Plasma ion mass analyzing apparatus

摘要

A mechanism is provided for reducing contamination of the interior of an apparatus by a sample and for performing a stable measurement. An ion lens has an Einzel lens for converging an ion beam, a deflector for deflecting the ion beam and a pair of compensation electrodes each composed of one or more elements. A mechanism is provided for controlling a voltage to be applied to each of the electrodes as desired. Also, alternatively, a shield plate is provided in a flow path of the ion beam. A drive mechanism is provided for projecting and retracting the shield plate. With such an arrangement, it is possible not only to effectively detect a small amount of impurities contained in a sample but also to stably measure the concentration thereof.