Comparison of Thermal Blooming and Self-focusing about Propagation of High Energy Laser in Atmosphere

By analyzing the critical value of thermal blooming and self -focusing, it is shown that the critical value of self-focusing is about five magnitude larger than thermal blooming's in the same atmospheric conditions. In addition, at the same power of pulse laser, the width of pulse also has impact on the two nonlinear effects. If the pulse width is above microsecond, the self-focusing can be neglected. However, when the length of pulse decreases to ultrashort, self- focusing must be considered for the propagation in atmosphere.