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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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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

High background photon counting lidar

Photon counting with lidar returns is usually limited to low light levels, while wide dynamic range is achieved by counting for long times. The broad emission spectrum of inexpensive high-power semiconductor lasers makes receiver filters pass too much background light for traditional photon counting in daylight. Very high speed photon counting is possible, however, at more than 500 MHz which allows the construction of eyesafe lidar operating in the presence of bright clouds. Detector improvements are possible to count to 20 GHz producing a single shot dynamic range of ten decades.

Lentz, W. J.↗
NASA NTRS1985

High dynamic GPS receiver validation demonstration

The Validation Demonstration establishes that the high dynamic Global Positioning System (GPS) receiver concept developed at JPL meets the dynamic tracking requirements for range instrumentation of missiles and drones. It was demonstrated that the receiver can track the pseudorange and pseudorange rate of vehicles with acceleration in excess of 100 g and jerk in excess of 100 g/s, dynamics ten times more severe than specified for conventional High Dynamic GPS receivers. These results and analytic extensions to a complete system configuration establish that all range instrumentation requirements can be met. The receiver can be implemented in the 100 cu in volume required by all missiles and drones, and is ideally suited for transdigitizer or translator applications.

Hurd, W. J.↗
NASA NTRSDate not supplied

Bootstrapping Multi-Agent Unmanned Aerial Vehicle (UAV) System Integration Using Ground-Based Assets: Lessons Learned

The highly dynamic nature of UAVs imposes significant challenges when conducting initial testing ranging from safety risks posed by high-capacity lithium batteries and spinning propellers to rigorous timing demands on controllers and the consequences of failures mid-air. Flight testing of a single vehicle is time and labor intensive due to these challenges and more, and the complexity increases exponentially with the number of vehicles. While simulations and hardware-in-the-loop bench testing can provide adequate environments for preliminary validation, differences in system deployment architecture, software interfaces, and hardware infrastructure between simulation and a fleet of real UAVs create a sizable gap that must be navigated carefully during system integration. In support of the Autonomy Teaming and TRAjectories for Complex Trusted Operational Reliability (ATTRACTOR) project, which had the goal of establishing a basis of certification of trust and trustworthiness in multi-agent autonomous systems, this gap was tackled from two directions. First, a novel mixed-reality simulation environment was engineered to blur the transition from simulation to flight hardware. Second, a fleet of Unmanned Surface Vehicles (USVs) was developed as a test and evaluation platform that more closely represented the final aerial fleet while eliminating many of the risks associated with air vehicles. This paper delves into the second element, analyzing the efficacy of the USV platform in performing system integration testing for the UAV system. In this paper we present the USV fleet and its role in reducing the aforementioned gaps in deployment architecture, software interfaces, and hardware infrastructure when moving from simulation to flight. An overview of the hardware and software onboard the vehicles will be provided along with supporting infrastructure. The system integration process will be documented including results in supporting both the overarching design reference mission (DRM) of ATTRACTOR and individual research efforts conducted during the project. Finally, we will discuss some of the practical lessons learned regarding the testing, deployment, and operation of multi-agent autonomous systems.

