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Results for “HELICAL WINDING”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

High-temperature superconducting CORC ® wires with record-breaking axial tensile strain tolerance present a breakthrough for high-field magnets

Cuprate high-temperature superconductors (HTS), such as RE-Ba 2 Cu 3 O 7–δ (REBCO, RE = rare earth), (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10–x and Bi 2 Sr 2 CaCu 2 O 8–x , have enabled the development of high-field superconducting magnets capable of generating magnetic fields far exceeding 20 T. The brittle nature of HTS requires elaborate means to protect them against the high stresses and strains associated with high-field magnet operation, and so far, has prevented reliable high-field HTS magnets from becoming a reality. Here we report a more than tenfold increase in the irreversible strain limit under axial tension (epsilonirr) to over 7% in optimized high-current conductor on round core (CORC®) conductors, compared to the REBCO tapes from which the CORC® conductor is wound. Minimizing the tape winding pitch of the helical wind mechanically decouples the brittle REBCO film from the overall conductor. The REBCO tapes behave as springs, limiting the rate at which applied strain is transferred to the ceramic film. In addition, high-strength alloy cores allow the critical stress (ϵ crit ) under axial tension at which initial degradation of CORC® conductors occurs to exceed 600 MPa, making them one of the strongest superconductors available. Mechanically decoupling the ceramic REBCO films from the overall CORC® conductor allows effective protection against the high operating stresses in high-field magnets. Furthermore, this breakthrough presents a monumental shift for HTS magnet technology, bringing reliable high-field superconducting magnets for compact fusion machines, the next generation of particle accelerators, and 40–60 T research solenoids within reach.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1988

Analytical models of helical wind-type astrophysical flows

Three classes of analytic solutions of the basic hydrodynamic equations assumed to govern plasma flow in the atmosphere of a rotating astrophysical object are presented. Attention is focused on the balance of the inertial and gravitational forces with suitable pressure gradients in the presence of rotation. The solutions are written in terms of dimensionless physical parameters in order to facilitate their direct application to specific astrophysical flows, such as winds from massive premain sequence objects and T Tauri stars, and bipolar flows in young stellar objects.

Tsinganos, K.↗
DOE OSTI2021

Helical superconducting undulator for 3rd and 4th generation of synchrotron light source and FELs

A helical superconducting undulator includes a cylindrical magnetic core through which a bore hole allows the passage of charged particles. A single superconducting wire wraps the magnetic core guided by helical flights and cylindrical protrusions, to create interleaved helical windings on the magnetic core. An electrical current may be supplied to the superconducting wire to generate a periodic helical magnetic field in the bore. The helical superconducting undulator also includes a strong-back enclosure that acts as an epoxy mold during epoxy impregnation, a structural support to ensure straightness of the undulator after epoxy impregnation, and assists in cooling and thermal control of the magnetic core and superconducting wire during device operation.

Gluskin, Efim↗
NASA NTRS1965

Helical coaxial-resonator makes excellent RF filter

Isolation of closely spaced transmitting and receiving frequencies of an antenna without insertion loss by filtering the receiver input is accomplished by an inner conductor with two winding helices and an outer conductor of aluminum. A tuning slug is at either end of the inner conductor form.

Source record↗
DOE OSTI2021

Improved prescription for winding an electromagnet

We describe an improvement on the magnetic scalar potential approach to design an electromagnet, which incorporates the need to wind the coil as a helix. Any magnetic field that can be described by a magnetic scalar potential is produced with high fidelity within a Target region; all fields are confined within a larger Return. The helical winding only affects the field in the Return.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Highly Symmetric, Self-Assembling 3D DNA Crystals with Cubic and Trigonal Lattices

The rational design of nanoscopic DNA tiles has yielded highly ordered crystalline matter in 2D and 3D. The most well-studied 3D tile is the DNA tensegrity triangle, which is known to self-assemble into macroscopic crystals. However, contemporary rational design parameters for 3D DNA crystals nearly universally invoke integer numbers of DNA helical turns and Watson–Crick (WC) base pairs. Here, in this study, 24-bp edges are substituted into a previously 21-bp (two helical turns of DNA) tensegrity triangle motif to explore whether such unconventional motif can self-assemble into 3D crystals. The use of noncanonical base pairs in the sticky ends results in a cubic arrangement of tensegrity triangles with exceedingly high symmetry, assembling a lattice from winding helical axes and diamond-like tessellation patterns. Reverting this motif to sticky ends with Watson–Crick pairs results in a trigonal hexagonal arrangement, replicating this diamond arrangement in a hexagonal context. These results showcase that the authors can generate unexpected, highly complex, pathways for materials design by testing modifications to 3D tiles without prior knowledge of the ensuing symmetry. This study expands the rational design toolbox for DNA nanotechnology; and it further illustrates the existence of yet-unexplored arrangements of crystalline soft matter.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Surface waves on solar wind tangential discontinuities

