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DOE OSTI2019

Floquet dynamics of classical and quantum cavity fields

We show that the time-dependence of electromagnetic field in a periodically modulated cavity can be effectively analyzed using a Floquet map. The map relates the field states separated by one period of the drive; iterative application of the map allows to determine field configuration after arbitrary number of drive periods. For resonant and near-resonant drives, the map has stable and unstable fixed points, which are the loci of infinite energy concentration in the long time limit. The Floquet map method can be applied both to classical and quantum massless field problems, including the dynamical Casimir effect. The stroboscopic time evolution implemented by the map can be interpreted in terms of the wave propagation in a curved space, with the fixed points of the map corresponding to the black hole and white hole horizons. More practically, the map can be used to design protocols for signal compression/decompression, cooling, and sensing.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2016

Chiral-symmetry breaking and confinement in Minkowski space

We present a model for the quark-antiquark interaction formulated in Minkowski space using the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. By applying the axial-vector Ward-Takahashi identity we show that our model satisfies the Adler-zero constraint imposed by chiral symmetry. For this model, our Minkowski-space results of the dressed quark mass function are compared to lattice QCD data obtained in Euclidean space. The mass function is then used in the calculation of the electromagnetic pion form factor in relativistic impulse approximation, and the results are presented and compared with the experimental data from JLab.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Magnetic Reconnection in Three Dimensions: Modeling and Analysis of Electromagnetic Drift Waves in the Adjacent Current Sheet

Magnetic reconnection at the subsolar magnetopause is persistently accompanied by strong fluctuations of the magnetic field (B), plasma density (n), and all components of the electric field (E) and current (J). The strongest fluctuations are at frequencies below the lower hybrid frequency and observed in a thin, intense current sheet adjacent to the electron diffusion region. In this current sheet, the background magnitudes of B and n are changing considerably, creating an inhomogeneous plasma environment. In this paper, we show that the fluctuations in B and n are consistent with an oscillatory displacement of the current sheet in the surface normal direction. The displacement is propagating parallel to the magnetic reconnection X-line. Wavelengths are on the order of or longer than the thickness of the current sheet to which they are confined, so we label these waves electromagnetic drift waves. E and J fluctuations are more complex than a simple displacement. They have significant variations in the component along B, which suggest that the drift waves also may be confined along B. The current sheet is supported by an electron drift driven by normal electric field, which, in turn, is balanced by an ion pressure gradient. We suggest that wave growth comes from an instability related to the drift between the electrons and ions. We discuss the possibility that drift waves can displace or penetrate into the electron diffusion region giving magnetic reconnection three-dimensional structure. Drift waves may corrugate the X-line, possibly breaking the X-line and generating turbulence.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

The nonlinear Schrödinger equation and the propagation of weakly nonlinear waves in optical fibers and on the water surface

The dynamics of waves in weakly nonlinear dispersive media can be described by the nonlinear Schrödinger equation (NLSE). An important feature of the equation is that it can be derived in a number of different physical contexts; therefore, analogies between different fields, such as for example fiber optics, water waves, plasma waves and Bose–Einstein condensates, can be established. Here, we investigate the similarities between wave propagation in optical Kerr media and water waves. In particular, we discuss the modulation instability (MI) in both media. In analogy to the water wave problem, we derive for Kerr-media the Benjamin–Feir index, i.e. a nondimensional parameter related to the probability of formation of rogue waves in incoherent wave trains.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2022

High-energy and ultra-high-energy neutrinos: A Snowmass white paper

Astrophysical neutrinos are excellent probes of astroparticle physics and high-energy physics. With energies far beyond solar, supernovae, atmospheric, and accelerator neutrinos, high-energy and ultra-high-energy neutrinos probe fundamental physics from the TeV scale to the EeV scale and beyond. They are sensitive to physics both within and beyond the Standard Model through their production mechanisms and in their propagation over cosmological distances. They carry unique information about their extreme non-thermal sources by giving insight into regions that are opaque to electromagnetic radiation. Here in this white paper describes the opportunities astrophysical neutrino observations offer for astrophysics and high-energy physics, today and in coming years.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

