Adiabatic Parameter Research Articles

Transport properties of high Mach number hypersonic air plasmas

Abstract The collisional and transport properties of hypersonic plasmas have been simulated by an air plasma chemistry model, which includes collisions with electrons, ions and neutral species, elastic scattering, vibrational relaxation and a transport model. Species and thermal fluxes at the surface of the vehicle have been investigated as a function of post-shock gas temperature and species sticking coefficient for a fixed altitude of 50 km. At temperatures below about 5,000 K, the leading species are vibrationally excited nitrogen molecules, while at higher temperatures the molecular nitrogen and atomic oxygen dominate. Large fluxes of oxygen atoms have been observed in the simulations, on the order of 10^20 cm^-2s^ -1, which may lead to high rates of surface oxidation. Another subject of this study is temperature equilibration. For electrons, equilibration takes tens of microseconds, while the vibrational temperature equilibration time vary widely; from a few microseconds to hundreds of microseconds, depending on the gas temperature. Finally, the adiabatic parameter  was calculated for post-shock gas temperatures 5,000 K and 10,000 K and total gas density 1.2×10^17 cm^(-3). For post-shock gas temperature 5,000 K, only a slight reduction of gamma from the ideal gas value of ~1.4 is observed, while for 10,000 K it drops to ~1.26, which has a considerable impact on plasma properties. It was further established that the vibrational kinetics plays a leading role. While a single excited vibrational level of the N2 molecule captures the salient properties of the plasma, a detailed vibration kinetics is required for high-fidelity simulations.

Investigation of temperature gradient effects and effective thermal inertia during adiabatic decomposition of substances with varying exothermic characteristics

To further study adiabatic parameters distortion, the adiabatic decomposition of 2,4-DNT, 20%DTBP, and 45%Glucose was systematically analyzed using thermal analysis calorimetry and numerical simulation methods. The study revealed the variation laws and influence mechanisms of the temperature gradient effects and thermal inertia in adiabatic systems. A numerical model for decomposition in a closed adiabatic system was developed by integrating the apparent kinetics into the CFD code. The results show that the temperature gradient effects during adiabatic decomposition initially increase and then decrease until reaching zero. The temperature gradient effects become more pronounced as the exothermic characteristics of substances increase. They are the most significant at the peak self-heating rate, with gradients of 182.4 °C·cm−1, 21.6 °C·cm−1, and 0.78 °C·cm−1, respectively. Specific data segments for adiabatic analysis should maintain α values below 0.138 for 2,4-DNT, 0.484 for 20%DTBP, and should utilize complete 100 % adiabatic data for 45%Glucose, aiming to mitigate potential distortion in adiabatic parameters. Furthermore, Фeff varies with the reaction, initially increasing and then decreasing in deviation from the theoretical value, with peak deviations of 60 %, 20 %, and 0.3 % for three substances, respectively. These findings lay the foundation for further optimizing the temperature gradient effects and establishing a dynamic Фeff correction model.

Field Line Curvature (FLC) Scattering in the Dayside Off‐Equatorial Minima Regions

AbstractMagnetic field line curvature (FLC) scattering is an effective mechanism for collisionless particle scattering. In the terrestrial magnetosphere, the FLC scattering plays an essential role in shaping the outer boundary of protons radiation belt, the rapid decay of ring current, and the formation of proton isotropic boundary (IB). However, previous studies have yet to adequately investigate the influence of FLC scattering on charged particles in the Earth's dayside magnetosphere, particularly in the off‐equatorial magnetic minima regions. This study employs T89 magnetic field model to investigate the impacts of FLC scattering on ring current protons in the dayside magnetosphere, with a specific focus on the off‐equatorial minimum regions. We analyze the spatial distributions of single and dual magnetic minima regions, adiabatic parameter, and pitch angle diffusion coefficients due to FLC scattering as functions of Kp. The results show that the effects of FLC scattering are significant not only on the dusk and dawn sides but also in the off‐equatorial minima regions on the noon. Additionally, we investigate the role of dipole tilt angle in the hemispheric asymmetry of FLC scattering effects. The dipole tilt angle controls the overall displacement of the dayside magnetosphere, resulting in different FLC scattering effects in the two hemispheres. Our study holds significance for understanding the FLC scattering effects in the off‐equatorial region of Earth's dayside magnetosphere and for constructing a more accurate dynamic model of particles.

