The results of investigation of the energy parameters of a nonstationary electric-arc spot on a copper cathode in an air atmosphere have been presented. The data published earlier on the thermal volt-equivalent of the cathode arc spot have been generalized. A nonlinear dependence of the current density on the magnetic field has been obtained. A comparison of the new results and those obtained earlier on other setups and their generalization have been made. © 2004 Plenum Publishing Corporation.772384391Esipchuk, A.M., Marotta, A., Sharakhovskii, L.I., Erosion of a copper cathode in a nonstationary arc spot. I. Experimental investigation (2004) Inzh.-Fiz. Zh., 77 (2), pp. 106-111Marotta, A., Sharakhovskii, L.I., Theoretical and experimental investigation of copper electrode erosion in electric arc heaters. I: The thermophysical model (1996) J. Phys. D: Appl. Phys., 29, pp. 2395-2403Marotta, A., Sharakhovskii, L.I., Borisyuk, V.N., Heat transfer and plasmatron electrode erosion (1997) Inzh.-Fiz. Zh., 70 (4), pp. 551-559Sharakhovskii, L.I., Marotta, A., Borisyuk, V.N., A theoretical and experimental investigation of copper electrode erosion in electric arc heaters. II: Experimental determination of arc spot parameters (1997) J. Phys. D: Appl. Phys., 30, pp. 2018-2025Sharakhovskii, L.I., Marotta, A., Borisyuk, V.N., A theoretical and experimental investigation of copper electrode erosion in electric arc heaters. III: Experimental validation and prediction of erosion (1997) J. Phys. D: Appl. Phys., 30, pp. 2421-2430Esipchuk, A.M., Marotta, A., Sharakhovskii, L.I., Bublievsky, D.A., Experimental investigation of the cathode spot parameters in magnetically driven arc (2003) Progress of Plasma Processing of Materials 2003, pp. 203-209. , P. Fauchais (ed.), Begell House, New YorkTeste, P., Leblanc, T., Chabrerie, J.-P., Study of the arc root displacement and three-dimensional modelling of the phenomena occurring in a hollow cathode submitted to an electric moving arc (1995) J. Phys. D: Appl. Phys., 28, pp. 888-898Esipchuk, A.M., Marotta, A., Sharakhovskii, L.I., Magnetic-field effect on heat transfer within a cathode arc spot (2000) Inzh.-Fiz. Zh., 73 (6), pp. 1245-1254Kiselev, Y.Y., Pogora, V.K., Radial current-density distribution in the main spots in a plasma cutting arc (1987) Inzh.-Fiz. Zh., 53 (2), pp. 284-289Esipchuk, A.M., Marotta, A., Sharakhovskii, L.I., Experimental investigation of the current density and the heat-flux density in the cathode arc spot (2001) Inzh.-Fiz. Zh., 74 (3), pp. 198-206Szente, R.N., Munz, R.J., Drouet, M.G., The influence of the cathode surface on the movement of a magnetically driven electric arc (1990) J. Phys. D: Appl. Phys., 23, pp. 1193-1200