gray/doc/man/gray.ini.5.md

---
title: GRAY.INI
section: 5
---

# NAME
gray.ini --- Configuration file for **gray**(1)

# CONFIGURATION
The configuration file is written in the INI format. The basic syntax
is:

    [group]
    ; comment
    parameter = value

Group is one of: *raytracing*, *ecrh_cd*, *antenna*, *equilibrium*,
*profiles*, *misc*.

Values are valid Fortran values, including numbers (integers or floating
points), strings (enclosed in quotes), booleans (*.true.*, *.false.*)
and named constants (e.g. *MODE_X*).

# PARAMETERS
Valid configuration parameters listed by group

Note: parameters with a default value are optional and can be omitted.

## raytracing
Raytracing parameters

**nrayr**
:   Number of rays in the radial direction

**nrayth**
:   Number of rays in the angular direction

**rwmax** (default: **1.0**)
:   Normalized maximum radius of the beam power

**igrad** (default: **0**)
:   Switch between simple raytracing (*0*) and beamtracing (*1*)

**ipass** (default: **1**)
:   Max number of crossing (out, in, out) of the plasma. When positive
    reflections occur on the plasma limiter provided by the G-EQDSK
    file; when negative on a simple limiter at R=*rwall*, see below.

**ipol** (default: **.false.**)
:   Whether to compute the wave polarisation from chi, psi (see below)

**dst**
:   Step size (cm) for the numerical integration

**nstep** (default: **12000**)
:   Max number of integration steps

**idst** (default: **STEP_TIME**)
:   Choice of the integration variable. One of:

    - *STEP_ARCLEN*, arc length (s)
    - *STEP_TIME*, time (actually c⋅t)
    - *STEP_PHASE*, phase (actually the real part of the eikonal S_r=k₀⋅φ)

## ecrh_cd
ECRH and current drive parameters

**iwarm** (default: **ABSORP_FULL**)
:   Choice of the power absorption model. One of:

    - *ABSORP_OFF*, no absorption at all
    - *ABSORP_WEAK*, weakly relativistic
    - *ABSORP_FULL*, fully relativistic (faster variant)
    - *ABSORP_FULL_ALT*, fully relativistic (slower variant)

    Note: *iwarm /= ABSORP_OFF* is required for current drive.

**ilarm** (default: **5**)
:   Order of the electron Larmor radius expansion (used by some
    absorption models)

**imx** (default: **-20**)
:   Max number of iterations for the solution of the dispersion relation
    (used by some absorption models)

    Note: if negative the result of the first iteration will be used in case
    the result doesn\'t converge within \|imx\| iterations.

**ieccd** (default: **CD_NEOCLASSIC**)
:   Current drive model. One of:

    - *CD_OFF*, no current drive at all
    - *CD_COHEN*, Cohen
    - *CD_NO_TRAP*, no trapping
    - *CD_NEOCLASSIC*, Neoclassical

## antenna
Antenna/beam launcher parameters

**alpha**
:   Poloidal launch angle (deg). Positive is down

**beta**
:   Toroidal launch angle (deg). Positive is right

**power** (default: **1.0**)
:   Injected power (MW)

**iox**
:   Polarisation mode. One of:

    - *MODE_O*, ordinary (O)
    - *MODE_X*, extraordinary (X)

**psi** (default: **0.0**)
:   ψ (deg), angle between the principal axes of the polarisation
    ellipse and the (x,y) axes

    Note: only used in alternative to *iox* if *ipol=.true.*.

**chi** (default: **0.0**)
:   χ=atan(ε) (deg), where ε is the ellipticity of the polarisation
    ellipse

    Note: only used in alternative to *iox* if *ipol=.true.*.

**ibeam** (default: **BEAM_0D**)
:   Beam parameters file format. One of:

    - *BEAM_0D*, fixed beam parameters
    - *BEAM_1D*, 1D steering angle table
    - *BEAM_2D*, 2D steering angles table

**filenm**
:   Filepath of the beam data (relative to the gray.ini file)

## equilibrium
MHD equilibrium parameters

**iequil** (default: **EQ_EQDSK_FULL**)
:   MHD equilibrium kind. One of:

    - *EQ_VACUUM*, vacuum (i.e. no plasma at all)
    - *EQ_ANALYTICAL*, analytical model
    - *EQ_EQDSK_FULL*, G-EQDSK format - data valid on the whole domain
    - *EQ_EQDSK_PARTIAL*, G-EQDSK format - data valid only inside the LCFS

**filenm**
:   Filepath of the equilibrium data (relative to the gray.ini file)

**icocos** (default: **3**)
:   COCOS index of the equilibrium data (G-EQDSK only)

**ipsinorm** (default: **.false.**)
:   Whether the poloidal function is normalised (G-EQDSK only)

    Note: Normalised means ψ(axis)=0, ψ(boundary)=1

**idesc** (default: **.true.**)
:   Whether the header starts with a description, a.k.a
    identification string (G-EQDSK only)

**ifreefmt** (default: **.false.**)
:   Whether the records have variable length (G-EQDSK only)

    Note: some non-compliant programs output numbers formatted with variable
    length instead of using the single (5e16.9) specifier.

