Pulse Duration Research Articles

Multibubble sonoluminescence in supercooled water.

Cavitation in supercooled water has been induced by the short ultrasound pulses of an ultrasonic horn driven at 20kHz. The cavitation during the ultrasonic pulses and occasionally the crystallization events thereafter have been imaged by a high-speed camera. The probability of ice crystallization in dependence on the pulse duration and temperature showed a high chance for the water to remain liquid if sufficiently short bursts of moderate acoustic power were applied. This regime has been used for the assessment of sonoluminescence (SL) from the generated cavitation bubbles in the supercooled liquid state. To this end, light emitting events were summed up over a number of ultrasonic pulses by an image intensifier. SL appeared mostly directly under the tip of the ultrasonic horn and sometimes also a few millimeters below the tip. The intensity of SL events showed a slight rise for a decrease in temperature, i.e., for an increase in supercooling. This behavior is in accord with the SL dependence on temperature above the freezing point and might be attributed to a further lowering of vapor pressure. An increase in the bubble collapse peak temperature for increased supercooling is calculated on the basis of spherical bubble model calculations, which supports the findings. The simulations predict further that the peak temperature will fall off again beyond a certain supercooling level.

Coherent beam combining of two all-PM thulium-doped fiber chirped pulse amplifiers

In this paper, we report a coherent beam combining (CBC) system that involves two thulium-doped all-polarization maintaining (PM) fiber chirped pulse amplifiers. Through phase-locking the two channels via a fiber stretcher by using the stochastic parallel gradient descent (SPGD) algorithm, a maximum average power of 265 W is obtained, with a CBC efficiency of 81% and a residual phase error of λ/17. After de-chirping by a pair of diffraction gratings, the duration of the combined laser pulse is compressed to 690 fs. Taking into account the compression efficiency of 90% and the main peak energy proportion of 91%, the corresponding peak power is calculated to be 4 MW. The laser noise characteristics before and after CBC are examined, and the results indicate that the CBC would degrade the low frequency relative intensity noise (RIN), of which the integration is 1.74% in [100 Hz, 2 MHz] at the maximum combined output power. In addition, the effects of the nonlinear spectrum broadening during chirped pulse amplification on the CBC efficiency are also investigated, showing that a higher extent of pulse stretching is effective in alleviating the spectrum broadening and realizing a higher output power with decent combining efficiency.Graphical

Ionizing terahertz waves with 260 MV/cm from scalable optical rectification.

Terahertz (THz) waves, known as non-ionizing radiation owing to their low photon energies, can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and space. Here, we demonstrate the generation of ionizing, multicycle, 15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses. A complete characterization of the generated THz waves in energy, pulse duration, and focal spot size shows that the field strength can reach up to 260 megavolts per centimeter. In particular, a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical simulations. Such intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma formation. This study also discusses the potential of nonperturbative THz-driven ionization in gases, which will open up new opportunities, including nonlinear and relativistic THz physics in plasma.

Smart integration of cold plasma stream and surface discharge with ns laser ablation for composite nanomaterial.

In this paper, smart integration of cold dielectric barrier discharge (DBD) plasma in various geometrical arrangements with laser ablation at atmospheric pressure for nanomaterial was described. A composite Co:ZnO target was ablated in an airflow by a nanosecond (ns) laser (wavelength: 1064 nm, pulse duration: 30 ns) using fluence of 5 J-cm-2 at a repetition rate of 10 Hz. The nanomaterial produced under vertical and oblique plasma streams, surface discharge and gas flow, were compared. Utilization surface discharge markedly improved the material adhesion by altering surface intrinsic behavior, inducing anticipated surface energy activation, chemical changes, and the formation of a densely packed solid structure. Under all conditions, the material consistently retained its crystalline nature, elemental composition, and ultraviolet emission characteristics. These preliminary findings hold promise for additional research, suggesting avenues for making complex materials in a flexible environment. Such new advancements could facilitate applications in the biomedical, catalysis, pharmaceutical, and surgical device domains.

