VMEC Input Namelist (v8.47)



The following table contains explanations for each variable in the input namelist used by VMEC. Not all values need be specified in a file. Examples can be found to guide the user in creating an input namelist for their application. The file containing the input namelist is a text file named input.run where 'run' is specified by the user and appended to all output files for a given run. The 'Type' column indicates the form of the data. Values denoted real(12,100) are reals defined by selected_real_kind(12,100), (12 point percision, and 100 point range). The 'Size' column indicates the size of the variable if it's an array (denoted 1 if it's just a scalar value).
Variable
Type
Size
Description
nfp
integer
1
Number of toroidal field periods
ncurr
integer
1
Switch for using (0) flux conservation or (1) prescribed toroidal current
nsin
integer
1
Deprecated parameters.
niter
integer
1
Total number of iterations
nstep
integer
1
Output interval to screen and threed1 file
nvacskip
integer
1
Interval for full update of vacuum solutions
mpol
integer
1
Poloidal Mode Number (m)
ntor
integer
1
Toroidal Mode Number (n)
ntheta
integer
1
Number of theta grid points (>=2*mpol+6)
nzeta
integer
1
Number of planes (in zeta) on which mgrid data has been calculated.
mfilter_fbdy
integer
1

nfilter_fbdy
integer
1

time_slice
real(12,100)
1
Time slice of equilibria (label)
curtor
real(12,100)
1
Total toroidal curent. [A]
delt
real(12,100)
1
Blending parameter
ftol
real(12,100)
1
Residual tolerance.
tcon0
real(12,100)
1
Weight factor for constrained force. (defaults to 1.0 for values greater than 1.0)
gamma
real(12,100)
1
Adiabatic index (compressional index)
phiedge
real(12,100)
1
Total enclosed toroidal flux [Wb].
spres_ped
real(12,100)
1
Value (in s) beyond which pressure profile is flat. (pedestal)
bloat
real(12,100)
1
Bloating factor for pressure and current profiles (bloats the domain not the value).
pres_scale
real(12,100)
1

prec2d_threshold
real(12,100)
1

am
real(12,100)
0:20
Mass or Pressure (gamma=0) expansion coefficients
ai
real(12,100)
0:20
Iota expansion coefficients
ac
real(12,100)
0:20
Toroidal current density expansion coefficients
aphi
real(12,100)
0:20
Deprecated parameters.
ns_array
integer
100
Number of radial grid points for each grid iteration
niter_array
integer
100
Maximum number of iterations for a given radial resolution
ftol_array
real(12,100)
100
Array of residual values at which a given multigrid iteration ends.
extcur
real(12,100)
500
Array of currents in each external group for free boundary run.
raxis
real(12,100)
0:61
see raxis_cc
zaxis
real(12,100)
0:61
see zaxis_cs
raxis_cc
real(12,100)
0:61
Radial Fourier Cosine Coefficients of magnetic Axis (R=raxis_cc*cos(-n*zeta))
raxis_cs
real(12,100)
0:61
Radial Fourier Sine Coefficients of magnetic Axis (R=raxis_cs*sin(-n*zeta))
zaxis_cc
real(12,100)
0:61
Vertical Fourier Cosine Coefficients of magnetic Axis (Z=zaxis_cc*cos(-n*zeta))
zaxis_cs
real(12,100)
0:61
Vertical Fourier Sine Coefficients of magnetic Axis (Z=zaxis_cs*sin(-n*zeta))
rbc
real(12,100)
-61:61,0:60
Boundary cosine coefficients for R cos(m*theta-n*zeta)
rbs
real(12,100)
-61:61,0:60
Boundary sine coefficients for R
zbc
real(12,100)
-61:61,0:60
Boundary cosine coefficients for Z
zbs
real(12,100)
-61:61,0:60
Boundary sine coefficients for Z
lfreeb
logical
1
Switch for free boundary run.
lrecon
logical
1
Switch for reconstruction run.
lmac
logcial
1

