We know that the toroidal flux ψt, safety factor q, and the Ψ in the GS equation are related by the following equations:
| (556) |
| (557) |
Define:
| (558) |
(In the Toray_ga code, the radial coordinate ρ is defined as
| (559) |
where Bt0 is a constant factor.ρ defined this way is of length dimension, which is an effective geometry radius obtained by approximating the flux surface as circular.)
I use Eq. (558) to define ρ. Then we have
| (560) |
| (561) |
| (562) |
| (563) |
| (564) |
Eq. (564) is used to transform between ψ and ρ.
dρ = dΦ = 2πqdψ = qdψ |
⇒ dψ = dρ(πa2) |