  Results are presented that have been obtained while operating the graphite
hollow cathode duoplasmatron ion source in dual mode under constant discharge
current. This dual mode operation enabled us to obtain the mass and emission
spectra simultaneously. In mass spectra C3 is the main feature but C4 and C5
are also prominent, whereas in emission spectra C2 is also there and its
presence shows that it is in an excited state rather than in an ionic state.
These facts provide evidence that C3 is produced due to the regeneration of a
soot forming sequence and leave it in ionic state. C3 is a stable molecule and
the only dominant species among the carbon clusters that survives in a
regenerative sooting environment at high-pressure discharges.
