A combination discharge, obtained by superimposing a low-voltage ac arc with condensed high-voltage discharges, has been investigated with respect to its applicability in spectrochemical analysis of metals. The stability of this combination discharge is comparable to that of a spark discharge and it is considerably more intense than the spark discharge alone. The vaporization of the electrode material can be controlled to some extent independently of excitation. There are indications that this may contribute to an understanding of the influence of extraneous elements.
H. E. BIBER and S. LEVY, "Characteristics of a Combination Discharge and Its Applicability in Spectrochemical Analysis of Metals," J. Opt. Soc. Am. 49, 349-355 (1959)