Ablation enhancement and plasma shielding effects during multiple pulses irradiation with different femtosecond laser repetition rates

TY - JOUR

T1 - Ablation enhancement and plasma shielding effects during multiple pulses irradiation with different femtosecond laser repetition rates

AU - Zhan, Jie

AU - Xu, Zhao

AU - Sun, Jiaxin

AU - Zhu, Weihua

AU - Wang, Sumei

AU - Lian, Yiling

AU - Jiang, Lan

AU - Zhao, Longjiang

N1 - Publisher Copyright: © 2025

PY - 2025/12/12

Y1 - 2025/12/12

N2 - The ultra-short pulse duration of femtosecond laser broadens the micro-machining applications in metals. Controlling plasma dynamics can change machining efficiency and quality. However, continuous pulse irradiation complicates plasma signal capture, preventing process optimization. The field programmable gate array (FPGA) and intensified charge-coupled device (ICCD) were employed to capture plasma signals for the first time after preset multiple pulses at varying repetition rates. Increasing the rate from 1 kHz to 50 kHz enhances plasma intensity, ejection height, and machining depth, indicating improved ablation efficiency. At 400 kHz, the plasma intensity decreases, but the ejection height continues to increase, and the machining depths of the grooves reduce. This is probably attributed to the plasma shielding effect, which means that the subsequent pulses' energy is absorbed by prior-induced plasma, reducing laser-metal interaction. The thermal effect was pronounced at 400 kHz, with a large recast layer and high oxygen content around the irradiation area. Optimal material removal and minimal ripple period (706.7 nm) occurred at the repetition rate of 50 kHz. Adjusting the femtosecond laser repetition rate can regulate ablation efficiency, plasma shielding and thermal accumulation, affecting micro-hole, groove and microstructure machining results.

AB - The ultra-short pulse duration of femtosecond laser broadens the micro-machining applications in metals. Controlling plasma dynamics can change machining efficiency and quality. However, continuous pulse irradiation complicates plasma signal capture, preventing process optimization. The field programmable gate array (FPGA) and intensified charge-coupled device (ICCD) were employed to capture plasma signals for the first time after preset multiple pulses at varying repetition rates. Increasing the rate from 1 kHz to 50 kHz enhances plasma intensity, ejection height, and machining depth, indicating improved ablation efficiency. At 400 kHz, the plasma intensity decreases, but the ejection height continues to increase, and the machining depths of the grooves reduce. This is probably attributed to the plasma shielding effect, which means that the subsequent pulses' energy is absorbed by prior-induced plasma, reducing laser-metal interaction. The thermal effect was pronounced at 400 kHz, with a large recast layer and high oxygen content around the irradiation area. Optimal material removal and minimal ripple period (706.7 nm) occurred at the repetition rate of 50 kHz. Adjusting the femtosecond laser repetition rate can regulate ablation efficiency, plasma shielding and thermal accumulation, affecting micro-hole, groove and microstructure machining results.

KW - Micro/nano machining

KW - ablation enhancement

KW - heat accumulation

KW - plasma shielding

UR - https://www.scopus.com/pages/publications/105018065504

U2 - 10.1016/j.jmapro.2025.10.019

DO - 10.1016/j.jmapro.2025.10.019

M3 - Article

AN - SCOPUS:105018065504

SN - 1526-6125

VL - 155

SP - 1

EP - 11

JO - Journal of Manufacturing Processes

JF - Journal of Manufacturing Processes

ER -