Abstract: Using a Hartree-polarization potential，the curve of the Ramsauer-Townsend effect obtained by a thyratron is analyzed. We also quantitatively investigate the phenomenon which occurs in the experiment of the Child-Langmuir law that the slope between ln I and ln Va ( where Va is the accelerating voltage) is less than 3 /2，by considering that the electrons have initial velocity.

Key words: Ramsauer-Townsend effect, Child-Langmuir law, Thyratron