High-energy, high-peak-power diode-pumped Q-switched Tm:YAG laser at 2.02 μm with tunable repetition rate from 100 Hz to 1000 Hz

A high-energy, high-peak-power Q-switched Tm:YAG laser at 2.02 μm with a tunable repetition rate from 100 Hz to 1000 Hz and pulse duration in the hundreds of nanoseconds is demonstrated. The high energy output was achieved by employing a thermally stable linear cavity, including two compact laser diode continuous-wave side-pumped Tm:YAG laser modules. For Q-switched operation, stable Q-switched performance from 100 Hz to 1000 Hz was realized at near-room temperature. At a repetition rate of 100 Hz, the laser delivered a maximum pulse energy of 215 mJ with a pulse duration of 124.4 ns, resulting in a peak power of up to 1.73 MW. When the repetition rate was tuned to 200 Hz, 500 Hz, and 1000 Hz, pulse energies of 212 mJ, 125.6 mJ, and 68.2 mJ were obtained, with pulse durations of 133.6 ns, 176.3 ns, and 262 ns, respectively. To the best of our knowledge, these results represent the highest single pulse energies and peak powers ever accomplished for a diode-pumped Q-switched Tm-doped 2 μm laser operating at high repetition rates exceeding 100 Hz.

Ternary ReS2(1-x)Se2xalloys of different composition for Q-switched and mode-locked all-fiber laser.

This paper systematically studied the composition-controlled nonlinear optical properties and pulse modulation of ternary ReS2(1-x)Se2xalloys for the first time. The compositionally modulated characteristics of ReS2(1-x)Se2xon the band gap were simulated based on the first principles. We investigated the effect of the band gap on the saturable absorption properties. In addition, we demonstrated the modulation characteristics of different components ReS2(1-x)Se2xon 1.5μm Q-switched pulse performance. The Q-switched threshold, repetition rate, and pulse duration increase as the S(sulfur)-element composition rise. And pulse energy also was affected by the S(sulfur)-element composition. The ReS0.8Se1.2SA was selected to realize a conventional soliton with high energy in the all-fiber mode-locked laser. The pulse was centered at 1562.9 nm with a pulse duration of 2.26 ps, a repetition rate of 3.88 MHz, and maximum pulse energy of 1.95 nJ. This work suggests that ReS2(1-x)Se2xhas great potential in laser technology and nonlinear optics, and widely extends the material applications in ultrafast photonics.

Head-to-head comparison of pulsed field ablation, very high power-short duration, cryoballoon and conventional radiofrequency ablation by LGE-MRI-based ablation lesion assessment

Abstract Background Novel concepts for pulmonary vein isolation (PVI) like pulsed field ablation (PFA) or high power-short duration ablation (HPSD) promise favourable profiles of safety and efficacy. However, clinical comparisons of ablation lesion quality are lacking. Purpose To systematically investigate lesion characteristics of novel ablation concepts, we performed a prospective head-to-head comparison between PFA, HPSD, conventional RF and latest generation cryoballoon ablation using late gadolinium enhancement (LGE)-MRI-based ablation lesion assessment. Methods This study included patients that underwent first-time PVI-only atrial fibrillation ablation - either by ablation index-guided RF ablation, cryoballoon ablation (Arctic Front Advance Pro), HPSD ablation (QDOT micro catheter, QMODE+, 90W, 4s) or PFA (Farapulse PFA system). All patients received an LGE-MRI 3 months post-ablation. LGE was quantified based on the signal intensity ratio of each voxel relative to the blood pool, applying a previously validated threshold of >1.2 to define LGE indicative of ablation-induced scarring using a dedicated software. LGE discontinuations of >3 mm were considered as gaps, and complete lesions were defined as LGE covering >90% of the peri-antral circumference of ipsilateral pulmonary vein (PV) pairs. Results Post-ablation LGE-MRIs from 120 patients were analysed (40 RF, 40 cryoballoon, 20 PFA, 20 HPSD). The proportion of complete PV-encircling LGE lesions was significantly higher with conventional RF than with cryoballoon ablation (50% vs. 34%; p=0.023). Importantly, HPSD ablation resulted in even more complete lesions than conventional RF (68%, p=0.004), whereas the proportion of complete LGE lesions was lowest with PFA (21%). Accordingly, the total number of gaps was lower with HPSD ablation (1.9 gaps/patient) compared to the other ablation concepts (conventional RF 2.7, cryoballoon 3.2, PFA 3.4 gaps/patient; p=0.034). As expected, large-area ablation with the cryoballoon (13.8 mm) and PFA (12.8 mm) single-shot devices resulted in the widest lesions. Of note, HPSD lesions were significantly wider than conventional RF lesions (11.1 mm vs. 8.9 mm; p=0.004). Conclusions HPSD ablation resulted in the most continuous lesions, translating in the lowest number of gaps. Of note, HPSD lesions were also significantly wider than conventional RF lesions, thus corroborating the concept of a shallower HPSD lesion geometry from experimental studies. Interestingly, conventional RF showed a higher proportion of complete PV-encircling lesions than cryoballoon ablation. While PFA lesions cover relatively large areas, comparable to cryoballoon ablation, lesions are more inhomogeneous. However, it remains to be determined, to what extent LGE discontinuities in PFA lesions indicate ineffective ablation or only reflect a different kind of remodeling compared to thermal ablation, which may be less detectable by LGE-MRI.

