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NASA NTRS2008

Impact of Universal Plasma and Energetic Particle Processes on Icy Bodies of the Kuiper Belt and the Oort Cloud

Modeling of space plasma and energetic particle interactions with icy bodies of the outer solar system is simplified when there is commonality of the underlying source, acceleration, and transport processes in spatially distinct regions from the supersonic heliosphere through the heliosheath into the local interstellar medium (LISM). Current trends in the Voyager heliosheath measurements suggest strong commonality to processes in the LISM. The Fisk-Gloeckler "universal" spectrum at suprathermal energies apparently plays a strong role in coupling the plasma and high energy particle regimes in the spatial and energetic transitions from the outer heliosphere to the LISM. Dominant processes in consecutive energy regimes project to varying effects versus irradiation depth on exposed upper surfaces of airless small icy bodies and to upper atmospheres of larger bodies such as Titan and Pluto. Relative absence of the universal suprathermal spectrum in the mid-heliospheric region of the classical Kuiper Belt may profoundly affect surface color diversity of icy bodies in this region.

Cooper, John F.↗

NASA NTRS2012

Magnetic and Electric Field Polarizations of Oblique Magnetospheric Chorus Waves

A theory was developed to explain the properties of the chorus magnetic and electric field components in the case of an arbitrary propagation angle. The new theory shows that a whistler wave has circularly polarized magnetic fields for oblique propagation. This theoretical result is verified by GEOTAIL observations. The wave electric field polarization plane is not orthogonal to the wave vector, and in general is highly elliptically polarized. A special case of the whistler wave called the Gendrin mode is also discussed. This will help to construct a detailed and realistic picture of wave interaction with magnetosphere electrons. It is the purpose of this innovation to study the magnetic and electric polarization properties of chorus at all frequencies, and at all angles of propagation. Even though general expressions for electromagnetic wave polarization in anisotropic plasma are derived in many textbooks, to the knowledge of the innovators, a detailed analysis for oblique whistler wave mode is lacking. Knowledge of the polarization properties is critical for theoretical calculations of resonant wave-particle interactions.

Verkhoglyadova, Olga↗

NASA NTRS2006

The Dissipation Mechanism in Collisionless Magnetic Reconnection

The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as PIC simulations of guide-field magnetic reconnection. We will show that the thermal electron inertia-based dissipation mechanism, expressed through nongyrotropic electron pressure tensors, remains viable in three dimensions. We will demonstrate the thermal inertia effect through studies of electron distribution functions. Furthermore, we will show that the reconnection electric field provides a transient acceleration on particles traversing the inner reconnection region. This inertial effect can be described as a diffusion-like term of the current density, which matches key features of electron distribution functions.

Hesse, Michael↗

NASA NTRS2008

The Electron Diffusion Region: Forces and Currents

The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as PIC simulations of guide-field magnetic reconnection. We will show that the thermal electron inertia-based dissipation mechanism, expressed through nongyrotropic electron pressure tensors, remains viable in three dimensions. We will demonstrate the thermal inertia effect through studies of electron distribution functions. Furthermore, we will show that the reconnection electric field provides a transient acceleration on particles traversing the inner reconnection region. This inertia1 effect can be described as a diffusion-like term of the current density, which matches key features of electron distribution functions.

Hesse, Michael↗

NASA NTRS2009

What Turns Reconnection On and Off

The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as PIC simulations of guide-field magnetic reconnection. We will show that the thermal electron inertia-based dissipation mechanism, expressed through nongyrotropic electron pressure tensors, remains viable in three dimensions. We will demonstrate the thermal inertia effect through studies of electron distribution functions. Furthermore, we will show that the reconnection electric field provides a transient acceleration on particles traversing the inner reconnection region. This inertial effect can be described as a diffusion-like term of the current density. which matches key features of electron distribution functions.

Hesse, Michael↗

NASA NTRS2009

The Electron Diffusion Region: Forces and Currents

Hesse, Michael↗

DOE OSTI2025

Fuel performance analysis of fully-resolved TRISO compact

The TRi-structural ISOtropic (TRISO) fuel multilayered coating structure offers multiple barriers to fission product release, enhancing safety and performance. The heterogeneous nature of TRISO fuel compacts, comprising thousands of randomly distributed coated fuel particles embedded in a graphite matrix, creates intricate stress fields and thermal gradients that cannot be accurately modeled using simplified one-dimensional or homogenized approaches. Consequently, three-dimensional modeling enables the prediction of fuel compact dimensional changes, internal pressure buildup, and fission product transport pathways under diverse irradiation and thermal conditions. This capability facilitates detailed analysis of particle-to-particle interactions, matrix cracking mechanisms, and the statistical distribution of coating failures, which directly impact fuel performance and safety margins. This capability is particularly critical for advanced reactors, such as high-temperature gas-cooled reactors and other Generation IV reactor designs where TRISO fuel operates at elevated temperatures and burn-up levels. This work introduces a novel method to generate an optimized packing of TRISO compacts and a complete 3D mesh with random distribution of TRISO particles, which are discretized into each coating component layer.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

