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in creator/contributor: "Suenaga, M."

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Critical current studies on fine filamentary NbTi accelerator wires

The magnets for the Superconductig Super Collider, a high energy proton colliding beam accelerator, require a superconductor with very high current density (>2400 A/mm/sup 2/ at 5 T) and very small filaments (approx. 2..mu..m in diameter). Previous work has shown that by controlling the formation of Cu/sub 4/Ti compound particles on the filament surfaces it is possible to make fine filamentary NbTi wire with high critical current density. The performance of multi-filamentary wire is characteriz… more

Date: January 1, 1985

Creator: Garber, M.; Suenaga, M.; Sampson, W.B. & Sabatini, R.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Demountable low stress high field toroidal field magnet system for tokamak fusion reactors

A new type of superconducting magnet system for large fusion reactors is described in this report. Instead of winding large planar or multi-axis coils, as has been proposed in previous fusion reactor designs, the superconducting coils are made by joining together several prefabricated conductor sections. The joints can be unmade and sections removed if they fail. Conductor sections can be made at a factory and shipped to the reactor site for assembly. The conductor stress level in the assembled… more

Date: January 1, 1977

Creator: Powell, J.; Hsieh, D.; Lehner, J. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Softening of Young's modulus of polycrystalline Nb/sub 3/Sn

Ultrasonic measurements show that the shear modulus (C/sub 11/-C/sub 12/)/2 softens dramatically as single crystals of Nb/sub 3/Sn approach the martensitic transition near 50K. It is expected that Young's modulus of polycrystals will olso soften, but previous ultrasonic measurements, which suffer from severe damping, fail to show the expected effect. We have measured Young's modulus of polycrystalline Nb/sub 3/Sn between 4.2K and 300K by static beam deflection methods, and observe marked soften… more

Date: June 1, 1979

Creator: Welch, D.O.; Bussiere, J.F. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superconducting properties of (Nb,Ti)/sub 3/Sn wires fabricated by the bronze process

A study was made of the influence of the alloying addition of Ti in the Nb core on the superconducting critical properties since (1) Ti is less expensive than Nb or Ta, (2) Ti has a lower melting temperature than Ta and Nb, thus making the alloy fabrication easier, (3) Ti-Nb alloys are also known to be easily fabricated in composite wires with Cu, and finally (4) it appears that an increased normal-state resistivity rho/sub n/, and therefore the upper critical field H/sub c2/, will lead to enha… more

Date: January 1, 1981

Creator: Suenaga, M.; Okuda, S.; Sabatini, R.; Itoh, K. & Luhman, T.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Flux pinning by grain boundaries in A15 superconductors

The form of the scaling law for flux pinning by grain boundaries in A15-structure compounds, primarily in the case of Nb3Sn and its alloys, is discussed, and the effect of alloying and radiation damage on the pinning strength is compared with predictions of the electron-scattering theory of the elementary pinning force. In addition, some preliminary results of 2-dimensional computer simulations are discussed in relation to the observed effects of alloying on the form of the scaling law for Nb3S… more

Date: January 1, 1985

Creator: Welch, D. O.; Suenaga, M.; Snead, C. L. Jr. & Hatcher, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of Cu/sub 4/Ti compound formation on the characteristics of NbTi accelerator magnet wire

High critical current density, J/sub c/ > 2500 A/mm/sup 2/, and small filament diameter, d approx. 3 ..mu..m, are required in multifilamentary NbTi wire used for superconducting accelerator magnets. Wires obtained from various commercial sources had J/sub c/'s in the range 1000 to 2800 A/mm/sup 2/ amd d's in the range 1 to 23 ..mu..m. The filaments were examined by means of scanning electron microscopy in order to determine the reason for the variation in J/sub c/. It was found that the filamen… more

Date: January 1, 1985

Creator: Garber, M.; Suenaga, M.; Sampson, W.B. & Sabatini, R.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Survey of high field superconducting material for accelerator magnets

The high field superconductors which could be used in accelerator dipole magnets are surveyed, ranking these candidates with respect to ease of fabrication and cost as well as superconducting properties. Emphasis is on Nb/sub 3/Sn and NbTi. 27 refs., 2 figs. (LEW)

Date: May 1, 1986

Creator: Scahlan, R.; Greene, A.F. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of alloying on the strain response of critical currents in Nb/sub 3/Sn conductors

The critical current, I/sub c/, of bronze-processed Nb/sub 3/Sn conductors vary when the conductors are mechanically strained in tension or compression. The variations in I/sub c/ are reversible until the strains are large enough to cause cracking of the Nb/sub 3/Sn compound. After cracking occurs the changes in I/sub c/ with strain are irreversible. The reversible and irreversible characteristics of I/sub c/ are influenced by alloy additions to the conductors. Alloy additions to both the bronz… more

