A new approach to the implementation of a delayed dc ramp quadrupole mass filter

Abstract

The new approach to the delayed dc ramp uses a set of small electrodes which are conveniently integrated into the exit aperture plate of the ion source. These electrodes are energized with dc potentials only, of polarity opposite to that of the rod electrodes with which they are associated. The delayed dc ramp is obtained by nulling or neutralizing the electric field from the rod potentials in the vicinity of the ion entrance aperture. Experimental data indicates that the new approach improves the performance of the quadrupole very much like the old improves it. The avoidance of ac potentials on these electrodes facilitates the mounting and the use of these electrodes. © 1974 IOP Publishing Ltd.