Closed jonmaddock closed 3 weeks ago
In GitLab by @asbrown on Nov 5, 2019, 13:00
Hi @mkovari,
What you have written is what I also understood from the paper.
It was discussed in the last PMI meeting (30/10/2019) that the new scaling could be easily implemented. This seems like a good opportunity to review the formulas currently in PROCESS
and the other formulas mentioned in the paper (K. Gi and IPDG).
The bootstrap fraction formula (switches ibss
1-4) in PROCESS are currently:
I've attached the ppt I made when reviewing the paper at the PMI Meeting (30/10/2019): Derivation_of_bootstrap_current_fraction_scaling_formula_for_0-D_system_codeanalysis-_Review.pptx
This might be a good start for anyone who wants to actually implement a new model, but doesn't want to spend all year on it.
In GitLab by @mkovari on Nov 5, 2019, 11:43
Derivation of bootstrap current fraction scaling formula for 0-D system code analysis by Sakai:
They constructed new scaling formulas for the bootstrap current faction fBS for tokamaks with full non-inductive operation with positive shear safety factor q profiles (q increases monotonically with the radius). A fitting database was built by the ACCOME code, which contains 12,150 cases of self-consistent equilibria with q > 1.0 everywhere and q95 > 3.0.
The best formula contained the inverse aspect ratio, the poloidal beta, the internal inductance, q95/q(0), and the profile shape indices for density and temperature as input.
All equilibria are fully non-inductive with neutral beam injection only.
This formula seems to be applicable to tokamak plasmas with a wide range of parameters. As far as I can see this is the recommended formula:
![image](https://github.com/ukaea/PROCESS/assets/9718416/e4ef3e3d-694b-444e-b865-30320d7228bf)
Thanks to @asbrown for studying this paper. Obviously I haven't read the paper. Adam - do you want to comment or add more detail? For example - can you fill in the range of applicability of this formula by giving upper and lower bounds for each of the six parameters?
Edit 19/3/24. Process has a model for the diamagnetic current - this may need to be turned off when this this scaling is used:
Another question can arise - how does ACCOME divide up the current between bootstrap and beam-driven fractions?
Note that Sakai does not include alphas or helium ions at all - the only impurity is carbon.
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