Simulations suggest that decreasing the spacing between the lenses so that they are less than the diameter of the smallest ring electrode could be a plausible solution to this problem.
[7] Another issue with the design is that the funnel is susceptible to noise with fast neutrals and charged droplets at many atmospheric interfaces during the initial vacuum phase.
The higher pressure required greater pumping in downstream vacuum chambers to compensate for the larger injection of gas.
The most effective resolution is the us of a jet disrupter that consists of a 9 mm diameter brass disk suspended perpendicular to the gas flow in the center of the ion funnel.
This loss was due to the increasing number of collisions undergone by ions with other gas molecules present in the atmosphere.
[5] Proton transfer reaction mass spectrometry has traditionally used drift tubes as ion traps.
However, radio frequency ion funnels offer an attractive alternative, as they improve compound specific sensitivity significantly.