| 摘要 |
PURPOSE: To decrease the spread of ion energy and enhance the sensing preciseness by heightening the gas pressure in a region of an ion optical element within a certain limit, using a comparatively small DC voltage difference, and lessening the converging aberration of the ion optical element. CONSTITUTION: Ions produced in an ionizing chamber 16 are moved through an orifice 26 and an opening 20 by a proper DC voltage on AC-only rod sets 32 and plates 22 and 28 and led into rod sets 40 upon being passed through the AC-only rod sets 32 and a space orifice 34. If at this time, the DC voltage difference between the orifice plate 28 and rod sets 32 is sunk to 1-30 volts, preferably 1-10 volts using the AC-only rod sets 32, the ion signal will increase to a considerable degree even though the pressure in a vacuum chamber 30 is raised. This allows heightening of the sensitivity more with a greater mass. |
