ABSTRAKT

The arc between graphite electrodes 6 mm in diameter under conditions favorable for fullerene synthesis (I = 60÷120 A, U = 20÷40 V, L = 1÷6 mm,p = 1÷200 torr) is considered. The parameters of plasma and macroparticles, time-spatial structure of the arc as well as properties of obtained materials were studied. For the first time it was found out that the electric arc between graphite electrodes exists in two modes. In the non-stationary mode the arc looks like two spiral channels coming from an anode spot and revolving on lateral surface of cylindrical electrodes. The observed unsteadiness arises from the development of overheating instability of heterogeneous plasma. It was ascertained that the growing part of voltage-current characteristic of the arc corresponds to its double-mode operation. The mechanism of cathode deposit formation in the carbon arc by macroparticles arisen from condensation and coalescence of products of graphite anode erosion was developed. Within the boundary layer of the particle collision with a cathode such conditions are realized under which their melting is possible, and then the stage of quasiepitaxial growth of deposit takes place from a liquid phase.