loldout
logical
1
Switch for old output format. This will produce a fort.8 file.
ledge_dump
logical
1
Output edge values to 'FORT.NEDGE0'.
lspectrum_dump
logical
1

lasym
logical
1
Non-stellarator symmetric configuration (T)
loptim
logical
1
Obsolete
lforbal
logical
1

lrfp
logical
1
Switch for using poloidal flux as radial coordinate.
l_spectrum_dump
1
Obsolete
mgrid_file
character
100
Vacuum Green's Function Filename
precon_type
character
10
Preconditioner type
pcurr_type
character
20
Current Profile type
piota_type
character
20
Iota Profile type
pmass_type
character
20
Pressure (mass) profile type
phidiam
real(12,100)
1
Diamagnetic toroidal flux [Wb].
psa
real(12,100)
100

pfa
real(12,100
100

isa
real(12,100)
100

ifa
real(12,100)
100

sigma_current
real(12,100)
1
Standard deviation in toroidal current [A]. Standard deviations <0 are interpreted as percent of respective measurement.
imatch_phiedge
integer
1
PHIEDGE switch: 0 use pressure profile, (1) match value, 2 use LIMPOS data (in mgrid), 3 use Ip (fixed boundary only)
iopt_raxis
integer
1

tensi
real(12,100)
1
Spline tension for iota profile
tensp
real(12,100)
1
Spline tension for pressure profile.
mseangle_offset
real(12,100)
1
Uniform experimental offset of MSE data (calibration offset)
imse
integer
1
Number of Motional Stark Effect (MSE) data points
isnodes
integer
1
Number of iota spline points (computed internally unless specified explicitly)
rstark
real(12,100)
100

datastark
real(12,100)
100
Pitch angle data from stark measurement
sigma_stark
real(12,100)
100
Standard deviation in MSE data [degrees]. Standard deviations of <0 are interpreted as a percent of the respective measurement.
itse
integer
1
Number of pressure profile data points.
ipnodes
integer
1
Number of pressure spline points (computed internally unless specified explicitly)
presfac
real(12,100)
1
Number by which Thomson scattering data is scaled to get actual pressure.
pres_offset
real(12,100)
1
Uniform arbitrary radial offset of pressure data.
rthom
real(12,100)
100
Radial coordinate Data for Thomson scattering. (lpofr=.true. then in real space, lpofr=.false. then in flux space)
datathom
real(12,100)
100
Pressure data from Thomson scattering.
sigma_thom
real(12,100)
100
Standard deviation for pressure profile data [Pa]. Standard deviations of <0 are interpreted as a percent of the respective measurement.
sigma_delphid
real(12,100)
1
Standard deviation for pressure profile data [Wb]. Standard deviations of <0 are interpreted as a percent of the respective measurement.
tensi2
real(12,100)
1
vbl spline tension for iota
fpolyi
real(12,100)
1
vbl spline tension form factor (note if tensi!=tensi2 then tension(ith point)=tensi+(tensi2-tensi)*(i/n-1)**fpolyi )
nflxs
integer
1
Number of flux loop measurements used in matching.
indxflx
integer
100
Array giving index of flux measurement in iconnect array.
dsiobt
real(12,100)
100
Measured flux loop signals corresponding to the combination of signals in iconnect array.
sigma_flux
real(12,100)
100
Standard deviation for external poloidal flux data [Wb]. Standard deviations of <0 are interpreted as a percent of the respective measurement.
nbfld
integer
5
Number of selected external bfield measurements used in matching.
indxbfld
integer
100,5
Array giving index of bfield measurement used in matching
bbc
real(12,100)
100,5
Measured magnetic field at rbcoil(m,n) zbcoil(m,n) at the orientation br*cos(abcoil) + bz*sin(abcoil)
sigma_b
real(12,100)
100,5
Standard deviation for external magnetic field data [T]. Standard deviations of <0 are interpreted as a percent of the respective measurement.
lpofr
logical
1
Switch for pressure data coordinates (.true. real space, .false. flux space)