Low-Frequency Instability of Linearly and   Circularly-Polarized-Microwave-Field Produced Plasmas
  The gas breakdown produced by high-power pulsed linearly and circularly polarized microwave fields which are much weaker than the atomic fields is investigated in the non-relativistic limit. Obtained the electron distribution function produced by the interaction with intense linearly and circularly polarized microwave fields, it is shown that it is non-equilibrium and anisotropic. Finding the general dispersion relation and analyzing it, we firstly obtain the low frequency oscillations and secondly we show that an instability may develop in the aforementioned system. It will be shown that for linearly polarized microwave fields this instability may always develop but for the circular polarization fields it grows only when ion density is higher than a critical density. 
B. Shokri (LRI), M. Ghorbanalilu (LRI)