| 摘要 |
PURPOSE:To exactly know the maintenance time of a liquid metal ion source by monitoring pickup voltage of the liquid metal ion source. CONSTITUTION:An ion source chamber 1 is provided with a liquid metal ion source 1a, a pickup electrode 1b, an acceleration cathode electrode (earth) 1c and a monitor aperture 1d, and a pickup voltage 2 and an acceleration voltage 3 are applied between the ion source 1a and the pickup electrode 1b, and between the ion source 1a and the acceleration cathode electrode 1c, respectively. Also, to the monitor aperture 1d, an ion current flows, when an ion beam is led out, and this ion current is converted to a voltage by a current - voltage converting circuit 4, a difference to a prescribed voltage 5a is obtained by a differential amplifying circuit 5, and the pickup voltage of the ion beam can be monitored therefrom. Therefore, when the ion beam is being led out surely by an integrating means 12, an emission time is obtained. In such a way, the maintenance time of a liquid metal ion source can be obtained exactly. |
