STELLOPT

State-of-the-art stellarator optimization code

Tutorial: VMEC Free Boundary Run

This tutorial will walk the user through running VMEC with a free boundary condition. For this example the National Compact Stellarator Experiment (NCSX) configuration will be used. This machine is stellarator symmetric with a periodicity of three.


Create the ‘mgrid’ file

First one must use the MAKEGRID (XGRID) routine to process the coils definition file and produce an ‘mgrid’ file. For this example we will use the ‘coils.c09r00’ file which has been developed for the NCSX device (coils.c09r00). We create a text file ‘input_xgrid.dat’ which contains:

c09r00
S
y
0.436
2.436
-1.0
1.0
36
201
201

Note that line two should be omitted for older (pre 8.0 versions of the VMEC suite of codes). > The xgrid code may then be executed with this input file (this may take some time depending on your computing power).

> ~/bin/xgrid < input_xgrid.dat >& log_xgrid.c09r00 &

or type it interactively

 Enter extension of "coils" file     :  
 Scale (S) bfield to unit current/turn OR use raw (R) currents from coils file:  
 Assume stellarator symmetry (Y/N)?  :  
 Enter rmin (min radial grid dimension)  :  
 Enter rmax (max radial grid dimension)  :  
 Enter zmin (min vertical grid dimension):  
 Enter zmax (max vertical grid dimension):  
 Enter number of toroidal planes/period  :  
 Enter number of r (radial) mesh points  :  
 Enter number of z mesh points  : 

or put a namelist in ‘input_xgrid.dat’:

&MGRID_NLI
  TASK = 'MGRID'
  MGRID_EXT = 'c09r00' 
  MGRID_MODE = 'S'
  LSTELL_SYM = T
  RMIN = 0.436
  RMAX = 2.436
  ZMIN =-1.000
  ZMAX = 1.000
  KP   = 36
  IR   = 201
  JZ   = 201
/

and call via

>~/bin/xgrid input_xgrid.dat

The code will begin to run and part of the screen output is:

 Stellarator symmetry IS assumed
 rmin =  0.436  rmax =  2.4359999999999999
 zmin =  -1.  zmax =  1.
 kp =  36  ir =  201  jz =  201
 
 Input  file: coils.c09r00
 Mgrid  file: mgrid_c09r00
 Extcur file: extcur.c09r00
 COIL GROUP          :  ModA
 TOTAL COILS IN GROUP:   6 TOTAL FILAMENTS:   2400
 K =    1 (OUT OF   36)
 K =    2
 K =    3
 K =    4
 K =    5
 K =    6
 K =    7
 K =    8
 K =    9
 K =   10
 K =   11
 K =   12
 K =   13
 K =   14
 K =   15
 K =   16
 K =   17
 K =   18
 K =   19
 COIL GROUP          :  ModB
 TOTAL COILS IN GROUP:   6 TOTAL FILAMENTS:   2400
 K =    1 (OUT OF   36)
 K =    2
 
.
.
.
 COIL GROUP          :  TF
 TOTAL COILS IN GROUP:  18 TOTAL FILAMENTS:   2196
 K =    1 (OUT OF   36)
 K =    2
 K =    3
 K =    4
 K =    5
 K =    6
 K =    7
 K =    8
 K =    9
 K =   10
 K =   11
 K =   12
 K =   13
 K =   14
 K =   15
 K =   16
 K =   17
 K =   18
 K =   19
 TIME IN PARSER =    0.397 SECONDS
 TIME IN BFIELD =  407.148 SECONDS
 THE BFIELDS HAVE BEEN STORED IN THE MGRID FILE IN SCALED MODE. THE EXTERNAL
 CURRENTS CORRESPONDING TO THOSE IN THE COILS-DOT FILE
 ARE GIVEN IN THE EXTCUR ARRAY IN THE FILE extcur.c09r00. 
 THEY SHOULD BE ENTERED INTO THE VMEC INPUT (INDATA) FILE.

This choice of parameters gives us [cm] scale resolution and provides us with enough toroidal resolution to run with 8 toroidal modes per field period. At the end of the run you should have produced the following files: mgrid_c09r00.nc (or mgrid.c09r00), extcur.c09r00, and log_xgrid.c09r00.

Edit the input namelist text file.

