The N2 flow of 2-3L/min is to keep the high voltage TOF electronics clean, dry and at a steady temperature. These electronics are on all the time and therefore the N2 flow is needed even when the instrument is idle. Keeping the electronics on keeps the mass accuracy and resolution stable. The flow is constant.
To purge the RIS we use up to 30L/min but this it only used when we are removing or inserting an ion source.
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