Date: January 1, 1979

Creator: Luhman, T.; Kaiho, K. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Magnetization and critical currents of tin-core multifilamentary Nb sub 3 Sn conductors

This paper presents critical current and magnetization data for some multifilamentary Nb{sub 3}Sn wires that have been produced by the internal-tin method. A comparison of magnetization and transport critical current measurements show that filament bridging during heat treatment is a common occurrence leading to effective filament diameters that are sometimes an order of magnitude larger than the geometrical filament size. At present, J{sub c}'s (in the non-copper region) greater than 1300 A/mm… more

Date: January 1, 1990

Creator: Ghosh, A.K. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superconducting properties of (Nb,Ta)/sub 3/Sn wires fabricated by the bronze process

Measurements of the superconducting critical temperature T/sub c/, critical current density, J/sub c/ (8<H<22.5 T), and the critical magnetic field H/sub c2/ were made on bronze processed (Nb,Ta)/sub 3/Sn monofilamentary wires. Ta content in the Nb/sub 3/Sn compound was varied by alloying the Nb core prior to a reaction heat treatment. Core compositions were 0, 3, 7, 10, and 20 wt% Ta and heat treatments for the reaction were 16, 64, and 120 h at 725/sup 0/C. For the 120 h heat treatment T/sub … more

Date: January 1, 1979

Creator: Suenaga, M.; Aihara, K.; Kaiho, K. & Luhman, T.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Magnetization of internal-tin processed Nb sub 3 Sn wire

This note briefly describes critical current and magnetization data taken on Nb{sub 3}Sn wire which have been recently manufactured by some of the US manufacturers. 6 refs., 3 figs., 1 tab.

Date: January 1, 1989

Creator: Ghosh, A.K. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Flux creep in multifilamentary conductors of NbTi and Nb sub 3 Sn

Long term decay of the sextupole field has been observed in accelerator dipole magnets, and this effect has been linked to flux creep'' in the superconductor. To study this problem, the decay of the magnetization of multifilamentary conductors of NbTi and Nb{sub 3}Sn have been measured as a function of time. Measurements show that as a function of ln{ital t} this decay cannot always be characterized by a single decay rate. Long time decay rates are sometimes approximately half that which is obs… more

Date: January 1, 1989

Creator: Ghosh, A.K.; Xu, Youwen & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superconducting current densities in bronze-processed Nb/sub 3/Sn multifilamentary wires

Five multifilamentary wires with diameters of 0.41 mm and different ratios of bronze to Nb (R = 2 to 3.7) were obtained from Airco. The superconducting critical currents were measured at 4.2/sup 0/K in magnetic fields of 8 to 19 T. Effects of heat treatments were investigated. 4 figures. (DLC)

Date: January 1, 1981

Creator: Okuda, S.; Suenaga, M. & Luhman, T.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Future prospects for Nb/sub 3/Sn and V/sub 3/Ga multifilamentary conductors

Since the discovery of the bronze process for fabrication of multifilamentary Nb/sub 3/Sn and V/sub 3/Ga composite wires, significant progress has been made in the production of commercial-scale conductors with these compounds. However, improvements in the values of the critical-current density J/sub c//sup +/ (the matrix and the superconductors) of these wires are desired and appear possible for high-magnetic-field applications. In this section, an attempt is made to assess the value of the cu… more

Date: January 1, 1981

Creator: Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Flux pinning by heavy-ion-irradiation induced linear defects in YBa[sub 2]Cu[sub 3]O[sub 7] epitaxial films

We report some transport measurements carried out to study flux pinning by heavy-ion-irradiation induced linear defects in Y[sub 1]Ba[sub 2]Cu[sub 3]O[sub 7] films. Our results show that in these in situ deposited films containing a large concentration of defects frozen-in at the time of film growth, a marginal enhancement in critical current density occurs when the density of linear defects < 5 [times] 10[sup 10]/cm[sup 2], and their diameter of the order of coherence length. This criterion is… more

Date: January 1, 1992

Creator: Budhani, R.C.; Zhu, Y. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microstructural factors influencing critical-current densities of high-temperature superconductors

Microstructural defects are the primary determining factors for the values of critical current densities in superconductors. A review is made to assess, (1) what would be the maximum achievable critical-current density in the oxide superconductors if nearly ideal pinning sites were introduced and (2) what types of pinning defects are currently introduced in these superconductors and how effective are these in pinning the vortices Only the case where the applied field is parallel to the c-axis i… more

Date: January 1, 1992

Creator: Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observations of vortex structure in YBa sub 2 Cu sub 3 O sub 7

