Production of low-density plasma by coaxially segmented rf discharge for void-free dusty cloud in microgravity experiments

A technique is presented for producing a low density plasma by introducing a coaxially segmented parallel-plate radio-frequency discharge for void-free dusty-cloud formation. 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. The core plasma density can be markedly decreased to reduce the ion drag force, which is important for a formation of void-free dusty cloud under microgravity.