Rn. Szente et al., COPPER NIOBIUM AND COPPER TUNGSTEN COMPOSITES AS PLASMA TORCH CATHODES, Journal of physics. D, Applied physics, 27(7), 1994, pp. 1443-1447
This work was performed to screen potential cathode materials for. use
in arc heaters with cylindrical electrodes. It focused on hot isostat
ic pressing consolidated copper composites; 10% composites of copper w
ith tungsten and niobium as well as 1.5% niobium were used. The compos
ite cathodes were tested in pure Ar, He and N2 as well as in mixtures
of Ar with CO, N2 and H-2, at atmospheric pressure and currents up to
150 A. The arc was driven around the circumference of the cathode with
an external magnetic field. The results are compared with those using
pure copper cathodes. The Cu-W cathode showed a better arc stability
and lower erosion rates than copper. The Cu-Nb cathode showed much low
er erosion rates and much better arc stability than copper for almost
all the different operating conditions and may be considered a promisi
ng new electrode material. The experimental results corroborated previ
ous interpretations of the relationships between arc velocity, erosion
rate, surface drag and electrode surface composition.