Effects of trapped electrons on ion reflection in an oblique shock wave

A magnetosonic shock wave propagating obliquely to an external magnetic field can trap electrons and accelerate them to ultrarelativistic energies. The trapped electrons excite two-dimensional (2D) electromagnetic fluctuations with finite wavenumbers along the shock front. We study effects of the trapped electrons on ion motions through the 2D fluctuations. It is analytically shown that the fraction of ions reflected from the shock front is enhanced by the 2D fluctuations. This is confirmed by 2D (two space coordinates and three velocities) relativistic, electromagnetic particle simulations with full ion and electron dynamics and calculation of test ions in the electromagnetic fields averaged along the shock front. A comparison between 2D and one-dimensional electromagnetic particle simulations is also shown.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2017

Optimization of sensors based on surface waves in flat-layered structures

A method for increasing the sensitivity of surface-wave sensors in multifilm structures is proposed based on the results of a theoretical study of the reflection of a plane electromagnetic wave from a flat-layered structure containing homogeneous films. A method for optimizing the parameters of the films forming the surface structure is developed and tested. The devices proposed are characterized by high field amplification in a surface layer of multifilm structure and a higher sensitivity to variations in the optical properties of the thin near-surface layer. Application of the proposed multifilm structures is expected to increase significantly the sensitivity of the existing sensors based on surface-plasmon polaritons, which are applied in modern optical multichannel biological, chemical, and physical sensor systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Pulse Shaping and Matched Filters for EMAT Communication System

Electromagnetic acoustic transducer (EMAT) is used as a noncontact sensor for acoustic communication in a stainless-steel plate channel. The acoustic wave multipath propagations within the channel cause intersymbol interference (ISI). ISI highly degrades the signal-to-noise ratio (SNR). The poor SNR will result in a low bitrate and a high bit error rate (BER). In this study, a test platform is designed to estimate the performance of the EMAT communication system. Two periodic-permanent-magnet (PPM) EMATs are designed to be used as a transmitter and a receiver. EMAT generates shear-horizontal (SH) wave propagating through the stainless-steel plate channel. We present methods to minimize the ISI effect and recover the message embedded in the received signals hampered by interference, reverberation and multipath effects. The root raised cosine (RRC) filters are introduced as a pulse-shaping filter for transmission and a matched filter for receiving messages. Amplitude Shift Keying (ASK) method is used for modulating the transmitted binary message. The pulse shaping and matched filters reduced the ISI caused by the undesirable multipath effect significantly to the extent that a 5-kbps bitrate can be achieved without any error (zero BER).

Huang, Xin↗

DOE OSTI2015

A contactless approach for respiratory gating in PET using continuous-wave radar

Purpose: Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient’s torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. Methods: The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient’s torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [{sup 18}F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. Results: The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69–0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53–0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin. Conclusions: Accurate respiratory signals were obtained successfully by the proposed method with high spatial and temporal resolution. By working without contact and passing through clothing and blankets, this approach minimizes preparation time and increases the convenience of the patient during the scan.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2024

COSMIC DAWN: Distributed Analysis of Wireless at Nextscale

Distributed Analysis of Wireless at Nextscale (DAWN) is a novel simulation framework for large-scale design-space exploration (DSE) of unmodified software-defined radio (SDR) applications interacting in a scalable, high-fidelity, virtual physics environment. The software-defined nature of the coupled software-physics simulation leverages hardware emulation to permit in-depth examination and modification of not only the electromagnetic environment, including each signal in flight, but also the precise state of system software and components. DAWN supports modular, customizable physics environments allowing realistic propagation effects so that computationally efficient empirical models, reduced order/surrogate models, or large-scale, high-fidelity, site-specific simulations can be used as a propagation medium based on scenario requirements. This paper introduces DAWN’s design and initial implementation, detailing key architectural components, including the Physics Realization Engine (PhyRE), Runtime Infrastructure for Simulation Environments (RISE), and the design space exploration (DSE) suite. It concludes with demonstrations using unmodified 4G/LTE software available from srsRAN on computing resources ranging from a small cluster to ORNL’s Frontier Exascale system.

