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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Feasibility of main thermal ion heating by ICRF waves using a top launcher in a tokamak with deuterium–tritium plasmas

A scenario of ion cyclotron range of frequency (ICRF) wave injection from a top launcher is proposed as an efficient and direct heating method for thermal deuterium ions in deuterium–tritium tokamak plasmas. Positioned between the tritium cyclotron layer and ion–ion hybrid layer, the top launcher allows effective wave penetration to the ion–ion hybrid layer and enables significant power transfer to thermal deuterium. This is achieved through favorable wave polarization for fundamental cyclotron damping. There is a Doppler broadening around the cyclotron resonance and this overlaps with the ion–ion hybrid layer. Low toroidal mode numbers and ion temperature in the range of 5–20 keV are favorable for enhancing the main ion damping relative to electron damping. In contrast to the neutral beam injection, which penetration strongly depends on machine size and plasma density, the proposed ICRF-based direct ion heating scenario is shown to be scalable and applicable to both larger and smaller tokamak devices within practical constraints.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Ultra-compact hybrid silicon:chalcogenide waveguide temperature sensor

We demonstrate a real-time, reusable, and reversible integrated optical sensor for temperature monitoring within harsh environments. The sensor architecture combines the phase change property of chalcogenide glasses (ChG) with the high-density integration advantages of high index silicon waveguides. To demonstrate sensor feasibility, ChG composition Ge 40 S 60 , which is characterized by a sharp phase transition from amorphous to crystalline phase around 415 °C, is deposited over a 50 µ m section of a single mode optical waveguide. The phase transition changes the behavior of Ge 40 S 60 from a low loss to high loss material, thus significantly affecting the hybrid waveguide loss around the phase transition temperature. A transmission power drop of over 40dB in the crystalline phase compared to the amorphous phase is experimentally measured. Moreover, we recover the amorphous phase through the application of an electrical pulse, thus showing the reversible nature of our compact temperature sensor. Through integrating multiple compositions of ChG with well-defined phases transition temperatures over a silicon waveguide array, it is possible to determine, in real-time, the temperature evolution within a harsh environment, such as within a nuclear reactor cladding.

Badamchi, Bahareh (ORCID:0000000193105300)↗
DOE OSTI2023

Demonstration of Magnetron as an Alternative RF Source for SRF Accelerators

Magnetron has been considered as alternate high-efficiency, low-cost RF sources for linacs and storage rings [1] for national labs and industrial applications. After the demonstration of magnetrons power to drive and combine for a radio frequency cavity at 2450 MHz in CW mode, we have used trim coils adding to a water-cooled magnetron and amplitude modulation feedback to further suppress the side-band noise to -46.7 dBc level. We also demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915 MHz with a 75 kW CW power delivered to a water load by using a -26.6 dBc injection signal [2]. The sideband noise from the 3-Phase SCRs DC power supply can be reduced to -16.2 dBc level. Further noise reduction and their power combining scheme using magic-tee and cavity type combiners for higher power application (2x75kW) are to be presented. We intent to use one power station to drive the normal conducting and superconducting RF cavities for the inductrial linac. We also going to demonstarte a vertical SRF cavity test with a high input coupling Q using a 2.45GHz magnetron and comparing with a baseline test result using a solid state amplifier.

Wang, H.↗
NASA NTRS1994

Identification of low-frequency fluctuations in the terrestrial magnetosheath

On the basis of magnetohydrodynamic (MHD) theory we develop a scheme for distinguishing among the four low-frequency modes which may propagate in a high-beta anisotropic plasma such as the magnetosheath: the fast and slow magnetosonic, the Alfven, and mirror modes. We use four parameters: the ratio of transverse to compressional powers in the magnetic field, the ratio of the wave powers in the thermal pressure and in the magnetic field, the ratio of the perturbations in the thermal and magnetic pressures, and the ratio of the wave powers in the velocity and in the magnetic field. In the test case of an Active Magnetospheric Particle Tracer Explorers/Ion Release Module (AMPTE/IRM) magnetosheath pass near the Sun-Earth line downstream of a quasi-perpendicular shock, the four modes can be clearly distinguished both spatially and spectrally. Near the bow shock, the waves are Alfvenic in a large frequency range, 1 to 100 mHz. In the middle and inner magnetosheath, the waves below 10 mHz are Alfvenic. The fast mode waves occur in the higher-frequency end of the enhanced spectrum, 80 mHz for the middle magnetosheath and 55 mHz for the inner sheath. The wave enhancement in the intermediate frequencies is slow modes in the inner sheath and mirror modes in the middle sheath. This confirms the earlier report of the existence of the slow mode waves near the magnetopause. These slow waves provide evidence that the magnetopause is an active source of the waves in the sheath. We also show that the measured frequency of a wave is close to an invariant if the magnetosheath flow is in a steady state. Therefore changes in the frequencies of enhanced waves indicate emergence, or damping, or mode conversion of the waves.

