Temperature effects on large amplitude electron plasma oscillations
We present a very simple model equation that can describe one-dimensional large amplitude electron plasma oscillations.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
SEARCH · Engineering Papers
Results for “AMPLITUDES”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Using domain walls to perform non-local measurements with high spin signal amplitudes
Standard non-local measurements require lateral spin-valves with two different ferromagnetic electrodes, to create and to detect the spin accumulation. Here we show that non-local measurements can also be performed in a cross-shaped nanostructure, made of a single ferromagnetic wire connected to an orthogonal non-magnetic wire. A magnetic domain wall located underneath the ferromagnetic/non-magnetic interface is used to control the magnetizations of the injection and detection zones. As these zones can be very close, our results display spin signals possessing amplitudes larger than those obtained in conventional non-local measurements. We also show that this method can be used as a domain wall detection technique.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Alfvén wave propagation through a moderate-amplitude transverse inhomogeneity in a magnetized plasma
Parallel propagation of a plane Alfvén wave in a moderate-amplitude Gaussian-shaped transverse inhomogeneity is studied numerically using a fluid model retaining low-frequency kinetic effects. It is shown that in such a situation, common in the solar wind where elongated pressure-balanced structures are frequently observed, phase mixing competes with wave focusing, in contrast with coronal loops or auroral regions where sharp gradients present at the edges of the inhomogeneities make phase mixing dominant. Some understanding about this competition is provided by a model based on an envelope formalism. Depending on the magnitude of the Alfvén wavelength and of the inhomogeneity transverse scale relative to the ion inertial length, various regimes can develop, ranging from the formation of localized gradients when phase mixing dominates to the development of an intense magnetic filament when focusing is stronger, with a different efficiency for the generation of magnetosonic and kinetic Alfvén waves. Electron parallel heating and parallel electric field generation are also briefly discussed.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Frequency response of a gas ring laser with a variable-sign frequency bias in the case of frequency nonreciprocity comparable with the bias amplitude
The dependence of the beat frequency of counterpropagating waves on the rotation rate is studied theoretically and experimentally in a gas ring laser (GRL) with a Zeeman effect-based, variable-sign frequency bias. Use is made of magneto-optical biases of two types, namely, a rectangular (meander) bias and a combined bias consisting of fast and slow meanders. At high rotation rates, when the frequency nonreciprocity determined by the rotation rate is close in magnitude to the amplitude of the variable-sign frequency bias, the dynamic locking bands take maximum values and there arise the most extensive deviations of the frequency response from the ideal response. Comparison of experimental and theoretical results for the widths of dynamic bands that appear in this region of the measured rotation rates shows good agreement between theory and experiment. The results suggest that the frequency response of a GRL in this region can be described by one differential equation for the phase difference of counterpropagating waves. (laser gyroscopes)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
A method for measuring the amplitude and phase of ultrashort laser pulses using self-modulation in a Kerr medium and spectral interferometry
A new method is proposed for measuring the field of ultrashort pulses by assessing spectral interference between an input pulse and the pulse transmitted through a Kerr medium. The proposed iterative algorithm allows the pulse amplitude and phase to be reconstructed. Our numerical experiments demonstrate that the proposed algorithm can be used to reconstruct pulses with complex intensity and phase shapes and is stable to a noise in input data. The method requires that only one nonlinear element be placed in the laser beam to be studied. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Decreasing the amplitude of macroscopic quantum fluctuations in the case of transient SRS
It is shown experimentally that, under the conditions of transient stimulated Raman scattering, pumping by two successive orthogonally polarised laser pulses makes it possible to reduce the amplitude of macroscopic quantum energy fluctuations of a Stokes pulse by a factor of 4 in comparison with single-shot pumping. An energy dispersion of 0.9 % for the first Stokes component is obtained in hydrogen at a relative energy dispersion of ytterbium laser pulses of 0.4 %. (nonlinear optical phenomena)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The SAGEX review on scattering amplitudes
This is an introduction to, and invitation to read, a series of review articles on scattering amplitudes in gauge theory, gravity, and superstring theory. Our aim is to provide an overview of the field, from basic aspects to a selection of current (2022) research and developments.
