Investigation of helium ion production in constricted direct current plasma ion source with layered-glows.
Generation of helium ions is experimentally investigated with a constricted direct current (DC) plasma ion source operated at layered-glow mode, in which electrons could be accelerated through multiple potential structures so as to generate helium ions including He(2+) by successive ionization collisions in front of an extraction aperture. The helium discharge is sustained with the formation of a couple of stable layers and the plasma ball with high density is created near the extraction aperture at the operational pressure down to 0.6 Torr with concave cathodes. The ion beam current extracted with an extraction voltage of 5 kV is observed to be proportional to the discharge current and inversely proportional to the operating pressure, showing high current density of 130 mA/cm(2) and power density of 0.52 mA/cm(2)/W. He(2+) ions, which were predicted to be able to exist due to multiple-layer potential structure, are not observed. Simple calculation on production of He(2+) ions inside the plasma ball reveals that reduced operating pressure and increased cathode area will help to generate He(2+) ions with the layered-glow DC discharge.
Development of a High-Current Helicon Ion Source With High Monatomic Fraction for the Application of Neutron Generators
A high-current helicon ion source has been developed for neutron generator application. High-density plasmas with high electron temperatures are generated by launching helicon waves with a half-helical antenna in various magnetic field configurations. Helicon plasmas with high power efficiency are favorable in building ion sources with high current density and high monatomic ion beam fraction that are required for compact neutron generators. A maximum hydrogen beam current of 50 mA is extracted at 34 kV from the helicon plasma source with 1.9-kW RF power at 13.56 MHz. High current densities of 212 mA/cm2 and high atomic fractions of up to 94% are achieved with this source. These measured beam parameters are mostly consistent with plasma parameters, except for unusually high monatomic beam fraction, which may be due to the existence of energetic electrons in helicon plasmas.
Production of intense atomic nitrogen beam used for doping and synthesis of nitride film
An arc‐heated source for producing an intense nitrogen atom beam with intensity of 1019 atoms/sr s and kinetic energies of 0.5–4 eV is presented. The arc discharge has been carried out in pure nitrogen gas and maintained stable in an arc operating pressure of 30–300 Torr. The beam kinetic energy changes with the arc pressure, and is insensitive to the arc current. Auger electron spectroscopy analysis showed that a TiNO layer with a thickness of about 100 A was formed on the smooth Ti wafer at room temperature with interaction of the atomic nitrogen beam.An arc‐heated source for producing an intense nitrogen atom beam with intensity of 1019 atoms/sr s and kinetic energies of 0.5–4 eV is presented. The arc discharge has been carried out in pure nitrogen gas and maintained stable in an arc operating pressure of 30–300 Torr. The beam kinetic energy changes with the arc pressure, and is insensitive to the arc current. Auger electron spectroscopy analysis showed that a TiNO layer with a thickness of about 100 A was formed on the smooth Ti wafer at room temperature with interaction of the atomic nitrogen beam.