Sublimation of graphite in continuous and pulsed arc discharges

Abstract

Sublimation of graphite has been investigated in continuous and pulsed arc discharges. The results of continuous arc discharge between graphite electrodes are compared with pulsed arc discharge between cylindrical Aluminum cathode and annular graphite anode. The sublimed species include monoatomic and diatomic carbon clusters with their relative composition depending upon the mechanism of energy dissipation in graphite electrodes. Diatomic carbon (C2) is the dominant subliming cluster. Emission spectroscopy of the Swan band system [d3πg-a3πu] of C2 has been used to investigate the thermodynamic state and to deduce the vibrational temperature (Tvib).The vibrational level densities indicate that local thermodynamic equilibrium exists in both types of discharges and Tvib ≈ 7000-9000 K. © TÜBİTAK.