Plasma cathodes are electron sources which use a plasma discharge in order to extract electrons. Plasma discharge of these cathodes is produced by various methods. The device takes its name from the method of plasma generation. After plasma generation, an extraction set up is used in order to obtain electron current from the bulk plasma. Extraction of electrons from a plasma cathode device is related to the bulk plasma parameters as well as the extraction apparatus geometry. So, the theory of radio frequency cathode consist of two parts: first, modeling a quasineutral inductively coupled plasma and second, modeling of plasma sheath and effects of applying a bias voltage on the plasma. Theory of quasineutral inductively coupled plasma has been developed widely and some zero-dimensional and multi-dimensional models have been introduced by numerous scientists. In contrast, theory of applying a positive potential and electron current extraction from a bulk plasma is considered in recent years. For this reason, there are limited models that can be used in this field. In this study, a novel 0-D model is proposed for numerical investigation of the current extraction mechanism of plasma cathode device. Also, a DC circuit is developed which models the electron current traveling from the grounded electrode to the positive electrode of the DC power source.
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