Matthew P Vaughan↗
NASA NTRS2007

Increasing Linear Dynamic Range of a CMOS Image Sensor

A generic design and a corresponding operating sequence have been developed for increasing the linear-response dynamic range of a complementary metal oxide/semiconductor (CMOS) image sensor. The design provides for linear calibrated dual-gain pixels that operate at high gain at a low signal level and at low gain at a signal level above a preset threshold. Unlike most prior designs for increasing dynamic range of an image sensor, this design does not entail any increase in noise (including fixed-pattern noise), decrease in responsivity or linearity, or degradation of photometric calibration. The figure is a simplified schematic diagram showing the circuit of one pixel and pertinent parts of its column readout circuitry. The conventional part of the pixel circuit includes a photodiode having a small capacitance, CD. The unconventional part includes an additional larger capacitance, CL, that can be connected to the photodiode via a transfer gate controlled in part by a latch. In the high-gain mode, the signal labeled TSR in the figure is held low through the latch, which also helps to adapt the gain on a pixel-by-pixel basis. Light must be coupled to the pixel through a microlens or by back illumination in order to obtain a high effective fill factor; this is necessary to ensure high quantum efficiency, a loss of which would minimize the efficacy of the dynamic- range-enhancement scheme. Once the level of illumination of the pixel exceeds the threshold, TSR is turned on, causing the transfer gate to conduct, thereby adding CL to the pixel capacitance. The added capacitance reduces the conversion gain, and increases the pixel electron-handling capacity, thereby providing an extension of the dynamic range. By use of an array of comparators also at the bottom of the column, photocharge voltages on sampling capacitors in each column are compared with a reference voltage to determine whether it is necessary to switch from the high-gain to the low-gain mode. Depending upon the built-in offset in each pixel and in each comparator, the point at which the gain change occurs will be different, adding gain-dependent fixed pattern noise in each pixel. The offset, and hence the fixed pattern noise, is eliminated by sampling the pixel readout charge four times by use of four capacitors (instead of two such capacitors as in conventional design) connected to the bottom of the column via electronic switches SHS1, SHR1, SHS2, and SHR2, respectively, corresponding to high and low values of the signals TSR and RST. The samples are combined in an appropriate fashion to cancel offset-induced errors, and provide spurious-free imaging with extended dynamic range.

Pain, Bedabrata↗
DOE OSTI2025

Probing the Effects of the First Atomic Layer on the Dynamic Behavior of Sub-2 nm MgO/Al 2 O 3 Memristors

As electronic devices continue to scale down from the current sub-5 nm range, atomic-scale control of defects becomes increasingly crucial to suppressing their impact on the physical properties of the devices. Memristors present an excellent example as a nonlinear and dynamic device with high speed and endurance required for electronic applications ranging from neuromorphic computing to nonvolatile memories. Herein we investigate the impact of atomic defects in sub-2 nm thick MgO/Al 2 O 3 atomic layer stack (ALS) memristors that use an M1 (switching layer)/M2 (oxygen vacancy reservoir layer) bilayer structure grown using in vacuo atomic layer deposition (iALD). Intriguingly, we revealed a direct correlation of the atomic defects in the M2 layer with the memristor dynamic behavior using a combined analysis of in situ scanning tunneling spectroscopy (iSTS) on the M2 layer and ex situ characterization on the memristors. Specifically, incomplete coverage of the 1st ALD atomic layer of M2 on the electrode yields defects at the M2/electrode interface. Despite the monotonic increase of ALD coverage, by almost three-fold from ~30% to >90%, at completion of the M2 layer of ~ 0.7 nm in thickness, the impact of the defects on the M2/electrode interface has been found detrimental to both memristor switching speed and endurance. Guided by atomistic simulation, we addressed the issue of interface defects via tuning of the Al surface hydroxylation to increase the first atomic layer ALD coverage to ~75%, leading to improved memristor switching speed and endurance by several orders of magnitude. In conclusion, these findings shed light on the correlation between the atomic defects and the dynamic behavior of sub-2 nm memristors and the importance of minimizing the atomic defects in memristors for future electronic applications.

Atomic Layer Deposition↗
NASA NTRS1994

High angle of attack flying qualities criteria for longitudinal rate command systems

This study was designed to investigate flying qualities requirements of alternate pitch command systems for fighter aircraft at high angle of attack. Flying qualities design guidelines have already been developed for angle of attack command systems at 30, 45, and 60 degrees angle of attack, so this research fills a similar need for rate command systems. Flying qualities tasks that require post-stall maneuvering were tested during piloted simulations in the McDonnell Douglas Aerospace Manned Air Combat Simulation facility. A generic fighter aircraft model was used to test angle of attack rate and pitch rate command systems for longitudinal gross acquisition and tracking tasks at high angle of attack. A wide range of longitudinal dynamic variations were tested at 30, 45, and 60 degrees angle of attack. Pilot comments, Cooper-Harper ratings, and pilot induced oscillation ratings were taken from five pilots from NASA, USN, CAF, and McDonnell Douglas Aerospace. This data was used to form longitudinal design guidelines for rate command systems at high angle of attack. These criteria provide control law design guidance for fighter aircraft at high angle of attack, low speed flight conditions. Additional time history analyses were conducted using the longitudinal gross acquisition data to look at potential agility measures of merit and correlate agility usage to flying qualities boundaries. This paper presents an overview of this research.

