Prediction of the irradiation doses from ultrashort laser-solid interactions using different temperature scalings at moderate laser intensities

Barkauskas, Vytenis; Plukis, A.

doi:10.1088/1361-6498/ac44fb

Cited by 6 publications

(3 citation statements)

References 42 publications

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“…Several investigations were performed to analyze the X-ray emission for different laser and process parameters during ultrashort pulse laser machining of various technical materials [5][6][7][8][9][10][11][12][13][14][15][16][17]. Recently, possibly harmful X-ray emission was observed already at laser irradiances below 10 13 W cm −2 [18,19].…”

Section: Introductionmentioning

confidence: 99%

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

et al. 2022

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Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 1013 W cm−2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 μm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances I0 ranging from 7.3 × 1013 W cm−2 up to 3.0 × 1014 W cm−2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 1014 W cm−2.

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Section: Introductionmentioning

confidence: 99%

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

et al. 2022

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“…This X-ray emission might lead to possibly hazardous dose rates for an operator. Today, it is generally presumed to be a safety issue that resulted in new regulations and numerous investigations [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Pulse Duration on X-ray Emission during Industrial Ultrafast Laser Processing

et al. 2022

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Soft X-ray emissions during the processing of industrial materials with ultrafast lasers are of major interest, especially against the background of legal regulations. Potentially hazardous soft X-rays, with photon energies of >5 keV, originate from the fraction of hot electrons in plasma, the temperature of which depends on laser irradiance. The interaction of a laser with the plasma intensifies with growing plasma expansion during the laser pulse, and the fraction of hot electrons is therefore enhanced with increasing pulse duration. Hence, pulse duration is one of the dominant laser parameters that determines the soft X-ray emission. An existing analytical model, in which the fraction of hot electrons was treated as a constant, was therefore extended to include the influence of the duration of laser pulses on the fraction of hot electrons in the generated plasma. This extended model was validated with measurements of H (0.07) dose rates as a function of the pulse duration for a constant irradiance of about 3.5 × 1014 W/cm2, a laser wavelength of 800 nm, and a pulse repetition rate of 1 kHz, as well as for varying irradiance at the laser wavelength of 1030 nm and pulse repetition rates of 50 kHz and 200 kHz. The experimental data clearly verified the predictions of the model and confirmed that significantly decreased dose rates are generated with a decreasing pulse duration when the irradiance is kept constant.

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“…A few recent studies have reported that X-ray radiation can be induced at peak intensities above 10 13 W cm À2 . [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In the meantime, more than 20 influencing factors have been identified for significantly affecting the X-ray dose rate induced during usp laser processing. Thereby, the peak intensity of the laser pulses is one of the most influencing factors, as doubling the peak intensity can increase the X-ray dose rate by a factor of 10.…”

Section: Introductionmentioning

confidence: 99%

Influence of Laser Process Factors on Laser‐Induced X‐Ray Emission in High‐Repetition Laser Processes

Kraft,

Schille,

Backe

et al. 2024

Physica Status Solidi (a)

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Lasers have established themselves as a versatile tool that generates innovations in a wide range of fields, from automotive to surface engineering, medical applications, etc. A current research field for lasers is surface texturing in biomimetic, which aims to mimic nature‐inspired functionalities and mechanisms, for example, to tailor and control wetting, adhesion/friction, or optical properties of technical surfaces. Therefore, ultrashort pulse lasers are often the right choice to alter surface structures at microscopic scale. Moreover, the ongoing trend toward high‐average power lasers reaching “kilowatt class” levels even for ultrashort pulse lasers seems to be beneficial to increase throughput of this powerful laser technology for industrial production. However, several recent studies are reported on harmful X‐ray emissions arising from high‐intense ultrashort laser pulses which must be considered as a secondary laser beam hazard in risk assessment. Shining light on this topic, this article reports on a set of experiments investigating X‐rays emission induced by ultrashort pulse laser processing of different laser‐pretreated stainless steel sheets. The X‐ray measurements show the effect of roughness and scan number on the laser‐induced X‐ray emission dose. In addition, the dependency of X‐ray emission on the scan direction relatively to the laser beam polarization state is discussed.

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Prediction of the irradiation doses from ultrashort laser-solid interactions using different temperature scalings at moderate laser intensities

Cited by 6 publications

References 42 publications

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

Influence of Pulse Duration on X-ray Emission during Industrial Ultrafast Laser Processing

Influence of Laser Process Factors on Laser‐Induced X‐Ray Emission in High‐Repetition Laser Processes

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