Impact of left bundle branch area pacing on right cardiac chambers dimensions and function. a medium term single center echocardiographic study

Abstract Introduction Left bundle branch area pacing (LBBAP) has become, in the last years, the preferred method for physiological pacing due to a wider target area, optimal pacing and sensing thresholds, and stable parameters over time. LBBAP ensures rapid and synchronous left ventricular (LV) activation through the left-sided conduction system. On the other hand, there is little data on right ventricular (RV) activation in LBBAP. The purpose of this study was to evaluate the impact of LBBAP on the right heart anatomy and function over a mid-term follow-up period. Material and methods All consecutive patients with successful LBBAP for bradyarrhythmic indications between February 2021 and July 2022 at our institution were eligible for this study. Left bundle branch capture was defined as a paced QRS complex of right bundle branch block morphology, and proof of transition from non-selective to selective capture with differential pacing maneuvers. To avoid confounders, patients with LV ejection fraction below 40% and with severe valvular disease were excluded. In the end, 57 patients were prospectively evaluated. Patient and procedural characteristics were recorded at baseline and follow-up. Also, right atrial (RA) volume, RV basal diameter, tricuspid annulus peak systolic elevation (TAPSE), RV S` wave (RVS`W), and tricuspid regurgitation (TR) were evaluated before the procedure and at the end of the follow-up period. Results The mean age of the patients was 68.9± 10 years, and 70% were males. 29.8% had a baseline right bundle branch block, and 22.8% had a left bundle branch block morphology. The baseline LV ejection fraction was 54.3 ± 9.9 %. The paced QRS duration was similar to the baseline values (128.5 ± 16.3 vs. 134.4 ± 30.4 msec, p=0.119). The pacing and sensing thresholds were 0.7 ± 0.3 V at 0.4 ms pulse duration and 9.7 ± 4.2 mV, respectively. The mean LV activation time (measured as the R wave peak time in V6) was 80.9 ± 12 msec, and the mean RV activation time (measured as the difference between QRS duration and LV activation time) was 51.9 ± 24.2 msec. The patients were followed over a mean period of 591.2 ± 150.3 days. There were no complications over the follow-up period that led to pacing interruption. The follow-up pacing (0.6 ± 0.2 V, p=0.003) and sensing (11.7 ± 6 mV, p= 0.023) thresholds showed significant improvement compared to the procedural values. The right heart echocardiographic evaluation showed non-statistically significant changes between the follow-up and the baseline values for RA volumes (57.9 ± 33.7 vs. 51.5 ± 28.4 ml, p=0.122), RV basal diameter (32.8 ± 5.4 vs. 31.8 ± 6.4 mm, p=0.31), RVS`W (12.8 ± 3.2 vs. 12.85 ± 2.7 cm/sec, p=0.933), and TR (1.8±0.8 vs. 2±1, p=0.07). On the other hand, there was a significant improvement in the TAPSE (22.2±4.3 vs. 20.7±3.6 mm, p=0.021). Conclusions LBBAP was associated with preserved dimensions and function of the right cardiac chambers over a medium-term follow-up period.

Systematic testing, verification and validation of laser treatments for unglazed earthenware affected by lichens and fungi biodeterioration

