Intense Pulses Research Articles

Oxygen isotopic compositions of fresh rooftop micrometeorites from the Budel collection—Insights into the contemporary cosmic dust flux

AbstractCosmic dust particles originate from a wide variety of solar system and interstellar objects, including sources not identified among meteorite collections. Particles that survive atmospheric entry are retrieved on the Earth's surface as micrometeorites. The recovery of these micrometeorites has recently advanced to rooftop sites. Here, we present the results of an extensive isotopic study on this type of rooftop micrometeorite from the Budel collection, the Netherlands, accreted to the Earth between October 31, 2018 and June 16, 2021. The triple oxygen isotopic compositions of 80 silica‐dominated cosmic spherules (CSs) with diameters ranging between 105 and 515 μm are obtained relying on 213 in situ spot analyses determined using ion microprobe. Our analyzed population spans a large range of isotopic compositions and is dominated by carbonaceous chondritic sources. In situ measurements on several CSs support a possible continuum between 16O‐rich and 16O‐poor compositions following the CM mixing line, showing that 16O‐poor CSs may be genetically related to aqueously altered carbonaceous chondrites. We demonstrate that weathering in the terrestrial environment has negligible effects on the isotopic compositions of the studied CSs and attempt to quantify the effects of kinetic mass‐dependent fractionation and admixture of terrestrial oxygen during atmospheric entry. The results further corroborate previously suggested relations between CS texture and the duration and intensity of the heating pulse experienced during atmospheric deceleration. Finally, the young and well‐constrained terrestrial age of the collection provides insights into the most recent flux of cosmic dust. Our results indicate no major recent changes in the global flux compared with collections sampled over thousand‐ to million‐year time scales and demonstrate that 16O‐poor material is still represented in the modern‐day cosmic dust flux at a relative abundance of ~13%–15%. As such, rooftop micrometeorites represent a valuable reservoir to study the characteristics of the contemporary cosmic dust flux.

Use of spatiotemporal couplings and an axiparabola to control the velocity of peak intensity.

This paper presents the first experimental realization of a scheme that allows for the tuning of the velocity of peak intensity of a focal spot with relativistic intensity. By combining a tunable pulse-front curvature with the axial intensity deposition characteristics of an axiparabola, an aspheric optical element, this system provides control over the dynamics of laser-wakefield accelerators. We demonstrate the ability to modify the velocity of peak intensity of ultrashort laser pulses to be superluminal or subluminal. The experimental results are supported by theoretical calculations and simulations, strengthening the case for the axiparabola as a pertinent strategy to achieve more efficient acceleration.

Two-Electron Scenario of High-Order Harmonics Generation by Atom in an Intense Infrared Field and Attosecond Pulse

The two-electron scenario is proposed for the high-order harmonic generation (HHG) by an atom interacting with an intense infrared field and attosecond pulse. The two-electron dynamics involved in the proposed scenario is realized for the specific attosecond pulse, which can excite the resonance between the valence and deeper shells. Within the numerical solution of the time-dependent Kohn–Sham equations, we analyze the contribution of the single [Phys. Rev. A 98, 063433 (2018)] and two-electron scenarios of HHG by decreasing the duration of attosecond pulse having carrier frequency detuned from the atomic resonance. Favorable conditions are formulated for the realization of a two-electron scenario, which causes the enhancement of the harmonic yield in the spectral range exceeding the cutoff energy of the HHG spectrum in the infrared field.

Mass transfer performance of pulsed disk and doughnut column (PDDC) in the extraction of active ingredients in peppermint extract obtained by hot percolation

AbstractThe active ingredients in peppermint are widely used in the pharmaceutical, food, cosmetic, and other industries. The traditional methods for producing peppermint extract through hydrodistillation (HD) and percolation are long process with low efficiency. The aim of this study is the improvement of the extraction performance and the efficiency of the extract obtained from hot percolation via pulsed disk and doughnut columns (PDDC), which is one of the most important pieces of liquid–liquid extraction (LLE) equipment. Peppermint extract was used as the continuous phase in the PDDC. n‐Hexane was considered as the dispersed phase in this column. In this study, the effects of three operating parameters were investigated, including the pulse intensity, continuous phase height, and dispersed phase flow rate, on the extraction efficiency of active ingredients in peppermint. The response surface method (RSM) was used to investigate the effect of these parameters on the extraction efficiency. The efficiency of this column in the extracting of active ingredients from peppermint was measured by UV–vis spectrophotometry, via the absorption rate of the main active ingredients of peppermint (menthol) in the samples, and the efficiency was 75% on average. The experimental and theorical of dispersed phase mass transfer coefficient were evaluated and compared. The results showed that the PDDC improved the extraction and mass transfer. By increasing the flow rate of the dispersed phase and the height of the continuous phase, the extraction efficiency and the mass transfer coefficient were increased.