Wilson, David J.↗
NASA NTRS1977

Improved scene generator capability

Components of an integrated system having all functions for model preparation and generation, image computation and scene generation, and collision detection and reporting for the visual simulation of space shuttle maneuvers and its interaction with the manipular arm and other objects, as well as during earth landing exercises are described. High surface solution by range priority allows for correct views of dynamically moving objects from any viewpoint. Smooth shading, anti-aliasing and edge smoothing techniques provide a high quality picture. The collision detection system allows for simulation of impenetrable objects and docking maneuvers, and the modeling systems permit production of new data bases for desired simulations.

Source record↗
DOE OSTI2026

Dynamics of McMillan mappings III. Symmetric map with mixed nonlinearity

This article extends the study of the dynamical properties of the symmetric McMillan map, emphasizing its utility in understanding and modeling complex nonlinear systems. Although the map features six parameters, we demonstrate that only two are irreducible: the linearized rotation number at the fixed point and a nonlinear parameter representing the ratio of terms in the biquadratic invariant. Through a detailed analysis, we classify regimes of stable motion, provide exact solutions to the mapping equations, and derive a canonical set of action-angle variables, offering analytical expressions for the rotation number and nonlinear tune shift. We further establish connections between general standard-form mappings and the symmetric McMillan map, using the area-preserving Hénon map and accelerator lattices with thin sextupole magnet as representative case studies. Our results show that, despite being a second-order approximation, the symmetric McMillan map provides a highly accurate depiction of dynamics across a wide range of system parameters, demonstrating its practical relevance in both theoretical and applied contexts.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Relative sensitivity of plastic scintillator: A comparative analysis with 60 Co gamma rays, deuterium–deuterium, and deuterium–tritium neutrons

A plastic scintillator has found extensive application in the realm of high-energy physics and national security science. Many applications in those fields often involve the simultaneous production of photons, neutrons, and charged particles, which makes the relative sensitivity information for these different radiation types important. In this study, we have adopted a multi-head detector comprised of a plastic scintillator and high gain phototubes, which provides a large dynamic range and linearity. A comparative study on the relative sensitivities of plastic scintillators was facilitated by adopting three distinct radiation calibration sources (i.e., 60 Co γ rays, DD neutrons, and DT neutrons). Neutrons from a DD source generate a comparable level of scintillation to gamma rays emitted by 60 Co (i.e., 60 Co-γ/DD-n = 0.92 ± 16%). DT neutrons induce ~3.5 times the scintillation observed with DD neutrons (i.e., DT-n/DD-n = 3.5 ± 28%). In addition, the Geant4 simulation granted us valuable insights into the relative sensitivity of the scintillator. This comparative study will provide a useful database for users in diverse applications.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Design of a Thomson scattering diagnostic for the SMall Aspect Ratio Tokamak (SMART)

Here, we describe the design of a Thomson scattering (TS) diagnostic to be used on the SMall Aspect Ratio Tokamak (SMART). SMART is a spherical tokamak being commissioned in Spain that aims to explore positive triangularity and negative triangularity plasma scenarios at a low aspect ratio. The SMART TS diagnostic is designed to operate at high spatial resolution, 6 mm scattering length in the low-field side and 9 mm in the high-field side regions, and a wide dynamic range, electron temperature from 1 eV to 1 keV and density from 5 x 10 18 m -3 to 1 x 10 20 m -3 ⁠, to resolve large gradients formed at the plasma edge and in the scrape-off layer (SOL) under different triangularities and low aspect ratios. A 2 J @1064 nm laser will be used that is capable of operating in the burst mode at 1, 2, and 4 kHz to investigate fast phenomena and at 30 Hz to study 1 s (or more) long discharges. The scattered light will be collected over an angular range of 60° – 120° from 28 spatial points in the midplane covering the entire plasma width and the outer midplane SOL. Each scattering signal will be spectrally resolved on five wavelength channels of a polychromator to obtain the electron temperature measurement. We will also present a method to monitor in situ laser alignment in the core during calibrations and plasma operations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1992