Thermal analysis of magnetohydrodynamic mixed convection in vented channel-driven cavity with corner heater: influence of adiabatic rod and flow parameters

Thermal analysis of magnetohydrodynamic mixed convection in vented channel-driven cavity with corner heater: influence of adiabatic rod and flow parameters

Compact and broadband silicon polarization splitter-rotator using adiabaticity engineering.

We propose and demonstrate a short and broadband silicon mode-conversion polarization splitter-rotator (PSR) consisting of a mode-conversion taper and an adiabatic coupler-based mode sorter both optimized by adiabaticity engineering (AE). AE is used to optimize the distribution of adiabaticity parameter over the length of the PSR, providing shortcut to adiabaticity at a shorter device length. The total length of the PSR is 85 µm. The design is compatible with standard silicon photonics platforms and requires only one patterning step. Fabricated PSR has a polarization cross talk of less than -20 dB over the entire O-band for the TE polarization and a polarization cross talk of less than -15 dB from 1267 to 1348 nm for the TM polarization. Overall, the PSR shows low polarization cross talk (-15 dB) over a bandwidth of 81 nm in the O-band. Cross-wafer measurements show that the PSR has good fabrication tolerance.

StyleGAN as an AI deconvolution operator for large eddy simulations of turbulent plasma equations in BOUT++

We present the use of StyleGAN, a face-synthesis generative adversarial network (GAN) developed by NVidia, as a deconvolution operator for large eddy simulation (LES) of plasma turbulence. The overall methodology, named style eddy simulation, has been integrated into the BOUT++ solver and tested on the original and modified Hasegawa–Wakatani models using different mesh sizes, 2562 and 5122, and different values of the adiabaticity parameter α and background density gradient κ. Using a LES resolution of 32 × 32 and 64 × 64, i.e., 64× smaller resolution than the corresponding direct numerical simulation (DNS), results show convergence toward the ground truth as we tighten the reconstruction tolerance, and an algorithm complexity O(N log N) is compared to the O(N2) of BOUT++. Finally, the trained GAN can be used to create valid initial conditions for a faster DNS by avoiding to start from nonphysical initial perturbations.

Negative Capacitance Effect Using a Pure Imaginary Electric Mobility Controlled By an Adiabatic Parameter in Thin Film Materials Based On Drude Model

Existence of a pure imaginary mobility of charge carriers in organic polymers materials, precisely the poly p-phenylene vinylene is explored in this work. Indeed, we propose a new model of dynamic equation of particles able to carry electric charges, we introduce a control parameter of the adiabatic evolution combined with a phase difference between the external perturbation of the material and the position of carrier, leading from then on to the non-use of the complex mobility. This model after transformation allowed us to demonstrate the existence of negative capacitance at low and high frequencies in the poly p-phenylene vinylene. Also thanks to this new model, we were able to obtain results in line with the experimental ones, thus confirming the validity of our model

Enhanced parameter estimation by measurement of non-Hermitian operators

Quantum metrology aims at delivering new quantum-mechanical improvement to technologies of parameter estimations with precision bounded by the quantum Cramér-Rao bound. The currently used quantum Cramér-Rao bound was established with measurements of observables restricted to be Hermitian. This constrains the bound and limits the precision of parameter estimation. In this paper, we lift the constraint and derive a previously unknown quantum Cramér-Rao bound. We find that the new bound can reach arbitrary small value with mixed states and it breaks the Heisenberg limit in some cases. We construct a setup to measure non-Hermitian operators and discuss the saturation of the present bound. Two examples—the phase estimation with Greenberger-Horne-Zeilinger states of trapped ions and the adiabatic quantum parameter estimation with the nuclear magnetic resonance—are employed to demonstrate the theory. The present study might open a new research direction—non-Hermitian quantum metrology.

Ultra-Broadband Integrated Optical Filters Based on Adiabatic Optimization of Coupled Waveguides