Song, P.↗
NASA NTRS2001

Hubble Space Telescope Servicing Mission 3A Rendezvous Operations

The Hubble Space Telescope (HST) hardware complement includes six gas bearing, pulse rebalanced rate integrating gyros, any three of which are sufficient to conduct the science mission. After the loss of three gyros between April 1997 and April 1999 due to a known corrosion mechanism, NASA decided to split the third HST servicing mission into SM3A, accelerated to October 1999, and SM3B, scheduled for November 2001. SM3A was developed as a quick turnaround 'Launch on Need' mission to replace all six gyros. Loss of a fourth gyro in November 1999 caused HST to enter Zero Gyro Sunpoint (ZGSP) safemode, which uses sun sensors and magnetometers for attitude determination and momentum bias to maintain attitude stability during orbit night. Several instances of large attitude excursions during orbit night were observed, but ZGSP performance was adequate to provide power-positive sun pointing and to support low gain antenna communications. Body rates in ZGSP were estimated to exceed the nominal 0.1 deg/sec rendezvous limit, so rendezvous operations were restructured to utilize coarse, limited life, Retrieval Mode Gyros (RMGs) under Hardware Sunpoint (HWSP) safemode. Contingency procedures were developed to conduct the rendezvous in ZGSP in the event of RMGA or HWSP computer failure. Space Shuttle Mission STS-103 launched on December 19, 1999 after a series of weather and Shuttle-related delays. After successful rendezvous and grapple under HWSP/RMGA, the crew changed out all six gyros. Following deploy and systems checkout, HST returned to full science operations.

Lee, S.↗
NASA NTRS2013

A One-year, Short-Stay Crewed Mars Mission Using Bimodal Nuclear Thermal Electric Propulsion (BNTEP) - A Preliminary Assessment

A crewed mission to Mars poses a significant challenge in dealing with the physiological issues that arise with the crew being exposed to a near zero-gravity environment as well as significant solar and galactic radiation for such a long duration. While long surface stay missions exceeding 500 days are the ultimate goal for human Mars exploration, short round trip, short surface stay missions could be an important intermediate step that would allow NASA to demonstrate technology as well as study the physiological effects on the crew. However, for a 1-year round trip mission, the outbound and inbound hyperbolic velocity at Earth and Mars can be very large resulting in a significant propellant requirement for a high thrust system like Nuclear Thermal Propulsion (NTP). Similarly, a low thrust Nuclear Electric Propulsion (NEP) system requires high electrical power levels (10 megawatts electric (MWe) or more), plus advanced power conversion technology to achieve the lower specific mass values needed for such a mission. A Bimodal Nuclear Thermal Electric Propulsion (BNTEP) system is examined here that uses three high thrust Bimodal Nuclear Thermal Rocket (BNTR) engines allowing short departure and capture maneuvers. The engines also generate electrical power that drives a low thrust Electric Propulsion (EP) system used for efficient interplanetary transit. This combined system can help reduce the total launch mass, system and operational requirements that would otherwise be required for equivalent NEP or Solar Electric Propulsion (SEP) mission. The BNTEP system is a hybrid propulsion concept where the BNTR reactors operate in two separate modes. During high-thrust mode operation, each BNTR provides 10's of kilo-Newtons of thrust at reasonably high specific impulse (Isp) of 900 seconds for impulsive transplanetary injection and orbital insertion maneuvers. When in power generation/EP mode, the BNTR reactors are coupled to a Brayton power conversion system allowing each reactor to generate 100's of kWe of electrical power to a very high Isp (3000 s) EP thruster system for sustained vehicle acceleration and deceleration in heliocentric space.