The input namelist (input.ncsx_c09r00_free) controls the execution of the VMEC code. The suffix of the input file will be appended to each of the output files as we will see after execution. The Fourier coefficient in this file have been generated through an optimization routine. In general, more simple initial conditions will suffice for the axis position and outer most flux surface. The name of the mgrid file must now be specified, along with setting LFREEB to true. The NZETA variable must match the value you selected for mgrid creation (see 7th line in the input_xgrid.dat file). You’ll notice that for the free boundary run the user must also specify the EXTCUR array. This array specifies the current running through each coil group. There should be one entry per coil group. The extcur file contains suggestions for these values based on the values it read from the coils file. These values can be copied and pasted directly into the VMEC ‘input’ file. Note that the traditional polynomial form of the current profile (NCURR=1) and pressure profile are being used. Note that if you have a binary ‘mgrid’ file then you’ll need to modify the MGRID_FILE variable to match the proper name.

&INDATA
!----- Runtime Parameters -----
  DELT =   9.00E-01
  NITER = 5000
  NSTEP =  200
  TCON0 =   2.00E+00
  NS_ARRAY =   9   29   49   99
  FTOL_ARRAY = 1.000000E-06  1.000000E-08  1.000000E-10  1.000000E-12
!----- Grid Parameters -----
  LASYM = F
  NFP =    3
  MPOL =   11
  NTOR =    6
  NZETA  =   36
  PHIEDGE =   4.97070205837336E-01
!----- Free Boundary Parameters -----
  LFREEB = T
  MGRID_FILE = 'mgrid_c09r00.nc'
  EXTCUR =   6.52271941985300E+05  6.51868569367400E+05  5.37743588647300E+05
  2.50000000000000E-07  2.50000000000000E-07  2.80949750000000E+04
  -5.48049500000000E+04  3.01228950000000E+04  9.42409100000000E+04
  4.55138737653200E+04
  NVACSKIP =    6
!----- Pressure Parameters -----
  GAMMA =   0.000000E+00
  BLOAT =   1.000000E+00
  SPRES_PED =   1.00000000000000E+00
  AM =   6.85517649352426E+04 -5.12027745123057E+03 -3.61510451745464E+04 -4.74263014113066E+05
  1.78878195473870E+06 -3.21513828868170E+06  2.69041023837233E+06 -8.17049854168367E+05
  0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
!----- Current/Iota Parameters -----
  CURTOR =  -1.78606250000000E+05
  NCURR =    1
  AI =   0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
  0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
  0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
  AC =   8.18395699999999E+03  1.43603560000000E+06 -1.07407140000000E+07  7.44389200000000E+07
 -3.22215650000000E+08  8.81050800000000E+08 -1.49389660000000E+09  1.52746800000000E+09
 -8.67901590000000E+08  2.10351200000000E+08  0.00000000000000E+00
!----- Axis Parameters -----
  RAXIS =   1.49569454253276E+00  1.05806400912320E-01  7.21255454715878E-03 -3.87402652289249E-04
 -2.02425864534069E-04 -1.62602353744308E-04 -8.89569831063077E-06
  ZAXIS =   0.00000000000000E+00 -5.19492027001782E-02 -3.18814224021375E-03  2.26199929262002E-04
  1.28803681387330E-04  1.11266150452637E-06  1.13732703961869E-05
!----- Boundary Parameters -----
  RBC(0,0) =   1.40941668895656E+00     ZBS(0,0) =   0.00000000000000E+00
  RBC(1,0) =   2.79226697269945E-02     ZBS(1,0) =  -1.92433268059631E-02