It is demonstrated that (tangential) discontinuities in the magnetic field direction can support MHD surface waves. The surface waves are similar to the usual Alfven wave, but there are seven important differences. The first is that the surface waves exhibit a low-frequency cutoff; the second is that the velocity and magnetic field fluctuations are elliptically, and sometimes circularly, polarized. It is noted that they may account for the solar wind helicity spectrum. The third difference is that the surface waves are compressive, although there are special cases where they are noncompressive. The fourth is that the wave vector k, the local normals to the surfaces of constant phase, and the magnetic minimum variance direction do not all coincide. The fifth is that there is a tendency for the minimum variance direction to align itself with the mean magnetic field direction. The sixth difference is that the waves can be intrinsically nonplanar, and the seventh is that equipartition between magnetic and kinetic energies is not obeyed locally. These properties of the surface waves are interpreted to mean that surface waves may be common in the solar wind.

Hollweg, J. V.↗
DOE OSTI2023

Consequences and Control of Multiscale Order/Disorder in Chiral Magnetic Textures

Transition metal intercalated transition metal dichalcogenides (TMDs) are promising platforms for next-generation spintronic devices based on their wide range of electronic and magnetic phases, which can be tuned by varying the host lattice or intercalant’s identity, stoichiometry, or spatial order. Some of these compounds host a chiral magnetic phase in which the helical winding of magnetic moments propagates along a high-symmetry crystalline axis. Previous studies have demonstrated that variation in intercalant concentrations can have a dramatic effect on the formation of chiral domains and ensemble magnetic properties. However, a systematic and comprehensive study of how atomic-scale order and disorder impact these chiral magnetic textures is so far lacking. Here, we leverage a combination of imaging modes in the (scanning) transmission electron microscope (S/TEM) to directly probe (dis)order across multiple length scales and show how subtle changes in the atomic lattice can tune the mesoscale spin textures and bulk magnetic response in Cr 1/3 NbS 2 , with direct implications for the fundamental understanding and technological implementation of such compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Design fabrication and nondestructive testing of six experimental AGCarb/Intermold 3 cylinder assemblies

Six subscale Intermold cylinder assemblies with a total of twelve different concepts for transition to AGCarb were fabricated. Three of the cylinder assemblies were made by helically winding the hoop fibers and three were of orthogonal configuration. The fabrication process is summarized and details of each manufacturing method are given. The objectives of the test program were to: (1) demonstrate the fabricability of the Intermold 3 subscale flanges, (2) produce an integral transition from Intermold 3 to AGCarb material, (3) define a workable manufacturing process, and (4) identify a best suited inspection method. The objectives were met and the results are described.

Thacher, E. F.↗
NASA NTRS1983

Stiffness Properties for Dynamic Modeling of Composite Graphite-Epoxy Cylindrical Orthotropic Shells

Traditional composite lamination theory was used to predict composite graphite-epoxy laminate stiffnesses for comparison to quasi-experimental stiffnesses developed from cylindrical bottle pressure testing. Stiffness sensitivities were examined for variations in constituent materials and geometric properties. The material component interactions examined were the fiber longitudinal and transverse Young's modulus, the fiber shear modulus and primary Poisson's ratio, the resin Young's modulus, shear modulus, and Poisson's ratio. The geometric variation of the helical winding angle was also examined. Two computer programs were written to generate the data used to demonstrate the stiffness variations.

Tolbert, R. N.↗
NASA NTRS1985

Solid Rocket Motor Case (SRMC) dynamic sensitivity to changes in composite properties

Traditional composite lamination theory was used to compute the constitutive matrices using a potential range of lamina properties. Sensitivity of vibrational frequencies was examined for variations in constituent materials and geometric properties. The material component interactions examined were the lamina longitudinal and transverse Young's modulus, the lamina Poisson's ratio, and the shear modulus. Fiber and resin properties were related to the frequency response through lamina properties. Geometric properties examined are void ratio and helical wind angle. Capabilities and applications of the SPAR and NASTRAN computer codes are examined for laminated cylindrical shells.

