87 lines
2.5 KiB
Markdown
87 lines
2.5 KiB
Markdown
|
---
|
|||
|
|
title: MAGNETICDATA.TXT
|
|||
|
|
section: 5
|
|||
|
|
---
|
|||
|
|
|
|||
|
|
# NAME
|
|||
|
|
magneticdata.txt --- MHD equilibrium data for **gray**(1)
|
|||
|
|
|
|||
|
|
# FORMAT
|
|||
|
|
The MHD equilibrium data can be specified in two ways: as the free parameters
|
|||
|
|
of a simple analytical model, or as numerical data in the G-EQDSK format.
|
|||
|
|
|
|||
|
|
## analytical equilibrium
|
|||
|
|
The format for the analytical magneticdata.txt file is as follows:
|
|||
|
|
|
|||
|
|
R₀ z₀ a
|
|||
|
|
B₀
|
|||
|
|
q₀ q₁ α
|
|||
|
|
npoints
|
|||
|
|
R₁ z₁
|
|||
|
|
R₂ z₂
|
|||
|
|
...
|
|||
|
|
|
|||
|
|
where:
|
|||
|
|
|
|||
|
|
- *R₀, z₀* are the coordinates of the magnetic axis (m)
|
|||
|
|
- *a* is the plasma boundary minor radius (m)
|
|||
|
|
- *B₀* is the value of toroidal field on the magnetic axis (T)
|
|||
|
|
- *q₀, q₁, α* are the parameters of the safety factors (see below)
|
|||
|
|
- *npoints* is the number of points in the plasma limiter contour
|
|||
|
|
that followsAa
|
|||
|
|
- *R_i, z_i* are the coordinates of the points in contour (m)
|
|||
|
|
|
|||
|
|
Note: When viewing the torus from above, a positive B₀ results in a
|
|||
|
|
counterclockwise toroidal field and the plasma current is
|
|||
|
|
clockwise if q and B₀ have opposite signs.
|
|||
|
|
|
|||
|
|
### analytical model notes
|
|||
|
|
The model used in GRAY describes a plsma with circular cross section centered
|
|||
|
|
on the magnetic axis at a major radius *R₀* and extending up to the minor
|
|||
|
|
radius *a*, where the density is exactly zero.
|
|||
|
|
There is no X point nor separatrix.
|
|||
|
|
|
|||
|
|
The flux surfaces are circular and the normalised toroidal radius is exactly:
|
|||
|
|
|
|||
|
|
ρ_t(R, z) = √[(R - R₀)² + (z - z₀)²]/a
|
|||
|
|
|
|||
|
|
The toroidal field is given explicitly by *B_t(R) = B₀ R/R₀*; the poloidal
|
|||
|
|
field is determined implicitly by the safety factor profile.
|
|||
|
|
The latter is parametrised as:
|
|||
|
|
|
|||
|
|
q(ρ_p) = q₀ + (q₁ - q₀)ρ_p^α,
|
|||
|
|
|
|||
|
|
where *ρ_p* is the normalised poloidal flux.
|
|||
|
|
|
|||
|
|
## numerical equilibrium
|
|||
|
|
The format of the numerical equilibrium is the G-EQDSK informal standard
|
|||
|
|
(See the GRAY manual for the specification).
|
|||
|
|
|
|||
|
|
The data strictly necessary to perform a GRAY simulation are limited to:
|
|||
|
|
poloidal flux, safety factor, poloidal current function, magnetic axis and
|
|||
|
|
plasma boundary.
|
|||
|
|
If a limiter contour is provided it will be used to compute reflections.
|
|||
|
|
|
|||
|
|
# EXAMPLES
|
|||
|
|
1. An analytical magneticdata.txt
|
|||
|
|
|
|||
|
|
2.96 0.0 1.25 ! R₀ z₀ a
|
|||
|
|
6 ! B₀
|
|||
|
|
3.5 10 2 ! q₀ q₁ α
|
|||
|
|
4 ! npoints
|
|||
|
|
1.61 -1.35 ! a simple square limiter
|
|||
|
|
1.61 +1.35
|
|||
|
|
4.31 +1.35
|
|||
|
|
4.31 -1.35
|
|||
|
|
|
|||
|
|
|
|||
|
|
2. An analytical magneticdata.txt without limiter
|
|||
|
|
|
|||
|
|
2.96 0.0 1.25 ! R₀ z₀ a
|
|||
|
|
6 ! B₀
|
|||
|
|
3.5 10 2 ! q₀ q₁ α
|
|||
|
|
0 ! no limiter contour
|
|||
|
|
|
|||
|
|
# SEE ALSO
|
|||
|
|
**gray**(1)
|