -2.8E-17 -2.8E-17 -2.8E-17 -4.2E-17 -1.4E-17 -2.8E-17 -2.8E-17  0.0E+00 -1.4E-17 -1.4E-17 -4.2E-17
 -4.7E-03 -2.9E-03 -1.5E-03 -2.9E-04  6.3E-04  1.3E-03  1.8E-03  2.1E-03  2.2E-03  2.2E-03  2.0E-03  1.8E-03  1.5E-03  1.1E-03  7.0E-04  2.9E-04 -1.2E-04 -5.0E-04 -8.4E-04 -1.1E-03 -1.4E-03 -1.5E-03 -1.6E-03 -1.6E-03 -1.4E-03 -1.2E-03 -8.9E-04 -4.5E-04  8.8E-05  7.3E-04  1.5E-03  2.3E-03
 maximum residual radial field [T] :                                                                5.551E-17
 maximum residual vertical field [T] :                                                              2.300E-03
 Smoothing parameter                                                      (alfapf)                  5.000E-10

2 Deleted function pfjalw as it is no longer used (and delete the commented-out calls to it).

3 subroutine ohcalc lines 919 etc

! Allowable coil overall current density at EOF
call superconpf(bmaxoh,vfohc,fcuohsu,abs(ric(nohc))/awpoh, &
! Allowable coil overall current density at BOP
call superconpf(bmaxoh0,vfohc,fcuohsu,abs(ric(nohc))/awpoh, &

These two calls refer to different time points, but they use the same current, which doesn't seem right:
ric(ngc2) : peak current in coil i (MA-turns)

I have replaced these current densities (winding area density) by

abs(coheof)*areaoh/awpoh
and
abs(cohbop)*areaoh/awpoh

I am a bit puzzled why this wasn't done in the first place.

Oddly, the temperature margin for the CS drops by about 1 K.