Research on the time and mechanism of laser-induced air plasmas ignition

Abstract

To research the initiation of breakdown and the earliest stages of plasma formation, analyzing the ignition time and mechanism is necessary. The ignition time of laser-induced air plasmas is numerically simulated on the basis of air breakdown conditions in atmospheric air. This time is on the order of a few nanoseconds, and increases with increasing laser facula radius and pulse width, and decreases with increasing laser wavelength and incident laser energy. In addition, images obtained using a high-speed camera (NX5-X2) indicate that the ignition process of laser-induced air plasmas includes preionization, ionization, significant ionization, plasma shielding , plasma ignition and extinction.