SM13E-2564
Generation of coherent ion acoustic solitary waves in inhomogeneous plasma by odd-symmetric trapped mode in an electron hole

Monday, 14 December 2015
Poster Hall (Moscone South)
Kyunghwan Dokgo1, Minho Woo2, Cheongrim Choi1, Kyoung W Min1 and Junga Hwang3, (1)KAIST Korea Advanced Institute of Science and Technology, Daejeon, South Korea, (2)NFRI National Fusion Research Institute, Deajeon, South Korea, (3)KASI Korea Astronomy and Space Science Institute, Daejeon, South Korea
Abstract:
The generation of coherent ion acoustic solitary waves (IASWs) due to interactions between an electron hole (EH) and density gradient of plasma is investigated by both 1D particle-in-cell (PIC) simulation and theory. In our simulation, an EH is generated by plasma blob injection at the beginning. When the EH passes density gradient region, two features are observed: one is oscillations of EH bipolar field and another is IASWs generation. We found that these E field oscillations correspond to odd-symmetric trapped mode in the EH (OSTM). Using theoretical formalism introduced by Lewis, we theoretically derived the structure and the dispersion relation of OSTM. The OSTM structures calculated from simulation and theory are in good agreement. In the presence of density gradient, OSTM structure is distorted and become spatially asymmetric; its potential is weak in the higher density side and strong in the lower density side. Ions are pulled and pushed by the OSTM potential. As a results of potential difference, ions are accelerated to the lower density side then they formed IASWs. These process are repeated in the density gradient region when EH are passing, so IASWs are generated coherently.