| 摘要 |
A shift of mass axis that occurs when the temperature of a vacuum container consisting of a vacuum chamber (15) and IT block (16) or that of a TOF power unit (20) for applying an ion acceleration voltage is changed, is respectively measured beforehand, and parameters expressing a transfer function based on its response are stored in a transfer function memory (24). During an analysis, a mass shift predicting operation section (25) estimates the current shift length of the mass axis from the current temperatures of the IT block (16) and TOF power unit (20) obtained by first and second temperature sensors (34 and 35) as well as from the two transfer functions stored in the memory (24). A mass shift correcting section (29) corrects the mass axis of the mass spectrum according to the estimated shift length. Thus, if the ambient temperature suddenly changes, the shift of the mass axis of the mass spectrum due to the temperature change is corrected with high accuracy, so that a mass spectrum with a high level of mass accuracy can be created.
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