NASA NTRS2003

Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The 2-7 May 1998 Storm

A complete description of a self-consistent model of magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves and back on waves are considered self-consistently by solving both equations on a global magnetospheric scale under nonsteady state conditions. The developed model is employed to simulate the entire 2-7 May 1998 storm period. First, the trapped number fluxes of the ring current protons are calculated and presented along with comparison with the data measured by the three- dimensional hot plasma instrument Polar/HYDRA. Incorporating in the model the wave-particle interaction leads to much better agreement between the experimental data and the model results. Second, examining of the wave (MLT, L shell) distributions produced by the model during the storm progress reveals an essential intensification of the wave emission about 2 days after the main phase of the storm. This result is well consistent with the earlier ground-based observations. Finally, the theoretical shapes and the occurrence rates of the wave power spectral densities are studied. It is found that about 2 days after the storm s main phase on 4 May, mainly non-Gaussian shapes of power spectral densities are produced.

Khazanov, G. V.↗

NASA NTRS2003

Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The May 2-7, 1998, Storm

Complete description of a self-consistent model for magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves, and back on waves, are considered self-consistently by solving both equations on a global magnetospheric scale under non steady-state conditions. In the paper by Khazanov et al. [2002] this self-consistent model has only been shortly outlined, and discussions of many the model related details have been omitted. For example, in present study for the first time a new algorithm for numerical finding of the resonant numbers for quasilinear wave-particle interaction is described, or it is demonstrated that in order to describe quasilinear interaction in a multi-ion thermal plasma correctly, both e and He(+) modes of electromagnetic ion cyclotron waves should be employed. The developed model is used to simulate the entire May 2-7, 1998 storm period. Trapped number fluxes of the ring current protons are calculated and presented along with their comparison with the data measured by the 3D hot plasma instrument Polar/HYDRA. Examining of the wave (MLT, L shell) distributions produced during the storm progress reveals an essential intensification of the wave emissions in about two days after main phase of storm. This result is well consistent with the earlier ground-based observations. Also the theoretical shapes and the occurrence rates for power spectral densities of electromagnetic ion cyclotron waves are studied. It is found that in about 2 days after the storm main phase on May 4, mainly non Gaussian shapes of power spectral densities are produced.

Khazanov, G. V.↗

NASA NTRS2015

Study of the Residual Background Events in Ground Data from the ASTRO-HSXS Microcalorimeter

The measured instrumental background of the XRS calorimeter spectrometer of Suzaku had several sources, including primary cosmic rays and secondary particles interacting with the pixels and with the silicon structure of the array. Prior to the launch of Suzaku, several data sets were taken without x-ray illumination to study the characteristics and timing of background signals produced in the array and anti-coincidence detector. Even though the source of the background in the laboratory was different from that in low-earth orbit (muons and environmental gamma-rays on the ground versus Galactic cosmic-ray (GCR) protons and alpha particles in space), the study of correlations and properties of populations of rare events was useful for establishing the preliminary screening parameters needed for selection of good science data. Sea-level muons are singly charged minimum-ionizing particles, like the GCR protons, and thus were good probes of the effectiveness of screening via the signals from the anti-coincidence detector. Here we present the first analysis of the on-ground background of the SXS calorimeter of Astro-H. On XRS, the background prior to screening was completely dominated by coincident events on many pixels resulting from the temperature pulse arising from each large energy deposition (greater than 200 keV) into the silicon frame around the array. The improved heat-sinking of the SXS array compared with XRS eliminated these thermal disturbances, greatly reducing the measured count rate in the absence of illumination. The removal of these events has made it easier to study the nature of the residual background and to look for additional event populations. We compare the SXS residual background to that measured in equivalent ground data for XRS and discuss these preliminary results.

