Mass spectrometer

A mass spectrometer comprising:

• an ion source unit configured to ionize a liquid sample;
• and an analysis unit including a vacuum chamber configured to perform mass spectrometry of an ion generated in the ion source unit,
• the ion source unit including:
• an ion source housing which is a sealed container;
• an ion source cover which accommodates the ion source housing;
• an ion source enclosure which accommodates the ion source cover;
• a probe which passes through the ion source cover and the ion source housing, the probe being configured to nebulize a liquid sample into the ion source housing;
• a heated gas nozzle including a main body portion which is hollow and located between the ion source cover and the ion source housing, a heater configured to heat a gas passing through the main body portion, and a gas outlet tube configured to discharge a gas heated by the heater into the ion source housing;
• an ion source enclosure intake port and an ion source enclosure exhaust port which are provided in the ion source enclosure;
• an ion source cover intake port and an ion source cover exhaust port which are provided in the ion source cover;
• a first exhaust fan configured to discharge air flowing into the ion source cover from the ion source cover intake port and passing through the ion source cover through the ion source cover exhaust port;
• and
• a second exhaust fan configured to discharge air discharged into the ion source enclosure from the ion source cover exhaust port and air flowing into the ion source enclosure from the ion source enclosure intake port and passing through the ion source enclosure, to an outside through the ion source enclosure exhaust port.