A mass spectrometer including an ion source, an ion guide, a pulsed converter, and an electrostatic analyzer is disclosed, along with a method of mass spectrometry and an ion injector. The ion source generates ions, such as ions within a continuous or a quasi-continuous ion beam. The ion guide receives a portion of the ions generated by the ion source. The pulsed converter, which receives ions from the ion guide, includes at least one electrode connected to a RF signal. The pulsed converter may include a means for ejecting the ions in the form of ion packets. The electrostatic analyzer forms a two-dimensional electrostatic field in an X-Y plane. The electrostatic field is substantially extended in a Z-direction that is locally orthogonal to the X-Y plane and may be curved or linear. Ions undergo isochronous ion oscillations in the electrostatic field. The pulsed converter and electrostatic analyzer are Z-directionally elongated.