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NASA NTRSDate not supplied

ETM: Upper Class E Traffic Management

This is a slide set as part of a meeting series with members of a working group aimed at the development of a concept that addresses needs and gaps in the management of high altitude airspace operations. This concept leverages elements developed through the UAS Traffic Management project with respect to a cooperative, service-based approach that provides services and capabilities in areas (e.g., Upper Class E airspace) that currently receive no or limited service from Air Traffic Control. This concept is meant to provide a safe, fair, and scalable approach to management of Upper Class E operations that reduces the burden on ATC while providing the flexibility and access desired by current and new users of the airspace. This set of slides includes an overview of discussions and industry news covering the time since the previous group meeting, a discussion of questions in response to a proposal document from Aerospace Industries Association (AIA), an update on modeling and simulation work, and announcements of upcoming plans for the project.

Upper E↗
DOE OSTI2016

Core Design Characteristics of the Fluoride Salt-Cooled High Temperature Demonstration Reactor

Fluoride salt-cooled high temperature reactors (FHRs) are a promising reactor technology option with significant knowledge gaps to implementation. One potential approach to address those technology gaps is via a small-scale demonstration reactor with the goal of increasing the technology readiness level (TRL) of the overall system for the longer term. The objective of this paper is to outline a notional concept for such a system, and to address how the proposed concept would advance the TRL of FHR concepts.Development of the proposed FHR Demonstration Reactor (DR) will enable commercial FHR deployment through disruptive and rapid technology development and demonstration. The FHR DR will close remaining gaps to commercial viability. Lower risk technologies are included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated within an acceptable budget and schedule. Important capabilities that will be demonstrated by building and operating the FHR DR include core design methodologies; fabrication and operation of high temperature reactors; salt procurement, handling, maintenance, and ultimate disposal; salt chemistry control to maximize vessel life; tritium management; heat exchanger performance; pump performance; and reactivity control. The FHR DR is considered part of a broader set of FHR technology development and demonstration efforts, some of which are already underway. Nonreactor test efforts (e.g., heated salt loops or loops using simulant fluids) can demonstrate many technologies necessary for commercial deployment of FHRs. The FHR DR, however, fulfills a crucial role in FHR technology development by advancing the technical maturity and readiness level of the system as a whole.

Brown, Nicholas↗
DOE OSTI2016

Phosphorus doped graphene by inductively coupled plasma and triphenylphosphine treatments

Highlights: • Substitution doping is a promising method for opening the energy band gap of graphene. • Substitution doping with phosphorus in the graphene lattice has numerous advantage such as high band gap, low formation energy, and high net charge density compared to nitrogen. • V{sub dirac} of Inductively coupled plasma (ICP) and triphenylphosphine (TPP) treated graphene was −57 V, which provided clear evidence of n-type doping. • Substitutional doping of graphene with phosphorus is verified by the XPS spectra of P 2p core level and EELS mapping of phosphorus. • The chemical bonding between P and graphene is very stable for a long time in air (2 months). - Abstract: Graphene is considered a host material for various applications in next-generation electronic devices. However, despite its excellent properties, one of the most important issues to be solved as an electronic material is the creation of an energy band gap. Substitution doping is a promising method for opening the energy band gap of graphene. Herein, we demonstrate the substitutional doping of graphene with phosphorus using inductively coupled plasma (ICP) and triphenylphosphine (TPP) treatments. The electrical transfer characteristics of the phosphorus doped graphene field effect transistor (GFET) have a V{sub dirac} of ∼ − 54 V. The chemical bonding between P and C was clearly observed in XPS spectra, and uniform distribution of phosphorus within graphene domains was confirmed by EELS mapping. The capability for substitutional doping of graphene with phosphorus can significantly promote the development of graphene based electronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2019

An Automated Vehicle Fuel Economy Benefits Evaluation Framework Using Real-World Travel and Traffic Data

