| 摘要 |
PURPOSE:To measure colliding ions with high accuracy by installing a Faraday cup, which has a double-walled structure consisting of an inner cylinder and an outer cylinder having many holes and applying a positive electric potential to the inner cylinder and a negative electric potential to the outer cylinder. CONSTITUTION:In a charged particle irrdiator such as an ion implantation device, an ion beam 1 is selected by a separator 3 and then caused to bump against a target 6 through an accelerating electrode 4 and a scanning electrode 5. Discharged secondary electrons are caught by a Faraday cup 7 installed near the target 6 before being measured by a current meter 8. The Faraday cup 7 has a double-walled structure consisting of an inner wall 27A and an outer wall 27B having many holes. A positive electric potential 11 relative to the target 6 is applied to the inner wall 27A and a negative electric potential 21 relative to the target 6 is applied to the outer wall 27B. And, the target 6 is connected to an ampere meter 8. As a result, secondary ions and gaseous ions produced in the Faraday cup 7 can be completely caught, thereby measuring the amount of ions with high accuracy. |
