Coordinate conventions in reference scenario

[mwiesenberger]

Hi, From the psi and fpol fields in the 65402t1.eqdsk file, what is the equation for the magnetic field (I am asking about what sign convention is used?) i.e. in $\vec B = F(\psi) \nabla \varphi + \sigma{Bp} \frac{1}{(2\pi)^{e{Bp}}} \nabla\varphi \times \nabla\psi $ what is the orientation of $\nabla \varphi$ (clockwise or counter-clockwise if viewed from the top?), do I have to divide $\psi$ by $2\pi$ and what is the sign for the poloidal field $\sigma{B_p}$.

I understand from the header of the file that it is a LIUQE generated file. I understand from https://crppwww.epfl.ch/~sauter/cocos/ that LIUQE uses cocos 17 as coordinate conventions, however the given file does not (the provided signs for plasma current and poloidal flux do not match those of cocos 17)

Any help is appreciated Matthias

[tbody-cfs]

Hi Matthias, "Favourable" is ion-grad-B from main plasma towards the X-point (clockwise from top) and "unfavourable" is anti-clockwise from top. For dividing by 2*pi, I'd recommend computing the q-profile and comparing it to the q-profile stored in the eqdsk (let me know if you'd like a hand with this). @dsoliveir were these shots counter- or co-Ip?

[tbody-cfs]

Looking at figure 11, subfigure 3B and 3F — looks like "positive" upar direction is always towards the outboard target (easier to see in GBS with the standard Bohm condition). So in that case it seems that Ip is always counter-clockwise when viewed from above, and so Bp is clockwise when looking at a poloidal slice.