Low Resistance and Long Lifetime Plasma Channel Generated by Filamentation of Femtosecond Laser Pulses in Air

An experimental investigation of the length and resistance of the laser plasma channel generated by filamentation of fs laser pulses in air was presented. It was found that the length of the plasma channel was different from that of the laser filament. This phenomenon was commensurate with a special self-guide mechanism without ionization. Through increase of the laser energy the plasma channel could be prolonged and the resistance could be reduced. To get even lower resistance, more effective control would be needed over the multi-filament. The lifetime of the plasma channel was increased by a factor of 4.5 by pulse sequences, which were generated by detuning the regenerative amplifier in the chirped pulse amplification （CPA） laser system.

飞秒光丝中等离子体密度时间演化特征

采用能够较为清晰、完整描述强飞秒激光等离子体通道内带电粒子产生过程及其演化的物理模型,进一步研究了飞秒光丝中等离子体密度的时间演化特征。计算结果表明:对于不同时间线型的脉冲,在等离子体通道形成过程中,氧气分子的电离贡献率及氮气分子的贡献率明显不同,不同线型的脉冲对高效维持高密度等离子体的寿命具有较大的影响。有效控制成丝脉冲线型能够达到对等离子体通道的高效利用。长脉冲、短波长虽能够获得较高密度等离子体通道,但其存活寿命却完全受限于通道的后期演化。