High current plasma electron emitter

Summary form only given. A high current plasma electron emitter based on a miniature plasma source has been developed. The source is characterized by a high electron emission current density and emission current, small size, and low impurity content. The emitting plasma is created by a pulsed high current gas discharge. The source is biased negatively to extract electrons. Electron currents of the order of 1 kA and the emission current density of 1 kA/cm/sup 2/ at a bias voltage of about 100 V are obtained. The source has a simple design and has proven to be very reliable in operation. Extensive studies of the effect of the source geometry and materials have been conducted. The gas feed through, power dissipation, and impurity content were measured. In particular, spectroscopic measurements revealed that the impurities generated by the source electrodes are trapped inside by the source plasma. A high emission current, small size (3-4 cm in diameter), and low impurity generation make the source attractive for a variety of fusion, general science, and technological applications.