The STIS MAMA status: Current detector performance

The STIS (Space Telescope Imaging Spectrograph) is a second generation Hubble instrument scheduled to fly in 1997. Through a variety of modes, the instrument will provide spectral resolutions from R approximately 50 in the objective spectroscopy mode to 100,000 in the high resolution echelle mode in the wavelength region from 115 to 1000 nm. In the UV the instrument employs two MAMA (Multimode Anode Microchannel plate Arrays) 1024 by 1024 pixel detectors, which provide high DQE (Detective Quantum Efficiency), and good dynamic range and resolution. The current progress and performance of these detectors are reported, illustrating that the technology is mature and that the performance is very close to flight requirements.

Danks, A. C.↗
NASA NTRS2000

HST Studies of the Chromospheres, Wind, and Mass-Loss Rates of Cool Giant and Supergiant Stars

UV spectra of K-M giant and supergiant stars and of carbon stars have been acquired with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). These spectra have been used to measure chromospheric flow and turbulent velocities, study the acceleration of their stellar winds, acquire constraints on their outer atmospheric structure, and enable estimates of their mass-loss rates. Results from our observations of the giant stars Gamma Dra (K5 III hybrid), Alpha Tau (K5 III), Gamma Cru (M3.4 III), Mu Gem (M3 IIIab), and 30 Her (MG III), the supergiants Alpha Ori (M2 Iab) and Lambda Vel (K5 Ib), and the carbon stars TX Psc (NO; C6,2) and TW Hor (NO; C7,2) will be summarized and compared. The high resolution and wavelength accuracy of these data have allowed the direct measurement of the acceleration of the stellar winds in the chromospheres of several of these stars (from initial velocities of 3-9 km/s to upper velocities of 15-25 km/s) and of the chromospheric macroturbulence (-25-35 km/s). The high signal-to-noise and large dynamic range of these spectra have allowed the detection and identification of numerous new emission features, including weak C IV emission indicative of hot transition-region plasma in the non-coronal giant Alpha Tau, many new fluorescent lines of Fe II, and the first detection of fluorescent molecular hydrogen emission and of Ca II recombination lines in the UV spectrum of a giant star. The UV spectrum of two carbon stars have been studied with unprecedented resolution and reveal extraordinarily complicated Mg II lines nearly smothered by circumstellar absorptions. Finally, comparison of synthetic UV emission line profiles computed with the Lamers et al. (1987) Sobolev with Exact Integration (SEI) code with observations of chromospheric emission lines overlain with wind absorption features provides estimates of the mass-loss rates for four of these stars.

Carpenter, Kenneth G.↗
NASA NTRS2018

Magnetotail Boundary Crossings at Lunar Distances: ARTEMIS Observations

We compare results from a preliminary analysis of two years of ARTEMIS magnetopause boundary crossings at lunar distances with available empirical models. We remove the effects of variable solar wind flow directions and aberration angles to study the magnetotail cross-section as a function of solar wind conditions. The average magnetopause distance from the central axis is 26 RE, but this distance ranges from 10 RE for high solar wind dynamic pressures and strong northward IMF orientations to 39 RE for low solar wind dynamic pressures and weak southward IMF orientations compared to the nominal solar wind conditions. The time-independent Howe and Binsack (1972) model describes the average location of the crossings very well. For high solar wind dynamic pressures, the Lu et al., (2011) model performs best, while for low pressures the Petrinec and Russell (1996) model gives the closest prediction. As predicted by theory and seen in past studies, the magnetotail cross-section is suggestive of prolate during intervals of strong IMF By, but oblate during intervals of strong IMF Bz. Any asymmetric variation of the tail boundary with respect to the sign of IMF By was not observed. The decreasing size of boundary with the increasing dynamic pressure was found when dynamic pressures are smaller than 2nPa. Although the scatter is larger, the tail size for pressures larger than 2nPa suggests a constant radius. The tail boundary size decreases as the strength of IMF Bz increases regardless of its polarity. However, it was also observed that an even stronger southward IMF Bz can cause larger magnetopause size in the presence of large dynamic pressures.