Increasing automation is a consistent development trend in the automobile industry. However, real-world evaluation of the operational and energy consumption differences between automated vehicles and comparable manually driven vehicles has been limited. This study helps fill the information gap by comparing the operation and fuel economy of vehicles in adaptive cruise control (ACC) and non-ACC modes based on large-scale field test data collected by Volvo Car Corporation (Volvo Cars) from vehicles traveling on the designated 'Drive Me' project road network in Gothenburg, Sweden. The test vehicles' travel data are classified by driving mode (ACC vs. non-ACC) and driving conditions, which refer to traffic speed and road grade in this study. The results from the data logging fleet are used to estimate the aggregate fuel consumption differences at the Drive Me road-network level for vehicles traveling in ACC vs. non-ACC mode based on appropriately weighting the total amount of travel that took place on the network under different driving conditions. At the ACC penetration levels observed in the field test data, vehicles tended to drive more smoothly in ACC mode than in non-ACC mode. The corresponding travel-weighted fuel consumption rate for vehicles in ACC mode was about 5%-7% lower than for vehicles in non-ACC mode when traveling at similar conditions. Sensitivity analyses impart confidence in this result, and in the future, the established evaluation framework could be used to objectively quantify potential on-road fuel consumption impacts from vehicles with even higher levels of automated driving capability.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2016

Pathways to exotic metastable silicon allotropes

The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, signifi- cant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. Furthermore, this review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner

36 MATERIALS SCIENCE↗
DOE OSTI2023

MRT 7365: Power flow physics and key physics phenomena

The Z accelerator at Sandia National Laboratories conducts z-pinch experiments at 26 MA in support of DOE missions in stockpile stewardship, dynamic materials, fusion, and other basic sciences. Increasing the current delivered to the z-pinch would extend our reach in each of these disciplines. To achieve increases in current and accelerator efficiency, a fraction of Z’s shots are set aside for research into transmission-line power flow. These shots, with supporting simulations and theory, are incorporated into this Advanced Diagnostics milestone report. The efficiency of Z is reduced as some portion of the total current is shunted across the transmission-line gaps prior to the load. This is referred to as “current loss”. Electrode plasmas have long been implicated in this process, so the bulk of dedicated power-flow experiments are designed to measure the plasma environment. The experimental analyses are enhanced by simulations conducted using realistic hardware and Z voltage pulses. In the same way that diagnostics are continually being improved for sensitivity and resolution, the modeling capability is continually being improved to provide faster and more realistic simulations. The specifics of the experimental hardware, diagnostics, simulations, and algorithm developments are provided in this report. The combined analysis of simulation and data confirms that electrode plasmas have the most detrimental impact on current delivery. Experiments over the last three years have tested the theoretical current-loss mechanisms of enhanced ion current, plasma gap closure, and Hall-related current. These mechanisms are not mutually exclusive and may be coincident in the final feed as well as in upstream transmission lines. The final-feed geometries tested here, however, observe lower-density plasmas without dominant ion currents which is consistent with a Hall-related current. The picture of plasma formation and transport formed from experiment and simulation is informing hardware designs being fielded on Z now and being proposed for the Next-Generation Pulsed Power (NGPP) facility. In this picture, the strong magnetic fields that heat the electrodes above particle emission thresholds also confine the charged particles near the surface. Some portion of the plasmas thus formed is transported into the transmission-line gap under the force of the electric field, with aid from plasma instabilities. The gap plasmas are then transported towards the load by a cross-field drift, where they accumulate and contribute to a likely Hall-related cross-gap current. The achievements in experimental execution, model validation, and physical analysis presented in this report set the stage for continued progress in power flow and load diagnostics on Z. The planned shot schedule for Z and Mykonos will provide data for extrapolation to higher current to ensure the predicted performance and efficiency of a NGPP facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Measurements of time and spatial resolution of AC-LGADs with different designs

