Acceleration Mechanism Research Articles

Artificial intelligence-based optimization techniques for optimal reactive power dispatch problem: a contemporary survey, experiments, and analysis

The optimization challenge known as the optimal reactive power dispatch (ORPD) problem is of utmost importance in the electric power system owing to its substantial impact on stability, cost-effectiveness, and security. Several metaheuristic algorithms have been developed to address this challenge, but they all suffer from either being stuck in local minima, having an insufficiently fast convergence rate, or having a prohibitively high computational cost. Therefore, in this study, the performance of four recently published metaheuristic algorithms, namely the mantis search algorithm (MSA), spider wasp optimizer (SWO), nutcracker optimization algorithm (NOA), and artificial gorilla optimizer (GTO), is assessed to solve this problem with the purpose of minimizing power losses and voltage deviation. These algorithms were chosen due to the robustness of their local optimality avoidance and convergence speed acceleration mechanisms. In addition, a modified variant of NOA, known as MNOA, is herein proposed to further improve its performance. This modified variant does not combine the information of the newly generated solution with the current solution to avoid falling into local minima and accelerate the convergence speed. However, MNOA still needs further improvement to strengthen its performance for large-scale problems, so it is integrated with a newly proposed improvement mechanism to promote its exploration and exploitation operators; this hybrid variant was called HNOA. These proposed algorithms are used to estimate potential solutions to the ORPD problem in small-scale, medium-scale, and large-scale systems and are being tested and validated on the IEEE 14-bus, IEEE 39-bus, IEEE 57-bus, IEEE 118-bus, and IEEE 300-bus electrical power systems. In comparison to eight rival optimizers, HNOA is superior for large-scale systems (IEEE 118-bus and 300-bus systems) at optimizing power losses and voltage deviation; MNOA performs better for medium-scale systems (IEEE 57-bus); and MSA excels for small-scale systems (IEEE 14-bus and 39-bus systems).

Statistical study of the peak and fluence spectra of solar energetic particles observed over four solar cycles

Context. Solar energetic particles (SEPs) are an important space radiation source, especially for the space weather environment in the inner heliosphere. The energy spectrum of SEP events is crucial both for evaluating their radiation effects and for understanding their acceleration process at the source region, along with their propagation mechanism. Aims. In this work, we investigate the properties of the SEP peak flux spectra and the fluence spectra and their potential formation mechanisms using statistical methods. We aim to advance our understanding of SEP acceleration and propagation mechanisms. Methods. Employing a dataset from the European Space Agency’s Solar Energetic Particle Environment Modelling (SEPEM) program, we obtained and fit the peak-flux and fluence proton spectra of more than a hundred SEP events from 1974 to 2018. We analyzed the relationship among the solar activity, X-ray peak intensity of solar flares, and the SEP’s spectral parameters. Results. Based on the assumption that the initial spectrum of accelerated SEPs generally displays a power-law distribution and that the diffusion coefficient has a power-law dependence on the particle energy, we can assess both the source and propagation properties using the observed SEP event peak flux and fluence energy spectra. We confirm that the spectral properties of SEPs are influenced by the solar source and the interplanetary conditions, whereas their transportation process can be influenced by different phases of solar cycle. Conclusions. This study provides an observational perspective on the double power-law spectral characteristics of the SEP energy spectra, revealing their correlation with the adiabatic cooling and diffusion processes during the particle propagation from the Sun to the observer. This result contributes to forging a deeper understanding of the acceleration and propagation of SEP events, in particular, the possible origins of the double power law.

Coupling of Fluid and Particle-in-Cell Simulations of Ambipolar Plasma Thrusters

Ambipolar plasma thrusters are an appealing technology due to multiple system-related advantages, including propellant flexibility and the absence of electrodes or neutralizer. Understanding the plasma generation and acceleration mechanisms is key to improving the performance and capabilities of these thrusters. However, the source and plume regions inside are often simulated separately, and no self-consistent strategy exists which can couple these different simulations together. This paper introduces the MUlti-regime Plasma Equilibrium Transport Solver (MUPETS), a self-consistent coupled model integrating a fluid solver for the plasma dynamics in the source, which are collision-driven, with a kinetic Particle-In-Cell (PIC) code for the plasma dynamics in the magnetic nozzle, which involve expansion across a diverging magnetic field. The methodology begins by solving the plasma source with the classical Bohm condition at the thruster’s throat. The resulting plasma profiles (density, temperature, speed) are input into the PIC code for the magnetic nozzle. The PIC code calculates the plasma plume expansion and determines the electric field at the thruster’s throat. This electric field is then used as a boundary condition in the fluid code, where it replaces the Bohm assumption, and the fluid simulation is repeated. This iterative process continues until convergence. In comparing the MUPETS results with those for an experimental thruster, the plasma densities at the thruster’s throat differed by less than 2–5% between the fluid and PIC regions. The thrust predictions agreed with the experimental trend, and were kept well within the measurement’s uncertainty band. These results validate the effectiveness of the coupling strategy for enhancing plasma thruster simulation accuracy.

