Time of flight mass analyzer having improved mass resolution and method of operating same

A flight tube arrangement for use in a time-of-flight mass analyzer comprising:

• a first electrode having a generally cylindrical electrode surface facing an interior portion thereof, said first electrode further having an ion inlet disposed through a side thereof;
• a second electrode having a generally cylindrical electrode surface facing an exterior portion thereof, said second electrode being concentrically disposed with said first cylindrical electrode, said second electrode further having an opening through an arcuate portion of the electrode surface at least in a region proximate said ion inlet;
• a third electrode having an arcuate electrode surface facing an exterior portion thereof, said third electrode being disposed in said arcuate opening of said second electrode;
• and
• at least one power supply connected to said first, second and third electrodes, said power supply being operable to generate a generally static electric field between said first and second electrodes, said power supply further being alternately operable between at least a first state in which the region between said first and third electrodes proximate said ion inlet is generally field free, and a second state in which a generally static electric field is generated in the region between said first electrode and said second and third electrodes.

A time-of-flight mass analyzer comprising:

• an ionizer adapted to generate ions of a sample substance to be analyzed;
• a flight tube having at least one linear portion defined by a linear axis, said flight tube further having an input region accepting ions generated by the ionizer, said flight tube adapted to constrain said ions in a substantially static electric field having non-linear equipotential field lines that circumvent said linear axis;
• said ions being provided to said input region of said flight tube at an angle that is tangential to said equipotential field lines of said substantially static electric field to thereby initially trap said ions in said input region of said flight tube;
• an electrode disposed for use in generating an electric field that imparts a velocity component along said linear axis to said ions whereby said ions move away from said input region of said flight tube;
• an ion detector disposed to detect ions exiting said flight tube;
• at least one timer adapted to determine the flight time of said ions along an ion path that comprises at least said flight tube.