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Linear dispersion relation of parametric instabilities of a left hand circularly polarized wave in a three species plasma consisting electrons, protons, and α particles is derived and the obtained dispersion relation is numerically solved. It is shown that the so-called super Alfvénic waves, which are thought to play important roles in preferential acceleration of heavy ions, can get excited through a parametric decay instability when the parent wave is on the proton cyclotron branch and the plasma beta is sufficiently low. A variety of other parametric instabilities are also generated.

One of the important and interesting problems in astrophysics and plasma physics is collimation of plasma jets. The collimation mechanism, which causes a plasma flow to propagate a long distance, has not been understood in detail. We have been investigating a model experiment to simulate astrophysical plasma jets with an external magnetic field [Nishio et al., EPJ. Web of Conferences 59, 15005 (2013)]. The experiment was performed by using Gekko XII HIPER laser system at Institute of Laser Engineering, Osaka University. We shot CH plane targets (3 mm × 3 mm × 10 μm) and observed rear-side plasma flows. A collimated plasma flow or plasma jet was generated by separating focal spots of laser beams. In this report, we measured plasma jet structure without an external magnetic field with shadowgraphy, and simultaneously measured the local parameters of the plasma jet, i.e., electron density, electron and ion temperatures, charge state, and drift velocity, with collective Thomson scattering.

Collective scattering of an incident monochromatic circularly polarized electromagnetic wave in an unmagnetized non-equilibrium plasma is investigated. The wave equation of the scattered waves are numerically solved by giving wave spectra of the incident electromagnetic wave and a variety of longitudinal fluctuations of a plasma. In addition to the well known symmetric ion and electron features of frequency spectrum in an equilibrium plasma, some asymmetries are found in a frequency spectrum when anisotropic longitudinal wave propagation or the effect of the presence of a beam mode are taken into account.

Electron acceleration in a high plasma beta and low Mach number quasiperpendicular shock is investigated by using two-dimensional full particle-in-cell simulation. Although efficient shock drift acceleration followed by reflection was observed in the previous one-dimensional simulation, no reflected electrons are found due to the effect of shock surface rippling for the particular parameters examined here. Structure of the shock transition region is complex in spite of the high beta and low Mach number situation. In addition to the ion scale fluctuations including the ripple, electron scale fluctuations are also recognized. Among these, downstream fluctuations are dominated by Alfven ion cyclotron instability, the fluctuations in the foot are due to modified two-stream instability. Electron distribution function in the transition region indicates non-thermal nature. The energy gained by the non-thermal electrons is not explained merely by the shock drift acceleration, implying the importance of local wave- particle interactions.