[P-EM16] Space Plasma Physics: Theory and Simulation

[PEM16-P09] On multiple parametric decay instability of arc-polarized Alfven waves

*Yasuhiro Nariyuki¹ (1.Faculty of Education, University of Toyama)

Keywords:nonlinear Alfven wave, parametric instability

Finite amplitude Alfven wave is an exact solution of the ideal magnetohydrodynamic (MHD) system. It is important that the angle between the ambient magnetic field and the wave number vector can be finite even in exact Alfven waves. The arc-polarized Alfven wave is one of such Alfven waves and unstable to the parametric decay instability [e.g., Del Zanna (2001); Del Zanna et al (2015)]. In this presentation, we revisit the parametric decay instability of arc-polarized Alfven waves. Since more than one frequency component is included in arc polarized waves, parametric decay instabilities satisfying different resonance conditions simultaneously occur. Occurrence of such multiple parametric decay instability is demonstrated by using the three-dimensional MHD simulation. Dependence of the decay instability on anisotropy of the wave number spectra is discussed.