Apparatus and method for focusing ions and charged particles at atmospheric pressure

Apparatus for the collection and focusing of an aerosol of gas-phase charged droplets or particles at or near atmospheric pressure, the apparatus comprising:

• a. a source of charged droplets or particles;
• b. a conductive high transmission surface with a plurality of holes through which said aerosol of charged droplets pass, unobstructed on the way to a target surface, said high transmission surface having a topside and an underside, said high transmission surface being supplied with an attracting electrostatic potential by connection to a voltage supply, and generating an electrostatic field between said source of charged droplets, and said topside of said high transmission surface, whereby said electrostatic field at said underside of said high transmission surface is greater than said electrostatic field at said topside of said high transmission surface;
• c. a target surface for receiving said charged particles, said target surface being supplied with a second ion-attracting and higher strength electrostatic potential by connection to said voltage supply, and generating an electrostatic field between said underside of said high transmission surface and said target surface whereby electrostatic field lines are concentrated to a reduced cross-sectional on said target surface;
• d. an inner field-shaping electrode for focusing said charged particles exiting said underside of said high transmission surface whereby approximately all said charged droplets are focused onto said target surface.

A Method for the transfer of charged particles or ions from a highly dispersive area or source at or near atmospheric pressure and focusing approximately all said charged particles or ions into an inlet aperture for gas-phase ion analysis, the method comprising:

• a. providing electrostatic attraction to said charged particles or ions with electrostatic fields provided by a perforated high transmission surface said perforated high transmission surface having an ion drawing potential, such that electrostatic field lines between said source of gas-phase charged particles or ions and said perforated high transmission surface are concentrated on the topside of said perforated high transmission surface;
• b. transmitting said charged particles or ions through said perforated high transmission surface by allowing the unobstructed passage into a focusing region by providing a plurality of holes in said perforated high transmission surface with low depth aspect ratio, a high openness aspect ratio, and a an electrostatic potential ratio greater than one, between the underside and said topside of said perforated high transmission surface and;
• c. providing electrostatic attraction to said charged particles or ions in said focusing region with a second electrostatic field generated by a target surface, said target surface having an ion-drawing potential such that electrostatic field lines between said underside of said perforated high transmission surface and an inlet aperture in said target surface are concentrated onto said target surface urging approximately all said charged particles or ions in said focusing region to be directed towards said target surface whereby approximately all said charged particles or ions flow into said inlet aperture as a reduced cross-sectional area.