A small magnetic analyzer mass spectrometer with a velocity filter for residual gas analysis

Abstract

A simple magnetic analyzer mass spectrometer is described which has a sensitivity of 10−2|torr at a resolving power of 20. The use of a miniature Wien velocity filter preceding the magnetic analyzer allows a sensitivity of 5 × 10−3|torr to be achieved at a resolving power of 40.The design features for the basic mass spectrometer are discussed and ion paths in the magnetically immersed ion source are traced. The criteria for sensitivity and resolving power in small instruments are discussed in terms of the common aberrations encountered.