97 MATHEMATICS AND COMPUTING↗
The SAGEX review on scattering amplitudes Chapter 15: The multi-Regge limit
We review the Regge and multi-Regge limit of scattering amplitudes in gauge theory, focusing on QCD and its maximally supersymmetric cousin, planar $\mathcal{N}=4$ super-Yang–Mills theory. We identify the large logarithms that are developed in these limits, and the progress that has been made in resumming them, towards next-to-next-to-leading logarithms for BFKL evolution in QCD, as well as all-orders proposals in planar $\mathcal{N}=4$ super-Yang–Mills theory and the perturbative checks of those proposals. We also cover the application of single-valued multiple polylogarithms to this important kinematical limit of particle scattering.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The SAGEX review on scattering amplitudes Chapter 2: An invitation to color-kinematics duality and the double copy
Abstract Advances in scattering amplitudes have exposed previously-hidden color-kinematics and double-copy structures in theories ranging from gauge and gravity theories to effective field theories such as chiral perturbation theory and the Born–Infeld model. These novel structures both simplify higher-order calculations and pose tantalizing questions related to a unified framework underlying relativistic quantum theories. This introductory mini-review article invites further exploration of these topics. After a brief introduction to color-kinematics duality and the double copy as they emerge at tree and loop-level in gauge and gravity theories, we present two distinct examples: (1) an introduction to the web of double-copy-constructible theories, and (2) a discussion of the application of the double copy to calculation relevant to gravitational-wave physics.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Supertranslations from Scattering Amplitudes
On shell methods have found a new application to local observables such as asymptotic radiation fields and gravitational waveforms. While these observables are invariant under small gauge transformations, they are known to depend on a choice of asymptotic gauge; in gravity on asymptotically Minkowski spacetimes, this is a choice of Bondi-Van der Burg-Metzner-Sachs frame. In this Letter, we provide a method for capturing these supertranslations, to all orders in perturbation theory, using the on shell framework of scattering amplitudes.
Classical black holes↗
Unitarity of the infinite-volume three-particle scattering amplitude arising from a finite-volume formalism
Hansen and Sharpe derived a relation between the scattering amplitude of three identical bosons, $\mathcal M_3$, and a real function referred to as the divergence-free $K$ matrix and denoted $\mathcal K_{df,3}$. The result arose in the context of a relation between finite-volume energies and $\mathcal K_{df,3}$, derived to all orders in the perturbative expansion of a generic low-energy effective field theory. In this work we set aside the role of the finite volume and focus on the relation between $\mathcal K_{df,3}$ and $\mathcal M_3$. We show that, for any real choice of $\mathcal K_{df,3}$, $\mathcal M_3$ satisfies the three-particle unitarity constraint to all orders. Given that $\mathcal K_{df,3}$ is also free of a class of kinematic divergences, the function may provide a useful tool for parametrizing three-body scattering data. Applications include the phenomenological analysis of experimental data (where the connection to the finite volume is irrelevant) as well as calculations in lattice quantum chromodynamics (where the volume plays a key role).
43 PARTICLE ACCELERATORS↗
Analytic continuation of the relativistic three-particle scattering amplitudes
We investigate the relativistic scattering of three identical scalar bosons interacting via pair-wise interactions. Extending techniques from the nonrelativistic three-body scattering theory, we provide a detailed and general prescription for solving and analytically continuing integral equations describing the three-body reactions. We use these techniques to study a system with zero angular momenta described by a single scattering length leading to a bound state in a two-body subchannel. We obtain bound-state-particle and three-particle amplitudes in the previously unexplored kinematical regime; in particular, for real energies below elastic thresholds and complex energies in the physical and unphysical Riemann sheets. We extract positions of three-particle bound-states that agree with previous finite-volume studies, providing further evidence for the consistency of the relativistic finite-volume three-body quantization conditions. We also determine previously unobserved virtual bound states in this theory. Lastly, we find numerical evidence of the breakdown of the two-body finite-volume formalism in the vicinity of the left-hand cuts and argue for the generalization of the existing formalism.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Transmission of Images With Ultrasonic Elastic Shear Waves on a Metallic Pipe Using Amplitude Shift Keying Protocol
Transmission of information using ultrasonic elastic waves on existing metallic pipes provides an alternative communication option across physical barriers in a highly partitioned industrial complex, such as a nuclear facility. This work investigates the feasibility of the transmission of digital images over metallic pipes. Ultrasonic communication systems for transmission of images on a nuclear-grade stainless steel pipe were assembled for bench-scale demonstration. Information carriers in this system are refracted shear waves transmitted and received with piezoelectric transducers (PZTs) operating at 2-MHz nominal frequency. The refraction and propagation of ultrasonic shear waves were modeled with COMSOL software. An amplitude shift keying (ASK) communication protocol for image transmission was developed and implemented in the GNURadio software-defined radio (SDR) environment. Digital information was converted to analog ultrasonic signals using Red Pitaya electronic boards. The performance of the ASK protocol is evaluated at the output of every block in the GNURadio program by monitoring the transmission of select characters. Using the ASK communication protocol, the transmission of the 32-KB image was demonstrated at 2-Kbps bitrate across 6-ft-long stainless steel pipe. Finally, preliminary evaluation of ultrasonic communication on the piping of a nuclear facility, such as signal transmission on bent pipes, was performed with COMSOL computer simulations.
