Abstract
The ion current of an ionization gauge controlled by a commercially available gauge controller is usually accompanied with high level noise of 50 to 100Hz. The noise disturbs the measurement of abrupt change of pressure which terminates in the time duration less than 1 sec. The noise superposed on the ion current is found to be induced electro-statically by the noise of filament power supply circuit of the controller.
Performance of the improved circuit and that of the low pass filter used to reduce the noise at the output of dc amplifier are measured and discussed.
