Plasma Generation in Air by Intense Laser Pulses with Various Pulse Durations

We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air. This breakdovn is produced by ultrashort laser pulses with various durations ranging from 200fs to 2ps at a fixed pulse energy of 8mJ. We found that the plasma yield increases first with the increment of pulse duration and then reaches a plateau at a duration longer than 500fs. The generated plasma temperature is estimated to be higher than 5x 10⁵ K .