Laser heating of a molecular gas channel

The first steps toward laser initiated discharge channels are outlined. The temperature and density changes which are to be expected with reasonable laser energies are determined. To this end, absorption cross sections were measured as a function of gas pressure, line tuning, and laser energy for NH3 and C2H4 gases. Based on these values a number of hydrodynamic simulations were performed with the CHARTB hydrocode which show that an efficient conversion of initial vibrational temperature into translational temperature occurs. Moreover, it is seen that the hydrodynamic motion is slow compared to reasonable relaxation times so that this efficiency is not unique to NH3 with its anomalously fast relaxation time.