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The cutting of lithium metal anodes is one of the key operations in the manufacturing chain for all-solid-state batteries. Due to its ductility and high surface adhesion, pure lithium is a difficult material for mechanical separation. The non-contact nature of laser-based technology, combined with its scalability for production lines, makes it a promising method for cutting lithium foil substrates. However, adequate pulse durations and cutting strategies have yet to be explored. In the scope of this work, picosecond- and nanosecond-pulsed laser systems were compared for the cutting of lithium–copper foil compounds. The influence of the layer sequence, driven by the distinct thermophysical properties of involved materials, on the process behaviour was tested by penetrating the workpiece from either the lithium or the copper side. Cause-effect relations between laser parameters and quality aspects were examined experimentally. Various cutting types were identified for the different configurations using scanning electron and laser scanning microscopy. Nanosecond-pulsed processing achieved cutting speeds of up to 2.75 and 5.00 m/s when penetrating the samples from the lithium and copper sides, respectively. Using the picosecond-pulsed laser allowed the reduction of the heat-affected zone compared to nanosecond-pulsed processing, with cutting speeds limited to 0.40 m/s, independent of the upper layer in the compound.

The flow control effects of a nanosecond-pulse-driven dielectric barrier discharge plasma actuator (ns-DBDPA) in dynamic stall flow were experimentally investigated. The ns-DBDPA was installed on the leading edge of an airfoil model designed in the form of a helicopter blade. The model was oscillated periodically around 25% of the chord length. Aerodynamic coefficients were calculated using the pressure distribution, which was obtained by the measurement of the unsteady pressure by sensors inside the model. The flow control effect and its sensitivity to pitching oscillation and ns-DBDPA control parameters are discussed using the aerodynamic coefficients. The freestream velocity, the mean of the angle of attack, and the reduced frequency were employed as the oscillation parameters. Moreover, the nondimensional frequency of the pulse voltage, the peak pulse voltage, and the type and position of the ns-DBDPA were adopted as the control parameters. The result shows that the ns-DBDPA can decrease the hysteresis of the aerodynamic coefficients and a flow control effect is obtained in all cases. The flow control effect can be maximized by adopting the low nondimensional frequency of the pulse voltage.

Hydroxyl radicals (OH) play a crucial role in plasma-bio applications. As pulsed plasma operation is preferred, and even expanded to the nanosecond range, it is essential to study the relationship between OH radical production and pulse characteristics. In this study, we use optical emission spectroscopy to investigate OH radical production with nanosecond pulse characteristics. The experimental results reveal that longer pulses generate more OH radicals. To confirm the effect of pulse properties on OH radical generation, we conduct computational chemical simulations, focusing on two types of pulse properties: pulse instant power and pulse width. The simulation results show that, similar to the experimental results, longer pulses generate more OH radicals. In the nanosecond range, reaction time is critical for OH radical generation. In terms of chemical aspects, N2 metastable species mainly contribute to OH radical generation. It is a unique behavior observed in nanosecond range pulsed operation. Furthermore, humidity can turn over the tendency of OH radical production in nanosecond pulses. In a humid condition, shorter pulses are advantageous for generating OH radicals. Electrons play key roles in this condition and high instant power contributes to them.

Trepanning pattern is an important factor in laser hole machining, affecting both the hole quality and process efficiency. The influence of laser trepanning patterns on the hole ablating using nanosecond pulse laser in Al2O3 ceramics substrate was studied. Two laser trepanning patterns were evaluated, filled spiral trepanning and multiple rings trepanning, with the optimized laser machining parameters. In conjunction with the studies, the hole saturated taper and the saturated processing time were taken as the primary criteria for evaluation of the hole quality and the machining efficiency, respectively. Finally, the trepanning patterns were optimized aiming for the high hole quality; the process was based on the saturated hole tapers. The hole high qualities and machining efficiencies were obtained based on the saturated processing time, which was proven to have a great significance when using the nanosecond pulse laser to machine Al2O3 ceramics substrate.

