Ion energy and charge state distributions in zirconium nitride arc plasma

The charge states and ion energy distributions (IEDs) of cathodic arc zirconium (Zr) plasma in vacuum and in nitrogen are reported. The dominant charge states in vacuum and in nitrogen were found to be Zr4+ and Zr2+, respectively. In addition to Zrn+, N-2(+) and N+ species along with ionized zirconium nitride (ZrNn+) were also detected. The peak ion energies of all Zrn+ species in vacuum were found to be slightly higher (similar to19 eV) than in nitrogen (similar to15 eV). The IEDs of N-2(+) species exhibited two peaks, one at 2-4 eV and the other at similar to15 eV. The dual peaks in the N-2(+) IEDs indicate that some species are ionized in the plasma and others are emitted from, or near, the surface of the cathode. The peak energies of ZrN2+ and ZrN+ species were found to be similar to15 eV, indicating that they are emitted from the nitrided ("poisoned") surface of the cathode or the from the dense plasma region above the arc spot. (C) 2003 American Institute of Physics.