AC-LGAD sensors are prime candidates for fast and precise measurement of charged particles in a variety of applications. In a fine-pitched pixel or strip AC-LGAD sensor, the signal generated by the passage of a particle is not localized in a limited volume in the sensor, but is shared among multiple electrodes. This signal sharing characteristic allows us to improve the spatial resolution of AC-LGAD sensors beyond the capabilities of common silicon trackers. Since the magnitude of the shared signal depends on the distance between the pixels or strips and the point of passage of the particle, signal sharing is strongly influenced by the geometry of the sensor. The electrode pitch and gap size as well as the shape can be fine tuned to maximize the space resolution, while keeping the detector granularity and the number of channels to be read out under control. Prototypes of AC-LGAD sensors produced at the Brookhaven National Laboratory covering a variety of possible geometries have been studied via Transient Current Technique using an infrared laser, and the signal sharing, spatial resolution, and time resolution of the different topologies have been measured. These results have been compared with measurements performed in test-beams with 120 GeV protons at the Fermilab Test Beam Facility. A time resolution of ~30 ps can be achieved using AC-LGAD sensors with a thickness of 50 μm, compatible to that of standard DC-coupled LGADs, while presenting a far superior spatial resolution. Finally, this combination of high precision, fast timing capabilities, and low material budget makes AC-LGADs an ideal choice for a truly 4D detector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Porous Cu 2 BaSn(S,Se) 4 Film as a Photocathode Using Non-Toxic Solvent and a Ball-Milling Approach

Cu 2 BaSn(S,Se) 4 (CBTSSe) has been proposed as an alternative to Cu 2 ZnSn(S,Se) 4 (CZTSSe) for solar absorbers due to its reduced propensity for antisite disorder and band tailing, while maintaining the desirable characteristics of band gap tunability, earth-abundance, and low toxicity constituent metals. However, current film deposition methods require high-vacuum conditions or toxic solvents, less desirable features for prospective large-scale production. Here, ball milling is demonstrated as a route towards a scalable processing method for CBTSSe, using a precursor ink consisting of common elements Cu 2 S, BaS, Sn, and S in low-toxicity ethanol. A final film with a thickness and average grain size on the order of 1 µm was synthesized with a band gap of 1.56 eV, corresponding to a Cu 2 BaSnS 4-x Se x (x ≈ 3) stoichiometry. A porous CBTSSe photocathode with Pt/TiO 2 /CdS overlayers was fabricated to demonstrate the photocurrent-generating capabilities of the film, yielding current densities of as high as 5.54 mA/cm 2 at 0 V versus a reversible hydrogen electrode (V/RHE) .

14 SOLAR ENERGY↗
DOE OSTI2016

Sub-band gap photo-enhanced secondary electron emission from high-purity single-crystal chemical-vapor-deposited diamond

Secondary-electron-emission (SEE) current measured from high-purity, single-crystal (100) chemical-vapor-deposited diamond is found to increase when sub-band gap (3.06 eV) photons are incident on the hydrogenated surface. Although the light does not produce photoemission directly, the SEE current increases by more than a factor of 2 before saturating with increasing laser power. In energy distribution curves (EDCs), the emission peak shows a corresponding increase in intensity with increasing laser power. However, the emission-onset energy in the EDCs remains constant, indicating that the bands are pinned at the surface. On the other hand, changes are observed on the high-energy side of the distribution as the laser power increases, with a well-defined shoulder becoming more pronounced. From an analysis of this feature in the EDCs, it is deduced that upward band bending is present in the near-surface region during the SEE measurements and this band bending suppresses the SEE yield. However, sub-band gap photon illumination reduces the band bending and thereby increases the SEE current. Because the bands are pinned at the surface, we conclude that the changes in the band levels occur below the surface in the electron transport region. Sample heating produces similar effects as observed with sub-band gap photon illumination, namely, an increase in SEE current and a reduction in band bending. However, the upward band bending is not fully removed by either increasing laser power or temperature, and a minimum band bending of ∼0.8 eV is established in both cases. The sub-band gap photo-excitation mechanism is under further investigation, although it appears likely at present that defect or gap states play a role in the photo-enhanced SEE process. In the meantime, the study demonstrates the ability of visible light to modify the electronic properties of diamond and enhance the emission capabilities, which may have potential impact for diamond-based vacuum electron sources, particle detectors, and other electronic devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Unveiling the ambipolar carrier transport property of SnO 2–X for multiple-functional interlayers in perovskite solar cells

Tin oxides are the most promising electron transport layers in perovskite solar cells. An ambipolar carrier transport property has been recently demonstrated which enables a simple interconnection structure for all-perovskite tandem solar cells. However, the underlying mechanism for its ambipolar behavior is unclear which cannot be explained by the intrinsic defects in SnO 2-x . Here by using density functional theory calculations, we unveil the origin of the ambipolar carrier transport of non-stoichiometry SnO 2-x with a structure of SnO embedded in SnO 2 matrix. The hybridization of O 2p and Sn 5s orbitals of SnO introduces mid-gap states in the bandgap of SnO 2 , enabling hole transport property for SnO 2-x when x is > 0.2. Increasing the percentage of SnO in SnO 2-x significantly enhances the hole transport capability of SnO 2-x due to the enlarged Sn-O-Sn angles that increases orbital overlapping between O and Sn atoms, thus providing strategies for the further tuning of the carrier transport properties of SnO 2-x by compositional and structural designs.