Broadband spectral filters are highly sought-after in many integrated photonics applications such as ultra-broadband wavelength division multiplexing, multi-band spectroscopy, and broadband sensing. In this study, we present the design, simulation, and experimental demonstration of compact and ultra-broadband silicon photonic filters with adiabatic waveguides. We first develop an optimization algorithm for coupled adiabatic waveguide structures, and use it to design individual, single-cutoff spectral filters. These single-cutoff filters are 1×2 port devices that optimally separate a broadband signal into short-pass and long-pass outputs, within a specified device length. We control the power roll-off and extinction ratio in these filters using the adiabaticity parameter. Both outputs of the filters operate in transmission, making it possible to cascade multiple filters in different configurations. Taking advantage of this flexibility, we cascade two filters with different cutoff wavelengths on-chip, and experimentally demonstrate band-pass operation. The independent and flexible design of these band edges enables filters with bandwidths well over 100 nm. Experimentally, we demonstrate band-pass filters with passbands ranging from 6.4 nm up to 96.6 nm. Our devices achieve flat-band transmission in all three of the short-pass, band-pass, and long-pass outputs with less than 1.5 dB insertion loss and extinction ratios of over 15 dB. These ultra-broadband filters can enable new capabilities for multi-band integrated photonics in communications, spectroscopy, and sensing applications.

K-shell X-ray production cross sections of Ti, Cr, Ni and Zn induced by chlorine ions

In this work we report on the results of the total K-shell X-ray production cross sections of Ti, Cr, Ni and Zn induced by Cl4+ and Cl5+ ions with energies ranging from 4 MeV to 10 MeV. The experimental results were compared with Atomic Orbitals Coupled-Channels (CC) calculations based on the independent electron model. The experimental X-ray production cross sections vary from about 10−2 barns for Zn up to 102 barns for Ti. The results obtained for Ti indicate that the present CC calculations underestimate the experimental cross sections up to two orders of magnitude at 10 MeV chlorine bombarding energy. However, the discrepancy between CC calculations and experimental results decreases as both bombarding energy and the atomic number of the target species increase. The dependency of the experiment-theory agreement on the asymmetry and adiabaticity parameters α and η respectively is discussed.

Neutrino flavor oscillations inside matter in conformal coupling models

We recently studied neutrinos flavor oscillations in vacuum within conformal coupling models. In this paper, we extend that analysis by investigating neutrino flavor oscillations inside matter within a general conformal coupling scenario. We first derive the general formula for the flavor transition probability inside matter in arbitrary static and spherically symmetric spacetimes. The modified resonance formula of the MSW effect is derived and the corresponding adiabaticity parameter of the effect is extracted. An application of our results to the case of two-flavor neutrinos within the well-known chameleon and symmetron conformal coupling models is made.

Kajian Literatur Fase Adiabatik untuk mempercepat Dinamika Kuantum Adiabatik pada Osilator Harmonik

<p>This research is a theoretical research by reviewing the literature that discusses the method of accelerating quantum dynamics adiabatically. This method for accelerating quantum dynamics is so- called the fast-forward method. This method was proposed by Masuda and Nakamura in 2010. In this method, the ground state and first excited state wave function is modified by adding an additional term to the wave function which is called the adiabatic phase. This is done so that the time-dependent Schrodinger equation remains fulfilled. The accelerating process is carried out using an adiabatic parameter that goes to zero. Fast-forward method is applied first to get the adiabatic phase. Furthermore, by reviewing the wave function at the ground state and first excited state we get the adiabatic phase which ensures that the harmonic oscillator can move from the initial state to the final state in a shorter time.</p>

Design and performance of a double-solenoid magnetic bottle photoelectron spectrometer for attosecond metrology.

The design and performance of an in-house developed double-solenoid magnetic bottle (MB) time-of-flight photoelectron spectrograph are presented. A combination of a strong permanent magnet (Sm2Co17) with a soft iron cone and a double-solenoid geometry is used to generate MB configuration. The first solenoid (length ∼150mm) is placed inside the vacuum, and the second solenoid (length ∼1m) is placed outside the vacuum. The double-solenoid geometry improves the effective conductance and reduces overall material outgassing. Due to this, an ultra-high vacuum (∼5 × 10-8mbar) desirable for the working of the spectrograph was achieved using a small capacity (300 lps) turbo-molecular pump. An optimization of solenoid current generates a smooth magnetic field variation in MB, which keeps the adiabaticity parameter ∼0.6 at ∼25eV photoelectron energy. The double-solenoid geometry also provides high collection efficiency as well as high energy resolution of the spectrograph. The experimentally measured energy resolution (ΔE) of the spectrograph is better than ∼60meV at ∼15eV photoelectron energy. The collection efficiency is estimated to be ∼25% under optimum conditions as compared with ∼10-4 in field-free configuration. The calibrated MB spectrograph is used for the characterization of the attosecond pulse train using a cross-correlation "RABBITT" technique. The attosecond pulse train is generated from 15th to 25th odd high-harmonic orders, in argon filled cell. Attosecond pulses of average duration ∼260 as (FWHM) have been measured. The proposed MB electron spectrograph design provides a compact experimental setup for attosecond metrology and pump-probe studies with a relaxed requirement on vacuum pump capacity.

