Abstract
Non-contact plasma refers to a state in which plasma is isolated from solid walls, and plasma that is disappearing through volume recombination is called recombining plasma. In magnetic confinement fusion reactors, thermal control via non-contact plasma is envisioned, and it is important to deepen our understanding of this approach through basic research. Linear plasma devices with simple geometric structures can be used to study atomic and molecular processes, as well as other physical phenomena involved in the formation and maintenance of non-contact plasma. Many previous studies have used direct-current discharges, but at Tohoku University's DT-ALPHA device, research is advancing with an electrode-less radio-frequency plasma approach. In this seminar, we introduce the characteristics of radio-frequency plasma and the insights on plasma measurements and the behavior of recombining plasma obtained so far at DT-ALPHA. More recently, collaborative research using multiple linear devices, including DT-ALPHA, GAMMA 10/PDX, and PGX-SC, has been underway, and the motivations and future prospects for this work will also be introduced.