Tolbert, R. N.↗
NASA NTRS1985

Ultrasonic evaluation of mechanical properties of thick, multilayered, filament wound composites

A preliminary investigation is conducted to define capabilities and limitations of ultrasonic and acousto-ultrasonic measurements related to mechanical properties of filament wound graphite/epoxy composite structures. The structures studied are segments of filament wound cylinders formed of multiple layers of hoop and helical windings. The segments consist of 24 to 35 layers and range from 3.02 to 3.34 cm in wall thickness. The resultant structures are anisotropic, heterogeneous, porous, and highly attenuating to ultrasonic frequencies greater than 1 MHz. The segments represent structures to be used for space shuttle booster cases. Ultrasonic velocity and acousto-ultrasonic stress wave factor measurement approaches are discussed. Correlations among velocity, density, and porosity, and between the acousto-ultrasonic stress wave factor and interlaminar shear strength are presented.

Kautz, H. E.↗
NASA NTRS1987

Ultrasonic evaluation of mechanical properties of thick, multilayered, filament-wound composites

A preliminary investigation is conducted to define capabilities and limitations of ultrasonic and acousto-ultrasonic measurements related to mechanical properties of filament wound graphite/epoxy composite structures. The structures studied are segments of filament wound cylinders formed of multiple layers of hoop and helical windings. The segments consist of 24 to 35 layers and range from 3.02 to 3.34 cm in wall thickness. The resultant structures are anisotropic, heterogeneous, porous, and highly attenuating to ultrasonic frequencies greater than 1 MHz. The segments represent structures to be used for Space Shuttle booster cases.Ultrasonic velocity and acousto-ultrasonic stress wave factor measurement approaches are discussed. Correlations among velocity, density, and porosity, and between the acousto-ultrasonic stress wave factor and interlaminar shear strength are presented.

Kautz, H. E.↗
NASA NTRS1993

High-Temperature, Flexible, Fiber-Preform Seals

High-temperature, flexible, fiber-preform seal includes axial core and helical windings, and abrasion-resistant sheath. Seals tailored to service in variety of environments. Used between movable and stationary panels in advanced aircraft engines or to seal gaps of high-temperature furnaces.

Steinetz, Bruce M.↗
NASA NTRS2011

Scale Dependence of Magnetic Helicity in the Solar Wind

We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

Brandenburg, Axel↗
NASA NTRS1981

Determination of magnetic helicity in the solar wind and implications for cosmic ray propagation

Magnetic helicity (Hm) is the mean value of the correlation between a turbulent magnetic field and the magnetic vector potential. A technique is described for determining Hm and its 'reduced' spectrum from the two point magnetic correlation matrix. The application of the derived formalism to solar wind magnetic fluctuations is discussed, taking into account cases for which only single point measurements are available. The application procedure employs the usual 'frozen in approximation' approach. The considered method is applied to an analysis of several periods of Voyager 2 interplanetary magnetometer data near 2.8 AU. During these periods the correlation length, or energy containing length, was found to be approximately 3 x 10 to the 11th cm

Matthaeus, W. M.↗
NASA NTRS1979

Tone Noise of Three Supersonic Helical Tip Speed Propellers in a Wind Tunnel

Three supersonic helical tip speed propellers were tested in the NASA Lewis 8- by 6-foot wind tunnel. This is a perforated-wall wind tunnel but it does not have acoustic damping material on its walls. The propellers were tested at tunnel through flow Mach numbers of 0.6, 0.7, 0.75, 0.8, and 0.85 with different rotational speeds and blade setting angles. The three propellers, which had approximately the same aerodynamic performance, incorporated different plan forms and different amounts of sweep and yielded different near field noise levels. The acoustically designed propeller had 45 deg of tip sweep and was significantly quieter at M = 0.8 cruise than the straight bladed propeller. The intermediate 30 deg tip sweep propeller, which was swept for aerodynamic purposes, exhibited noise that was between the other two propellers. Noise trends with varying helical tip Mach number and blade loading were also observed.

Dittmar, J. H.↗
NASA NTRS1981

Determination of magnetic helicity in the solar wind and implications for cosmic ray propagation

The mean value of the correlation between local magnetic field and vector potential, known as the magnetic helicity, is a measure of the lack of mirror reflection symmetry of magnetic covariances in a turbulent medium. A method is presented for extraction of helicity spectra from magnetometer data, and applied to an evaluation of the magnetic helicity of interplanetary magnetic fluctuations.

Matthaeus, W. H.↗