Signatures of Dynamically Dressed States.

The interaction of a resonant light field with a quantum two-level system is of key interest both for fundamental quantum optics and quantum technological applications employing resonant excitation. While emission under resonant continuous-wave excitation has been well studied, the more complex emission spectrum of dynamically dressed states-a quantum two-level system driven by resonant pulsed excitation-has so far been investigated in detail only theoretically. Here, we present the first experimental observation of the complete resonance fluorescence emission spectrum of a single quantum two-level system, in the form of an excitonic transition in a semiconductor quantum dot, driven by finite Gaussian pulses. We observe multiple emerging sidebands as predicted by theory, with an increase of their number and spectral detuning with excitation pulse intensity and a dependence of their spectral shape and intensity on the pulse length. Detuning-dependent measurements provide additional insights into the emission features. The experimental results are in excellent agreement with theoretical calculations of the emission spectra, corroborating our findings.

Attosecond Probing of Nuclear Vibrations in the D2+ and HeH+ Molecular Ions.

We study the ultrafast photodissociation of small diatomic molecules using attosecond laser pulses of moderate intensity in the (extreme) ultraviolet regime. The simultaneous application of subfemtosecond laser pulses with different photon energies─resonant in the region of the molecular motion─allows one to monitor the vibrational dynamics of simple diatomics, like the D2+ and HeH+ molecular ions. In our real-time wave packet simulations, the nuclear dynamics is initiated either by sudden ionization (D2+) or by explicit pump pulses (HeH+) via distortion of the potential energy of the molecule. The application of time-delayed attosecond pulses leads to the breakup of the molecules, and the information on the underlying bound-state dynamics is imprinted in the kinetic energy release (KER) spectra of the outgoing fragments. We show that the KER-delay spectrograms generated in our ultrafast pump-probe schemes are able to reconstruct the most important features of the molecular motion within a given electronic state, such as the time period or amplitude of oscillations, interference patterns, or the revival and splitting of the nuclear wave packet. The impact of probe pulse duration, which is key to the applicability of the presented mapping scheme, is investigated in detail.

Simulating radio-off fractions in rotating radio transients

We aim to simulate the proportions of non-detectable emission, measured as radio-off fractions ($f_ off $), in rotating radio transients (RRATs). We also investigate the properties related to the underlying mechanism for such sporadic emission. From observations of intermittent pulsars, radio emission originates from two distinct emission states and it becomes non-detectable when the pulsar switches to an emission state characterized by magnetospheric plasma density of zero. We performed simulations of $f_ off $ based on 10,000 samples, each with 10,000 rotations and using a model that tracks changes in the plasma density in a pulsar magnetosphere with multiple emission states. We assumed that (i) RRATs are radio pulsars, (ii) radio pulse intensity is correlated with the emitting plasma density as stated in the conventional models, and (iii) a pulse emission corresponds to a change in the plasma density under favorable conditions. A best-fit distribution for $f_ off $ is obtained when emission from RRATs is defaulted to radio-off. The resulting wait time distribution can be fitted by two functions of an exponential and a Gaussian, which is consistent with the observations. We demonstrate that the switch rate is low and that the burst rate is dependent on rotation period. In addition, the switch rate is related to the obliquity angle, which implies that the mechanism varies over time. Our results suggest that switching to radio-on is a random process, which implies that the burst rate is different for different RRATs. We show that RRAT emission and pulse nulling may share similar origins, but with different default emission. We discuss how the emission may change from that of RRAT to pulse nulling (or vice versa) as a pulsar evolves.

Generation of isolated attosecond electron sheet via relativistic spatiotemporal optical manipulation

Novel phase-locked acceleration of a relativistic isolated attosecond electron sheet was realized using a relativistic reflected spatiotemporal optical vortex (STOV) pulse in three-dimensional particle-in-cell simulations. Electrons can be trapped in a spatiotemporal phase singularity within the STOV pulse center, modulated into an approximately 600-attosecond duration sheet. Furthermore, electrons can be phase-locked accelerated to the order of GeV in the longitudinal direction. Such an isolated attosecond electron sheet driven by the intense STOV pulse can be used in isolated attosecond pulse generation, ultrashort x/-ray radiation, and attosecond electron diffraction. Published by the American Physical Society 2024

Realization of High Mobility Synaptic Transistor through Control of Cross‐Linking Agent in a Polymer Dielectric Layer for Emerging Electric Double Layer

