Copper vapour diffusion in a nitrogen arc chamber

The steady state of the discharge was determined close to the copper anode of a low current ( approximately 20 A) atmospheric pressure, nitrogen arc, assuming local thermodynamic equilibrium. Copper vapour velocities were measured from the propagation velocities along the chamber axis of perturbations in the total intensity of the 5105 AA CuI line: the velocity of the light perturbation was of order 20 m s -1 . This propagation phenomenon is attributed to copper vapour diffusion in the chamber with a diffusion speed between 10 and 20 m s -1 . Diffusion speed of neutral copper was computed using diffusion coefficients determined following the Chapman-Enskog method: the results were of order 10 m s -1 .