Search

The high temperature superconducting (HTS) magnets can be utilized by using second generation conductors, but is very problematic as quench has become undetectable when the operating temperature is in the 65-77 K range. The different commercial codes are evaluated and a simple three-dimensional homogenized model is used for a racetrack coil.

The design of a High Temperature Superconducting (HTS) motor with safety torque for general aviation aircraft is discussed. Results suggest that the new motor leads to an increase in reliability at the expense of an increased motor weight.

The scaling up of a non-conventional motor for aircraft propulsion is discussed. Findings reveal the possible facilitation of integration of the motor in the ducted fan systems by increasing the motor length.

The design of a high power density superconducting motor is presented by using trapped flux magnets as excitation systems. Results suggest that the axial-flux configuration enables the use of one or several conventional permanent magnet rotors for the generation of minimum safety torque in case of loss of superconductivity.

The design and testing of an eight-pole superconducting rotating machine, which is based on an unconventional topology leading to an increase in power density, is presented. The Markov chain Monte Carlo (MCMC) method is used to calculate the magnetic scalar potential in selected regions of the discrete geometry.

Magnetic compensation of gravity allows for ground-based experiments to be carried out under weightless conditions at reasonable cost and without the time limitation of systems such as zero-g airplanes or drop towers. Most of the time classical superconducting solenoids are operated to perform such experiments, which lead to a poor quality of the gravity compensation due to the non-ideal shape of the current and field distribution. In order to improve the quality of simulated microgravity, scientists need to build novel ground-based systems fully dedicated to magnetic levitation. The magnetic design of these levitation apparatuses would be based on theoretical studies of magnetic forces and associated field distributions. The work presented in this paper demonstrates the possibility of producing a magnetic force on paramagnetic and diamagnetic materials that is constant, thus providing a uniform gravity compensation, along a segment in a 3D geometry. These results come from both the decomposition in spherical harmonics of the magnetic field and specific conditions applied on the magnetic force. The magnetic field configuration leads to conical-shape isohomogeneity of the resulting acceleration. As an additional remark to previous works, the impossibility to get a magnetic force varying as 1/r2 is briefly described. [ABSTRACT FROM AUTHOR]

Classical numerical techniques remain very computationally expensive to model the magnetization of twisted multifilamentary superconductors in three dimensions because they require solving a large system of equations. In this paper, a reduced model is proposed to approximate the ac losses of these types of wires. It is established through the projection of the physical problem in a helical Frenet basis and the use of periodic boundary conditions on a slice of the wire. The reduced model on the slice leads to systems of more reasonable size leading to smaller and faster simulations than when the whole wire is modeled. Simulation results show that the proposed method leads to computed losses similar to those obtained on a whole wire. Several simulation cases are proposed to prove the validity of the proposed model, and a comparison to some ac loss measurements is proposed to show the effectiveness of the proposed approach. The implementation relies on the H-formulation and is solved with the open-source solver, Getdp. [ABSTRACT FROM AUTHOR]

High-speed, fully superconducting electric rotating machines are highly sought for naval and aerospace applications, to provide significantly higher power density than can be achieved by other means. We examined the use of an MgB2 -based, two-stage, cabled conductor for the armature winding of a medium power (10–15 MW) electric generator, operating near 20 K at a nominal peak phase current of 2 kA. We chose MgB2 because it is electromagnetically isotropic and can be manufactured as round, multifilamentary strands. This paper describes the proposed conductor and presents our prototype manufacturing efforts. Prototype cables were fabricated using fine filament (15-μm filament diameter) strand manufactured by Hyper Tech Research. AC losses in MgB2 triplet bundles were measured at 20 K using a calorimetric technique. We present measured AC loss data for the MgB2 triplets and evaluate those losses in relation to the strand composition and strand and cable configurations. [ABSTRACT FROM PUBLISHER]

AC losses in an isolated superconducting round wire with a power-law electrical behavior produced by the combined effect of transverse alternating and rotating fields, i.e., an elliptical field, are investigated. The goal is to provide semianalytical expressions of the magnetization losses with a high enough reliability to be used in sizing code development or optimization methods. The fit expressions are based on data generated by means of a 2-D numerical model using the well-known and proved H-formulation. In the meantime, data processing allows for revealing a universal variable cn of utmost importance in magnetization loss calculation. This variable depends on the n-value of the power-law resistivity, and both the dimensionless magnetic field b* and frequency f*. [ABSTRACT FROM PUBLISHER]

