title: Operating conditions for the generation of stable anode spot plasma in front of a positively biased electrode.
abstract: Stability of an anode spot plasma, which is an additional high density plasma generated in front of a positively biased electrode immersed in ambient plasma, is a critical issue for its utilization to various types of ion sources. In this study, operating conditions for the generation of stable anode spot plasmas are experimentally investigated. Diagnostics of the bias current flowing into the positively biased electrode and the properties of ambient plasma reveal that unstable nature of the anode spot is deeply associated with the reduction of double layer potential between the anode spot plasma and the ambient plasma. It is found that stability of the anode spot plasma can be improved with increasing the ionization rate in ambient plasma so as to compensate the loss of electrons across the double layer or with enlarging the area of the biased electrode to prevent electron accumulation inside the anode spot. The results obtained from the present study give the guideline for operating conditions of anode spot plasmas as an ion source with high brightness.
authors.affiliation: Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea.
authors.forename: Yeong-Shin
authors.initials: YS
authors.lastname: Park
authors.affiliation: Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea.
authors.forename: Yuna
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea.
authors.forename: Jeong-Jeung
authors.initials: JJ
authors.lastname: Dang
authors.affiliation: Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744, South Korea.
authors.forename: Kyoung-Jae
authors.initials: KJ
authors.lastname: Chung
authors.affiliation: Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea.
authors.forename: Y S
authors.initials: YS
authors.lastname: Hwang