Plasma wave, and sounder experiments (PWS) on board the EROS-D (Akebono) satellite are continuously providing the wide variety of data which contribute to the studies on plasma wave phenomena associated with the wave particle interactions in the regions of the cusp, auroral particle acceleration, and magnetic equator. Observation results of the auroral kilometric radiation (AKR) with Poynting vector, polarization as well as the dynamic spectra, have indicated that the generation mechanism of AKR is not necessarily due to the cyclotron maser mechanism but majority parts of AKR's are caused by the conversion of upper hybrid waves through the Doppler conversion processes and also through irregularities of the plasma in the auroral particle acceleration regions. Propagating electromagnetic wave phenomena in the plasmasphere are 1) banded rising and falling LF waves (ERIFLE), 2) discrete HF emissions, and 3) terrestrial hectometric radiations. There are localized modes of the plasma waves such as 4) upper hybrid mode waves, 5) Z-mode waves and 6) quasi-electrostatic whistler mode waves. Reflecting the evidence of the strong wave particle interactions, in the region of the cusp and auroral particle precipitation region, 7) broad band electrostatic noises are frequently observed and these become good indicator of the particle precipitation when the low energetic particle detector makes a pause of their operation in the low latitude range. Storm time effects of the plasma waves show also unique and important features; plasmaspheric odd harmonic, (n+1/2) fc emissions which have never detected in the plasmasphere inside of the plasmapause in the regular condition of the magnetic field activities take place even in the plasmasphere inside of the plasmapause in the times of large magnetic storm.The plasma density profiles obtained from the observed upper hybrid waves provide wide variety of variation of the plasmasphere and plasmapause structure with informations of the plasma instabilities there. A review has been made for the instabilities identified in the magnetic equator whose occurrence region is circulating at the magnetic equator covering the altitude from 1, 000km to 10, 000km. In the storm time, the plasmapause has apparently been disrupted with depressed density and loosing sharp edge of the density variation. In the recovery phase of the large magnetic storm, the plasma density distribution shows large disturbances where the amplitudes of the irregular variation of the plasma density become 5 to 6 times or sometimes an order of magnitude of the background density itself. Also during recovery phase of the storm, a large scale cavity of the plasma is formed centered at the magnetic equator coinciding with the position of expected ring current. All of these results show that the PWS on board the EROS-D satellite are making effective contribution to study on the energy transfer through the plasmasphere providing data of the electron density, temperature anisotropy and informations on existing free energy of the plasma and the energetic particles.