In recent years, there has been a growing interest in exploring environmentally friendly and healthy alternatives to conventional solvent cleaning and biocides in the conservation of stone artworks. Here, we focus on the potential of laser-based photonic methods for treating biodeteriorated earthenware artefacts. The investigation was conducted on Roman dolia (jars) of the International Museum of Ceramics, Faenza, Italy. Three removal methods were tested and compared: (i) brushing using a soft-bristled electric brush and water, referred to as brush cleaning; (ii) a combination of brushing and laser ablation; and (iii) biocide and brushing. Four laser systems with different wavelengths and optimized pulse durations in nanosecond or microsecond regimes were used in the tests. Systematic irradiation tests were conducted to determine the damage thresholds and define safe laser irradiation levels. The characterizations of the surfaces under treatment were carried out pre- and post-laser irradiation using optical microscopy, 3D photogrammetry, and Pulse-Amplitude-Modulated Chlorophyll-Fluorometry. Furthermore, spectroscopic methods based on FTIR, Raman, and LIBS techniques were used to assess the effectiveness of the removal process and the composition of uncovered surfaces. Results have indicated that gentle brushing and water is the most effective approach for safely removing around 60% of the bio-colonization weakly anchored to the substrate over the area under treatment. This comprised viable species, whereas the remaining 40% of the area included endolithic species, mostly thalli of Verrucaria nigrescens and rock-dwelling fungi. The eradication of the latter was the real conservation concern requiring attention. Following the experimentation, the optimal method for safely uncovering the earthenware surface was a combination of water-assisted brushing and 1064 nm laser irradiation as a finishing treatment.

Machinability and pulse characteristics of Ti-16Al-14Nb (α/β) alloy in wire-electric discharge machining process: A surface integrity study

The goal of the present work is to produce the efficient cutting of Ti-16Al-14Nb (α/β) alloy through wire-electric discharge machining and contemplate the terminologies such as machining ability, surface integrity and material removing capability. For this, the experimentation has been designed by considering three process parameters, pulse-on time ( Ton), pulse-off time ( Toff) and peak current ( Ip) at three significant levels (low, high, intermediate) in L27 order designed from design of experiments. The effect of these process variables on pulse characteristics, surface roughness ( Ra), kerfwidth ( Kw) and material removal rate ( MRR) is analyzed and mathematically modeled with analysis of variance. The results state that the highest MRR (0.521, 0.51, 0.506 mm3/sec) and low surface roughness (8.91, 8.89, 8.68 µm) values are observed at the highest level (110 µs, 15 µs, 8 A). If the pulse duration is kept at low ( Ton = 40µs, Toff = 3µs), the increase in peak current from 3 A to 8 A leads to a 64.54% increase in MRR and a 52.9% increase in Ra values. ANOVA results stated that Ton has contributed 20.4%, 35.8% and 19.3%, and Ip has contributed 43.1%, 30.5% and 46.6% influence on MRR, Kw and Ra respectively. The voltage–current characteristics studies confirmed that the strong intense pulses at a higher peak current (8 A) resulted in the increased MRR (0.521 mm3/sec) and Ra (8.43 µm) leading to the formation of swages and ridges. The surface integrity analysis derived from Abbott–Firestone curve agreed that the lowest level has shown better skewness ( Rsk = −0.274) and at highest level showed a larger deviation in skewness ( Rsk = +2.672) signifies that higher asymmetry (poor) of the surface.

GHz-rate 57-fs acousto-optic mode-locking fiber laser based on cascaded all-fiber pulse compression.

We demonstrate a compact ultrafast fiber laser system that can deliver 1.87 GHz pulse train at 1550 nm with a pulse energy of 52 pJ and an ultrashort pulse duration of 57 fs. While an acousto-optic mode-locking fiber laser was used as the seed light source at GHz rate, a stage of Er-doped fiber amplifier boosted the laser power to ∼320 mW, giving a pulse energy of ∼170 pJ. Then, a pulse compression setup was constructed, providing a high compression ratio of ∼10 with a total efficiency of ∼32%. In the cascaded compression configuration, multiple fiber samples with alternately normal and anomalous dispersion were fused together, providing efficient nonlinear spectral broadening while suppressing excessive pulse broadening over propagation. This GHz-rate ultrafast fiber laser, with compact configuration, broad optical spectrum, and high time-resolving ability could be used as the seed light source for constructing high-rate, high-power ultrafast laser systems and may find a few applications in optical measurements and microwave photonics.