Superconducting synchronous machines require Direct Current (DC) excitation for their field windings which can be achieved via brushless exciters or by direct connection to current leads. However, the resulting heat loads limit their application. An excitation system consisting of a High-temperature Superconducting (HTS) full wave rectified flux pump eliminates these issues and enables operation at high currents. [ABSTRACT FROM AUTHOR]

\YBa2\Cu3\O7 - \delta coated conductors have very slow normal-zone propagation velocity, which renders quench detection and protection very difficult. To develop effective quench detection methods, it is paramount to study the underlying behavior that drives quench propagation at the micrometer-scale level. Toward this end, numerical mixed-dimensional models, composed of multiple high-aspect-ratio thin layers, are developed. The high-aspect-ratio modeling issues are tackled by approximating the thin layers either as a 2-D surface or as an analytical contact resistance interior boundary condition, which also acts as a coupling bridge between the 2-D and 3-D behaviors. The tape models take into account the thermal and electrical physics of each layer in actual conductor dimensions and are implemented using commercial finite-element analysis software. In the first part of this two-part paper, the mixed-dimensional models are introduced and then computationally and experimentally validated. Validations are gauged by comparisons in normal-zone propagation velocity and in the time-dependent voltage and temperature profiles. Results show that the mixed-dimensional models can not only effectively address the high-aspect-ratio modeling issues of thin films but also accurately and efficiently reproduce physical quench phenomena in a coated conductor. [ABSTRACT FROM AUTHOR]

Superconducting power devices are considered for many applications, including airborne applications. For the devices of interest the operating temperature needs to remain around 70 K in order to minimize the weight and volume of the associated cooling system. The use of YBa2Cu3Ox (YBCO) coated conductors allows for operation at fairly high temperature (65-77 K) while maintaining high current carrying capabilities. Unfortunately, when a hot spot is created in a coated conductor wound magnet, the quench propagates so slowly that it cannot be detected using conventional methods and therefore those magnets may remain unprotected. To address this quench detection issue, we must better understand the physics of the quench and the phenomena that drive it so it can be accurately simulated. We have modeled YBCO tapes using Finite Element Analysis to assess the role of the contact resistance between the different layers composing the tape. Indeed, if the temperature rises, the YBCO layer becomes highly resistive and the current redistributes into the stabilization layers. The contact resistance between the YBCO layer and the copper is likely to play a very important role in terms of the current sharing length and voltage difference between the layers. This paper presents a model implemented in COMSOL Multiphysics, simulation results and a discussion. [ABSTRACT FROM AUTHOR]

This article introduces a new conceptual design tool for an environmentally sustainable method of aeropropulsion: a ducted fan system driven by a fully superconducting electrical machine. Such a system could help mitigate aviation's contribution to global climate change by enabling the reduction of greenhouse gas emissions from aircraft. An electro-thermal motor sizing model was coupled with cycle analysis and weight estimation routines to create an automated environment for rapid design trade studies. The resulting parametric cycle analysis and sizing outcomes revealed the system's operational boundaries for a given aspiration space. [ABSTRACT FROM AUTHOR]

Sustainability in the aviation industry calls for aircraft that are significantly quieter and more fuel efficient than today's fleet. Achieving this will require revolutionary new concepts, in particular, electric propulsion. Superconducting machines offer the only viable path to achieve the power densities needed in airborne applications. This paper outlines the main issues involved in using superconductors for aeropropulsion. We review our investigation of the feasibility of superconducting electric propulsion, which integrate for the first time, the multiple disciplines and areas of expertise needed to design electric aircraft. It is shown that superconductivity is clearly the enabling technology for the more efficient turbo-electric aircraft of the future. [ABSTRACT FROM AUTHOR]

