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

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.