AbstractThe development of high‐mobility neuromorphic transistors is essential to increase signal transmission speed and solve the von Neumann bottleneck issue. Herein, this work proposes cross‐linked Poly(4‐vinylphenol) (c‐PVP) as a dielectric layer to form an electric double layer (EDL), which plays a key role in synaptic transistors, and measure the ratio‐dependent characteristics of cross‐linking agents in c‐PVP. When the ratio of PVP to poly(melamine‐co‐formaldehyde) methylated (PMF) is 10:1, neuromorphic transistors is found to show the best performance with a memory window of 2.2 V and a mobility of 93.4 cm2 V−1 s−1. Fourier‐transform infrared spectroscopy (FT‐IR) results show that the reduction in the concentration of the cross‐linking agent generates more hydroxyl groups within the c‐PVP film. The 10:1 c‐PVP‐based synaptic device has an ultra‐low energy consumption of 15.8 pJ for a single pulse and a maximum paired pulse facilitation (PPF) index value of 291%. Additionally, synaptic characteristics, such as pulse duration time dependent plasticity, pulse intensity dependent plasticity, pulse rate dependent plasticity (SRDP), high band filtering, and short‐term memory (STM) conversion to long‐term memory (LTM), are also described and discussed. These results suggest that c‐PVP/ZnON‐based neuromorphic devices can be promising artificial synapses for memory and learning capabilities.

Optimal remote restoring of quantum states in communication lines via local magnetic field

Optimal state transport across spin chains, which are proposed as quantum wires for information transfer in solid state quantum architectures, is an important topic for quantum technologies. In this work, we study the remote restoring of a quantum state transferred along a spin chain. The structural state-restoring technique provides proportionality between the appropriate elements of the density matrices of the initial sender state and receiver state at some time instant. We develop a remote state-restoring protocol which uses an inhomogeneous magnetic field with step-wise time-dependent Larmor frequencies as the state-control tool. For simulating the multiparametric Hamiltonian we use two approximating models. First model is based on the Trotter-Suzuki method, while the second model is based on using short pulses of high intensity. In both cases we estimate the accuracy of the approximation and find the optimal restoring parameters (Larmor frequencies) of the protocol which maximize the coefficients in the proportionality for spin chains of various lengths.

Observation of a single protein by ultrafast X-ray diffraction

The idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many. It was one of the arguments for building X-ray free-electron lasers. According to theory, the extremely intense pulses provide sufficient signal to dispense with using crystals as an amplifier, and the ultrashort pulse duration permits capturing the diffraction data before the sample inevitably explodes. This was first demonstrated on biological samples a decade ago on the giant mimivirus. Since then, a large collaboration has been pushing the limit of the smallest sample that can be imaged. The ability to capture snapshots on the timescale of atomic vibrations, while keeping the sample at room temperature, may allow probing the entire conformational phase space of macromolecules. Here we show the first observation of an X-ray diffraction pattern from a single protein, that of Escherichia coli GroEL which at 14 nm in diameter is the smallest biological sample ever imaged by X-rays, and demonstrate that the concept of diffraction before destruction extends to single proteins. From the pattern, it is possible to determine the approximate orientation of the protein. Our experiment demonstrates the feasibility of ultrafast imaging of single proteins, opening the way to single-molecule time-resolved studies on the femtosecond timescale.

Interplay between intervalley scattering and impact ionization induced by intense terahertz pulses in InSb thin films

Interplay between intervalley scattering and impact ionization induced by intense terahertz pulses in InSb thin films

Spectroscopically resolved resonant interatomic Coulombic decay in photoexcited large He nanodroplets

Interatomic Coulombic decay (ICD) processes play a crucial role in weakly bound complexes exposed to intense or high-energy radiation. Using large helium nanodroplets, we demonstrate that ICD is efficient even when the droplets are irradiated by weak synchrotron radiation at relatively low photon energies. Below the ionization threshold, resonant excitation of multiple centers efficiently induces resonant ICD as previously observed for intense pulses [A. C. LaForge , ]. More surprisingly, we observe ICD even above the ionization threshold due to recombination of photoelectrons and ions into excited states which subsequently decay by ICD. This demonstrates the importance of secondary processes, in particular electron scattering and recombination, in inducing ICD in extended condensed phase systems. High-resolution ICD electron spectra in combination with coincidence imaging of electrons and ions reveal the relaxation dynamics of highly excited and ionized weakly bound nanosystems. Published by the American Physical Society 2024

Variable step size VLF/ELF nonlinear channel adaptive filtering algorithm based on Sigmoid function