Magnetotail↗
NASA NTRS1999

NASA/NOAA: Earth Science Electronic Theater 1999

The Electronic Theater (E-theater) presents visualizations which span the period from the original Suomi/Hasler animations of the first ATS-1 GEO weather satellite images in 1966 to the latest 1999 NASA Earth Science Vision for the next 25 years. Hot off the SGI-Onyx Graphics-Supercomputer are NASA's visualizations of Hurricanes Mitch, Georges, Fran and Linda. These storms have been recently featured on the covers of National Geographic, Time, Newsweek and Popular Science. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on National and International network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1-min GOES images that appeared in the November BAMS. The visualizations are produced by the NASA Goddard Visualization and Analysis Laboratory (VAL/912), and Scientific Visualization Studio (SVS/930), as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the Earth Science E-Theater 1999 recently presented in Tokyo, Paris, Munich, Sydney, Melbourne, Honolulu, Washington, New York, and Dallas. The presentation Jan 11-14 at the AMS meeting in Dallas used a 4-CPU SGI/CRAY Onyx Infinite Reality Super Graphics Workstation with 8 GB RAM and a Terabyte Disk at 3840 X 1024 resolution with triple synchronized BarcoReality 9200 projectors on a 60ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense HyperImage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites, HyperImage datasets, because they have such high resolution in the spectral, temporal, spatial, and dynamic range domains. The traditional numerical spreadsheet paradigm has been extended to develop a scientific visualization approach for processing HyperImage datasets and 3D model results interactively. The advantages of extending the powerful spreadsheet style of computation to multiple sets of images and organizing image processing were demonstrated using the Distributed image SpreadSheet (DISS). The DISS is being used as a high performance testbed Next Generation Internet (NGI) VisAnalysis of: 1) El Nino SSTs and NDVI response 2) Latest GOES 10 5-min rapid Scans of 26 day 5000 frame movie of March & April '98 weather and tornadic storms 3) TRMM rainfall and lightning 4)GOES 9 satellite images/winds and NOAA aircraft radar of hurricane Luis, 5) lightning detector data merged with GOES image sequences, 6) Japanese GMS, TRMM, & ADEOS data 7) Chinese FY2 data 8) Meteosat & ERS/ATSR data 9) synchronized manipulation of multiple 3D numerical model views; and others will be illustrated. The Image SpreadSheet has been highly successful in producing Earth science visualizations for public outreach. Many of these visualizations have been widely disseminated through the world wide web pages of the HPCC/LTP/RSD program which can be found at http://rsd.gsfc.nasa.gov/rsd The one min interval animations of Hurricane Luis on ABC Nightline and the color perspective rendering of Hurricane Fran published by TIME, LIFE, Newsweek, Popular Science, National Geographic, Scientific American, and the "Weekly Reader" are some of the examples which will be shown.

Hasler, A. Fritz↗
NASA NTRS1999

NASA/NOAA: Earth Science Electronic Theater 1999. Earth Science Observations, Analysis and Visualization: Roots in the 60s - Vision for the Next Millennium

