| 摘要 |
PURPOSE:To electrically shield a gastight wall against a positive electrode core line so as to prevent an error in measurement, by setting a grid electrode whose electric potential is not higher than that of the gastight wall, to lie midway between the gastight wall and the positive electrode core line. CONSTITUTION:A grid electrode 5 which is formed of many electric conductive lines which connect both side surfaces of a gastight wall 1 to each other, is set inside the gastight wall 1. This electrode 5 is formed cylindrically around a core line 3 as its axis, kept equipotential with the gastight wall 1, and a big space (s) is made between the wall 1 opposite to a window 4 of radiation incidence in relation to the core line 3, and the electrode 5. The space is not made at the window 4. In this way, most of the incident radiation taken from the window 4 excites gas molecules in the electrode 5, and disappears. A part of the radiation incident upon the wall 1 opposite to the window 4, generates fluorescent X-ray and Auger electron, but an error in measurement due to generation of X-ray or Auger electron can be prevented, as a big space (s) is made at the wall 1 opposite to the window 4. |
