The influence of processing parameters on X-ray emission during ultra-short pulse laser machining

Legall, Herbert; Schwanke, Christoph; Krüger, Jörg

doi:10.1007/s00339-019-2827-y

Cited by 20 publications

(31 citation statements)

References 14 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With every pulse, some material is evaporated and a small dimple created. Shielding of the emitted X-rays due to kerf walls or borehole walls around the processed region can significantly influence the measured dose rate [32]. For the present experiments, the laser spot was scanned over a small area of 20 mm × 20 mm on the surface of the steel sample with the direction of movement of the beam towards the detector.…”

Section: Dose Ratementioning

confidence: 99%

Expected X-ray dose rates resulting from industrial ultrafast laser applications

et al. 2019

View full text Add to dashboard Cite

An analytical model is presented, which allows estimating the expected dose rates resulting from X-ray emission from ultrashort-pulse laser-produced plasma under industrial conditions. The model is based on the calculation of the Bremsstrahlung spectrum in the X-ray region between about 5 keV and 50 keV, which is created by the hot electrons in the plasma. The model was calibrated with both spectral and dose rate measurements. The scaling of the hot-electron temperature and the fraction of hot electrons in the plasma served as calibration values. The agreement between experiments and model for the investigated irradiances in range from 10 12 to 10 15 W/cm 2 is excellent. The expected Ḣ (0.07) and Ḣ (10) dose rates at a distance of 20 cm from the process in air were calculated for upcoming lasers with 1 kW of average power. Although the dose rates close to the plasma significantly exceed the allowed dose of 50 mSv per year for an irradiance exceeding about 2·10 15 W/cm 2 , the calculations show that shielding with a 2-mm sheet of iron already at a distance of 20 cm attenuates the radiation to a safe value below 0.4 µSv/h.

show abstract

Section: Dose Ratementioning

confidence: 99%

Expected X-ray dose rates resulting from industrial ultrafast laser applications

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Thereby, the attenuation coefficient depends strongly on the photon energy and varies in air between 0.94 cm −1 ≤ µ ≤ 6.36 × 10 2 cm −1 for the X-ray photons between 2 keV ≤ E phot ≤ 20 keV [ 10 ]. The attenuation coefficients derived from the fitting curves presented in Figure 2 a amount to µ = 0.05 ± 0.02 cm − 1 (SILIX) or µ = 0.03 ± 0.02 cm − 1 (OD-02), which is about two orders of magnitude lower than the literature data.…”

Section: Resultsmentioning

confidence: 99%

“…A remarkable influence of the intra-line distance between the impinging ultrashort laser pulses on X-ray emission has already been reported for tungsten studied with PRFs in the range between 50 kHz < PRF < 400 kHz [ 10 ]. Pronounced X-ray emission maxima and minima have been detected where the amplitude of the X-ray doses varied by a factor up to two depending on the spatial distance of the next impinging pulse.…”

Section: Resultsmentioning

confidence: 99%

“…However, recent works have shown that the X-ray photon emission increases proportionally with higher average laser power, and actual X-ray emission dose rates can cause serious health risks for the laser operators [ 9 , 10 , 11 , 12 , 13 , 14 ]. In particular, this is the case when high-pulse repetition frequency lasers will be used in materials ablation as the X-ray emission per pulse can accumulate to harmful X-ray photon dose over time.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study on X-ray Emission Using Ultrashort Pulsed Lasers in Materials Processing

et al. 2021

View full text Add to dashboard Cite

The interaction of ultrashort pulsed laser radiation with intensities of 1013 W cm−2 and above with materials often results in an unexpected high X-ray photon flux. It has been shown so far, on the one hand, that X-ray photon emissions increase proportionally with higher laser power and the accumulated X-ray dose rates can cause serious health risks for the laser operators. On the other hand, there is clear evidence that little variations of the operational conditions can considerably affect the spectral X-ray photon flux and X-ray emissions dose. In order to enhance the knowledge in this field, four ultrashort pulse laser systems for providing different complementary beam characteristics were employed in this study on laser-induced X-ray emissions, including peak intensities between 8 × 1012 W∙cm−2 < I0 < 5.2 × 1016 W∙cm−2, up to 72.2 W average laser power as well as burst/bi-burst processing mode. By the example of AISI 304 stainless steel, it was verified that X-ray emission dose rates as high as H˙′ (0.07) > 45 mSv h−1 can be produced when low-intensity ultrashort pulses irradiate at a small 1 µm intra-line pulse distance during laser beam scanning and megahertz pulse repetition frequencies. For burst and bi-burst pulses, the second intra-burst pulse was found to significantly enhance the X-ray emission potentially induced by laser pulse and plasma interaction.

show abstract

“…From the previous results, it can be seen that the intensities of the emission lines increase with increasing of the laser pulse energy and repetition rate [18]. The increasing of the pulse energy means the increase of its absorption by the plasma leading to more ablation from the target and finally increasing of the emission line intensity [19]. The second ionization stage of (Ho) theoretically computed using Cowan code covering wavelength region between 320 to 400 nm.…”

Section: -Holmium Emission At 10 Hz Repetition Ratementioning

confidence: 95%

Effect of Laser Energy and Repetition Rate on Holmium Plasma Emission

mahmoad

Mahmoad

2020

IJP

View full text Add to dashboard Cite

The holmium plasma induced by a 1064-nmQ-switched Nd:YAG laser in air was investigated. This work was done theoretically and experimentally. Cowan code was used to get the emission spectra for different transition of the holmium target. In the experimental work, the evolution of the plasma was studied by acquiring spectral images at different laser pulse energies (600,650,700, 750, and 800 mJ). The repetition rates of (1Hz and 10Hz) in the UV region (200-400 nm). The results indicate that, the emission line intensities increase with increasing of the laser pulse energy and repetition rate. The strongest emission spectra appeared when the laser pulse energy is 800mJ and 10 Hz repetition rate at λ= 345.64nm, with the maximum intensity of 77000 counts.

show abstract

The influence of processing parameters on X-ray emission during ultra-short pulse laser machining

Cited by 20 publications

References 14 publications

Expected X-ray dose rates resulting from industrial ultrafast laser applications

Expected X-ray dose rates resulting from industrial ultrafast laser applications

Study on X-ray Emission Using Ultrashort Pulsed Lasers in Materials Processing

Effect of Laser Energy and Repetition Rate on Holmium Plasma Emission

Contact Info

Product

Resources

About