Impulsively Accelerated Ions as the Source of Ion Acoustic Waves in Solar Wind

Ion acoustic waves are pervasive at the Earth’s bow shock and in regions of active plasmas. Recently, frequency-dispersed ion acoustic-like waves have been observed by Parker Solar Probe in the near-Sun solar wind. These waves are electrostatic, propagate nearly along the magnetic field, and have frequencies on the order of the ion plasma frequency. Frequency-dispersed emissions appear in short (<1 s) bursts and exhibit rising and/or falling tones. This article has a narrow focus, to determine if impulsively accelerated ions are a plausible generation mechanism. We show that velocity dispersion from impulsively accelerated ions can generate a positive slope in the ion distribution that changes in space and time, which can lead to emissions with rising or falling tones given a substantial Doppler shift from the solar wind. The phase velocity is at the velocity of the positive slope, which can differ from the ion acoustic speed, but otherwise these waves are similar to ion acoustic waves. Wave growth is strongest when the positive slope velocity is near the ion acoustic speed. Two mechanisms for impulsive ion acceleration are explored. One mechanism imparts equal energy into the source ions as expected from a parallel potential. The other mechanism imparts equal velocity into the source ions such as that expected from impulsive magnetic reconnection. Both mechanisms result in similar wave characteristics with only subtle differences. Given the persistent appearance of these ion acoustic-like waves, these results suggest that impulsively accelerated ions may be abundant in the near-Sun solar wind.

Mechanism of Spontaneous Acceleration of Slow Flame in Channel

This paper is devoted to the numerical analysis of the spontaneous acceleration of a slow flame in a semi-closed channel. In particular, the flow development in the channel ahead of the propagating flame is analyzed. The applied detailed numerical model allows the clear observation of all features intrinsic to the reacting flow evolution in the channel, including the formation of perturbations on the scale of the boundary layer and their further development. In all considered cases, perturbations of the boundary layer emerge in the early stages of flame acceleration and decay afterward. The flow stabilizes more rapidly in a narrow channel, where the velocity profile is close to the Poiseuille profile. At the same time, the compression waves generated in the reaction zone travel along the channel. The interaction between compression waves in the area of combustion products can lead to the formation of shock waves. The effect of shock waves on the flow in the fresh mixture causes an increase in the flame area and a corresponding flame acceleration. In addition, shock waves trigger boundary-layer instability in wide channels. The perturbations of the boundary layer grow and evolve into vortexes, while further vortex–flame interaction leads to significant flame acceleration.

The Spider Stellar Engine: a Fully Steerable Extraterrestrial Design?

A long-lived civilization will inevitably have to migrate towards a nearby star as its home star runs out of nuclear fuel. One way to achieve such a migration is by transforming its star into a stellar engine, and to control its motion in the galaxy. We first provide a brief overview of stellar engines and conclude that looking for technosignatures of stellar engines has taken two roads: on the observational side, hypervelocity stars have been the target of such searches, but without good candidates. On the theoretical side, stellar engine concepts have been proposed but are poorly linked to observable technosignatures. Since about half the stars in our galaxy are in binary systems where life might develop too, we introduce a model of a binary stellar engine. We propose mechanisms for acceleration, deceleration, steering in the orbital plane and outside of the orbital plane. We apply the model to candidate systems, spider pulsars, which are binary stars composed of one millisecond pulsar and a very low-mass companion star that is heavily irradiated by the pulsar wind. We discuss potential signatures of acceleration, deceleration, steering, as well as maneuvers such as gravitational assists or captures. Keywords: Pulsars: Spiders, Technosignatures, Stellar engine, Interstellar travel

