Ion funnels and systems incorporating ion funnels

An atmosphere-to-vacuum ion transport system comprising:

• an ion transfer tube extending between an atmospheric-pressure ionization chamber and a partially evacuated chamber;
• a first ion tunnel within the partially evacuated chamber configured to receive gas and charged particles from the ion transfer tube, comprising:
• a first plurality of plate electrodes configured as a stack, each electrode of the first plurality of electrodes having an aperture therein, all apertures of the first plurality of electrodes having a same diameter, θT;
• a second ion tunnel comprising:
• a second plurality of plate electrodes configured as a stack,
• each electrode of the second plurality of electrodes having an aperture therein, all apertures of the first plurality of electrodes having a same diameter, θ0, where θ0<θT and wherein θ0 is greater than or equal to three times an inter-electrode pitch, d, of the second plurality of plate electrodes;
• an exit electrode having an exit aperture therein having a diameter, ϑ, and configured to receive the charged particles from the second ion tunnel and to deliver the charged particles to a high-vacuum chamber, wherein ϑ<θ0;
• and
• an ion funnel within the partially evacuated chamber configured to receive the charged particles from the first ion tunnel and to deliver the charged particles to the second ion tunnel, comprising:
• a third plurality of plate electrodes configured as a stack, each electrode of the third plurality of electrodes comprising an aperture therein, each aperture having a respective diameter, θ, where θT≥θ≥θ0.