Speaker
Description
Weakly magnetized plasmas are found in natural plasmas such as the solar wind, but also in laboratory applications, e.g. in the edge of fusion plasmas. Ordering assumptions made in gyrokinetic theory—like low frequency or moderate gradients—may be challenged, particularly for the heavier ions. To overcome these limitations, the group derived equations for a hybrid model that includes fully kinetic physics for the ions, but gyrokinetic physics for the electrons.
The numerical implementation of the hybrid model has been implemented into the existing simulation code ssV, developed in the department of Theoretical Physics I at Ruhr-Universität Bochum. The ssV code is based on advanced Semi-Lagrangian-type methods (e.g. the PFC scheme [Filbet et al., JCP 2001]).
The study of instabilities and turbulence relevant to tokamak edge turbulence, has driven significant further enhancements to ssV: In particular when evolving the full particle distribution (“full-f”), it is challenging to preserve accurate long-term physics while resolving the gyration timescale. Both existing and novel higher-order schemes had to be implemented and tested as a remedy: For example, at least a 5th order scheme is needed in velocity space to gain sufficient accuracy for ion-temperature-gradient driven instability (ITG)
Ongoing work on ssV involves the addition of electromagnetic capabilities, which will enable application to space and astrophysical plasmas:For example, magnetic reconnection at the ion scales.