AN ENHANCEMENT IN THE COPPER ELECTRODE WEAR CHARACTERISTIC ELECTRICAL DISCHARGE MACHINED INCONEL 718 THROUGH ION NITRIDING, LASER SURFACE HARDENING AND HYBRID PROCESS

The virgin copper electrode has limited application due to its wear and mechanical properties using Electrical Discharge Machined (EDMed) on Inconel 718 superalloys. In order to enhance the performance of copper electrodes, in this work, Ion Nitriding (IN), Surface Hardening by Laser (LSH) and Hybrid Process ([Formula: see text]) are performed on copper electrodes to reduce the electrode wear in frontal and lateral. The electrode wear in the frontal and lateral of virgin copper electrode is processed and studied using EDM with varying pulse durations, current and Silicon Carbide (SiC) mixed EDM oil. The surface hardness in virgin and processed electrodes is also investigated. Overall analysis found that the hybrid technique produced a 59% higher hardness than that of virgin copper. The hardness in the EDMed surface was higher than that of the processed copper surface. A 1000[Formula: see text][Formula: see text]s pulse duration, 2 A current and 15 g/l SiC powder mixing EDM oil produced a low frontal wear in both virgin and processed copper electrodes. The electrode wear was reduced by 30% for frontal and 76% for lateral using a hybrid method.

High-power and narrow-linewidth nanosecond pulsed intracavity crystalline Raman laser operating at 1.7 µm

We report on a high-power and narrow-linewidth nanosecond pulsed intracavity crystalline Raman laser at 1.7 µm. Driven by an acousto-optically Q-switched 1314 nm two-crystal Nd:YLF laser, the highly efficient cascaded YVO4 Raman laser at 1715nm was obtained within the well-designed L-shaped resonator. Thanks to the absence of spatial hole burning in the stimulated Raman scattering process, significant spectral purification of second-Stokes radiation was observed by incorporating a fused silica etalon in the high-Q fundamental cavity. Under the repetition rate of 4 kHz, the highest average output power for single longitudinal mode operation was up to 2.2 W with the aid of precision vibration isolation and precision temperature controlling, corresponding to the pulse duration of ∼2.8 ns and the spectral linewidth of ∼330 MHz. Further increasing the launched pump power, the second-Stokes laser tended toward be always multimode, and the maximum average output power amounted to 4.8 W with the peak power of ∼0.8 MW and the spectral linewidth of ∼0.08 nm. The second-Stokes emission was near diffraction limited with M2 < 1.4 across the whole pump power range.

All-PM Yb-doped mode-locked fiber laser with high single pulse energy and high repetition frequency

We demonstrate an all-polarization-maintaining (PM) ytterbium (Yb)-doped fiber laser with a figure-of-9 structure to generate mode-locked pulses with high single pulse energy and high repetition frequency. By exploiting the nonlinear amplifying loop mirror, a stably self-started mode-locking is achieved with a spectrum bandwidth of 13 nm and a pulse duration of 4.53 ps. The fundamental frequency is 97.966 MHz at the maximum output power of 143 mW in single pulse mode-locked operation, corresponding to the single pulse energy is 1.46 nJ. The output pulses maintain both high repetition frequency and high single-pulse energy. This laser oscillator can be an ideal seed source for applications such as high-energy amplifiers.

Femtosecond pulse train-facilitated periodic nanostructuring on TiN films via laser-oxidation

Laser-induced periodic surface structure is a universal phenomenon observed when solid materials are irradiated with pulsed lasers. Typically, these structures are generated using Gaussian pulses. Here, we investigate the formation of periodic nanostructures on titanium nitride thin films using two different laser sources: Gaussian pulses and femtosecond pulse trains generated through a Fabry-Perot cavity. Our findings indicate that the formation of self-organized nanostructures on the thin films can occur through either laser-induced oxidation or laser ablation processes, depending on laser fluence, scanning speed, and pulse duration. Interestingly, when utilizing femtosecond pulse trains, we observe that the range of laser fluence thresholds for oxidative nanostructure formation is significantly wider compared to Gaussian pulses. To comprehend the underlying mechanisms driving these observations, we employ a two-temperature model to calculate the ultrafast dynamics of hot electrons when exposed to laser irradiation. Our results reveal that the initial sub-pulse generates a substantial population of hot electrons, exciting surface plasmons and resulting in the creation of a periodic energy distribution. Before these hot electrons can dissipate, subsequent sub-pulses reach the thin film, re-exciting a large number of hot electrons. Consequently, the periodic energy distribution persists for an extended duration, creating more favorable conditions for the formation of periodic oxidative nanostructures when using pulse trains. These findings contribute to a comprehensive understanding of the mechanisms involved in the formation of periodic nanostructures under femtosecond laser irradiation.