The signals received by very low-frequency/extremely low-frequency nonlinear receivers are frequently affected by intense atmospheric pulse noise stemming from thunderstorms and global lightning activity. Current noise processing algorithms designed for nonlinear channels within these frequency ranges, which are predicated on fractional p-order moment alpha stable distribution criteria (where 0 < p < α < 2, and p and α denote distinct characteristic indices of alpha stable distribution noise), are constrained by their reliance on limited p-order moment statistics. As a result, the performance of low-frequency nonlinear channel receivers experiences significant degradation when confronted with robust pulse noise interference (0 < p < α < 2). To tackle this challenge, the present study introduces a novel variable step robust mixed norm (RMN) adaptive filtering algorithm, designated as SVS-RMN, which is based on the Sigmoid function. Leveraging the nonlinearity of the Sigmoid function and building upon the power function Hammerstein nonlinear channel model, the algorithm aims to enhance the RMN algorithm by deriving new cost functions and adaptive iteration formulas. The performance of the proposed algorithm is evaluated in comparison to conventional RMN algorithms based on fractional low-order moment (FLOM) criteria (0 < p < 2), as well as other algorithms employing variable step sizes and either FLOM or radial basis function (RBF) criteria, across various intensities of pulse noise and mixed signal-to-noise ratios. The experimental results reveal the following: (1) The proposed algorithm effectively mitigates strong pulse noise interference and significantly enhances the tracking performance of the RMN algorithm compared to conventional RMN algorithms based on FLOM criteria. (2) In terms of computational efficiency, simplicity of structure, convergence speed, and stability, the proposed algorithm surpasses other algorithms based on FLOM or RBF criteria.

Generation and Dynamics of Multiple Pulses in an Ultrafast Fiber Laser with a Single-Mode Fiber–Graded-Index Multimode Fiber–Single-Mode Fiber-Based Saturable Absorber

In this study, we have investigated the evolution process and dynamic characteristics of a multi-pulse regime in an erbium-doped fiber ring laser based on a single-mode fiber–graded-index multimode fiber–single-mode fiber (SMF-GIMF-SMF) structure as an optical modulator. By utilizing the excellent nonlinear optical absorption of the SMF-GIMF-SMF (SMS) device with a modulation depth of ~8.68%, stable single-pulse mode locking at the frequency of 9.84 MHz can be readily observed at low pump power. In addition, the single-pulse operation can evolve into a multiple-pulse regime on account of the peak-power-clamping effect via suitably raising the pump power and carefully regulating the polarization state. Further, the single-shot temporal evolution of multiple pulses is monitored, indicating that this state shows unique and interesting temporal characteristics with variable pulse separations and inconsistent pulse intensities, which, as far as we know, is the first such observation in ultrafast fiber lasers. Additionally, this study, based on the time-stretch dispersive Fourier transformation method, suggests that these multiple pulses consist of chaotic wave envelopes with erratic intensities and changeable pulse energy. We believe that these findings have profound implications for revealing fascinating nonlinear pulse dynamics in ultrafast fiber optics.

Time-domain characterization of electric field vector in multi-terahertz pulses using polarization-modulated electro-optic sampling.

We demonstrated characterizing the electric field waveform of multi-terahertz pulses (10 - 50 THz) as vector quantities in the time domain by applying the polarization modulated electro-optic sampling (POMEOS) method. The problem of an ultrabroadband gate pulse was solved by modifying the fitting function in POMEOS, and its validity was confirmed through numerical simulations. High accuracy and precision of approximately 1 mrad with 3 s accumulation were demonstrated. Our method can be applied not only to multi-terahertz polarization measurements for linear response but also to the evaluation of the driving field of intense pulses for nonlinear response or material control.

Application of Pulsed Electric Field‐Ultrasound Technique for Antioxidant Extraction from Yarrow: ANFIS Modeling and Evaluation of Antioxidant Activity

Oxidation reactions negatively impact the taste and shelf life of the oils. Antioxidants are commonly employed to mitigate the development of off‐flavors and rancidity and thereby extend the shelf life of oil. In response to consumers’ increasing demand for healthy foods, there is a notable focus on incorporating naturally sourced antioxidants. Yarrow plant is a good source of natural antioxidants which could be used in improving the quality of the oils. Therefore, in this study, adaptive ANFIS was employed to investigate the extraction of antioxidant compounds from the yarrow plant using the pulsed electric field‐ultrasound method. The extraction process was performed at varying pulsed electric field intensities (0.25, 3.25, and 6.25 kV/cm) and different ultrasound durations (20, 40, and 60 minutes). Then, the impact of incorporating the plant extract on the oxidation parameters of sesame oil was assessed during storage. Results demonstrated that the extraction efficiency consistently increased with rising pulsed electric field intensity and ultrasound treatment time. However, the levels of total phenol, DPPH, and ascorbic acid content initially increased and then decreased at higher pulsed electric field intensity during longer ultrasound treatment. Furthermore, an increase in acidity and thiobarbituric acid index was found during prolonged storage time, while the peroxide level in the samples peaked on the 5th day of storage before declining. The high correlation coefficients between experimental results and model outputs underscored the models’ accuracy, representing their efficacy in controlling the extraction conditions using the pulsed electric field intensity‐ultrasound extraction method and utilizing the extract in sesame oil.

