An orthogonal pulse accelerator for a Time-of-Flight mass analyzer includes an electrically-conductive first plate extending in a first plane, and a second plate spaced from the first plate. The second plate includes a grid that defines a plurality of apertures each having a first dimension extending in a 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 begin larger than the first dimension. The first and second plates are positioned in the Time-of-Flight mass analyzer to receive, during operation of the mass analyzer, an ion beam propagating in the first direction in a region between the first and second plates, and the orthogonal pulse accelerator directs ions in the ion beam through the apertures.