Formation of voidless dusty plasma using coaxially-segmented RF discharge under microgravity condition

A technique is presented for producing a dusty plasma without void inside by introducing a coaxially-segmented parallel plate radio-frequency (RF) discharge under mictrogravity condition. Main plasma for the dusty plasma experiment is produced in a central core part of the parallel plate discharge, while a plasma for igniting the core plasma discharge is produced in the periphery region surrounding the core plasma. In order to reduce the ion drag force that is a cause of the void formation, the core plasma density can be markedly decreased owing to the supply of primary electrons from the periphery plasma. We observed a voidless disk-shape dusty plasma between the coaxially-segmented RF electrodes in the microgravity experiment.