A Plasma Arc-Based Electromechanical System Designed for Microchannel Processing

AbstractPlasma technology is based on a simple physical principle. When more energy enters the gas, it ionizes and becomes the fourth state of matter, the energy-dense plasma. The studies carried out within the scope of this study were designed to create microchannels on lamellar glass using an improved redesign of the current plasma arc device, which is the main subject of the paper. The created microchannel is examined at the microscale. Experimental analysis was conducted considering the effect of plasma on the effect of microchannel quality. We performed an experimental design study to determine the optimal parameter levels for improving microchannel quality. The predicted results have been validated with the experimental results. An experimental design study provides useful results, such as information about the distance between the probes, pulse duration, and material temperature, which enhances the channel dimensions. The improved device can be utilized effectively to establish microchannel processing in practice.

Tunable temporal dynamics of dipole response in graphene-wrapped core–shell nanoparticles

The investigation on the temporal dynamics of graphene-wrapped core–shell nanoparticles under the illumination of a Gaussian impulse have been carried out. By altering the graphene layers and the aspect ratio of the core–shell structure, we can adjust the resonant modes into typical cases in regime of terahertz. Accordingly, different scenarios for the temporal evolution are detected, which include two kinds of ultrafast oscillation with exponential decay tendency, pure exponential decay, and Gaussian shape, when the pulse duration of the incident pulse is much shorter than, similar to, and much longer than the localized surface plasmon lifetime. To one's interest, when the coupling between two resonant modes exists, one predicts the long-periodic oscillation, whose period is just the difference between the frequencies of the resonant modes. Hence, the intrinsic properties of the ultrafast oscillation can be hardly influenced by the input signals. Further quantitative calculation demonstrate that the periods of the ultrafast oscillations can be tuned by different physical mechanisms, which are, respectively, based on the self-interacting correction of a single resonance and the strong coupling between the resonant modes in frequency domain. Our results may be applicable in the fields of optical sensors, optical information processing, and other nanophotonic devices.

Mathematical Analysis for Optimizing Electro Discharge Machining Parameters and Enhancing Hastelloy Machining Efficiency

This study investigates the process parameter optimisation for Hastelloy electro discharge machining (EDM). The goal of the research is to increase machining accuracy and efficiency by precisely changing the EDM process factors. The most important variables affecting tool wear, surface quality, and material removal rate are identified. In order to improve the machining performance for Hastelloy components, the research highlights the importance of factors including discharge current, pulse duration, electrode material, and dielectric fluid properties. The study's conclusions give important information about how to improve EDM procedures for this tough, corrosion-resistant hastealloy. Extensive research is conducted into the features of tool wear and their connection to process parameters in an effort to increase tool life and reduce manufacturing costs. The findings of this research offer useful data for optimising the efficiency of the Hastelloy EDM process in terms of both money and time. The growing need for high-performance components in industries including aerospace, chemical, and nuclear engineering is being addressed by this study, which intends to lay the groundwork for the development of efficient and environmentally friendly machining practises for Hastelloy. To do this, one must get a thorough comprehension of the interrelationships between the various process parameters.

Maximum Operational Fluence Limits for Temporally Shaped Nanosecond Long Pulses

The maximum energy at which a laser can be operated safely is a matter of paramount importance. This is patently related to laser induced damage. In the nanosecond regime, this poses a unique challenge, as it is not solely influenced by laser intensity or thermal load. Instead, it arises from the cumulative effects that includes those two factors. While extensive research has explored this dependence for various pulse lengths, the exploration of different longitudinal modes and temporal shapes is relatively limited. Our study aims to fill this gap by determining the safe operational fluence for any pulse shape, leveraging established dependencies on pulse duration. We propose a straightforward and adaptable method to ascertain these operational limits, independent of the type or origin of laser damage. This approach allows us to derive fluence limits for diverse pulse shapes.

Mechanisms of deformation induced by high-current pulsed electron beam irradiation

AA2024 aluminum alloy was irradiated by a high-current pulsed electron beam with the following parameters: beam energy ∼0.3 MeV, current ∼2000A, pulse duration ∼5·10−6 s, beam diameter ∼3 cm. The thickness of the surface remelted layer reached 100 μm. Dynamic thermal stresses caused by irradiation, induced the development of deformation processes in the irradiated layer. Based on the study of surface morphology and structural state of the remelted layer, it was shown that deformation processes occur in the surface layer by the grain boundary sliding mechanism. The level of residual stresses in the irradiated layer was low and amounted to 34 MPa.