Spatial distribution of ion energies in an inertial electrostatic confinement device

The spatial distribution of ion energies was measured in an inertial electrostatic confinement device, which can be used as a small nuclear fusion source for the generation of neutrons. Using Doppler shift spectroscopy and a single ended Langmuir probe it was found that a virtual anode was established at the center of the electrostatic potential well resulting in much reduced ion energies at this point. Moreover, there was direct correlation between the ion energies and the spatial plasma potential showing the validity of the probe measurements. It was shown that the ion energy is a maximum at the point where the potential is the deepest, which occurs about halfway between the center and the cathode radius