Nanosecond pulse stimulation as a tumor ablation therapy has been studied for the treatment of various carcinomas in animal models and has shown a significant survival benefit. In the current study, we found that moderate heating at 43°C for 2 minutes significantly enhanced in vitro nanosecond pulse stimulation-induced cell death of KLN205 murine squamous cell carcinoma cells by 2.43-fold at 600 V and by 2.32-fold at 900 V, as evidenced by propidium iodide uptake. Furthermore, the ablation zone in KLN205 cells placed in a 3-dimensional cell-culture model and pulsed at a voltage of 900 V at 43°C was 3 times larger than in cells exposed to nanosecond pulse stimulation at room temperature. Application of moderate heating alone did not cause cell death. A nanosecond pulse stimulation electrode with integrated controllable laser heating was developed to treat murine ectopic squamous cell carcinoma. With this innovative system, we were able to quickly heat and maintain the temperature of the target tumor at 43°C during nanosecond pulse stimulation. Nanosecond pulse stimulation with moderate heating was shown to significantly extend overall survival, delay tumor growth, and achieve a high rate of complete tumor regression. Moderate heating extended survival nearly 3-fold where median overall survival was 22 days for 9.8 kV without moderate heating and over 63 days for tumors pulsed with 600, 100 ns pulses at 5 Hz, at voltage of 9.8 kV with moderate heating. Median overall survival in the control groups was 24 and 31 days for mice with untreated tumors and tumors receiving moderate heat alone, respectively. Nearly 69% (11 of 16) of tumor-bearing mice treated with nanosecond pulse stimulation with moderate heating were tumor free at the completion of the study, whereas complete tumor regression was not observed in the control groups and in 9.8 kV without moderate heating. These results suggest moderate heating can reduce the necessary applied voltage for tumor ablation with nanosecond pulse stimulation.

A fiber-based route to mid-infrared nanosecond pulse laser generation in gas-filled hollow-core anti-resonant fiber at 4.3 μm with 10-W-level average power is demonstrated. The demonstration experiments, harnessing a single pump pulse with 37 ns duration and 125 W output power at 2 μm in a CO2-filled large-mode-field hollow-core anti-resonant fiber, produce nanosecond pulses centered at the 4.3 μm band with the output power of 10.27 W, with a pulse width of 29 ns and a repetition rate of 10 MHz. Efficient high-power mid-infrared laser generation is realized by detuning the pump wavelength from the CO2 molecular absorption peak, leading to mitigating the gain saturation issue in the CO2-filled hollow-core anti-resonant fiber laser under high-power pumping. To the best of our knowledge, this represents the highest power reported for CO2-filled hollow-core fiber nanosecond pulse laser sources to date, demonstrating a 34-fold power improvement over previous works.

We report a novel coherent nanosecond pulse combination approach using four-channel non-polarization-maintaining large-mode-area (LMA) Ytterbium-doped (Yb-doped) fiber amplifiers. The stochastic parallel gradient descent (SPGD) and frequency dithering algorithm are introduced to stabilize the synchronization in polarizations and phases among all the channels. The system delivers an average power of ~250 W and a pulse duration of 4 ns with a combination efficiency of around 87% when the repetition rate of a single pulse is limited to 1 MHz, the polarization extinction ratio (PER) at 30 μm core diameter and 250 μm cladding diameter remains around 96%.

A series of low-voltage thyristor current switches based on (Al)GaAs/GaAs homo- and heterostructures with a volume charge region formed in the lightly doped p -GaAs base layer have been developed. The transient processes characteristics in pulse generation mode of nanosecond duration have been studied. It has been shown that the use of a wide-bandgap barrier based on AlGaAs at the n ‑emitter/ p -base junction allows reducing the minimum control current amplitude from 30 to 3 mA, and the turn-on delay time can be shortened to 6 ns. For the developed thyristor switches, a minimum transition time of 3.7–3.9 ns was demonstrated when operating in a circuit with a 1 nF capacitive load. In a circuit with a nominal 1 Ω resistive load, the thyristor switches provided a peak current of 17.5 A with a pulse duration of 3.7 ns.