Ion mobility spectrometer and method for operating an ion mobility spectrometer

An ion mobility spectrometer for determining the ion mobility of a sample gas in dry air as drift gas and comprising a drift chamber and a reaction chamber, the ion mobility spectrometer comprising:

• a dielectric barrier discharge ionisation source, DBDI source, arranged in the reaction chamber for ionising the sample gas;
• a pressure sensor arranged in the reaction chamber and a temperature sensor arranged in the reaction chamber;
• a light source for irradiating the DBDI source with light in a wavelength range from 240 nm to 480 nm;
• and
• a control unit, which is connected to the pressure sensor, the temperature sensor, the DBDI source and the light source and which is designed to set an ignition voltage of the DBDI source and to control the light source depending on a pressure value determined by the pressure sensor and a temperature value determined by the temperature sensor.