Burke, Laura M.↗
NASA NTRS2013

A One-year, Short-Stay Crewed Mars Mission Using Bimodal Nuclear Thermal Electric Propulsion (BNTEP) - A Preliminary Assessment

A crewed mission to Mars poses a signi cant challenge in dealing with the physiolog- ical issues that arise with the crew being exposed to a near zero-gravity environment as well as signi cant solar and galactic radiation for such a long duration. While long sur- face stay missions exceeding 500 days are the ultimate goal for human Mars exploration, short round trip, short surface stay missions could be an important intermediate step that would allow NASA to demonstrate technology as well as study the physiological e ects on the crew. However, for a 1-year round trip mission, the outbound and inbound hy- perbolic velocity at Earth and Mars can be very large resulting in a signi cant propellant requirement for a high thrust system like Nuclear Thermal Propulsion (NTP). Similarly, a low thrust Nuclear Electric Propulsion (NEP) system requires high electrical power lev- els (10 megawatts electric (MWe) or more), plus advanced power conversion technology to achieve the lower speci c mass values needed for such a mission. A Bimodal Nuclear Thermal Electric Propulsion (BNTEP) system is examined here that uses three high thrust Bimodal Nuclear Thermal Rocket (BNTR) engines allowing short departure and capture maneuvers. The engines also generate electrical power that drives a low thrust Electric Propulsion (EP) system used for ecient interplanetary transit. This combined system can help reduce the total launch mass, system and operational requirements that would otherwise be required for equivalent NEP or Solar Electric Propulsion (SEP) mission. The BNTEP system is a hybrid propulsion concept where the BNTR reactors operate in two separate modes. During high-thrust mode operation, each BNTR provides 10's of kilo- Newtons of thrust at reasonably high speci c impulse (Isp) of 900 seconds for impulsive trans-planetary injection and orbital insertion maneuvers. When in power generation / EP mode, the BNTR reactors are coupled to a Brayton power conversion system allowing each reactor to generate 100's of kWe of electrical power to a very high Isp (3000 s) EP thruster system for sustained vehicle acceleration and deceleration in heliocentric space.

Burke, Laura A.↗
DOE OSTI2020

The synthesis and versatile reducing power of low-valent uranium complexes

This Perspective provides a detailed overview of the chemistry of low-valent (di- and trivalent) uranium. The reactivity of uranium(II) and uranium(III) complexes is discussed both to illustrate the general types of reactions that might be expected and to highlight the many unusual modes of reactivity observed with this element. A particular emphasis is given to redox reactions with uranium(III) species, including reduction of small molecules, multi-electron reductions involving redox-active ligands, and formation of uranium–ligand multiple bonds. Redox-neutral adduct formation with uranium(III) complexes as well as the current state of the young field of uranium(II) redox chemistry are also covered. In addition, synthetic protocols to prepare a wide range of low-valent compounds are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Short Circuit Detection and Voltage Sense for High Voltage Ionization Tube Power Supplies

Fermilab's PIP-II upgrade requires new rack-mounted power supplies for Beam Loss Monitor (BLM) ionization tubes compatible with the microTCA 4.1 standard, supporting high-side current measurement for short circuit detection, voltage sense telemetry, and low-side current measurement for beam loss readout. This work presents the design and preliminary schematic of such a supply. A resistive current sensing approach was chosen over inductive, optical, and Hall-effect alternatives for its independence from cable length and component availability. A 500 mΩ inline shunt steps the 2 kV common mode voltage down to roughly 70 V, producing a ~27 μV pulse during a short, which is amplified 500x, compared against a 14-bit DAC threshold, and latched to drive a fault line. Voltage sense steps the 2 kV output down at a 1V/1000V ratio, buffers it with a low bias current amplifier, and digitizes it via a 24-bit ADC over SPI. Onboard power is regulated from 12 V down to isolated 5 V and 3.3 V rails, with capacitive isolation on FPGA communication lines. Lumped parameter models were developed for the ionization tube (0.327 nF, 20 to 200 GΩ dynamic resistance) and the RG-58 coaxial cable to support the design. Component selection is complete and a preliminary schematic has been drawn in Altium Designer, forming the foundation for future prototyping and validation.