Establishing the parameters of the operation mode of the electric pulse automobile muffler

The purpose of the research in the article is to obtain analytical and experimental results on the purification of internal combustion engine exhaust gases by an electric pulse, allowing us to determine the main parameters of the muffler operation. The set goal was achieved by performing the following methodology. A mathematical model of the motion of a gas particle in a muffler has been developed and investigated, the relationship between the capacity of the engine combustion chamber, the number of revolutions of the crankshaft, the pulse intensity, and the dynamic viscosity of the medium has been established. The condition of the muffler operation is determined through the parameter - the distance between the electrodes. The optimality criterion is justified - the smokiness of the gas before and after purification. A nonlinear experimental plan has been compiled using the methods of similarity theory and dimension analysis. An experimental stand has been developed and results linking the process parameters have been obtained. The results obtained are the basis for the methodology for calculating the design of electric pulse mufflers with optimal smoke ratios.

Discharge characteristics and parameter diagnosis of brush-shaped air plasma plumes under auxiliary discharge

Atmospheric pressure plasma jet (APPJ) can produce plasma plumes rich in active species, which has a wide scope of applications. From the perspective of applications, it is one of the hot issues in APPJ research to generate a diffuse plasma plume on a large scale. At present, large-scale plasma plume has been produced by noble working gases, which is more economic and valuable if it is reproduced by air used as the working gas. In this work, an APPJ with an auxiliary discharge is proposed, with which a large-scale air plasma plume with a brush shape is produced. Results indicate that the brush-shaped air plume can exist by changing voltage amplitude (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt;) in a certain range. The length and brightness of the plasma plume increase with &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increasing. The waveforms of voltage and light emission signalindicate that the discharge can start at most once within half a cycle of applied voltage. The probability of discharge and the intensity of light emission pulse for each half a voltage cycle increase with &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increasing, but the voltage value at the discharge moment decreases with &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increasing. High-speed imaging study shows that the generation mechanisms of diffuse brush-shaped air plasma plumes and small-scale air plasma are similar, both originating from the temporal superposition of bifurcated normal flow light. In addition, optical emission spectra from the brush-shaped air plasma plume are utilized to study electron temperature, electron density, molecular vibrational temperature, and gas temperature. With &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increasing, gas temperature is low and almost unchanged, while electron density, electron temperature, and molecular vibrational temperature increase. In addition, OH concentration of the plasma plume is investigated by laser-induced fluorescence, indicating that OH is uniformly distributed, and its concentration increases with the &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increasing. All these results mentioned above are qualitatively analyzed.

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization.

C-I bond extension and fission following ultraviolet (UV, 262 nm) photoexcitation of 2- and 3-iodothiophene is studied using ultrafast time-resolved extreme ultraviolet (XUV) ionization in conjunction with velocity map ion imaging. The photoexcited molecules and eventual I atom products are probed by site-selective ionization at the I 4d edge using intense XUV pulses, which induce multiple charges initially localized to the iodine atom. At C-I separations below the critical distance for charge transfer (CT), charge can redistribute around the molecule leading to Coulomb explosion and charged fragments with high kinetic energy. At greater C-I separations, beyond the critical distance, CT is no longer possible and the measured kinetic energies of the charged iodine atoms report on the neutral dissociation process. The time and momentum resolved measurements allow determination of the timescales and the respective product momentum and kinetic energy distributions for both isomers, which are interpreted in terms of rival 'direct' and 'indirect' dissociation pathways. The measurements are compared with a classical over the barrier model, which reveals that the onset of the indirect dissociation process is delayed by ∼1 ps relative to the direct process. The kinetics of the two processes show no discernible difference between the two parent isomers, but the branching between the direct and indirect dissociation channels and the respective product momentum distributions show isomer dependencies. The greater relative yield of indirect dissociation products from 262 nm photolysis of 3-iodothiophene (cf. 2-iodothiophene) is attributed to the different partial cross-sections for (ring-centred) π∗ ← π and (C-I bond localized) σ∗ ← (n/π) excitation in the respective parent isomers.