COALESCENCE OF 2 CURRENT LOOPS WITH A KINK INSTABILITY SIMULATED BY A3-DIMENSIONAL ELECTROMAGNETIC PARTICLE CODE

We have studied the dynamics of a coalescence of current loops using a three-dimensional electromagnetic (EM) particle simulation code. Our focus is the investigation of such kinetic processes as energy transfe r, heating of particles, and electromagnetic emissions associated with a current loop coalescence which cannot be studied by MHD simulations . First, the two loops undergo a pinching oscillation due to a pressur e imbalance between the inside and outside of the current loop. During the pinching oscillation, a kinetic kink instability is excited and e lectrons in the loops are heated perpendicularly to an ambient magneti c field. Next, the two current loops collide and coalesce, while at th e same time a helical structure grows further. Subsequently, the pertu rbed current, which is due to these helically bunched electrons, can d rive a whistler instability. It should be noted in this case that the whistler wave is excited by the kinetic kink instability and not a bea m instability. After the coalescence of two helical loops, tilting mot ions can be observed in the direction of left-hand rotation, and the h elical structure will relax resulting in strong plasma heating mostly in the direction perpendicular to the ambient magnetic field. It is al so shown that high-frequency electromagnetic waves can be emitted from the region where the two loops coalesce and propagate strongly in the direction of the electron drift velocity. These processes may be impo rtant in understanding heating mechanisms for coronal loops as well as radio wave emission mechanisms from active regions of solar corona pl asmas.