Orthogonal acceleration system for time-of-flight mass spectrometer

A method, comprising:

• directing an ion beam in a first direction within a first region between a first electrically-conductive plate extending in a first plane and a second plate extending in a second plane parallel to the first plane, the second plate comprising a grid that defines a plurality of apertures each having a first dimension extending in the first direction and a second dimension orthogonal to the first dimension, the first and second dimensions lying in the second plane and the second dimension being larger than the first dimension;
• while receiving the ion beam propagating in the first direction in the first region between the first and second plates:
• (i) applying voltages to the first and second plates to provide a first electric field between the first and second plates;
• (ii) applying a first voltage to a third plate positioned in a third plane spaced apart from and parallel to the second plane on an opposite side of the second plane from the first plane;
• and
• (iii) applying a second voltage to a fourth plate positioned in a fourth plane spaced apart from and parallel to the third plane on an opposite side of the third plane from the second plane, the first and second voltages establishing a second electric field between the third and fourth plates;
• adjusting the first voltage to minimize field penetration from the second electric field into the first region, such that the first electric field is essentially zero;
• applying a third voltage on the first electrically-conductive plate to produce a third electric field between the first and second plates to accelerate at least a portion of ions in the ion beam in the first region through the apertures of the second plate such that a strength of the second electric field in a region between the first and second plates is essentially identical to an electric field strength in a region on the opposite side of the second plate, away from the first plate, while applying a fourth voltage on the third plate essentially simultaneous with the application of the third voltage on the first plate, such that a strength of the third electric field in the first region between the first and second plates is essentially identical to an electric field strength in a region on the opposite side of the second plate, away from the first plate, and
• directing the ions which have passed through the apertures of the second plate through apertures of the third plate, and then through apertures of the fourth plate, while maintaining a fourth electric field between the third plate and the fourth plate.