Wise, Mike [ORNL] (ORCID:0000000266120641)↗

DOE OSTI2017

First Annual Progress Report on Transmission of Information by Acoustic Communication along Metal Pathways in Nuclear Facilities

The objective of this project is to develop and demonstrate methods for transmission of information in nuclear facilities by acoustic means along existing in-place metal piping infrastructure. Pipes are omnipresent in a nuclear facility, and penetrate enclosures and partitions, such as the containment building wall. In the envisioned acoustic communication (AC) system, packets of information will be transmitted as guided acoustic waves along pipes. Performance of AC hardware and network protocols for efficient and secure communications under development in this project will be eventually evaluated in a representative nuclear power plant environment. Research efforts in the first year of this project have been focused on identification of appropriate transducers, and evaluation of their performance for information transmission along nuclear-grade metallic pipes. COMSOL computer simulations were performed to study acoustic wave generation, propagation, and attenuation on pipes. An experimental benchtop system was used to evaluate signal attenuation and spectral dispersion using piezo-electric transducers (PZTs) and electromagnetic acoustic transducers (EMATs). Communication protocols under evaluation consisted on-off keying (OOK) signal modulation, in particular amplitude shift keying (ASK) and phase shift keying (PSK). Tradeoffs between signal power and communication data rate were considered for ASK and PSK coding schemes.

42 ENGINEERING↗

DOE OSTI2016

Manipulation of surface plasmon polariton propagation on isotropic and anisotropic two-dimensional materials coupled to boron nitride heterostructures

We present a comprehensive analysis of surface plasmon polariton dispersion characteristics associated with isotropic and anisotropic two-dimensional atomically thin layered materials (2D sheets) coupled to h-BN heterostructures. A scattering matrix based approach is presented to compute the electromagnetic fields and related dispersion characteristics of stacked layered systems composed of anisotropic 2D sheets and uniaxial bulk materials. We analyze specifically the surface plasmon polariton (SPP) dispersion characteristics in case of isolated and coupled two-dimensional layers with isotropic and anisotropic conductivities. An analysis based on residue theorem is utilized to identify optimum optical parameters (surface conductivity) and geometrical parameters (separation between layers) to maximize the SPP field at a given position. The effect of type and degree of anisotropy on the shapes of iso-frequency curves and propagation characteristics is discussed in detail. The analysis presented in this paper gives an insight to identify optimum setup to enhance the SPP field at a given position and in a given direction on the surface of two-dimensional materials.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2018

A unified approach to Plasmon–Polariton and Brewster mode dynamics in media with interfacial surface-admittance

In this article we develop an ab-initio formulation for the analysis of certain solutions to the macroscopic Maxwell equations in bulk homogeneous materials that are separated by a planar interface that may sustain field-dependent electric currents induced by a surface admittance tensor. Based on Clemmow’s description of complex inhomogeneous plane time-harmonic waves, a systematic procedure is given that yields particular global solutions in terms of solutions to a system of bivariate polynomial and linear eigen-value equations for a set of six complex dimensionless scalars. This algebraic system is amenable to rapid numerical analysis using Maple or Matlab on a laptop. From the resulting solutions, analytic formulae for the electromagnetic fields can be expressed in terms of values for these six scalars and the electromagnetic phenomenological properties of the bulk media and their interface. We show explicitly how general properties of Surface Plasmon–Polariton (SPP) and Brewster modes follow from this unified viewpoint without appeal to any reflections in a Fresnel formulation. In particular we emphasise that endowing the material interface with (in general) anisotropic admittance properties can lead to new global electromagnetic field characteristics offering new possibilities for the control of surface characteristics by using recent advances in the fabrication of meta-materials. We illustrate our results by showing how a mono-layer of graphene in a normal magneto-static field can be used to construct a tunable meta-surface for SPP generation and how a simple conducting Ohmic interface can be used to excite both transverse electric and transverse magnetic Brewster modes as a function of the interface admittance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2015

1D profiling using highly dispersive guided waves

Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. There are many situations where the actual defect location is not accessible, e.g., a pipe support or a partially buried pipe. Guided wave tomography has been developed to reconstruct the wall thickness. In case of bottom of the line corrosion, i.e., a single corrosion pit, a simpler approach may be followed. Data is collected in a pit-catch configuration at the 12 o'clock position using highly dispersive guided waves. The phase spectrum is used to invert for a wall thickness profile in the circumferential direction, assuming a Gaussian defect profile. An EMAT sensor design has been made to measure at the 12 o'clock position of a pipe. The concept is evaluated on measured data, showing good sizing capabilities on a variety simple defect profiles.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2021

Spin waves and high-frequency response in layered superconductors with helical magnetic structure