Regulatory Effects of the Combinations of Aggregate and Structural Monetary Policy Instruments: an application of New Keynesian DSGE model to China

This paper selects Chinese macroeconomic data from the first quarter of 2009 to the first quarter of 2020 and employs a New Keynesian dynamic stochastic general equilibrium model that incorporates the financial accelerator mechanism, price stickiness, and invisible government guarantees. The regulatory effects of different combinations of monetary policy instruments are compared from five perspectives: the shock effect of monetary policy, the magnitude of economic volatility of non-monetary policy shocks, the Central Bank loss function, the gap in the distribution of household income, and the heterogeneous firm external financing premium. Our findings indicate that the regulatory effects of the aggregate price-based and structural quantity-based monetary policy instrument combination are optimal, a conclusion that is further supported by the robustness test. It is therefore recommended that the Central Bank consider the potential benefits of a combined approach to aggregate and structural monetary policy instruments, with a view to enhancing credit availability for the real economy. This paper represents a significant contribution to the field, as it is the first to explicitly propose four distinct monetary policy instrument combinations, thereby overcoming the limitations of previous studies that have focused on a single instrument or a narrow range of instruments. The paper also contributes to the theoretical understanding of monetary policy instruments.

Lightning-induced relativistic electron precipitation from the inner radiation belt.

The Earth's radiation belts are maintained by a number of acceleration, loss and transport mechanisms, and the electron fluxes at any given time are highly variable. Microbursts, which are rapid (sub-second) bursts of energetic electrons entering the atmosphere from the magnetosphere, are one of the key loss mechanisms controlling radiation belt fluxes. Such rapid bursts are typically observed from the outer radiation belt and driven by interactions with whistler mode chorus waves, but they can also occur in the inner belt and slot region, driven by lightning-generated whistlers. This lightning-induced electron precipitation is typically observed at 10s-100s keV, but here we present direct observations of this phenomenon at MeV energies. This unveils a coupling between near-Earth processes, such as lightning, and radiation belt processes, such as relativistic electron microbursts, bridging the gap between Earth weather and space weather.

Relativistic Electrons from Vacuum Laser Acceleration Using Tightly Focused Radially Polarized Beams.

We generate a tabletop pulsed relativistic electron beam at 100Hz repetition rate from vacuum laser acceleration by tightly focusing a radially polarized beam into a low-density gas. We demonstrate that strong longitudinal electric fields at the focus can accelerate electrons up to 1.43MeV by using only 98GW of peak laser power. The electron energy is measured as a function of laser intensity and gas species, revealing a strong dependence on the atomic ionization dynamics. These experimental results are supported by numerical simulations of particle dynamics in a tightly focused configuration that take ionization into consideration. For the range of intensities considered, it is demonstrated that atoms with higher atomic numbers like krypton can favorably inject electrons at the peak of the laser field, resulting in higher energies and an efficient acceleration mechanism that reaches a significant fraction (≈14%) of the theoretical energy gain limit.

Solubility-controlled early age hydration of carbonate-activated slag: Underlying mechanisms and acceleration via seeding

The low environmental impacts and good performance of carbonate-activated binders have attracted substantial interest, while their intrinsically delayed reaction and prolonged setting times constrain widespread implementation. This study aims to investigate the early-age reaction kinetics of carbonate-activated binders, elucidate the underlying mechanisms and propose controlling methods. Results reveal that hydrotalcite and C-A-S-H gel precursors rapidly reach supersaturation within hours, yet precipitation of these phases remains absent. This phenomenon, coupled with high Si/Ca ratios in the pore solution, exhibits characteristics that may contribute to the observed reaction delays. A prolonged induction period and lethargic strength development are observed owing to the lack of strength-giving phases. The hydrotalcite and C-A-S-H concentrations surpass their theoretical solubility thresholds due to rising ionic strength and salt-in effects. The addition of a pH-neutral layered double hydroxide salt accelerates the reaction, confirming seeding impacts control pore solution saturation limits, constituting the underlying accelerator mechanism.

