Conditioning of Positive Inflector Voltage for The Injection of Negative Ions at TARN-II

摘要

An ultrahigh vacuum of the order of 10~(-8)Pa has been kept to obtain sufficient beam life times for the beam experiments at TARN-II. Recently, positive high voltage was applied to inflector electrodes to inject H~- ion beam in the ring. In this case, vacuum pressure rose up to the order of 10~(-6) Pa and residual gas components of CO and CO_2 remarkably increased. We tried to get a required inflector voltage at normal vacuum pressure by conditioning the electrodes. As a result, vacuum pressure was improved to 1.2×10~(-8)Pa at high voltage of +44 kV.