The remnant magnetic flux distribution in a single crystal and a sintered polycrystal was examined using the magnetic particle decoration technique. The single crystal, which was heavily twinned, showed only local order in the flux lattice. This was probably due to lattice distortions caused by interaction between twin boundaries and fluxons. In the polycrystal, flux pinning effectiveness was seen to vary significantly between grains, depending on size and orientation. Grains with the c axis ne… more

Date: September 24, 1990

Creator: Muller, H.; Wiesmann, H.J. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of Fe substitutions in YBa/sub 2/Cu/sub 3/O/sub 7/

Both near edge features and EXAFS results unequivocally demonstrate that Fe preferentially substitutes for Cu(1) atoms at the linear chain site for YBa/sub 2/(Cu/sub 1-x/Fe/sub x/)/sub 3/O/sub 7+delta/, where x = 0.02 to 0.15. Electronic and atomic structural changes associated with Fe content are discussed. 5 refs., 2 figs.

Date: January 1, 1988

Creator: Yang, C.Y.; Heald, S.M.; Tranquada, J.M.; Xu, Y.; Wang, Y.L.; Moodenbaugh, A.R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chemical compositions of grain boundaries in bronze-processed pure and alloyed Nb3Sn

Chemical compositions of grain boundaries in pure and alloyed Nb3Sn (with Ti and Ta) wires produced by the bronze process wire were measured using Auger electron spectroscopy. The amount of Ti at the grain boundaries was found to be approximately twice as much as that in the bulk. However, the amount of Ta at the grain boundaries was less than that in the bulk.

Date: January 1, 1985

Creator: Suenaga, M.; Corderman, R.R. & Welch, D.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Degradation mechanism of Nb/sub 3/Sn composite wires under tensile strain at 4. 2 K

Bronze-processed Nb/sub 3/Sn composite wire conductors exhibit changes in their superconducting parameters when strained in tension. This paper describes a detailed study of the effect of strain on critical current and an analysis by optical and SEM techniques of crack formation in the Nb/sub 3/Sn layer under strain. The effect of strain history on both reversible and irreversible changes in critical current and the roles of differential thermal contraction induced residual strains and of Nb/su… more

Date: September 28, 1978

Creator: Luhman, T.; Suenaga, M.; Welch, D.O. & Kaiho, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ac losses in YBa{sub 2}Cu{sub 3}O{sub 7} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Ci{sub 3}O{sub 10} superconductors at power frequencies

Ac losses of sintered and melt-textured YBa{sub 2}Cu{sub 3}O{sub 7} bars and powder-in-a-tube processed Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} tapes were measured at 4.2, 65, 70 and 77 K and at 15--180 Hz. In general, the results are well described by the critical state model for the ac losses. However, the losses for the Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} tapes at 4.2 K exhibited significant contributions from the eddy currents in the Ag sheath.

Date: December 31, 1991

Creator: Orehotsky, J.; Reilly, K. M.; Suenaga, M.; Hikata, T.; Ueyama, M. & Sato, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microstructural factors influencing critical-current densities of high-temperature superconductors

Microstructural defects are the primary determining factors for the values of critical current densities in superconductors. A review is made to assess, (1) what would be the maximum achievable critical-current density in the oxide superconductors if nearly ideal pinning sites were introduced? and (2) what types of pinning defects are currently introduced in these superconductors and how effective are these in pinning the vortices? Only the case where the applied field is parallel to the c-axis… more

Date: December 31, 1992

Creator: Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Flux pinning by heavy-ion-irradiation induced linear defects in YBa{sub 2}Cu{sub 3}O{sub 7} epitaxial films

We report some transport measurements carried out to study flux pinning by heavy-ion-irradiation induced linear defects in Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} films. Our results show that in these in situ deposited films containing a large concentration of defects frozen-in at the time of film growth, a marginal enhancement in critical current density occurs when the density of linear defects < 5 {times} 10{sup 10}/cm{sup 2}, and their diameter of the order of coherence length. This criterion is… more

Date: December 31, 1992

Creator: Budhani, R. C.; Zhu, Y. & Suenaga, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superconducting properties, chemical compositions, and lattice parameters of Pb-, Sn- and (Pb{sub 1-x}Sn{sub x})Mo{sub 6}S{sub 8}

The values of critical temperatures for alloys of Pb- and SnMo{sub 6}S{sub 8} were shown to be lower than those of the respective pure Chevrel phases. Chemical compositional analysis of the compounds revealed that the decreased {Tc} in the alloys are due to the off-stoichiometric compositions in the alloys. Although alloying slightly increased the values of the upper critical field H{sub c2} over that for PbMo{sub 6}S{sub 8}, the H{sub c2} values for these specimens were substantially lower tha… more

Date: December 31, 1991

Creator: Sadakata, N.; Corderman, R.; Asano, T.; Cox, D.; Suenaga, M.; Foner, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department