Negative hydrogen ion source with gas-provide system, based on metal-hydride

Summary form only given, as follows. The dissociative attachment of low energy electrons to molecules or atoms of a gas is the preferable mechanism in negative ion sources. One of the methods to obtain low energy electrons is the return of an electron trajectory in the device. The presence of a great number of low energy electrons secures the effective interaction in return region. In this paper the results of an experimental study of negative hydrogen ion source, using electrons of a Penning discharge plasma, are represented. The positive potential of the source anode was (0.5-1) kV, the strength of external magnetic field was (0.1-0.6) kOe, the pressure of gas (hydrogen) was (10/sup -4/-10/sup -3/) Torr. In such discharges the electrons oscillate between reflecting electrodes and have a minimal energy in the return region. The coordinates of the return point were defined by the distribution of the electrical field near the cathode. That is why the source cathode, placed near the extractor, was made in the form of a hollow cylinder with a metal-hydride disk as a bottom. The cylinder had zero potential. The metal-hydride disk had a negative potential of (10-100) V. The point of electron return was placed near the extractor chick by means of variation of metal-hydride disk negative potential. The gas entrance was carried out as a result of hydrogen desorption from the metal-hydride. Rotational and vibrational excitation of desorbed hydrogen molecules increases the cross section of the dissociative attachment process, and therefore the quantity of extracted negative hydrogen ions increases too.