  RBC(2,0) =  -1.54739398509667E-03     ZBS(2,0) =   1.11459511078088E-02
  RBC(3,0) =   2.90733840104882E-03     ZBS(3,0) =  -3.97869471888770E-03
  RBC(4,0) =  -8.91322016448873E-04     ZBS(4,0) =   1.34394804673514E-03
  RBC(5,0) =  -7.81997770407839E-05     ZBS(5,0) =  -1.57143910159387E-04
  RBC(6,0) =   1.06129711928351E-04     ZBS(6,0) =   9.58024291307491E-05
  RBC(-6,1) =  2.48228899767757E-05     ZBS(-6,1) = -2.28386224209054E-05
  RBC(-5,1) =  8.23567667077671E-05     ZBS(-5,1) =  3.30176003890210E-04
  RBC(-4,1) = -7.20220898033597E-04     ZBS(-4,1) =  1.28038328362904E-04
  RBC(-3,1) =  2.76250777733235E-03     ZBS(-3,1) =  3.43199911886317E-04
  RBC(-2,1) = -1.24883373588382E-02     ZBS(-2,1) =  6.12174680232785E-04
  RBC(-1,1) =  1.52272804511910E-02     ZBS(-1,1) = -2.70066914159594E-02
  RBC(0,1) =   2.89195233044040E-01     ZBS(0,1) =   4.50462554508443E-01
  RBC(1,1) =  -1.17988850341728E-01     ZBS(1,1) =   1.93490230971634E-01
  RBC(2,1) =  -3.84923299492945E-03     ZBS(2,1) =   5.72865331625290E-03
  RBC(3,1) =  -1.44452305429529E-03     ZBS(3,1) =   2.19788951889214E-03
  RBC(4,1) =  -2.11622985211109E-04     ZBS(4,1) =   1.31883972780290E-03
  RBC(5,1) =   1.79091719677667E-04     ZBS(5,1) =  -5.63363462408534E-04
  RBC(6,1) =   1.31982402741742E-04     ZBS(6,1) =  -9.31801467009349E-05
  RBC(-6,2) = -2.40882614870476E-05     ZBS(-6,2) = -3.95416405717970E-05
  RBC(-5,2) = -4.92449386382591E-05     ZBS(-5,2) = -3.25048356502217E-06
  RBC(-4,2) =  1.50530476034115E-04     ZBS(-4,2) =  4.61522421935086E-05
  RBC(-3,2) = -1.23084235126550E-03     ZBS(-3,2) = -3.40868203306282E-04
  RBC(-2,2) =  2.01350576071929E-04     ZBS(-2,2) = -4.19781517712033E-03
  RBC(-1,2) =  2.36777003797179E-03     ZBS(-1,2) =  1.98753868216412E-02
  RBC(0,2) =   5.73443941583452E-02     ZBS(0,2) =   4.81527027892127E-03
  RBC(1,2) =   6.89385874058265E-02     ZBS(1,2) =  -9.28353553039424E-03
  RBC(2,2) =   4.71996849673782E-02     ZBS(2,2) =  -2.04292782322197E-02
  RBC(3,2) =  -5.50889052720066E-04     ZBS(3,2) =   8.81593501270446E-04
  RBC(4,2) =   4.24491391207156E-04     ZBS(4,2) =  -6.08871281835245E-04
  RBC(5,2) =  -2.07538883155595E-04     ZBS(5,2) =  -3.88708113241096E-04
  RBC(6,2) =  -1.62304038006678E-04     ZBS(6,2) =   1.72340342752605E-04
  RBC(-6,3) = -1.01105699684233E-04     ZBS(-6,3) = -6.16215454248342E-05
  RBC(-5,3) =  5.15925605980565E-05     ZBS(-5,3) =  1.23419431936950E-04
  RBC(-4,3) = -3.79290487874111E-05     ZBS(-4,3) =  3.98637008165582E-06
  RBC(-3,3) = -2.96154201246223E-04     ZBS(-3,3) = -7.01248486620889E-04
  RBC(-2,3) =  1.27628943631957E-03     ZBS(-2,3) =  3.19332333533202E-03
  RBC(-1,3) =  3.12803506573940E-03     ZBS(-1,3) = -8.24657727838880E-03
  RBC(0,3) =  -1.34574092972690E-02     ZBS(0,3) =   5.05936199755365E-03
  RBC(1,3) =  -8.02339287294677E-03     ZBS(1,3) =  -3.90421394288867E-03
  RBC(2,3) =  -1.68510947837154E-02     ZBS(2,3) =   3.75441853342170E-03
  RBC(3,3) =  -8.00581733372124E-03     ZBS(3,3) =   6.00542774606014E-03
  RBC(4,3) =   1.80667899211621E-03     ZBS(4,3) =  -4.16787432635077E-04
  RBC(5,3) =   3.10773970094350E-05     ZBS(5,3) =   5.44335921432213E-05
  RBC(6,3) =   8.32496816115997E-05     ZBS(6,3) =  -4.15830451164888E-05
  RBC(-6,4) = -1.19874891436340E-05     ZBS(-6,4) =  1.56845408711308E-05
