Enhanced X-ray Emissions Arising from High Pulse Repetition Frequency Ultrashort Pulse Laser Materials Processing.

Area of Science:

• Materials Science and Engineering
• Laser Physics
• Radiation Safety

Background:

• Ultrashort pulse lasers are crucial for advanced manufacturing but pose health risks due to X-ray emission.
• Over twenty factors influence X-ray generation, necessitating focused research on critical parameters.
• High pulse repetition frequency (PRF) operation is a key area of concern for increased X-ray output.

Purpose of the Study:

• To investigate enhanced X-ray emission from high PRF ultrashort pulse laser processing.
• To identify and analyze the interrelation of the most significant parameters affecting X-ray emission.
• To provide insights for developing effective X-ray protection strategies in industrial and academic settings.

Main Methods:

• Experimental analysis of X-ray photon emission from AISI 304 substrates under varying ultrashort laser pulse conditions.
• Systematic variation of laser parameters including peak intensity, pulse repetition frequency, spot size, and pulse duration.
• Investigation of the influence of suction flow conditions in the laser processing area on X-ray dose rate.

Main Results:

• X-ray photon emission exceeding legal dose rate limits was observed at peak intensities below 1 × 10¹³ W/cm² with 0.5 MHz PRF.
• The peak intensity threshold for significant X-ray emission decreases with increased laser spot sizes and longer pulse durations.
• Suction flow conditions were found to significantly affect the released X-ray emission dose rate.

Conclusions:

• High PRF ultrashort pulse laser processing presents a considerable risk of exceeding safe X-ray exposure levels.
• Laser parameters such as intensity, spot size, pulse duration, and processing environment (suction flow) are critical for managing X-ray emission.
• The findings are essential for designing and implementing robust X-ray shielding and safety protocols for laser operators.