Measurement of plasma parameters in zirconium plasma using langmuir probe

Abstract

Zirconium (Zr) plasma is produced by electron-impact ionization during Zr vapor evaporation in an electron beam evaporator. The plasma is embedded in the vapor. It expands along with the vapor in a transverse magnetic field. Parameters like ion density, electron temperature, space potential, floating potential of the plasma were measured by a disc type Langmuir probe. Since Zr metal has high melting point (~ 2128 K), the evaporator is filled with condensable vapor and remains at high temperature (~ 700 K). The probe was designed and fabricated in a manner that the insulator was protected from the direct deposition of Zr vapor. The measurement shows that the e-beam generated plasma is weakly ionized (degree of ionization ~ 0.1 %) and it has low electron temperature (~ 0.1 eV). It is also observed that the plasma ions have a flow velocity in vertical direction similar to the neutral atoms.