Multi-reflection mass spectrometer

A method of operating a multi-reflection mass analyser, the method comprising:

• with a controller, placing electrical potentials on a series of electrodes such that a potential difference between adjacent electrodes of a first pair of adjacent electrodes of the series of electrodes is at least ten times higher than a potential difference between adjacent electrodes of a second pair of adjacent electrodes of the series of electrodes,
• wherein the multi-reflection mass analyser comprises:
• a pair of opposed ion-optical mirrors elongated linearly along a longitudinal axis that extends centrally through the multi-reflection mass analyser, wherein either one or both ion-optical mirrors comprises the series of spaced apart electrodes,
• wherein:
• each electrode is elongated along the longitudinal axis;
• the series of electrodes extend in a direction transverse to the longitudinal axis and the electrodes are spaced apart by a series of gaps;
• the first pair of adjacent electrodes are separated by a straight gap defined by respective straight edges of the adjacent electrodes;
• and
• the second pair of adjacent electrodes are separated by a curved gap defined by respective curved edges of the adjacent electrodes.