Here, we evaluate the spin-wave spectrum and dynamic susceptibility in a layered superconductor with helical interlayer magnetic structure. We especially focus on the structure in which the moments rotate 90 degrees from layer to layer realized in the iron pnictide RbEuFe 4 As 4 . While in nonmagnetic superconductors low-frequency magnetic field decays on the distance of the order of the London penetration depth, spin waves mediate its propagation to much larger distances limited by external dissipation mechanisms. The spin-wave spectrum in superconductors is strongly renormalized due to the long-range electromagnetic interactions between the oscillating magnetic moments. This leads to strong enhancement of the frequency of the mode coupled with uniform field and this enhancement exists only within a narrow range of the c-axis wave vectors of the order of the inverse London penetration depth. The key feature of materials like RbEuFe 4 As 4 is that this uniform mode corresponds to the maximum frequency of the spin-wave spectrum with respect to the c-axis wave vector. As a consequence, the high-frequency surface resistance acquires a very distinct asymmetric feature spreading between the bare and renormalized frequencies. Finally, we also consider excitation of spin waves with the Josephson effect in a tunneling contact between helical-magnetic and conventional superconductors and study the interplay between the spin-wave features and geometrical cavity resonances in the current-voltage characteristics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

FFA@CEBAF beam transport error and tolerance simulation studies

The Continuous Electron Beam Accelerator Facility (CEBAF) is a 12 GeV recirculating electron accelerator at the Thomas Jefferson National Accelerator Facility (JLAB). Major upgrades to the accelerator are being investigated which include a new 650 MeV injection beamline and state-of-the-art fixed-field alternating (FFA) gradient recirculation arcs. The upgrade will extend the energy of the electron beam to over 20 GeV. In this paper, we provide an error and tolerance simulation study of the amended beam optics transport of the existing accelerator tuned for 22 GeV operation. The study is conducted with the particle tracking codes elegant and Bmad in two parts. In the first part, we treat each section of the accelerator (electromagnetic arcs and linacs) modularly with ideal conditions at the beginning. The second part is a pseudo start-to-end (S2E) simulation with accumulated errors propagating from one beamline to the next.

Accelerator Physics↗

DOE OSTI2015

Beyond the electric-dipole approximation: A formulation and implementation of molecular response theory for the description of absorption of electromagnetic field radiation

We present a formulation of molecular response theory for the description of a quantum mechanical molecular system in the presence of a weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on a description of linear absorption by adopting the energy-loss approach in combination with the complex polarization propagator formulation of response theory. Going beyond the electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and in general, non-dipolar effects become increasingly important when addressing spectroscopies involving higher-energy photons. These two aspects are examined by our study of the near K-edge X-ray absorption fine structure of the alkaline earth metals (Mg, Ca, Sr, Ba, and Ra) as well as the trans-polyenes. In following the series of alkaline earth metals, the sizes of non-dipolar effects are probed with respect to increasing photon energies and a detailed assessment of results is made in terms of studying the pertinent transition electron densities and in particular their spatial extension in comparison with the photon wavelength. Along the series of trans-polyenes, the sizes of non-dipolar effects are probed for X-ray spectroscopies on organic molecules with respect to the spatial extension of the chromophore.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Novel methods for the time-dependent Maxwell's equations and their applications

This dissertation investigates three different mathematical models based on the time-domain Maxwell's equations using three different numerical methods: a Yee scheme using a non-uniform grid, a nodal discontinuous Galerkin (nDG) method, and a newly developed discontinuous Galerkin method named the weak Galerkin (WG) method. The non-uniform Yee scheme is first applied to an electromagnetic metamaterial model. Stability and superconvergence error results are proved for the method, which are then confirmed through numerical results. Additionally, a numerical simulation of backwards wave propagation through a negative-index metamaterial is given using the presented method. Next, the nDG method is used to simulate signal propagation through a corrugated coaxial cable through the use of axisymmetric Maxwell's equations. Stability and error analysis are performed for the semi-discrete method, and are verified through numerical results. The nDG method is then used to simulate signal propagation through coaxial cables with a number of different corrugations. Finally, the WG method is developed for the standard time-domain Maxwell's equations. Similar to the other methods, stability and error analysis are performed on the method and are verified through a number of numerical experiments.

97 MATHEMATICS AND COMPUTING↗