THE CATHODE BULK TEMPERATURE INFLUENCE ON CHARACTERISTICS OF NON-STATIONARY SPOT
Yu. L. Vasenin
E.O. Paton Electric Welding Institute, 11 Bozhenko Str., 252650 Kiev-5, GSP, Ukraine
The paper presents the results of computational experiments on the basis of the non-stationary cathode spot model (ID approach - a "cavity on plane" geometry) with the self consistent boundary conditions for the current density, plasma pressure and energy balance on the active surface of the spot.
The following time dependent parameters were used to characterize dynamics of the single low current cathode spot (or its fragment): radii of the active spot surface and melted zone, the near cathode potential fall Uc , overage lifetime, erosion rate and some others. The given cathode bulk temperatures were used in computations up to the melting temperature.
It is shown the melt zone radius increasing with rising of the bulk temperature while the lifetime decreases and active spot radius remains the same. The significant rise of lifetime and size of the cathode spot on copper cathode occurs with rising the spot electric current and at transition from the non-stationary mode to a quasi-stationary state for Iα>20 A.