Yu, Kellen [Cornell U.]↗
DOE OSTI2022

Domain wall enabled steep slope switching in MoS2 transistors towards hysteresis-free operation

Abstract The device concept of ferroelectric-based negative capacitance (NC) transistors offers a promising route for achieving energy-efficient logic applications that can outperform the conventional semiconductor technology, while viable operation mechanisms remain a central topic of debate. In this work, we report steep slope switching in MoS 2 transistors back-gated by single-layer polycrystalline PbZr 0.35 Ti 0.65 O 3 . The devices exhibit current switching ratios up to 8 × 10 6 within an ultra-low gate voltage window of $$V_{{{\mathrm{g}}}} = \pm \! 0.5$$ V g = ± 0.5 V and subthreshold swing (SS) as low as 9.7 mV decade −1 at room temperature, transcending the 60 mV decade −1 Boltzmann limit without involving additional dielectric layers. Theoretical modeling reveals the dominant role of the metastable polar states within domain walls in enabling the NC mode, which is corroborated by the relation between SS and domain wall density. Our findings shed light on a hysteresis-free mechanism for NC operation, providing a simple yet effective material strategy for developing low-power 2D nanoelectronics.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Design of a 140 GHz waveguide notch filter for millimeter-wave receiver module protection in fusion plasma diagnostics

A carefully designed waveguide-based millimeter-wave notch filter, operating at 140 GHz, safeguards plasma diagnostic instruments from gyrotron leakage. Here, utilizing cylindrical cavity resonators with aperture coupling, the filter efficiently resonates 140 GHz wave-power into the TE 11p mode, optimizing various geometrical parameters for practical fabrication and high-yield production. Thorough thermal analysis ensures its ability to handle power. The filter achieves outstanding performance with over 90 dB rejection at 140 GHz while providing low insertion loss over the passband (110–138 GHz), which is ideally suited for system-on-chip approach F-band diagnostic system applications.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Assessing plasma face component thermal response to rotating 3D magnetic fields for SPARC tokamak

Thermal response simulations of plasma-facing components (PFCs) in the SPARC tokamak, performed with the HEAT code, show that three-dimensional (3D) heat loads resulting from stationary n=1 perturbations require highly radiative scenarios, with up to 95% of the power crossing the separatrix (P SOL ) being radiated, to maintain PFC temperatures within acceptable operational limits, whereas the application of slowly rotating 3D fields substantially reduces the thermal loads. The HEAT module, developed to predict heat loads from non-axisymmetric plasmas, is extended to model time-dependent heat flux patterns generated by rotating 3D fields, and a comprehensive thermal analysis is performed on PFCs subjected to both the maximum and minimum power loads, as well as to rotating heat flux distributions, to evaluate the temperature evolution for varying perturbation amplitudes and rotation frequencies. The extension of this analysis to 3D fields with toroidal mode number n=2 shows that this configuration leads to weaker localized heat flux peaks relative to the n=1 case, enabling safe operation with less than 80% of the power radiated when static 3D fields of low amplitude are applied, while using slowly rotating fields at higher amplitudes. These results indicate that n=2 perturbations are generally less detrimental to divertor power exhaust, emphasizing the strong dependence of divertor power exhaust on the characteristics of the applied 3D fields.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Core-Pedestal Plasma Configurations in Advanced Tokamaks

Here, several configurations for the core and pedestal plasma are examined for a predefined tokamak design by implementing multiple heating/current drive (H/CD) sources to achieve an optimum configuration of high fusion power in a noninductive operation while maintaining an ideally magnetohydrodynamic (MHD) stable core plasma using the IPS-FASTRAN framework. IPS-FASTRAN is a component-based lightweight coupled simulation framework that is used to simulate magnetically confined plasma by integrating a set of high-fidelity codes to construct the plasma equilibrium (EFIT, TOQ, and CHEASE), calculate the turbulent heat and particle transport fluxes (TGLF), model various H/CD systems (TORIC, TORAY, GENRAY, and NUBEAM), model the pedestal pressure and width (EPED), and estimate the ideal MHD stability (DCON). The TGLF core transport model and EPED pedestal model are used to self-consistently predict plasma profiles consistent with ideal MHD stability and H/CD (and bootstrap) current sources. In order to evaluate the achievable and sustainable plasma beta, varying configurations are produced ranging from the no-wall stability to with-wall stability regimes, simultaneously subject to the self-consistent TGLF, EPED, and H/CD source profile predictions that optimize configuration performance. The pedestal density, plasma current, and total injected power are scanned to explore their impact on the target plasma configuration, fusion power, and confinement quality. A set of fully noninductive scenarios are achieved by employing ion-cyclotron, neutral beam injection, helicon, and lower-hybrid H/CDs to provide a broad profile for the total current drive in the core region for a predefined tokamak design. These noninductive scenarios are characterized by high fusion gain (Q ~ 4) and power (P fus ~ 600 MW), optimum confinement quality (H 98 ~ 1.1), and high bootstrap current fraction (f BS ~ 0.7) for Greenwald fraction below unity. The broad current profile configurations identified are stable to low-n kink modes either because the normalized pressure β N is below the no-wall limit or a wall is present.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Wind Turbine Aeroelastic Stability in OpenFAST

