| 摘要 |
PURPOSE:To prevent both the breaking of a filament by vibration and shortening of life caused by the sticking of a sputtering material emited from the filament occurring during use, by forming the cathoed structure of a magnetron in such configuration that the part of its lower end hat supporting the lower end of the filament covers the peripheral portion of the filament side end surface of a ceramic spacer in a pent roof shape. CONSTITUTION:In the figure, index 8 represents a lower end hat related to this ivention. Its part 8a supporting the lower end of a filament is projected inward in a pent roof shape so as to cover the peripheral portion of the upper end surface 6a of a ceramic spacer, apart from this end surface. Then, the diameter of the ring like part of the upper end surface 6a of the ceramic spacer on which a sputtering material emitted from the filament sticks becomes smaller than the former size, and a wide part having high surface resistance which is not stuck and contaminated with the sputtering material is remained on its periphery. As this part is not heated by the electric field of a microwave, a short life accident caused by the emission of gas from its vicinity, dielectric breakdon or the like may not occur. The, even if the diameter of a lead wire for supporting th filament is made small, no problem seems to lake place. |
