Effect of kinetic ions on the toroidal double-tearing modes

We investigate the effects of kinetic ions on double-tearing modes (DTMs) using the gyrokinetic particle-in-cell simulation code GEM with a gyrokinetic ion/fluid electron hybrid model. It is found that the ion kinetic effects can decrease the growth rate of the DTMs. This effect is more significant for stronger coupling of DTMs with smaller distance between the rational surfaces. Kinetic ions can also enhance the coupling effect between the two rational surfaces. Energy transfer analyses between particles and wave fields show that the stabilizing effect of kinetic ions comes mainly from the perpendicular magnetic drift of ions in the coupling region and around the outer rational surface.

Automated summary

We study the effects of kinetic ions on double-tearing modes using the GEM gyrokinetic particle-in-cell simulation code with a gyrokinetic ion/fluid electron hybrid model. Our results show that ion kinetic effects can decrease the growth rate of these modes, with a stronger effect for modes coupled to rational surfaces at smaller distances. Kinetic ions also enhance the coupling effect between the rational surfaces. Energy transfer analyses reveal that the stabilizing effect of kinetic ions is mainly attributed to the perpendicular magnetic drift of ions in the coupling region and around the outer rational surface.