Energetic neutral atom Energetic neutral atom Energetic neutral atom (ENA) imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and throughout the heliosphere, even to its outer boundary. This constitutes the far-flung edge of the solar system. The solar wind consists of ripped-apart atoms (called plasma) flying out of the Sun. This is mostly hydrogen, that is, bare electrons and protons, with a little bit of other kinds of nuclei, mostly helium. The space between solar systems is similar, but they come from other stars in our galaxy.
Plasma acceleration from the center of wake by the ponderomotive force or the electrostatic fields from the exciting fields (electron or laser). Plasma ions are too massive to move significantly and are assumed to be stationary at the time-scales of plasma electron response to the exciting fields. As the exciting fields pass through the plasma, the plasma electrons experience a massive attractive force back to the center of the wake by the positive plasma ions chamber, bubble or column that have remained positioned there, as they were originally in the unexcited plasma. This forms a full wake of an extremely high longitudinal