| 摘要 |
PURPOSE:To enhance magnetic flux density within an arc chamber and reduce the size of apparatus by providing, to both ends of arc chamber forming the magnetic field, a member for concentrating the line of magnetic force of a ferromagnetic body of such a shape that the area being in contact with the arc chamber is smaller than the area of opposite side. CONSTITUTION:Electrons emitted from a hot cathode 3 are ionized through collision with gas introduced from the gas introducing entrance 4. A ferromagnetic member 6 for concentrating the line of magnetic force is provided outside the upper and lower ends of an arc chamber 2 being held at a high voltage by a high voltage power supply 13. This concentration member 6 is formed in a trapezoid where the area being in contact with the arc chamber is narrow but the opposite area is wide. Owing to this ferromagnetic member 6, the magnetic flux passes through the internal side of arc chamber 2 and thereby a large magnetic flux density in the arc chamber can be obtained. |