14 SOLAR ENERGY↗
DOE OSTI2026

A Systematic Review on Coordinated Restoration Strategies for Power Distribution Grids

Power distribution grids are increasingly exposed to High-Impact Low-Probability (HILP) events, which cause widespread disruptions with severe societal and economic impacts. The growing complexity of modern grids, driven by the integration of distributed energy resources and smart grid technologies, has introduced new challenges to effective service restoration. While significant research has explored individual restoration strategies, such as network reconfiguration and microgrid formation, limited attention has been given to methods in which they can be effectively coordinated. Furthermore, the absence of systematic review papers addressing this issue hampers the development of cohesive restoration frameworks capable of addressing the operational complexities of modern grids. This paper presents a systematic review synthesizing existing knowledge on power grid restoration, identifying key limitations, and highlighting opportunities for coordinated strategies. By addressing research gaps and emphasizing the integration of diverse approaches, this study provides critical insights for advancing grid resiliency and recovery, offering a foundation for future research and practical applications in the face of HILP events.

Systematic review↗
DOE OSTI2017

Description of the LASSO Alpha 1 Release

The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility began a pilot project in May 2015 to design a routine, high-resolution modeling capability to complement ARM’s extensive suite of measurements. This modeling capability has been named the Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) project. The availability of LES simulations with concurrent observations will serve many purposes. LES helps bridge the scale gap between DOE ARM observations and models, and the use of routine LES adds value to observations. It provides a self-consistent representation of the atmosphere and a dynamical context for the observations. Further, it elucidates unobservable processes and properties. LASSO will generate a simulation library for researchers that enables statistical approaches beyond a single-case mentality. It will also provide tools necessary for modelers to reproduce the LES and conduct their own sensitivity experiments. Many different uses are envisioned for the combined LASSO LES and observational library. For an observationalist, LASSO can help inform instrument remote-sensing retrievals, conduct Observation System Simulation Experiments (OSSEs), and test implications of radar scan strategies or flight paths. For a theoretician, LASSO will help calculate estimates of fluxes and co-variability of values, and test relationships without having to run the model yourself. For a modeler, LASSO will help one know ahead of time which days have good forcing, have co-registered observations at high-resolution scales, and have simulation inputs and corresponding outputs to test parameterizations. Further details on the overall LASSO project are available at http://www.arm. gov/science/themes/lasso.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Advanced High Torque Density Magnetically Geared Generator