  RBC(-5,4) =  1.22793444338155E-04     ZBS(-5,4) = -3.97576733690054E-05
  RBC(-4,4) = -1.30945484439682E-04     ZBS(-4,4) = -7.22429623460448E-05
  RBC(-3,4) = -1.21368603604647E-04     ZBS(-3,4) =  3.52928331257216E-04
  RBC(-2,4) =  1.00352526472782E-03     ZBS(-2,4) = -1.23710282249961E-04
  RBC(-1,4) = -1.73680844498789E-03     ZBS(-1,4) = -1.50689928334813E-03
  RBC(0,4) =   1.80149787198970E-03     ZBS(0,4) =   1.56109492686192E-03
  RBC(1,4) =   3.82771889154294E-03     ZBS(1,4) =   3.80910842862487E-03
  RBC(2,4) =   5.43835034437129E-03     ZBS(2,4) =   2.06275075117804E-03
  RBC(3,4) =   8.39729828422411E-04     ZBS(3,4) =  -1.54779126563731E-03
  RBC(4,4) =   6.74263596810560E-04     ZBS(4,4) =  -1.33149943553452E-03
  RBC(5,4) =  -6.98647584180715E-04     ZBS(5,4) =   3.81307095116973E-04
  RBC(6,4) =   8.77670652920776E-05     ZBS(6,4) =  -1.40433963574141E-05
  RBC(-6,5) =  6.78635213884316E-06     ZBS(-6,5) = -1.22283666932084E-05
  RBC(-5,5) =  3.87846546342867E-05     ZBS(-5,5) =  4.64829761643373E-05
  RBC(-4,5) = -3.78300368387435E-05     ZBS(-4,5) = -7.03801581329045E-05
  RBC(-3,5) = -1.21743926248229E-05     ZBS(-3,5) =  1.85735151533626E-04
  RBC(-2,5) = -2.68229697014545E-04     ZBS(-2,5) = -9.33216243296025E-04
  RBC(-1,5) =  1.19567316567517E-03     ZBS(-1,5) =  2.12648562837673E-03
  RBC(0,5) =  -7.12579133390599E-04     ZBS(0,5) =  -1.97890515574565E-03
  RBC(1,5) =   8.81127157923892E-04     ZBS(1,5) =   2.71321673191593E-03
  RBC(2,5) =   9.67210453659238E-04     ZBS(2,5) =   8.74618447862515E-04
  RBC(3,5) =   2.11794179698155E-04     ZBS(3,5) =   8.43817701627930E-04
  RBC(4,5) =   1.29403911922840E-03     ZBS(4,5) =   6.51808476607835E-04
  RBC(5,5) =  -1.30477683585083E-04     ZBS(5,5) =   1.01349326961770E-04
  RBC(6,5) =   1.86680624010370E-04     ZBS(6,5) =  -2.13838628730300E-04
  RBC(-6,6) = -4.08213549686361E-05     ZBS(-6,6) = -7.53394429655583E-06
  RBC(-5,6) =  7.11305157811999E-05     ZBS(-5,6) =  2.54876062250879E-05
  RBC(-4,6) = -1.33727065581923E-04     ZBS(-4,6) = -1.70180862196520E-05
  RBC(-3,6) =  1.65191943182183E-06     ZBS(-3,6) = -1.31350577800873E-04
  RBC(-2,6) =  2.19460449719541E-04     ZBS(-2,6) =  4.38914760402648E-04
  RBC(-1,6) =  4.68618562605432E-04     ZBS(-1,6) = -4.44537659614533E-04
  RBC(0,6) =  -8.51896573200937E-04     ZBS(0,6) =   7.36122964253313E-04
  RBC(1,6) =  -5.26623264534578E-05     ZBS(1,6) =  -1.12352425125337E-03
  RBC(2,6) =  -1.31954654361710E-04     ZBS(2,6) =  -2.22905186553194E-03
  RBC(3,6) =  -8.91482312658694E-04     ZBS(3,6) =  -2.11193996461398E-03
  RBC(4,6) =  -3.89733094884781E-04     ZBS(4,6) =  -3.44184359663702E-04
  RBC(5,6) =  -2.74329775462215E-04     ZBS(5,6) =  -5.06914660659672E-05
  RBC(6,6) =   2.47385092660320E-04     ZBS(6,6) =   3.74971583066409E-05
  RBC(-6,7) =  9.61516193308531E-06     ZBS(-6,7) = -3.66121037894761E-06
  RBC(-5,7) = -2.51122684780459E-05     ZBS(-5,7) =  3.72828134065079E-05
  RBC(-4,7) =  4.44568599556351E-05     ZBS(-4,7) = -8.74488353626824E-05
  RBC(-3,7) = -1.42433799354752E-04     ZBS(-3,7) =  1.48694485468843E-04
  RBC(-2,7) =  4.85802385952487E-04     ZBS(-2,7) = -2.27519962800893E-04
  RBC(-1,7) = -9.00652688032426E-04     ZBS(-1,7) =  4.16601324903870E-04
  RBC(0,7) =   9.59457670863182E-04     ZBS(0,7) =  -3.25818663499641E-04