ASTRO-H↗

NASA NTRS1993

Optical observations of the beam-plasma discharge phenomenon

Spectroscopic observations of optical emissions from the beam-plasma discharge (BPD) phenomenon were made with NASA's vacuum chamber facility, at the Johnson Space Center, configured to simulate the physical conditions of magnetospheric electron beam injection into the ionospheric/upper-atmospheric environment. Nonlinear N2 and N2(+) optical emission growth rates (with respect to incremental electron beam current values) were observed from the chamber gas during transition to the BPD state. For electron-beam currents (I) near the BPD transition value (I(sub c)), the band emissions from the chamber gas produced by relatively low energy (less than or equal to 50 eV) electrons interacting with N2 were anomalously more intense than those requiring higher energy (greater than 100 eV) electrons to excite them. For I more greater than I(sub c), the optical emissions increased linearly with I (as was the case for I less than I(sub c)) and their ratios decreased significantly from the peak values attained when I approximately equals I(sub c). These observations suggest that during BPD some of the energy of the primary electron beam is efficiently transferred, via wave-particle interactions, to local electrons produced through ionization of the chamber gas; the resulting suprathermal electrons provide an additional source of excitation for the relatively low energy states (A, B and C) of N2. Such nonlinear excitation of upper atmospheric gas may occur in certain auroral events wherein the current due to the precipitating electrons approaches a value close to I(sub c).

Sivjee, G. G.↗

DOE OSTI2024

Dynamical Inference and 3D Imaging of Magnetized Dusty Plasmas

This is the final technical report for this DOE award. The motion of dust particles in a laboratory plasma has been studied for nearly 30 years and has led to the discovery of strongly-coupled crystalline structures and nonequilibrium dynamics governed by gravitational, hydrodynamic, and electrostatic forces. Many of the inter-particle forces are complex; they can be non-reciprocal, and non-additive. Deciphering the mélange of particle interactions has been a challenging task, nevertheless, magnetized dusty plasmas remains an open challenge with limited understanding. With applications ranging from magnetically-confined plasmas for fusion to near-surface planetary environments, this research field is ripe for well-controlled, laboratory experiments and new theoretical tools. In collaboration with the MDPX experiment at Auburn University, this proposal aims to tease apart both the known and unknown forces that drive dusty plasmas in magnetized environments using high-resolution, three-dimensional imaging and particle tracking coupled with modern dynamical inference and machine learning techniques.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS1985

Evaluation of parameters for particles acceleration by the zero-point field of quantum electrodynamics

That particles may be accelerated by vacuum effects in quantum field theory has been repeatedly proposed in the last few years. A natural upshot of this is a mechanism for cosmic rays (CR) primaries acceleration. A mechanism for acceleration by the zero-point field (ZPE) when the ZPE is taken in a realistic sense (in opposition to a virtual field) was considered. Originally the idea was developed within a semiclassical context. The classical Einstein-Hopf model (EHM) was used to show that free isolated electromagnrtically interacting particles performed a random walk in phase space and more importantly in momentum space when submitted to the perennial action of the so called classical electromagnrtic ZPE.

Rueda, A.↗

NASA NTRS2004

Cross-Scale Coupling in the Inner Magnetosphere

Magnetosphere-ionosphere (MI) coupling has interested scientists for decades and, in spite of experimental and theoretical research efforts, is still one of the least well-known dynamic processes in space plasma. The reason for this is that the numerous physical processes associated with MI coupling occur over multiple spatial lengths and temporal scales. One typical example of MI coupling is small- and large-scale ring current (RC) electrodynamic coupling. In this talk, we will address the two primary issues of RC electrodynamic coupling: (1) RC self-consistent coupling with electromagnetic ion cyclotron (EMIC) waves (small-scale electrodynamic coupling) and (2) RC self-consistent MI coupling that includes calculation of the magnetospheric electric field (large-scale electrodynamic coupling). We also will emphasize the role of the heavy ions in the number of wave-particle interaction magnetospheric processes. In particular, we will discuss some of the experimental and theoretical studies that have investigated the role of the heavy ions (mainly He(+) and O(+)) in generation and propagation of electromagnetic ion cyclotron waves and their contribution to the heating of magnetospheric electrons and ions. The more recent studies have also shown that the heavy ions can greatly contribute to a generation of lower hybrid waves, ring current precipitation phenomena, and the overall energy redistribution in the inner magnetosphere. Using newly developed 2.5-dimensional particle-in-cell simulations, we study the energization and nonlinear coupling of different plasma waves in the presence of the heavy ions. We have shown that the high frequency wave modes critically depend on the heavy ion density and irrespective of the driven wave modes, both the light and heavy ions undergo significant transverse acceleration. But for the large heavy-ion densities, even the electrons are significantly accelerated in the parallel direction by the waves below the LH frequency.

