Abstract
A new total pressure measurement method in a quadrupole mass analyzer is described. A needle collector inserted in the grid functions as an ion collector of a Bayard-Alpert gauge when the needle collector is biased at ground potential via an electrometer. The sensitivity factor is about 0.016 Pa-1 with 2 mA emission current. The ion current via the needle collector is linear between 10-9 Pa and 10-1 Pa. When the needle collector is biased at gird potential, the peak height of spectrum increased by a factor of 19. Thus, once the multiplied value of a secondary electron multiplier is confirmed for the total pressure values with the needle collector at around 10-8 Pa, we are able to measure the total pressure of 10-11 Pa with the new RGA as well as the partial pressure quantitatively.