  RBC(1,7) =  -3.37159659594826E-04     ZBS(1,7) =  -2.34240245561361E-04
  RBC(2,7) =  -4.64969900861713E-04     ZBS(2,7) =   4.87821281121050E-04
  RBC(3,7) =  -4.09185322970312E-04     ZBS(3,7) =   8.50140634573578E-04
  RBC(4,7) =   5.32088748759921E-05     ZBS(4,7) =   5.93528572346752E-04
  RBC(5,7) =  -3.21692982976907E-04     ZBS(5,7) =  -2.54775193277671E-04
  RBC(6,7) =  -4.82403633897412E-05     ZBS(6,7) =   1.41947169759239E-05
  RBC(-6,8) = -2.23522770283961E-05     ZBS(-6,8) = -4.00911971000495E-06
  RBC(-5,8) =  3.95696912099304E-05     ZBS(-5,8) =  1.34684147523625E-05
  RBC(-4,8) = -6.50775924544567E-05     ZBS(-4,8) = -2.94168940555405E-05
  RBC(-3,8) =  1.71610112932980E-04     ZBS(-3,8) =  2.17875987311858E-05
  RBC(-2,8) = -3.45412623614909E-04     ZBS(-2,8) = -7.26482153663716E-05
  RBC(-1,8) =  5.61089095467387E-04     ZBS(-1,8) =  2.51145295676537E-04
  RBC(0,8) =  -5.84359101746051E-04     ZBS(0,8) =  -5.42465826224607E-04
  RBC(1,8) =  -6.16860761080513E-05     ZBS(1,8) =   3.93697603313273E-04
  RBC(2,8) =   5.99275780897287E-04     ZBS(2,8) =   3.30798770955874E-04
  RBC(3,8) =   5.68520162541870E-04     ZBS(3,8) =   5.47788467933391E-04
  RBC(4,8) =   4.47404034542356E-04     ZBS(4,8) =   2.43547539548605E-04
  RBC(5,8) =   2.76704814165950E-04     ZBS(5,8) =   9.15194583315619E-05
  RBC(6,8) =   2.97621090888441E-04     ZBS(6,8) =   1.65605427353701E-04
  RBC(-6,9) = -3.78145897931544E-06     ZBS(-6,9) = -1.85759364750771E-06
  RBC(-5,9) = -1.57985677623482E-05     ZBS(-5,9) =  1.06970045147331E-05
  RBC(-4,9) =  7.91641381274532E-05     ZBS(-4,9) = -1.16252171939772E-05
  RBC(-3,9) = -1.97587428419659E-04     ZBS(-3,9) = -3.08457797690412E-05
  RBC(-2,9) =  3.95855751452672E-04     ZBS(-2,9) =  2.03418980231168E-04
  RBC(-1,9) = -5.41153103221438E-04     ZBS(-1,9) = -3.99552958537408E-04
  RBC(0,9) =   4.98714381092541E-04     ZBS(0,9) =   4.32916759100965E-04
  RBC(1,9) =  -8.06048953531492E-05     ZBS(1,9) =  -1.84722027458208E-04
  RBC(2,9) =  -8.67990109801738E-05     ZBS(2,9) =   2.52568631885491E-04
  RBC(3,9) =   4.35340840113358E-04     ZBS(3,9) =  -3.50159782847442E-04
  RBC(4,9) =   2.33585243788111E-04     ZBS(4,9) =  -7.06133299107118E-04
  RBC(5,9) =  -7.69581174305243E-06     ZBS(5,9) =  -3.79072907220561E-04
  RBC(6,9) =  -2.85256407945938E-05     ZBS(6,9) =  -4.49599333610498E-05
  RBC(-6,10) =  1.20206720198758E-05     ZBS(-6,10) =  4.73580005255806E-06
  RBC(-5,10) =  7.02670536357846E-06     ZBS(-5,10) = -6.99664911015022E-06
  RBC(-4,10) = -2.76926398374910E-05     ZBS(-4,10) = -9.18014408856618E-06
  RBC(-3,10) =  5.20223745639364E-05     ZBS(-3,10) =  6.80574180383753E-05
  RBC(-2,10) = -7.88310431749746E-05     ZBS(-2,10) = -1.06370673487973E-04
  RBC(-1,10) =  1.21755712542490E-05     ZBS(-1,10) =  1.22161894513591E-04
  RBC(0,10) =  3.22193519645521E-05     ZBS(0,10) = -6.04052049877600E-05
  RBC(1,10) = -1.08453911913102E-06     ZBS(1,10) =  8.60890353665843E-05
  RBC(2,10) =  1.04051545504927E-04     ZBS(2,10) = -2.17661420286656E-04
  RBC(3,10) = -5.21965328013036E-04     ZBS(3,10) = -2.67111216700977E-04
  RBC(4,10) = -4.95991087393098E-04     ZBS(4,10) =  2.43875640076056E-05
  RBC(5,10) = -1.94520415280627E-04     ZBS(5,10) =  1.55759001593971E-04
  RBC(6,10) = -6.94143617569942E-05     ZBS(6,10) =  4.40565098025554E-05
/
&END

