Collapse of Lagmuir solitons in inhomogeneous plasmas
Y.Nishimura1*, Y.A.Cheng1, C.Z.Cheng1, Y.Nishida1
1Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan
* presenting author:Yasutaro Nishimura,
A numerical experiment of Langmuir soliton in inhomogeneous plasma is reported. Incorporating the background density gradient, Langmuir solitons are accelerated. Ion density pulses exactly at the ion acoustic wave velocity are emitted during the acceleration of Langmuir solitions. When the electric field quickly spread with the density inhomogeneity above the threshold, the density cavity lose sustaining mechanism by the ponderomotive force. The solitons then collapse into two clumps of ion cavities released at the ion acoustic wave velocity when the acceleration is above the threshold.
Hinted by the emission of density pulse during the acceleration,
collapse threshold of Langmuir solitions is discussed.

Keywords: Langmuir soliton, Zakharov system, Soliton acceleration