Fast-forward adiabatic quantum dynamics of XY spin model on three spin system

We discussed a method to accelerate an adiabatic quantum dynamics of XY spin model by using the fast-forward method proposed by Masuda and Nakamura. The Accelerated scheme is constructed by adding the driving Hamiltonian to the original Hamiltonian and speeding it up with a large time-scaling factor and an adiabatic parameter that realizes adiabatic quantum dynamics in a shortened time. Accelerated adiabatic dynamics start by assuming the candidate of driving Hamiltonian consists of the pair-wise exchange interaction and magnetic field. The driving Hamiltonian terms multiplied by the velocity function together with the original Hamiltonian give fast-forward driving for adiabatic states. We apply our method to XY spin model by considering three spin systems on the Kagome lattice. In this model, we obtained the XY pair-wise exchange interaction of nearest neighbors and next-nearest neighbors should be added to the original Hamiltonian as a driving interaction to accelerate the adiabatic motion. This pair-wise driving interaction in the fast-forward scheme guarantees the complete fidelity of accelerated states.

Design, Synthesis of Some Innovative Indolo[3,2-c]Isoquinoline-5-One Analogs and Associated Bioactivities, Pharmacophore, Molecular Docking, MEP, and Conceptual DFT Studies

A series of novel triazolothiadiazolethione and triazolothiadiazine appended indolo[3,2-c]isoquinoline-5-one were designed, synthesized, and validated by IR, 1H, 13C NMR, and mass spectroscopy strategies. All compounds are determined by their DFT investigations with B3LYP/def2-TZVP basis set level, ionization potentials, and electron affinities at vertical (IPv and EAv) and adiabatic parameters (IPA and EAA). Compound 3a has demonstrated the greatest values for these parameters. The compounds’ HOMO-LUMO (FMOs) and MEP maps were performed. The optimized structure of the compounds was estimated in global hardness, softness, global electrophilicity, and dipole moment. To find new drug candidates, different in vitro biological activities were implemented employing antimicrobial activity: Gram-negative bacteria were significantly suppressed by compound 4a, whereas gram-positive bacteria were strongly inhibited by compounds 3c and 3a has significant antifungal and anticancer effects. Compound 4b is profoundly antioxidant with IC50 value of 8.74 ± 1.93 µg/mL and MIC value of 0.25 µg/mL for antituberculosis properties. Thereafter, all of the compounds were subjected to e-pharmacophore approach to molecular docking studies. Compound 4a exhibited the best docking score (−8.458 kcal/mol) and docking interactions with active binding sites of 1TL8 receptor.

Study of the adiabatic passage in tripod atomic systems in terms of the Riemannian geometry of the Bloch sphere

We present an analysis of the stimulated Raman adiabatic passage (STIRAP) processes based on the methods of differential geometry. The present work was inspired by an excellent article by Shore et al (Unanyan et al 1999 Phys. Rev. A 59 2910). We demonstrate how a purely geometric interpretation of the adiabatic passage in quantum tripod systems as a Riemannian parallel transport of the dark state vector along the Bloch sphere allows describing the evolution of the system for a given sequence of Stokes, pump and control laser excitation pulses. In combination with the Dykhne–Davis–Pechukas adiabaticity criterion and the minimax principle for circles on a sphere, this approach allows obtaining the analytical form of the optimal laser pulse sequences for a high fidelity tripod fractional STIRAP. In contrast to the conventional STIRAP in Λ-systems, the Gaussian approximations of the optimal laser pulse sequences allow reaching the infidelity of 10−7 for the adiabaticity parameter of 300 without noticeable oscillatory or other detrimental effects on population transfer accuracy.

