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ukaea / PROCESS

PROCESS is a systems code at UKAEA that calculates in a self-consistent manner the parameters of a fusion power plant with a specified performance, ensuring that its operating limits are not violated, and with the option to optimise to a given function of these parameters.
https://ukaea.github.io/PROCESS/
MIT License
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Toroidal field ripple for resistive TF coils #867

Open jonmaddock opened 5 years ago

jonmaddock commented 5 years ago

In GitLab by @mkovari on Jun 15, 2019, 12:59

If the TF coil is resistive then there is no winding pack - the whole coil is conductor, apart from the steel bucking cylinder. Therefore when calculating the ripple on the plasma outboard edge, the winding pack dimensions should be set to the dimensions of the coil.

@stuartmuldrew @skahn

Updated issue

  1. On coil ripple : Axisymmetric conductor layer, therefore no inboard ripple is present.
  2. Ouboard plasma ripple : To be updated with the resisitve coil thickness. Howerver, this needs to be modified for picture frame coil anyway, and verified for less that 16 coil !

Additionnal error spotted on the way

  1. ripple_amplitude called in machine_build uses wwp1 effectively calculated after in sctfcoil. For this reason, the wwp1 used for the plasma ripple calculation is never consistent and such glitch can cause some nasty issue in the VMCON derivative caculation ...

wwp1 is given by 

\Delta t_\mathrm{WP} = 2 \left( R_\mathrm{WP}^\mathrm{max, min} \tan\left(\frac{\pi}{N_\mathrm{TF}}\right) - \Delta t_\mathrm{case} - \Delta t_\mathrm{ins} -  \Delta t_\mathrm{insert} \right)

with $R_\mathrm{WP}^\mathrm{max, min}$ the minimum WP radius where the WP has its largest size in the toroidal direction. If the side case thickness is set by a fraction, we can inject the fraction parametrization of the side case thickness

\Delta t_\mathrm{case} = 2f_\mathrm{lateral\ case} R_\mathrm{WP}^\mathrm{in} \tan\left(\frac{\pi}{N_\mathrm{TF}}\right)

to get the following expression of the WP toroidal thickness used for the ripple calculation :

\Delta t_\mathrm{WP} = 2 \left[ \left( R_\mathrm{WP}^\mathrm{max, min} -  R_\mathrm{WP}^\mathrm{in} \right) \tan\left(\frac{\pi}{N_\mathrm{TF}}\right) - \Delta t_\mathrm{ins} -  \Delta t_\mathrm{insert} \right]
jonmaddock commented 4 years ago

In GitLab by @skahn on Nov 19, 2020, 15:25

As resistive coil can have a bucking cylinder now, but the outboard leg has not for now.

However I expect the ouboard coil to be contained in some sort of support structure as some conductor may not be stiff enough at room temperature.

Updating the description with the opened issue

jonmaddock commented 4 years ago

In GitLab by @mkovari on Nov 20, 2020, 13:44

wwp1 used for the plasma ripple calculation is never consistent

Yes, getting rid of this is an improvement.