The Etheater presents visualizations which span the period from the original Suomi/Hasler animations of the first ATS-1 GEO weather satellite images in 1966, to the latest 1999 NASA Earth Science Vision for the next 25 years. Hot off the SGI-Onyx Graphics-Supercomputer are NASA''s visualizations of Hurricanes Mitch, Georges, Fran and Linda. These storms have been recently featured on the covers of National Geographic, Time, Newsweek and Popular Science. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on National and International network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1-min GOES images that appeared in the November BAMS. The visualizations are produced by the NASA Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the Earth Science ETheater 1999 recently presented in Tokyo, Paris, Munich, Sydney, Melbourne, Honolulu, Washington, New York, and Dallas. The presentation Jan 11-14 at the AMS meeting in Dallas used a 4-CPU SGI/CRAY Onyx Infinite Reality Super Graphics Workstation with 8 GB RAM and a Terabyte Disk at 3840 X 1024 resolution with triple synchronized BarcoReality 9200 projectors on a 60ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense HyperImage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites, HyperImage datasets, because they have such high resolution in the spectral, temporal, spatial, and dynamic range domains. The traditional numerical spreadsheet paradigm has been extended to develop a scientific visualization approach for processing HyperImage datasets and 3D model results interactively. The advantages of extending the powerful spreadsheet style of computation to multiple sets of images and organizing image processing were demonstrated using the Distributed Image SpreadSheet (DISS). The DISS is being used as a high performance testbed Next Generation Internet (NGI) VisAnalysis of: 1) El Nino SSTs and NDVI response 2) Latest GOES 10 5-min rapid Scans of 26 day 5000 frame movie of March & April 198 weather and tornadic storms 3) TRMM rainfall and lightning 4)GOES 9 satellite images/winds and NOAA aircraft radar of hurricane Luis, 5) lightning detector data merged with GOES image sequences, 6) Japanese GMS, TRMM, & ADEOS data 7) Chinese FY2 data 8) Meteosat & ERS/ATSR data 9) synchronized manipulation of multiple 3D numerical model views; etc. will be illustrated. The Image SpreadSheet has been highly successful in producing Earth science visualizations for public outreach.

Hasler, A. Fritz↗
NASA NTRS1989

Frequency estimation techniques for high dynamic trajectories

A comparison is presented of four different estimation techniques applied to the problem of continuously estimating the rapidly varying parameters of a sinusoidal signal, observed in the presence of additive noise. Frequency estimates are emphasized, although phase and/or frequency rate are also estimated by some of the algorithms. These parameters are related to the velocity, position, and acceleration of the maneuvering receiver or transmitter. Estimated performance at low carrier-to-noise ratios and high dynamics is investigated for the purpose of determining the useful operating range of an approximate maximum-likelihood estimator, an extended Kalman filter, a cross-product automatic frequency loop, and a phase-locked loop. Numerical simulations are used to evaluate performance while tracking a common trajectory exhibiting high dynamics.

Vilnrotter, Victor A.↗
NASA NTRS1988

A comparison of frequency estimation techniques for high-dynamic trajectories

A comparison is presented for four different estimation techniques applied to the problem of continuously estimating the parameters of a sinusoidal Global Positioning System (GPS) signal, observed in the presence of additive noise, under extremely high-dynamic conditions. Frequency estimates are emphasized, although phase and/or frequency rate are also estimated by some of the algorithms. These parameters are related to the velocity, position, and acceleration of the maneuvering transmitter. Estimated performance at low carrier-to-noise ratios and high dynamics is investigated for the purpose of determining the useful operating range of an approximate Maximum Likelihood (ML) estimator, an Extended Kalman Filter (EKF), a Cross-Product Automatic Frequency Control (CPAFC) loop, and a digital phase-locked loop (PPL). Numerical simulations are used to evaluate performance while tracking a common trajectory exhibiting high dynamics.

Vilnrotter, V. A.↗
NASA NTRSDate not supplied

Ionospheric Response to Electron Precipitation Driven by Whistler-Mode Chorus Waves Measured by Arase Satellite and Simulated by STET and SPEAH-RIT

The origin of pulsating auroras has long been an open question. Arase satellite observation reported the direct evidence that precipitated electrons in pulsating aurora are driven by whistler-mode chorus wave activity. Our study presents the theoretical analysis of this observational event based on SuperThermal Electron Transport (STET) code that simulates the highly dynamic environment of measured wave intensities and particle fluxes. Specifically, the STET code simulated results confirm the delicate loss-cone observation results of this mission and reveal the broader energy range of precipitated electron fluxes that were not measurable by Arase satellite. These highly dynamic precipitating electron fluxes were applied to a newly developed code, the Superthermal Proton, Electron and Atomic Hydrogen tRansport in the Ionosphere and Thermosphere (SPEAH-RIT), to simulate ionospheric response of this phenomena, in particular, the enhancement of electron density, plasma temperatures, and ionospheric electric conductance at the footprints of Arase satellite.

George V. Khazanov↗