【摘要】 纳秒脉冲激光烧蚀金属元靶产生等离子体,由于极少量速度较快的电子逃逸造成了等离子体区域出现微量剩余正电荷,并在周围空间激发电场。通过在靶上偏置负高压(0～1 000 V)研究了金属靶由于受等离子体作用而出现的电势变化。实验发现:靶上电势信号整体呈单峰分布,并在早期阶段(<700 ns)出现强烈振荡现象,振荡频率(约40 MHz)不随靶偏置电压与激光能量发生变化。并首次对该振荡信号的产生机制进行了分析,认为靶上电势振荡是靶材偏置负压与等离子体中的净余电荷相互作用的结果。更多还原

【Abstract】 Net charges appear in plasma induced by a Nd:YAG laser(8 ns) due to high speed electrons going away from plasma.Research on the electrical potential signals induced by plasma on a brass target with bias-voltage(0~1 000 V) is developed.The experimental results showed a single peak distribution in the signal wave with oscillation at the early stage(<700 ns),and the frequency of oscillation(~40 MHz) is independent of the laser energy and additional voltage.For the first time the oscillation generation mechanism is investigated,which is attributed to the interaction between the bias-electric field and the net charges in plasma.更多还原