A Time of Flight mass analyzer is disclosed comprising one or more acceleration electrodes and a first device arranged and adapted to apply a DC voltage pulse to the one or more acceleration electrodes. The DC voltage pulse causes ions to be accelerated into a time of flight or drift region and the DC voltage pulse is applied, in use, to the one or more acceleration electrodes between a time T1 and a time T2. A second device is arranged and adapted to apply a single phase oscillating voltage to the one or more acceleration electrodes, wherein the single phase oscillating voltage undergoes multiple oscillations between the time T1 and the time T2. The application of the DC voltage pulse and the single phase oscillating voltage to the one or more acceleration electrodes establishes an homogeneous electric field having a net force towards the time of flight or drift region.