Correlation of pinch voltage with ion angular emission characteristics at varying D2 gas filling pressures in a low energy plasma focus device

Acceleration of deuterium ions to high energies and their anisotropic emission has been tried to be understood from pinch voltage (Vp) perspectives using 3.1 kJ plasma focus device. The D2 gas filling pressure was varied from 2 to 4 mbar at an operating energy of 1.1 kJ (10 μF, 15 kV). The pinch voltage was seen to be varying with filling pressure and it was found to be maximum 16.26 ± 0.56 kVat 3 mbar. The most probable energy (MPE) of deuterium ions followed the pinch voltage and maximum 11.36 ± 0.68 keV and 6.82 ± 0.41 keV were measured in the axial and radial direction respectively at 3 mbar. Maximum energies of deuterium ions were observed to be in the range of 700 to 1000 keV. Correspondence between MPE and the pinch voltage as well as higher measured maximum energy than the value eVp suggested m=0 sausage instability might be the principal mechanism of ion acceleration coexisting with other acceleration mechanism. The energy spectrum suggested that number of high energetic deuterium ions decreases faster in the axial direction than in the radial direction. This report discusses in details about the experimental observations and various other aspects of the measurements.

A Magnetized Strongly Turbulent Corona as the Source of Neutrinos from NGC 1068

The cores of active galactic nuclei are potential accelerators of 10–100 TeV cosmic rays, in turn producing high-energy neutrinos. This picture was confirmed by the compelling evidence of a TeV neutrino signal from the nearby active galaxy NGC 1068, leaving open the question of what is the site and mechanism of cosmic-ray acceleration. One candidate is the magnetized turbulence surrounding the central supermassive black hole. Recent particle-in-cell simulations of magnetized turbulence indicate that stochastic cosmic-ray acceleration is nonresonant, in contrast to the assumptions of previous studies. We show that this has important consequences on a self-consistent theory of neutrino production in the corona, leading to a more rapid cosmic-ray acceleration than previously considered. The turbulent magnetic-field fluctuations needed to explain the neutrino signal are consistent with a magnetically powered corona. We find that strong turbulence, with turbulent magnetic energy density higher than 1% of the rest-mass energy density, naturally explains the normalization of the IceCube neutrino flux, in addition to the neutrino spectral shape. Only a fraction of the protons in the corona, which can be directly inferred from the neutrino signal, are accelerated to high energies. Thus, in this framework, the neutrino signal from NGC 1068 provides a testbed for particle acceleration in magnetized turbulence.

Deflagration-to-detonation transition and detonation propagation in supersonic flows with hydrogen injection and downstream ignition

This study investigates the mechanisms of flame acceleration and deflagration-to-detonation transition (DDT) in supersonic flows using transverse hydrogen injection and downstream ignition. Utilizing the graphics processing unit accelerated adaptive mesh refinement approach, we examine the influence of downstream ignition jet pressure on DDT through high-resolution computational simulations. Our results indicate that the transverse injection of hydrogen into the supersonic mainstream generates strong turbulence and numerous vortices due to Kelvin–Helmholtz instability, enhancing fuel mixing efficiency along the flow but deviating from the ideal premixed state. Following the injection of the downstream ignition jet into the supersonic main flow, initial flame acceleration is less effective than in the premixed state due to the non-uniformity of the incoming flow. However, within the boundary layer, the flame remains stable, and the intense turbulence fosters shock–flame interactions. The convergence of multiple compression waves into a shock wave facilitates energy deposition, coupling with the flame to trigger local detonation via the reactive gradient mechanism. The detonation wave exhibits complex wavefront structures, including vertical and oblique fronts induced by boundary layer interactions. Ignition jet pressure significantly impacts the DDT process and detonation wave characteristics, reducing ignition time and affecting the detonation temperature, pressure, and propagation speed. This study provides valuable insights into the dynamics of flame acceleration and DDT in supersonic flows with non-uniform fuel distribution and downstream jet ignition. The findings highlight the critical role of ignition jet pressure in optimizing ignition and detonation processes, offering new perspectives for achieving low-energy, rapid detonation initiation within the tube.

Multispacecraft Observations of Protons and Helium Nuclei in Some Solar Energetic Particle Events toward the Maximum of Cycle 25

The intricate behavior of particle acceleration and transport mechanisms complicates the overall efforts in formulating a comprehensive understanding of solar energetic particle (SEP) events; these efforts include observations of low-energy particles (from tens of keV to hundreds of MeV) by space-borne instruments and measurements by the ground-based neutron monitors of the secondary particles generated in the Earth atmosphere by SEPs in the GeV range. Numerous space-borne missions provided good data on the nature/characteristics of these solar particles in past solar cycles, but more recently—concurrently with the rise toward the maximum of solar cycle 25—the High-Energy Particle Detector (HEPD-01) proved to be well suited for the study of solar physics and space weather. Its nominal 30–300 MeV energy range for protons can enlarge the detection capabilities of solar particles at low Earth orbit, closer to the injection limit of many SEP events. In this work, we characterize three SEP events within the first six months of 2022 through spectral and velocity dispersion analysis, assessing the response of HEPD-01 to >M1 events.

