Study On The Heat Transfer Characteristics Of Lightning Return Stroke Channel

Using the time-resolved spectra of cloud-to-ground lightning return stroke processes recorded by a slit less high-speed spectrograph and combing with multiple spectral lines method, Stark broadening and collision integral, then the physical characteristically parameters of lightning return stroke channel at different time are calculated and the evolutional characteristics with time of channel temperature, thermal conductivity and thermal diffusivity of different return stroke processes are discussed. The distribution of temperature along the radial direction of the channel at the peak current stage of return stroke is also calculated, and then the heat transferring characteristics along radial direction of the channel are analyzed. The calculated values are within the reasonable range. The results show that a temperature gradient along radial direction of lightning channel is formed due to the outward heat transfer. The closer to the current core channel, the greater the temperature gradient is, and the more heat is transferred along the radial direction of the channel. The heat transferring in per unit length of the channel and per unit time is in the order of 10~4 J/m × s at the initial moment of lightning return stroke. After the peak current, the channel temperature decreases slowly and the heat transport coefficients vary as a monotonically decreasing function.