The objective of this research project was to investigate the fundamental torque density limitations of multistage flux focusing magnetic gears and magnetically geared direct-drive generators for wind turbines. Magnetic gears create non-contact speed amplification by modulating the air-gap magnetic field harmonics created by magnetic rotors. By integrating a stator into the magnetic gear structure a very high torque density direct-drive generator can be created. Magnetic geared systems offer unique capabilities that are currently not available using existing mechanically geared systems, such as overload protection. Magnetic gears also offer the potential for higher reliability, higher efficiency and quieter operation than is currently achievable using a mechanically geared generator. By increasing reliability and design life magnetic gears could decrease the overall life-cycle costs when compared with equivalent mechanical or direct-drive drivetrains. This research project investigated and experimentally testing two sub-scale magnetic gearboxes (0.12 m diameter) and two large diameter magnetic gearboxes (0.56m and 0.63m diameter). The goal of the project was to demonstrate a torque density >300Nm/L for a multistage magnetic gearbox with integrated stator. A nested multistage magnetic gear structure was first proposed and studied. However, it was shown that the nested design greatly increased mechanical complexity and therefore a two-stage series typology was utilized. A multi-stage magnetic gear with a 59:1 gear ratio was successfully experimentally tested. A peak torque of 4.25 kN·m was measured and this resulted in an overall active region torque density of 141 N·m/L (when including support rings). The torque density was significantly reduced from what was computed using 2-D electromagnetic analysis. This reduction was due to the 3-D edge effects, increased power losses and the inclusion of additional mechanical support rings as well as other mechanical assembly design changes. At large diameters contiguous lamination parts could not be fabricated and so a segmented laminated rotor design had to be used. This reduced the mechanical strength of the design when compared to small diameter magnetic gears and resulted in the need for the addition of mechanical support rings to prevent deflection. The final experimentally tested design also had a high torque ripple and the power loss within the magnetic gear did not change significantly with load. This therefore resulted in the efficiency being high only at peak loads. Despite not experimentally achieving the 2-D calculated high torque density the analysis has shown that the problems encountered with the scaling can be overcome with careful design changes. For example, understanding the unique mechanical deflection requirements during the electromagnetic design of the large diameter magnetic gears is key to achieving both a high torque density based on the electromagnetic analysis and a high torque density based on the mechanical support needs. Furthermore, ensuring that end plates are made of non-conductive material and minimizing other conductive support elements within the magnetic structure is a key requirement for reducing eddy current losses. In summary, if the mechanical design can be made more robust and eddy current loss mitigation strategies are used in the mechanical design phase then the magnetic gear is capable of being scaled up whilst operating at a very high torque density. This will then enable it to be potentially performance and cost competitive with alternative direct-drive and mechanically geared wind turbine drivetrains.

17 WIND ENERGY↗
DOE OSTI2022

Development of In-Situ Corrosion Kinetics and Salt Property Measurements (Final Technical Report)

The goal of this research is to fill the knowledge gaps of salt properties and gain a fundamental understanding of corrosion mechanisms, thereby to guiding material selections of salts and containment materials. The proposed research is focused on building unique cross-cutting research capabilities that can perform research and analysis relevant to the following three research topics important for Generation 3 Concentrating Solar Power Systems: (1) Material characterization including investigations of fluid thermophysical properties and stability, (2) Durability testing of containment materials, and (3) Corrosion behavior characterization relative to levels of known contaminants (e.g., water and oxygen) in Heat Transfer Fluid (HTF).

14 SOLAR ENERGY↗
NASA NTRS1994

System concept definition of the Grumman superconducting Electromagnetic Suspension (EMS) Maglev design

Grumman, under contract to the Army Corps of Engineers, completed a System Concept Definition (SCD) study to design a high-speed 134 m/s (300 m.p.h.) magnetically levitated (Maglev) transportation system. The primary development goals were to design a Maglev that is safe, reliable, environmentally acceptable, and low-cost. The cost issue was a predominant one, since previous studies have shown that an economically viable Maglev system (one that is attractive to investors for future models of passenger and/or freight transportation) requires a cost that is about $12.4 M/km ($20 Million per mile). The design is based on the electromagnetic suspension (EMS) system using superconducting iron-core magnets mounted along both sides of the vehicle. The EMS system has several advantages compared to the electrodynamic suspension (EDS) Maglev systems such as low stray magnetic fields in the passenger cabin and the surrounding areas, uniform load distribution along the full length of the vehicle, and small pole pitch for smoother propulsion and ride comfort. It is also levitated at all speeds and incorporates a wrap-around design of safer operation. The Grumman design has all the advantages of an EMS system identified above, while eliminating (or significantly improving) drawbacks associated with normal magnet powered EMS systems. Improvements include larger gap clearance, lighter weight, lower number of control servos, and higher off line switching speeds. The design also incorporates vehicle tilt (plus or minus 9 deg) for higher coordinated turn and turn out speed capability.