Wind turbines are growing in size and increasingly suffer from aeroelastic instabilities. Unfortunately, numerical models often show inconsistent results during verification studies. We address this gap by first introducing novel linearization capabilities within the open-source aero-hydro-servo-elastic framework OpenFAST. Next, a code-to-code benchmark study is presented that compares modal parameters between OpenFAST and HAWCStab2 for a land-based version of the International Energy Agency 15-MW reference wind turbine modeled with quasi-steady aerodynamics. The two solvers are in strong agreement except for discrepancies in the second rotor flapwise modes. The differences are attributed to the torsional flexibility of the tower, which is assumed torsionally stiff in the OpenFAST model. Work is ongoing to close this modeling gap. The aeroelastic stability of a low-specific-power land-based wind turbine is also investigated. The impact of design choices is discussed, high-lighting how narrow the margins are between a stable design and an unstable design.

17 WIND ENERGY↗
DOE OSTI2024

Early-stage Testing of Thermal Power Dispatch Simulator for Subjective Mental Workload and Evolution Time

The excess thermal energy produced by nuclear power plants (NPPs) during low electricity demands can be utilized in industrial processes, such as hydrogen production, through a thermal power dispatch (TPD) system. Initial testing of the first iteration of a single-train TPD design with a manual control mode at the Idaho National Lab (INL) revealed a high operator workload and degraded control capability. The current study evaluated the impact of an enhanced dual-train TPD design on operators’ subjective mental workload and evolution task-time while completing two operating scenarios in manual and automatic control modes. The results showed no statistically significant difference between participants’ mental workload using both control modes. Evolution time in automatic control mode took a shorter time than in manual control, with participants completing all evolutions in less than the 10-min set as the design specification limit. The shorter evolution time is discussed within the context of plant safety and operational efficiency.

Gideon, Olugbenga↗
NASA NTRS1976

Studies on immiscible alloys

To illustrate the behavior of immiscible liquids of different densities in zero-gravity and to determine the rate of coalescence like droplets, a demonstration experiment was performed on the Skylab 4 mission. Dispersions of oil-in-water and of water-in-oil were prepared by the astronauts and their appearance photographed over a time span of 10 hours. The experiment indicated that all emulsions were stable over this period and that the coalescent rate was at least 3 times 10 to the 5th power times smaller on Skylab than on earth. The recorded melting of a cylindrical piece of ice on Skylab 3 is used to study the mode of heat transfer for the latent heat of melting in low-gravity.

Otto, G.↗
NASA NTRS1977

Linear radial and nonradial modes of oscillation of hot white dwarfs

Low-order linear radial and nonradial quadrupole modes of oscillation of hot white dwarfs with hydrogen envelopes are evaluated in the quasi-adiabatic approximation. Luminosities range from 10 to the 36th to 10 to the 38th power. Masses range between 0.6 and 1.4 solar masses. Models are found with unstable radial modes as high as the third harmonic. The first nonradial quadrupole gravity mode is always unstable. The results may be relevant to pulsating X-ray sources in general and are specifically applied to Cen X-3, Her X-1, and SMC X-1.

Degregoria, A. J.↗
NASA NTRS1980

Sub mm laser local oscillators: Design criteria and results

Diagnostic results are given of the spectral features and the power conversion efficiency of submillimeter (SMM) laser local oscillators. Several criteria are obtained for the design of frequency stable and efficient smm lasers for local oscillator applications. Finally, a design is described and results on the power output and power and frequency stability are given. The mode pattern is very close to a Gaussian profile so that efficient coupling to a quasioptical mixer is possible. The laser provides sufficient output power at a large number of lines to drive the mixer into the low conversion loss regime. Radiometric integration times of several minutes with a spectral resolution of 1 MHz will be possible. With present state-of-the-art Schottky mixers and low noise preamplifiers a radiometric temperature resolution of a few K can be expected over a spectral range from 500to 900 GHz.

Koepf, G. A.↗