Spectral Properties and the Influence of Coronal Mass Ejections in 3He-rich Solar Energetic Particle Events

We analyze the spectral properties of 3He and 4He as well as the heavy ions (oxygen, neon, magnesium, silicon, and iron) in 80 3He-rich solar energetic particle (SEP) events observed by the Ultra-Low-Energy Ion Spectrometer on board the Advanced Composition Explorer spacecraft since its launch in 1997 until 2024. We split the spectral analysis into two criteria: events with fast and wide coronal mass ejections (CMEs; called “FW events”) and events with slow, narrow, or no observed CMEs (called “non-FW events”). Overall, we find that events with fast and wide CMEs exhibit more uniform spectra across all species, and their low-energy spectral indices are strongly correlated, suggesting a CME provides an additional reacceleration mechanism for the 3He-rich SEPs. When comparing each species’ low-energy spectral index for events with no associated fast-and-wide CME, we find a primary peak in the spectral hardness of 3He, and a secondary peak in Mg and Si. If we consider a plasma temperature of 1.0–1.3 MK, Mg and Si have a charge-to-mass ratio (Q/M) nearest to one-third (1/3), directly half that of 3He. Thus, our results support the results of Roth & Temerin, which suggest heavy ions resonate with the second harmonic of the same ion cyclotron waves energizing 3He. However, it is unclear why the Fe enhancement is not reflected in its spectral index, and we propose that additional acceleration and/or transport mechanisms are playing a role in the abundance enhancement of Fe and heavier ions.

Ion velocity separation mechanism during vacuum spark stage

Abstract Supersonic ion jets produced in vacuum arc discharges have a wide range of applications, where precise control of ion kinetic energy is crucial. However, a comprehensive understanding of the ion acceleration mechanism remains elusive, particularly regarding whether there is ion velocity separation in the vacuum spark stage. In this paper, a 1D spherical implicit particle-in-cell (PIC) with Monte Carlo collision (MCC) model is employed to investigate the ion velocity separation in multi-charged vacuum arc plasma with varying electrode bias voltages and plasma ion densities. The results show that ion kinetic energy can reach hundreds of electron volts due to continuous acceleration by the formed potential valley, which leads to ion velocity separation at low electrode bias voltage or low plasma density. An increasing electrode bias voltage flattens the potential valley, reducing the electric field acceleration. While increasing the plasma density deepens the valley and intensifies Coulomb collisions, resulting in nearly-equal velocities across ions in different charge states. These findings can theoretically explain the discrepancies observed in previous experiments regarding the dependence of the ion velocity on its charge state during the vacuum spark stage.

Fermi acceleration under Lorentz invariance violation

In this paper, the acceleration of particles in astrophysical sources by the Fermi mechanism is revisited under the assumption of Lorentz invariance violation (LIV). We calculate the energy spectrum and the acceleration time of particles leaving the source as a function of the energy beyond which the Lorentz invariance violation becomes relevant. Lorentz invariance violation causes significant changes in the acceleration of particles by the first and second-order Fermi mechanisms. The energy spectrum of particles accelerated by first-order Fermi mechanism under LIV assumption shows a strong suppression for energies above the break. The calculations presented here complete the scenario for LIV searches with astroparticles by showing, for the first time, how the benchmark acceleration mechanisms (Fermi) are modified under LIV assumption.

