Multi-pass mass spectrometer

A time-of-flight mass spectrometer comprising:

• at least one ion mirror for reflecting or turning ions in a first dimension (X-dimension);
• an ion accelerator for pulsing ion packets into the ion mirror;
• an ion detector;
• and
• an ion guide being part of the ion accelerator and having electrodes arranged to receive ions travelling along a first axis (Z-dimension), including a plurality of DC electrodes spaced along the first axis, and DC voltage supplies configured to apply different DC potentials to alternate ones of said DC electrodes such that when ions travel through the ion guide along the first axis they experience an ion confining force, generated by the DC potentials, in at least one dimension (X- or Y-dimension) orthogonal to the first axis.

A time-of-flight mass analyser comprising:

• at least one ion mirror for reflecting ions in a first dimension (X-dimension);
• an ion accelerator for pulsing ion packets into the ion mirror;
• and
• an ion detector;
• wherein the mass analyser comprises focusing electrodes that are spaced apart from each other in the first dimension by a gap, wherein the gap is elongated in a second dimension (Z-dimension) that is orthogonal to the first dimension, and wherein the longitudinal axis of the gap curves.