The plasma parameters of laser-ablated Zirconium (Zr) using a Langmuir probe technique have been investigated by employing a Q-switched Nd:YAG laser (532 nm, 6 ns) at various irradiances ranging from 8.6 to 15.5 GW/cm 2 . All the measurements have been performed under an ultra-high vacuum condition while keeping the probe at a fixed distance of 4 mm from the target. By varying the biasing voltages from 1 to 75 V, the corresponding values of electric currents are measured by the probe on the oscilloscope. Laser-induced Zr plasma parameters such as electron temperature, electron number density, plasma potential, Debye length, and thermal velocity have been evaluated from I–V characteristic curves of Langmuir probe data. It is found that both the electron temperature and thermal velocity of Zr plasma reveal an increasing trend from 18 to 41 eV and 2.8 × 10 8 to 4.3 × 10 8 cm/s, respectively, with increasing laser irradiance which is attributed to more energy deposition and enhanced ablation rate. However, the electron number density of Zr plasma exhibits a non-significant increase from 6.5 × 10 14 to 6.7 × 10 14 cm −3 with increasing irradiance from 8.6 to 10.9 GW/cm 2 . A further increase in irradiance from 12 to 15.5 GW/cm 2 causes a reduction in the number density of Zr plasma from 6.1 × 10 14 to 5.6 × 10 14 cm −3 which is attributed to the formation of thick sheath, ambipolar electric field, and laser-supported detonation waves (Shock front). Scanning electron microscope analysis has been performed to reveal the surface morphology of irradiated Zr. It reveals the formation of cracks, ridges, cones, and grains. It was observed at high irradiances the ridges are vanished, whereas cones and cracks are dominant features. By controlling plasma parameters, surface structuring of materials can be controlled, which has a vast range of applications in the industry and medicine.

中文翻译：

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通过朗缪尔探针表征评估激光烧蚀 Zr 等离子体的电子温度和电子密度及其与表面改性的相关性

已经通过在 8.6 到 15.5 GW/cm 2 范围内的各种辐照度下采用 Q 开关 Nd:YAG 激光器（532 nm，6 ns）研究了使用 Langmuir 探针技术的激光烧蚀锆 (Zr) 的等离子体参数。所有测量均在超高真空条件下进行，同时将探头与目标保持 4 毫米的固定距离。通过将偏置电压从 1 到 75 V 变化，相应的电流值由示波器上的探头测量。激光诱导的 Zr 等离子体参数，如电子温度、电子数密度、等离子体势、德拜长度和热速度，已经从朗缪尔探针数据的 I-V 特性曲线中进行了评估。结果表明，Zr 等离子体的电子温度和热速度均显示出从 18 到 41 eV 和 2 的增加趋势。分别为 8 × 10 8 到 4.3 × 10 8 cm/s，随着激光辐照度的增加，这是由于更多的能量沉积和提高的烧蚀率。然而，随着辐照度从8.6 增加到10.9 GW/cm 2 ，Zr 等离子体的电子数密度从6.5 × 10 14 到6.7 × 10 14 cm -3 没有显着增加。辐照度从 12 进一步增加到 15.5 GW/cm 2 导致 Zr 等离子体的数密度从 6.1 × 10 14 减少到 5.6 × 10 14 cm -3 这归因于形成厚鞘、双极电场，和激光支持的爆震波（激波前沿）。已经进行了扫描电子显微镜分析以揭示经辐照的 Zr 的表面形态。它揭示了裂缝、脊、锥体和颗粒的形成。在高辐照度下观察到脊消失了，而锥体和裂纹是主要特征。通过控制等离子体参数，可以控制材料的表面结构，这在工业和医学中有广泛的应用。