3He and Fe Spectral Properties in 3He-rich Solar Energetic Particle Events

We have surveyed 3He-rich events on the Solar Orbiter mission from 2020 April to 2024 April, selecting isolated injections whose rollover 3He spectral shape is presumed to represent the initial acceleration state, unprocessed by subsequent activity such as coronal mass ejections or jets. A main goal has been to find relationships between the spectra of 3He and heavy ions C–Fe, in order to explore a common acceleration mechanism in spite of the fact that these events show 3He enrichments of up to ∼104, while the heavy-ion enrichment is rarely larger than ∼10. Selecting 34 3He injections, we find that heavy ions are always present, and arrive at the same time as the 3He signaling a common origin. Concentrating on Fe since it is a minor ion but with higher abundance than many others, we find its spectral shape and intensity is similar to 3He. In ∼two-thirds of the cases, if the 3He spectrum is shifted to lower energy by a factor 3.0 ± 1.3, it nearly coincides with the Fe spectrum, illustrating their close connection. Several plasma wave turbulence models have calculated spectra that also show the ion rollovers around 1 MeV nucleon−1. The unique mass-to-charge ratio of 3He allows it to interact more efficiently with the turbulence, thereby gaining several times more energy per nucleon than the other heavy ions. In the spectral rollover region this can lead to the observed enormous enhancements of 3He. The acceleration appears to be associated with magnetic reconnection in emerging flux regions on the Sun.

The observational evidence that all microflares that accelerate electrons to high energies are rooted in sunspots

In general, large solar flares are more efficient at accelerating high-energy electrons than microflares. Nonetheless, sometimes microflares that accelerate electrons to high energies are observed. Their origin is unclear. We statistically characterized microflares with strikingly hard spectra in the hard X-ray (HXR) range, which means that they are efficient at accelerating high-energy electrons. We refer to these events as "hard microflares." We selected 39 hard microflares, based on their spectral hardness estimated from the Solar Orbiter/STIX HXR quicklook light curves in two energy bands. The statistical analysis is built on spectral and imaging information from STIX combined with extreme ultraviolet (EUV) and magnetic field maps from SDO/AIA and SDO/HMI. The key observational result is that all hard microflares in this dataset have one of the footpoint rooted directly within a sunspot (either in the umbra or the penumbra). This clearly indicates that the underlying magnetic flux densities are large. For the events with the classic two-footpoints morphology, the absolute value of the mean line-of-sight magnetic flux density (and vector magnetic field strength) at the footpoint rooted within the sunspot ranges from 600 to 1800 G (1500 to 2500 G), whereas the outer footpoint measures from 10 to 200 G (100 to 400 G), therefore about ten times weaker. In addition, approximately 78&lt;!PCT!&gt; of the hard microflares, which exhibited two HXR footpoints, have similar or even stronger HXR flux from the footpoint rooted within the sunspot. This contradicts the magnetic mirroring scenario. The median footpoint separation, measured through HXR observations, is approximately 24 Mm, which aligns with regular events of similar GOES classes. In addition, about 74&lt;!PCT!&gt; of the events could be approximated by a single-loop geometry, demonstrating that hard microflares typically have a relatively simple morphology. Out of these events, around 54&lt;!PCT!&gt; exhibit a relatively flat flare loop geometry. We conclude that all hard microflares are rooted in sunspots, which implies that the magnetic field strength plays a key role in efficiently accelerating high-energy electrons, with hard HXR spectra associated with strong fields. This key result will allow us to further constrain our understanding of the electron acceleration mechanisms in flares and space plasmas.

Modeling Multiband SEDs and Light Curves of BL Lacertae Using a Time-dependent Shock-in-jet Model

The origin of fast flux variability in blazars is a long-standing problem, with many theoretical models proposed to explain it. In this study, we focus on BL Lacertae to model its spectral energy distribution (SED) and broadband light curves using a diffusive shock acceleration process involving multiple mildly relativistic shocks, coupled with a time-dependent radiation transfer code. BL Lacertae was the target of a comprehensive multiwavelength monitoring campaign in early 2021 July. We present a detailed investigation of the source’s broadband spectral and light-curve features using simultaneous observations at optical–UV frequencies with the Swift Ultraviolet/Optical Telescope, in X-rays with the Swift X-Ray Telescope and AstroSat-SXT/LAXPC, and in gamma rays with Fermi-LAT, covering the period from 2021 July to August (MJD 59400–59450). A fractional variability analysis shows that the source is most variable in gamma rays, followed by X-rays, UV, and optical. This allowed us to determine the fastest variability time in gamma rays to be on the order of a few hours. The AstroSat-SXT and LAXPC light curves indicate X-ray variability on the order of a few kiloseconds. Modeling simultaneously the SEDs of low- and high-flux states of the source and the multiband light curves provided insights into the particle acceleration mechanisms at play. This is the first instance of a physical model that accurately captures the multiband temporal variability of BL Lacertae, including the hour-scale fluctuations observed during the flare.