The present invention provides a device (10) for generating a non-thermal gaseous plasma which may be a flow of gas plasma in the form of a gas plasma plume emitted from the device. The device comprises a gas capsule, or pressure vessel, (12) for holding a gas or gases (14) under pressure and forming a flow of gas through a plasma generator (16) to an applicator (18) when released from the capsule. Gas released from the gas capsule is energised in the reaction generator to form a gas plasma. The device has a housing (28) for the plasma generator (16), a battery (116) and a signal generator (58) for energising the plasma generator. The gas capsule (12) docks with the housing (28). The device is adapted to be hand-held, typically by the gas capsule (12), and operated to allow it to be used for instance for cleaning and whitening teeth.
