Modified extractor gauge

Abstract

The design and performance of a modified extractor gauge for ultrahigh vacuum pressure measurement is described. The open end construction of the grid cage prevents the x rays from striking the ion collector directly except for those minor indirect x rays that are reflected at respective electrodes. The sensitivity factor is about 8.3×10−2 Pa−1 (11 Torr−1) at an electron current of 1 mA corresponding to the residual gases. Pressure measurements were carried out in the range of 1×10−6 to 9×10−10 Pa (1×10−8 to 7×10−12 Torr). It is confirmed that the x‐ray limit of the gauge is lower than that of the nude‐type B–A gauge. Description is also given of the modified design of the gauge for high vacuum pressure measurements facilitated by the cap electrode mounted on the top of the grid cage.