42 ENGINEERING↗
Amplitude Instability in Two-Dimensional Hexagonal Clusters
The conditions for the formation of amplitude instabilities in two-dimensional Yukawa systems consisting of seven charged particles have been investigated. An analytical approach to searching for a criterion of the development of such instabilities based on the determination of the inflection point of a system’s potential energy when the particles deviate from their equilibrium positions is considered. The results obtained are compared with the melting criteria for extended two-dimensional systems.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Propagation of current pulses with an amplitude of up to 85 kA in soil over distances of several tens of meters
Conditions for the propagation in soil of current pulses with an amplitude of up to 85 kA and temporal characteristics typical of a lightning stroke are studied with the help of a specially designed mobile test complex on the basis of a 4-MJ capacitive energy storage with an output voltage of up to 2 MV. In contrast to the conventional opinion that the ionization processes in highly conductive soils are weakly pronounced, a dramatic reduction in the grounding resistance at a resistivity of about 100 Ω m and currents above 10 kA was observed. A time interval in which the grounding resistance is determined by the skin effect in soil is revealed. It is shown that the grounding resistance continues to decrease behind the front of the current pulse due to the continuous growth of spark channels in soil. Time variations in the grounding resistance cannot be related to the formation of a continuous ionization zone near the grounding electrodes and are explained only by the simultaneous growth of several long spark channels extending from the grounding device.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Treaty Monitoring Using Seismology, with Focus on High Frequency Amplitude Models
This is the Heiland Lecture at the Colorado School of Mines. It describes the seismological effects of nuclear testing and other high frequency amplitude occurrences.
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
Initial Characterization of the NREL Large-Amplitude Motion Platform
The Large Amplitude Motion Platform (LAMP) at NREL represents a significant advancement in the controlled testing of Wave Energy Converters (WECs) under laboratory conditions. Originally designed by E2M as a six-degree-of-freedom (DOF) Stewart platform for flight simulation, LAMP has been adapted by NREL to facilitate the mounting and evaluation of WECs. This adaptation enables dry testing of WECs using motion profiles similar to the ocean, facilitating the iterative design, testing, and validation of WEC performance prior to ocean deployments. This report presents the initial work completed to characterize LAMP, with particular emphasis on its stability and operational capabilities across various single and multi-degree-of-freedom (DOF) motion profiles. The report includes planned comparisons at three distinct mass payloads, aimed at assessing the platform's positional accuracy, frequency response, and endurance over extended runtime periods. These experimental tests are critical for establishing the platform's limitations and ensuring that the data generated during WEC validation is both accurate and reproducible. The outcomes of this study not only contribute to a deeper understanding of LAMP's capabilities but also lay the groundwork for future advancements in WEC testing methodologies. By providing robust and reliable performance data within a controlled laboratory setting, the findings are expected to significantly enhance the development and commercialization of marine energy technologies. This report presents the initial findings of the LAMP Characterization work and proposed steps to further understand and characterize LAMP. Data collected during this work can be found on MHKDR at: https://mhkdr.openei.org/submissions/602 Note that this report shares the measured/found instantaneous maximum operating range of LAMP. For most applications the maximum operating range cannot be used for system health and longevity. The operating range and capabilities of LAMP will be evaluated on a case-by-case basis, single-DOF position, velocity, and acceleration values presented in Table 4a-c, and Table 5 should be taken as instantaneous absolute maximum values. Future use of LAMP will likely be limited to smaller values.
16 TIDAL AND WAVE POWER↗
Influence of Input Acceleration of Broad-Band Random Vibrations on the Amplitude–Frequency Characteristics of Hydraulic Bearings
The amplitude–frequency characteristics of hydraulic bearings under the action of broad-band random vibrations with different input root-mean-square acceleration are investigated. The damping of the vibrational signals by the hydraulic bearings is studied experimentally.
42 ENGINEERING↗