GENE-3D and plasma physics progress

Today I heard about how the Max Planck Institute has made further inroads in terms of fusion power plant progress, with the announcement of a sweeping generalisation of a previous plasma physics numerical simulator (a piece of software), called GENE, to “GENE-3D”. (Progress in software might not necessarily sound as exciting as progress in hardware, but in complex projects like nuclear fusion, if one has better and more precise ways of modelling a real system, then this enables and facilitates later hardware improvements. In this way, hardware and software work synergistically in a form of feedback loop, one improving the other, in terms of sharpening one’s ability to solve a particular focused engineering problem.)

GENE, an acronym for “Gyrokinetic Electromagnetic Numerical Experiment”, presents a highly simplified form of plasma physics equations (presumably making various dimension reductions and asymptotic simplifications vis a vis similar methods applied to Navier Stokes within the operating regime of the plasma), which they term “gyrokinetic equations”. Previously GENE was a 2-dimensional model which was highly efficacious at helping to optimise Tokamak designs and procedures, such as that fast ions can greatly reduce turbulent transport in tokamak plasmas.

Turbulent transport is a problem for efficient operation of a candidate fusion power plant, as it leads to loss and potential leakage from the contained plasma, which leads to requirements for larger plants and more maintenance in order to control and/or deal with the leakage, which leads to more expensive energy. Therefore any way that engineers can find to reduce it is good.

Regardless, even with the highly simplified gyrokinetic plasma equations, GENE was still constrained by a 2d model of a highly symmetric system, a tokamak. And even with those assumptions, the most powerful supercomputers struggled (and still struggle!) to run the simulations.

That is what makes this forthcoming paper so impressive, since Maurice Maurer and co-authors were able to generalise this model to 3 dimensions, and in particular the types of geometry that are found in Stellarators – evidently much less regular and symmetric than a tokamak! Evidently they were able to do this in a way still tractable for a modern supercomputer to solve. In particular, initial simulations suggested that the fast ions trick (suggested by its predecessor GENE-2D for tokamaks) should be able to decrease turbulent transport in a stellarator by more than 50%, which would be tremendously useful. The paper, “GENE-3D: A global gyrokinetic turbulence code for stellarators”, can be found here (forthcoming November 2020 publication of the Journal of Computational Physics).

Tags: nuclear fusion