Swirling main flow effects on film cooling: Time resolved adiabatic effectiveness measurements in a gas turbine combustor model

Lean burn swirl stabilized combustors represent the key technology to reduce NOx emissions in modern aircraft engines. The high amount of air admitted directly trough the injection system and the higher levels of pressure and temperature requested by the engine cycle make the design of even more efficient cooling systems and the correct estimation of combustor liners heat load a crucial task for the combustor durability. One of the technologies used for the cooling of these components is the effusion cooling, which promotes the formation of a cold layer to protect the liner walls, whose cooling capabilities are described with the adiabatic effectiveness parameter. The effectiveness of these systems is severely influenced by the swirling flows generated by the swirler injectors which promote the mixing between cold and the hot gases of the combustion process. The development of the swirling flow structures inside the combustor chamber and the grade of interaction between swirling flow and the liner walls can be described by the swirl number (SN). In order to investigate the impact of the effects of the SN parameter on the adiabatic film effectiveness, a dedicated non-reactive single-sector linear combustor test rig was designed and equipped with three different axial injectors (SN=0.6−0.8−1.0) and a cylindrical holes effusion plate to simulate the liner cooling system. Film effectiveness was acquired using Fast response Pressure Sensitive Paint (FPSP) technique; the scale of the model and the acquisition frequency of 1 kHz allowed to track the effusion jets and main flow interactions. The collected results show the importance of using an unsteady analysis to perform an in-depth characterization of the mixing phenomena between the main flow and the coolant which are significantly affected by the swilring characteristics.

Lagrangian conditional statistics and flow topology in edge plasma turbulence

Lagrangian statistics and particle transport in edge plasma turbulence are investigated using the Hasegawa–Wakatani model and its modified version. The latter shows the emergence of pronounced zonal flows. Different values of the adiabaticity parameter are considered. The main goal is to characterize the role of coherent structures, i.e., vortices and zonal flows, and their impact on the Lagrangian statistics of particles. Computationally intensive long time simulations following ensembles of test particles over hundreds of eddy turnover times are considered in statistically stationary turbulent flows. The flow topology is characterized using the Lagrangian Okubo–Weiss criterion in order to split the flow into topologically different domains. In elliptic and hyperbolic regions, the probability density functions (PDFs) of the residence time have self-similar algebraic decaying tails. However, in the intermediate regions, the PDFs exhibit exponentially decaying tails. Topologically conditioned PDFs of the Lagrangian velocity, and acceleration and density fluctuations are likewise computed. The differences between the classical Hasegawa–Wakatani system and its modified version are assessed, and the role of zonal flows is highlighted. The density flux spectrum, which characterizes the contributions of different length scales, is studied, and its inertial scaling is found to be in agreement with predictions based on dimensional arguments. Analyzing the angular change of particle tracers at different time scales, corresponding to coarse grained curvature, completes the study, and these multiscale geometric statistics quantify the directional properties of the particle motion in different flow regimes.

An analytic evaluation of gravitational particle production of fermions via Stokes phenomenon

The phenomenon of gravitational particle production can take place for quantum fields in curved spacetime. The abundance and energy spectrum of gravitationally produced particles is typically calculated by solving the field’s mode equations on a time-dependent background metric. For purposes of studying dark matter production in an inflationary cosmology, these mode equations are often solved numerically, which is computationally intensive, especially for the rapidly-oscillating high-momentum modes. However, these same modes are amenable to analytic evaluation via the Exact Wentzel-Kramers-Brillouin (EWKB) method, where gravitational particle production is a manifestation of the Stokes phenomenon. These analytic techniques have been used in the past to study gravitational particle production for spin-0 bosons. We extend the earlier work to study gravitational production of spin-1/2 and spin-3/2 fermions. We derive an analytic expression for the connection matrix (valid to all orders in an adiabatic parameter ħ) that relates Bogoliubov coefficients across a Stokes line connecting a merged pair of simple turning points. By comparing the analytic approximation with a direct numerical integration of the mode equations, we demonstrate an excellent agreement and highlight the utility of the Stokes phenomenon formalism applied to fermions. We discuss the implications for an analytic understanding of catastrophic particle production due to vanishing sound speed, which can occur for a spin-3/2 Rarita-Schwinger field.

Analytical solution for the inverting pulses with constant adiabaticity

The exact solution was found for inverting pulses with constant adiabaticity for spin ½. The analytical relationship between the time-varying frequency of the microwave resonant field (or RF field in the case of NMR) and its amplitude time dependence such that the adiabaticity parameter remains constant for the single isochromat throughout the pulse is found. Comparison with EPR (hyperbolic tangent)-(hyperbolic secant) pulse method was carried out. On the basis of the analytical solution the pulses with different dependences of the microwave field amplitude conserving the constant adiabaticity have been constructed. The pulses exhibit rather sharp inversion selectivity that can be used in the field of EPR, NMR and MRI.