Execute the code.

To simplify execution of the code, the VMEC compilation scripts create a directory called bin in your home () directory. Symbolic links are then placed there pointing to each of the compiled codes in their respective ‘Vrelease’ subdirectories. In practice, the screen output from VMEC should be redirected to a log file and put in the background (>& log.ncsx_c09r00_free &). This is done by passing the suffix of the input file to the VMEC code through the command line.

>~/bin/xvmec2000 ncsx_c09r00_free
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  VMEC OUTPUT FILES ALREADY EXIST: OVERWRITING THEM ...
  SEQ =    1 TIME SLICE  0.0000E+00
  PROCESSING INPUT.ncsx_c09r00_free
  THIS IS VMEC2000, A 3D EQUILIBRIUM CODE, VERSION 8.47
  Lambda: Full Radial Mesh. L-Force: hybrid full/half.
  
  COMPUTER: computer.domain.net   OS: Linux   RELEASE: 2.6.18-194.17.4.el5  DATE = Sep 06,2011  TIME = 13:13:44
  Opening vacuum field file: mgrid_c09r00.nc
  Time to read MGRID file:   3.10E+00 s
  NS =    9 NO. FOURIER MODES =  137 FTOLV =  1.000E-06 NITER =   5000
 ITER    FSQR      FSQZ      FSQL     RAX(v=0)      WMHD      DEL-BSQ
    1  5.24E+01  6.99E+00  1.63E-01  1.608E+00  3.7781E+00  1.000E+00
  In VACUUM, np =  3  mf = 12  nf =  6 nu = 28  nv =   36
  2*pi * a * -BPOL(vac) =  -1.89E-01 TOROIDAL CURRENT =  -1.89E-01
  R * BTOR(vac) =   2.37E+00 R-BTOR =   2.38E+00
  VACUUM PRESSURE TURNED ON AT   82 ITERATIONS
  165  9.55E-07  2.25E-07  4.60E-07  1.609E+00  3.5227E+00  4.634E-03
  NS =   29 NO. FOURIER MODES =  137 FTOLV =  1.000E-08 NITER =   5000
 ITER    FSQR      FSQZ      FSQL     RAX(v=0)      WMHD      DEL-BSQ
    1  6.96E-02  3.27E-02  3.97E-04  1.609E+00  3.5227E+00  4.634E-03
  200  6.23E-08  1.59E-08  8.03E-09  1.609E+00  3.5199E+00  2.732E-03
  287  9.99E-09  2.61E-09  2.17E-09  1.609E+00  3.5199E+00  2.818E-03
  NS =   49 NO. FOURIER MODES =  137 FTOLV =  1.000E-10 NITER =   5000
 ITER    FSQR      FSQZ      FSQL     RAX(v=0)      WMHD      DEL-BSQ
    1  3.14E+00  1.57E+00  4.90E-06  1.609E+00  3.5198E+00  2.818E-03
  200  2.19E-08  8.35E-09  1.21E-09  1.608E+00  3.5197E+00  2.585E-03
  400  1.28E-09  3.24E-10  2.86E-10  1.608E+00  3.5197E+00  2.756E-03
  600  3.28E-10  8.59E-11  5.96E-11  1.608E+00  3.5197E+00  2.848E-03
  782  9.95E-11  2.66E-11  1.57E-11  1.608E+00  3.5197E+00  2.873E-03
  NS =   99 NO. FOURIER MODES =  137 FTOLV =  1.000E-12 NITER =   5000
 ITER    FSQR      FSQZ      FSQL     RAX(v=0)      WMHD      DEL-BSQ
