Time of Flight mass analyser and method of Time of Flight mass spectrometry

A Time of Flight (TOF) mass analyser, comprising:

• an ion source;
• a detector, wherein the ion source and the detector are arranged to define an ion flight path from the ion source to the detector, the ion flight path comprising a first region and a second region, wherein thermal expansion of the TOF mass analyser results in a first mass shift per Kelvin of ions detected at the detector;
• and
• a compensation electrode thermally coupled to the TOF mass analyser and arranged along the ion flight path in the second region of the ion flight path, the compensation electrode configured to cause ions to travel along the ion flight path in the second region at a higher speed than a speed of the ions in the first region
• wherein the compensation electrode has a thermal expansion coefficient such that the thermal expansion of the compensation electrode causes a second mass shift per Kelvin of ions detected at the detector which compensates for the first mass shift per Kelvin.

A method of Time of Flight (TOF) mass spectrometry comprising:

• measuring a time of flight for ions to travel along an ion flight path from an ion source to a detector using a TOF mass analyser, wherein an electrode is arranged along the ion flight path and receives an output voltage,
• wherein thermal expansion of the TOF mass analyser results in a first mass shift per Kelvin of ions detected at the detector,
• wherein the TOF mass analyser is provided with a resistive divider comprising first and second resistors, the resistive divider thermally coupled to the TOF mass analyser, and configured to receive an input voltage and output the output voltage to the electrode,
• wherein the first and second resistors have respective first and second temperature coefficients which result in a voltage shift per Kelvin to the output voltage to the electrode which results in a second mass shift per Kelvin of ions detected at the detector which compensates for the first mass shift per Kelvin.

A method of TOF mass spectrometry comprising:

• measuring a time of flight for ions to travel along an ion flight path from an ion source to a detector using a TOF mass analyser, the ion flight path comprising a first region and a second region;
• wherein thermal expansion of the TOF mass analyser results in a first mass shift per Kelvin of ions detected at the detector, and
• the TOF mass analyser is provided with a compensation electrode thermally coupled to the time of flight mass analyser and arranged along the ion flight path in the second region of the ion flight path, wherein the compensation electrode is configured to cause ions to travel along the ion flight path in the second region at a higher speed than a speed of the ions in the first region,
• wherein the compensation electrode has a thermal expansion coefficient such that thermal expansion of the compensation electrode causes a second mass shift per Kelvin of ions detected at the detector which compensates for the first mass shift per Kelvin.