A photo ionizer is provided to absorb a vibration and extend a life time of an x-ray tube by having a silicon tap having elasticity and expansion/extraction. A photo ionizer includes a plurality of head units and a control unit. The head units emit a soft x-ray to a charged object and ionize a gas of an air by the emitted soft x-ray. The head units generate the soft x-ray to a charge of the charged object by at least one of an electron, a positive ion and a negative ion which are generated from an ionized gas. The control unit controls the head units. A power unit is included in the control unit. A high voltage generation unit receives a low voltage from the power unit and boosts up the low voltage to a high voltage. An x-ray tube(500) receives the high voltage from the high voltage generation unit and generates the x-ray. A silicon cap is fixedly installed on the x-ray tube, and molds an inlet with silicon to prevent an electric accident by the high voltage applied to the x-ray tube. The silicon cap protects the x-ray tube from a vibration by absorbing the vibration generated from an external. A tube(510) generates an electron. A target extracts the electron generated from the tube by a potential difference from an anode. An output window emits the x-ray generated by an impact of the electron.
