A mass spectrometer, comprising a time-of-flight, TOF, analyzer, comprising: an accelerator stage comprising a plurality of electrodes (1, 2, 3) and adapted to receive and accelerate a plurality of ions, wherein said accelerator stage comprises a first electrode, a second electrode disposed downstream of said first electrode, and a third electrode disposed downstream of the second electrode, wherein the accelerator stage is configured to receive the ions into a space between the first and second electrodes, a drift chamber disposed downstream of said accelerator stage for receiving at least a portion of the accelerated ions, a pulser coupled to the accelerator stage for applying one or more voltages to said plurality of electrodes, a controller coupled to the pulser and adapted to cause the pulser to adjust one or more voltages applied to said electrodes so as to configure the accelerator stage to receive and accelerate positive and negative ions during different cycles of an ion detection period, wherein said controller is configured to cause the pulser to: maintain said first and second electrodes at a ground electric potential during a first phase of a cycle for detecting positive or negative ions so as to allow accumulation of a plurality of positive or negative ions in the space between said first and second electrodes, apply equal positive or negative voltages, respectively, to said first and second electrodes during a second phase of said cycle so as to inhibit entrance of additional positive or negative ions, respectively, into the space between the first and the second electrodes and to create an electric field between the second and third electrodes, apply a voltage differential between said first and second electrodes during a third phase of said cycle so as to accelerate the ions accumulated in the space between the first and second electrodes toward said drift chamber, wherein the electric field created between the second and third electrodes in the second phase persists in the third phase, and maintain said first and second electrodes at the ground electric potential during a fourth phase of said cycle in which the accelerated ions pass through the drift chamber. an accelerator stage comprising a plurality of electrodes (1, 2, 3) and adapted to receive and accelerate a plurality of ions, wherein said accelerator stage comprises a first electrode, a second electrode disposed downstream of said first electrode, and a third electrode disposed downstream of the second electrode, wherein the accelerator stage is configured to receive the ions into a space between the first and second electrodes, a drift chamber disposed downstream of said accelerator stage for receiving at least a portion of the accelerated ions, a pulser coupled to the accelerator stage for applying one or more voltages to said plurality of electrodes, a controller coupled to the pulser and adapted to cause the pulser to adjust one or more voltages applied to said electrodes so as to configure the accelerator stage to receive and accelerate positive and negative ions during different cycles of an ion detection period, wherein said controller is configured to cause the pulser to: maintain said first and second electrodes at a ground electric potential during a first phase of a cycle for detecting positive or negative ions so as to allow accumulation of a plurality of positive or negative ions in the space between said first and second electrodes, apply equal positive or negative voltages, respectively, to said first and second electrodes during a second phase of said cycle so as to inhibit entrance of additional positive or negative ions, respectively, into the space between the first and the second electrodes and to create an electric field between the second and third electrodes, apply a voltage differential between said first and second electrodes during a third phase of said cycle so as to accelerate the ions accumulated in the space between the first and second electrodes toward said drift chamber, wherein the electric field created between the second and third electrodes in the second phase persists in the third phase, and maintain said first and second electrodes at the ground electric potential during a fourth phase of said cycle in which the accelerated ions pass through the drift chamber. maintain said first and second electrodes at a ground electric potential during a first phase of a cycle for detecting positive or negative ions so as to allow accumulation of a plurality of positive or negative ions in the space between said first and second electrodes, apply equal positive or negative voltages, respectively, to said first and second electrodes during a second phase of said cycle so as to inhibit entrance of additional positive or negative ions, respectively, into the space between the first and the second electrodes and to create an electric field between the second and third electrodes, apply a voltage differential between said first and second electrodes during a third phase of said cycle so as to accelerate the ions accumulated in the space between the first and second electrodes toward said drift chamber, wherein the electric field created between the second and third electrodes in the second phase persists in the third phase, and maintain said first and second electrodes at the ground electric potential during a fourth phase of said cycle in which the accelerated ions pass through the drift chamber.