Proise, M.↗
NASA NTRS2009

Zinc Alloys for the Fabrication of Semiconductor Devices

ZnBeO and ZnCdSeO alloys have been disclosed as materials for the improvement in performance, function, and capability of semiconductor devices. The alloys can be used alone or in combination to form active photonic layers that can emit over a range of wavelength values. Materials with both larger and smaller band gaps would allow for the fabrication of semiconductor heterostructures that have increased function in the ultraviolet (UV) region of the spectrum. ZnO is a wide band-gap material possessing good radiation-resistance properties. It is desirable to modify the energy band gap of ZnO to smaller values than that for ZnO and to larger values than that for ZnO for use in semiconductor devices. A material with band gap energy larger than that of ZnO would allow for the emission at shorter wavelengths for LED (light emitting diode) and LD (laser diode) devices, while a material with band gap energy smaller than that of ZnO would allow for emission at longer wavelengths for LED and LD devices. The amount of Be in the ZnBeO alloy system can be varied to increase the energy bandgap of ZnO to values larger than that of ZnO. The amount of Cd and Se in the ZnCdSeO alloy system can be varied to decrease the energy band gap of ZnO to values smaller than that of ZnO. Each alloy formed can be undoped or can be p-type doped using selected dopant elements, or can be n-type doped using selected dopant elements. The layers and structures formed with both the ZnBeO and ZnCdSeO semiconductor alloys - including undoped, p-type-doped, and n-type-doped types - can be used for fabricating photonic and electronic semiconductor devices for use in photonic and electronic applications. These devices can be used in LEDs, LDs, FETs (field effect transistors), PN junctions, PIN junctions, Schottky barrier diodes, UV detectors and transmitters, and transistors and transparent transistors. They also can be used in applications for lightemitting display, backlighting for displays, UV and visible transmitters and detectors, high-frequency radar, biomedical imaging, chemical compound identification, molecular identification and structure, gas sensors, imaging systems, and for the fundamental studies of atoms, molecules, gases, vapors, and solids.

Ryu, Yungryel↗
NASA NTRS2010

From Shuttle Main Engine to the Human Heart: A Presentation to the Federal Lab Consortium for Technology Transfer

A NASA engineer received a heart transplant performed by Drs. DeBakey and Noon after suffering a serious heart attack. 6 months later that engineer returned to work at NASA determined to use space technology to help people with heart disease. A relationship between NASA and Drs. DeBakey and Noon was formed and the group worked to develop a low cost, low power implantable ventricular assist device (VAD). NASA patented the method to reduce pumping damage to red blood cells and the design of a continuous flow heart pump (#5,678,306 and #5,947,892). The technology and methodology were licensed exclusively to MicroMed Technology, Inc.. In late 1998 MicroMed received international quality and electronic certifications and began clinical trials in Europe. Ventricular assist devices were developed to bridge the gap between heart failure and transplant. Early devices were cumbersome, damaged red blood cells, and increased the risk of developing dangerous blood clots. Application emerged from NASA turbopump technology and computational fluid dynamics analysis capabilities. To develop the high performance required of the Space Shuttle main engines, NASA pushed the state of the art in the technology of turbopump design. NASA supercomputers and computational fluid dynamics software developed for use in the modeling analysis of fuel and oxidizer flow through rocket engines was used in the miniaturization and optimization of a very small heart pump. Approximately 5 million people worldwide suffer from chronic heart failure at a cost of 40 billion dollars In the US, more than 5000 people are on the transplant list and less than 3000 transplants are performed each year due to the lack of donors. The success of ventricular assist devices has led to an application as a therapeutic destination as well as a bridge to transplant. This success has been attributed to smaller size, improved efficiency, and reduced complications such as the formation of blood clots and infection.

Fogarty, Jennifer A.↗
NASA NTRS2011

Development of Low Density Flexible Carbon Phenolic Ablators

Phenolic Impregnated Carbon Ablator (PICA) was the enabling TPS material for the Stardust mission where it was used as a single piece heatshield. PICA has the advantages of low density (0.27g/cm3) coupled with efficient ablative capability at high heat fluxes. Under the Orion program, PICA was also shown to be capable of both ISS and lunar return missions however some unresolved issues remain for its application in a tiled configuration for the Orion-specific design. In particular, the problem of developing an appropriate gap filler resulted in the Orion program selecting AVCOAT as the primary heatshield material over PICA. We are currently looking at alternative architectures to yield flexible and more conformal carbon phenolic materials with comparable densities to PICA that will address some of the design issues faced in the application of a tiled PICA heat shield. These new materials are viable TPS candidates for upcoming NASA missions and as material candidates for private sector Commercial Orbital Transportation Services (COTS). This presentation will discuss flexible alternatives to PICA and include preliminary mechanical and thermal properties as well as arc jet and LHMEL screening test results.

Stackpole, Mairead↗