A coated fan rotor blade and method for coating a fan rotor blade. The locking device having two rings with teeth on the outer side, each ring to fit around one of the connectors, and assembled with a body with teeth on the inner side, enclosing the two rings, where the mating teeth of ring and body generate the ratchet, to allow ratcheting the ring in one axial direction, and blocking the axial rotation of the ring and connector in the opposite direction. The larger size ionizers of this invention enable analysis of trace of sample compounds in the gas phase. The metal plate has a channel for venting gaseous matter and at least a vertical vent hole for guiding the gaseous reactants into the vacuum chamber.