Generation of waves by active plasma releases in the magnetosphere and solar wind

Active experiments in the ionosphere, magnetosphere and solar wind play a role in understanding fundamental plasma physics processes. Different types of active experiments are conducted including using intense electromagnetic radiation to excite plasma waves, generating turbulence that heats the plasma, or releasing plasma into the medium and measure the response. In this talk I will present theory, 3D hybrid simulations and full PIC simulations of the interaction involving the release of different plasma ions in the magnetosphere and solar wind. Both electromagnetic and plasma release experiments can generate strong wave activity over a range of frequencies. A particularly interesting series of experiments carried out by the Active Magnetospheric Particle Tracer Explorers (AMPTE) satellite mission was the release of neutral barium atoms and lithium atoms in the magnetosphere and solar wind. The AMPTE mission was designed to study the access of solar wind lithium ions into the magnetosphere and the formation of an artificial comet by barium ions. The mission was composed of three spacecraft two of the spacecraft the Ion Release Module (IRM) and the UK Satellite (UKS) were in the same orbit that took them out into the solar wind while a third spacecraft the Charge Composition Explorer (CCE) remained inside the magnetosphere where it could measure the lithium ions that made their way into the magnetosphere. The lithium atoms ionized relatively slowly allowing the lithium atoms to spread out before ionizing forming a large area in front of the magnetosphere. The barium atoms ionized by photoionization extremely rapidly forming a dense, expanding, plasma cloud that interrupted the solar wind flow creating diamagnetic cavities. On the upstream side of the cavity a region of compressed plasma and enhanced magnetic field was created as the result of being produced by the slowing down and deflection of the solar wind, and magnetic field line draping. Intense electrostatic and magnetic turbulence was observed by both the IRM satellites at the boundary of the diamagnetic cavity, with the most intense waves being detected near the outer boundary of the compressed region. Theory and simulations examine how the newly created expanding plasma couples to the solar wind by means of plasma-beam and current-driven instabilities, it is shown how lower-hybrid and lower-hybrid drift waves are generated by cross-field proton-barium streaming instabilities and cross-field electron currents. The saturation mechanism for these waves is shown to be the modulational instability described by Zakharov like equations for wave collapse. This instability can also lead to filamentation and coupling to magnetosonic modes, which are also observed. As the result of the modulational instability heating and acceleration of electrons occurs, that is consistent with the observations. The talk will present data, theory and simulations of the plasma release experiments.