Khazanov, G. V.↗

NASA NTRS2004

The Role of the Heavy Ions in the Wave Magnetospheric Phenomena

This talk will emphasize the role of the heavy ions in the number of wave-particle interaction magnetospheric processes. In particular, we will discuss some of the experimental and theoretical studies that have investigated the role of the heavy ions (mainly He(+) and O(+)) in generation and propagation of electromagnetic ion cyclotron waves and their contribution to the heating of magnetospheric electrons and ions. The more recent studies have also shown that the heavy ions can greatly contribute to a generation of lower hybrid waves, ring current precipitation phenomena, and the overall energy redistribution in the inner magnetosphere. Using newly developed 2.5-dimensional particle-in-cell simulations, we study the energization and nonlinear coupling of different plasma waves in the presence of the heavy ions. We have shown that the high frequency wave modes critically depend on the heavy ion density and irrespective of the driven wave modes, both the light and heavy ions undergo significant transverse acceleration. But for the large heavy-ion densities, even the electrons are significantly accelerated in the parallel direction by the waves below the LH frequency.

Khazanov, G. V.↗

DOE OSTI2025

Whistler Chorus Amplification in the Magnetosphere: The Nonlinear Free‐Electron Laser Model and the Ginzburg‐Landau Equation

We present a novel nonlinear model for whistler-mode chorus amplification based on the free-electron laser (FEL) mechanism. First, we derive the nonlinear collective variable equations for the whistler-electron interaction. Consistent with in situ satellite observations, these equations predict that a small seed wave can undergo exponential growth, reaching a peak of a few hundred picoteslas after a few milliseconds, followed by millisecond timescale amplitude modulations. Next, we show that when one accounts for multiple wave frequencies and wave spatial variations, the amplitude and phase of the whistler wave can be described by the Ginzburg-Landau equation (GLE), providing a framework for the investigation of solitary wave behavior of chorus modes. These findings enhance our understanding of wave-particle interactions and space weather in the Van Allen radiation belts, deepen the connection between whistler-electron dynamics and FELs, and reveal a novel connection between whistler-mode chorus and the GLE.

Ginsburg-Landau equation↗

DOE OSTI2026

Search for heavy long-lived charged particles with level-1 trigger scouting data from proton-proton collisions at $\sqrt{s} = 13.6$ TeV

A search for heavy long-lived charged particles at the LHC is presented. Particles interacting with the CMS muon detector across several bunch crossings are searched for using a data sample of proton-proton collisions at $\sqrt{s}$ = 13.6 TeV collected with the CMS detector in 2024, corresponding to an integrated luminosity of 3.7 fb$^{-1}$. This is the first search relying on the novel level-1 trigger scouting data set collected without any trigger selection, allowing correlations between bunch crossings to be analyzed. The results are interpreted as upper limits on the cross sections of several benchmark processes with pair production of heavy long-lived charged particles. Upper limits on the fiducial cross section of a heavy long-lived charged particle with $p_\mathrm{T}$$\gt$ 500 GeV and $\lvertη\rvert$$\lt$ 0.83 are also set in different ranges of $β=v/c$. This analysis is a crucial proof of concept for the level-1 trigger data scouting system and complements existing searches for heavy long-lived charged particles by extending the sensitivity to lower $β$ values.

CMS↗

NASA NTRSDate not supplied

Higher-Order Approximations for Stabilizing Zero-Energy Modes in Peridynamics Crystal Plasticity Models with Large Horizon Interactions

The non-ordinary state-based peridynamics theory combines non-local dynamic techniques with a desirable correspondence material principle, allowing for the use of continuum mechanics constitutive models. Such an approach presents a unique capability for solving problems involving discontinuities (e.g., strain localization, fracture, and fragmentation). However, the correspondence-based peridynamics models often suffer from zero-energy mode instabilities in numerical implementation, primarily due to the approximations of the non-local deformation gradient tensor. This paper focuses on a computational scheme for eliminating the zero-energy mode oscillations using a choice of influence functions that improve the truncation error in a higher-order Taylor series expansion of the deformation gradient. The novelty here is a tensor-based derivation of the linear constraint equations, which can be used to systematically identify the particle interaction weight functions for various user-specified horizon radii. In this paper, the proposed higher-order stabilization scheme is demonstrated for multi-dimensional examples involving polycrystalline and composite microstructures, along with comparisons against conventional finite element methods. The proposed stabilization scheme is shown to be highly effective in suppressing the spurious zero-energy mode oscillations in all numerical examples while enabling efficient simulations of strain localizations across material interfaces.

Non-Ordinary State-Based Peridynamics↗