**ixp** (default: **X_IS_MISSING**)
:   Position of the X point. One of:

    - *X_IS_MISSING*, No X point
    - *X_AT_TOP*, At the top of the plasma
    - *X_AT_BOTTOM*, At the bottom of the plasma

**ssplps** (default: **0.005**)
:   Tension for the ψ_n(R,Z) spline, normalised poloidal flux

    Note: 0 means perfect interpolation

**ssplf** (default: **0.01**)
:   Tension for the F(ψ)=R⋅B_T spline, poloidal current function

    Note: 0 means perfect interpolation

**sgnb** (default: **0**)
:   Force the sign of the toroidal field. One of:

    - *+1*, counter-clockwise (viewed from above)
    - *-1*, clockwise
    - *0*, use sign from COCOS

**sgni** (default: **0**)
:   Force the sign of the plasma current. One of: *+1*,

    - *+1*, counter-clockwise (viewed from above)
    - *-1*, clockwise
    - *0*, use sign from COCOS

**factb** (default: **1.0**)
:   Rescaling factor for the magnetic field

## profiles
(input) plasma profiles parameters

**iprof**
:   Plasma profiles kind. One of:

    - *PROF_ANALYTIC*, analytical model
    - *PROF_NUMERIC*, numerical data (ρ, n_e, T_e, table)

**irho**
:   Plasma profiles radial coordinate. One of:

    - *RHO_TOR*, ρ_t = √Φ (where Φ is the normalised toroidal flux)
    - *RHO_POL*, ρ_p = √ψ (where ψ is the normalised poloidal flux)
    - *RHO_PSI*, normalised poloidal flux ψ

**filenm**
:   Filepath of the plasma profiles data (relative to the gray.ini file)

**sspld** (default: **0.1**)
:   Tension of the electron density spline

    Note: 0 means perfect interpolation

**factte** (default: **1.0**)
:   Rescaling factor for the electron temperature factte = 1

**factne** (default: **1.0**)
:   Rescaling factor for the density temperature

**iscal** (default: **SCALE_OFF**)
:   Choice of model for rescaling the temperature, density with the
    magnetic field (if factb ≠ 0 only). One of:

    - *SCALE_OFF*, don't rescale at all
    - *SCALE_COLLISION*, scale while preserving collisionality
    - *SCALE_GREENWALD*, scale while preserving the Greenwald fraction

## output

Output data parameters

**ipec** (default: **RHO_TOR**)
:   ECRH&CD profiles grid: Radial coordinate of the uniform grid.
    One of:

    - *RHO_TOR*, ρ_t = √Φ (where Φ is the normalised toroidal flux)
    - *RHO_POL*, ρ_p = √ψ (where ψ is the normalised poloidal flux)

**nrho** (default: **501**)
:   Number of in the radial grid

**istpr** (default: **5**)
:   Subsampling factors for the beam cross section (units 8, 12)

**istpl** (default: **5**)
:   Subsampling factors for the outer rays data (unit 33)

## misc

Other parameters

**rwall**

:   Radius of the inner wall (m). Used to build a simple limiter for
    reflections (only when *ipass\<0*)

# EXAMPLE

Below is an example of a gray.ini file

    [raytracing]
    ; beamtracing with 16×24 rays
    nrayr = 16
    nrayth = 24
    igrad = 1
    ; integrate in the phase
    dst = 0.05
    nstep = 2400
    idst = STEP_PHASE

    [antenna]
    ; vertical launch
    alpha = 89.45
    beta = 0.0
    iox = MODE_X
    ibeam = BEAM_1D
    filenm = "beamdata.txt"

    [equilibrium]
    filenm = "equilibrium.eqdsk"
    icocos = 2

    [profiles]
    ; analytical profiles
    iprof = PROF_ANALYTIC
    irho = RHO_TOR
    filenm = "profiles.txt"
    sspld = 0.01

    [output]
    ipec = RHO_POL
    nrho = 1001

    [misc]
    rwall = 0.6

# SEE ALSO

**gray**(1), **beamdata.txt**(5), **profiles.txt**(5), **magneticdata.txt**(5)