Onset of Tilt Instability in FRC Plasmas

Tilt instability in FRC plasmas is a well-known MHD phenomenon that has been extensively investigated over the years by different authors and an empirical scaling law of the numerical growth rate versus the plasma E/S* parameter has been discussed in the literature. FPIC, TAE Technologies’ proprietary hybrid code, was also recently deployed to study the n=1 toroidal modes as tilt, radial shift and interchange. In spite of the investigations already carried out what is the exact onset mechanism and what are the plasma structures which characterize the very early phase of the tilt instability remain largely unknown and any possible investigation requires very large computational resources. Thanks to computing resources provided at ALCF by the 2018 INCITE program it has been possible to utilize HPC capabilities and apply FPIC at unprecedented levels of resolution. Detailed plasma structures at tilt onset and subsequent times are presented and discussed.