Current high temperature superconducting (HTS) wires exhibit high current densities enabling their use in electrical rotating machinery. The possibility of designing high power density superconducting motors operating at reasonable temperatures allows for new applications in mobile systems in which size and weight represent key design parameters. Thus, all-electric aircrafts represent a promising application for HTS motors. The design of such a complex system as an aircraft consists of a multi-variable optimization that requires computer models and advanced design procedures. This paper presents a specific sizing model of superconducting propulsion motors to be used in aircraft design. The model also takes into account the cooling system. The requirements for this application are presented in terms of power and dynamics as well as a load profile corresponding to a typical mission. We discuss the design implications of using a superconducting motor on an aircraft as well as the integration of the electrical propulsion in the aircraft, and the scaling laws derived from physics-based modeling of HTS motors. [ABSTRACT FROM AUTHOR]

NASA conducts and funds research to advance the state of the art in aeronautics, including improvements in aircraft design leading to enhanced performance in areas such as noise, emissions, and safety. A particular initiative involves development of an all-electric aircraft requiring significant improvements in certain technologies. NASA has started a new project with one of the objectives being the development of enabling technologies for an all-electric aircraft. Electrical aeropropulsion requires the design of more compact and efficient electrical motors. In order to me crease the power density, the weight/size must be minimized and the air gap flux density must increase significantly the use of superconducting materials is an obvious choice. Existing HTS motors are proof-of-principle demonstrators and exhibit power densities lower than 1 HP/lb, which is too low to be considered in mobile systems. This paper deals with a preliminary electromagnetic design of a 200 HP high temperature superconducting motor optimized in terms of power density. The presented configuration is a synchronous motor with a nonconventional topology enhanced by HTS bulk material. The design targets the Cessna 172 propulsion requirements that are 200 HP at 2700 RPM. [ABSTRACT FROM AUTHOR]

Thermal aspects of a novel high temperature superconducting motor design are examined for use in the propulsion of an aero-vehicle. To simplify the refrigeration, focus is on conduction cooling of the superconducting material directly from the cold head of the cryocooler. A brief description of the motor is followed by an analysis of the conduction cooling apparatus. An experimental setup has been developed, including a cryocooler, a cryostat, and a mockup of the HTS motor, to validate the system model. [ABSTRACT FROM AUTHOR]

This paper describes the design of a new kind HTS motor. Superconducting plates used as magnetic screen that cause a spatial variation of the flux density. It is theoretically possible to obtain an air gap flux density variation greater than 3 T. We perform a dimensionless study of the device showing that the torque depends on shape parameters and is limited by the maximum field on the superconducting wire. In the last section, we discuss the performance of the device in term of torque density. [ABSTRACT FROM AUTHOR]

Blockade of interleukin (IL)-23 or IL-17 with biologics is clinically validated as a treatment of psoriasis. However, the clinical impact of targeting other nodes within the IL-23/IL-17 pathway, especially with small molecules, is less defined. We report on a novel small molecule inverse agonist of retinoid acid-related orphan receptor (ROR) γ t and its efficacy in preclinical models of psoriasis and arthritis. 1-(2,4-Dichloro-3-((1,4-dimethyl-6-(trifluoromethyl)-1H-indol-2-yl)methyl)benzoyl)piperidine-4-carboxylic acid (A-9758) was optimized from material identified from a high-throughput screening campaign. A-9758 is selective for ROR γ t and exhibits robust potency against IL-17A release both in vitro and in vivo. In vivo, we also show that IL-23 is sufficient to drive the accumulation of ROR γ t + cells, and inhibition of ROR γ t significantly attenuates IL-23-driven psoriasiform dermatitis. Therapeutic treatment with A-9758 (i.e., delivered during active disease) was also effective in blocking skin and joint inflammation. Finally, A-9758 exhibited efficacy in an ex vivo human whole blood assay, suggesting small molecule inverse agonists of ROR γ t could be efficacious in human IL-17-related diseases. SIGNIFICANCE STATEMENT: Using a novel small molecule inverse agonist, and preclinical assays, we show that ROR γ t is a viable target for the inhibition of ROR γ t/Th17-driven diseases such as psoriasis. Preclinical models of psoriasis show that inhibition of ROR γ t blocks both the accumulation and effector function of IL-17-producing T cells., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)