    1  9.60E+00  4.73E+00  2.02E-06  1.608E+00  3.5197E+00  2.873E-03
  200  3.97E-08  2.25E-08  9.27E-11  1.608E+00  3.5196E+00  2.605E-03
  400  1.13E-09  1.52E-10  4.09E-11  1.608E+00  3.5196E+00  2.611E-03
  600  3.86E-10  5.73E-11  2.43E-11  1.608E+00  3.5196E+00  2.620E-03
  800  1.49E-10  2.82E-11  1.36E-11  1.608E+00  3.5196E+00  2.627E-03
 1000  5.74E-11  1.33E-11  6.58E-12  1.608E+00  3.5196E+00  2.632E-03
 1200  2.00E-11  4.94E-12  2.76E-12  1.608E+00  3.5196E+00  2.634E-03
 1400  7.79E-12  1.87E-12  1.13E-12  1.608E+00  3.5196E+00  2.635E-03
 1600  3.57E-12  8.99E-13  4.91E-13  1.608E+00  3.5196E+00  2.634E-03
 1800  1.39E-12  3.28E-13  2.27E-13  1.608E+00  3.5196E+00  2.634E-03
 1881  9.93E-13  2.53E-13  1.68E-13  1.608E+00  3.5196E+00  2.634E-03
 EXECUTION TERMINATED NORMALLY
 FILE : ncsx_c09r00_free
 NUMBER OF JACOBIAN RESETS =    3
    TOTAL COMPUTATIONAL TIME             501.04 SECONDS
    TIME TO READ IN DATA                   3.13 SECONDS
    TIME TO WRITE DATA TO WOUT             0.30 SECONDS
    TIME IN EQFORCE                        7.22 SECONDS
    TIME IN VACUUM LOOP                   82.27 SECONDS
    TIME IN FOURIER TRANSFORM            117.16 SECONDS
    TIME IN INVERSE FOURIER XFORM         80.03 SECONDS
    TIME IN FORCES                        95.99 SECONDS
    TIME IN BCOVAR                        77.08 SECONDS
    TIME IN RESIDUE                        2.29 SECONDS
    TIME (REMAINDER) IN FUNCT3D           34.30 SECONDS

Examine the output.

For this example four files were created (jxbout.ncsx_c09r00_free, mercier.ncsx_c09r00_free, threed1.ncsx_c09r00_free, and wout.ncsx_c09r00_free). As was mentioned before, each file had the suffix of the input file appended to it’s name. This allows multiple runs to be stored in the same directory for comparison. The jxbout file contains values for various quantities on a grid throughout the simulation domain. The mercier file contains radial profiles (radial index in VMEC is denoted by the variable s) of various quantities. The threed1 file can be considered an expanded log file where various quantities are calculated which were not output to the screen. This file is fairly self explanatory. The wout file is the data file for the run. It contains the Fourier Coefficients for the magnetic field along with various quantities. A few packages exist to visualize this data and the user is encourage to use these as templates for their own visualization routines.