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Search Publications by: Theodore C. Stauffer ()

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Displaying 1 - 25 of 34

Implications of the strain irreversibility cliff on the fabrication of particle-accelerator magnets made of restacked-rod-process Nb3Sn wires

April 2, 2019
Author(s)
Najib Cheggour, Theodore C. Stauffer, Loren F. Goodrich, Jolene D. Splett, William Starch, Arup Ghosh
The strain irreversibility cliff (SIC), marking the abrupt change of the intrinsic irreversible strain limit ε_irr,0 as a function of heat-treatment (HT) temperature θ in Nb3Sn superconducting wires made by the restacked-rod process (RRP), is confirmed in

Precipitous change of the irreversible strain limit with heat-treatment temperature in Nb3Sn wires made by the restacked-rod process

August 26, 2018
Author(s)
Najib Cheggour, Theodore C. Stauffer, W. Starch, P. J. Lee, Jolene D. Splett, Loren F. Goodrich, A. K. Ghosh
The intrinsic irreversible strain limit εirr,0 of Nb3Sn superconducting wires, made by the restacked-rod process and doped with either Ti or Ta, undergoes a precipitous change as a function of temperature /theta of the final heat-treatment for forming the

Influence of the heat-treatment conditions, microchemistry, and microstructure on the irreversible strain limit of a selection of Ti-doped internal-tin Nb 3 Sn ITER wires

August 19, 2014
Author(s)
Najib Cheggour, Loren F. Goodrich, Z-H Sung, Theodore C. Stauffer, Jolene D. Splett, P. J. Lee, Matthew C. Jewell
Systematic studies of the intrinsic irreversible strain limit ε irr0, microstructure, and microchemistry were made on several internal-tin Nb 3Sn pre-production wires fabricated for the domestic agencies of the U.S.A. and China participating in the

Strain and Magnetic-Field Characterization of a Bronze-Route Nb 3 Sn ITER Wire: Benchmarking of Strain Measurement Facilities at NIST and University of Twente

June 1, 2012
Author(s)
Najib Cheggour, Arend Nijhuis, H J. Krooshoop, Xifeng Lu, Jolene D. Splett, Theodore C. Stauffer, Loren F. Goodrich, Matthew C. Jewell, Arnaud Devred, Y Nabara
A benchmarking experiment was conducted to compare strain measurement facilities at the National Institute of Standards and Technology (NIST) and the University of Twente. The critical current of a bronze-route Nb 3Sn wire, which was fabricated for the

Reversible effect of strain on transport critical current in Bi 2 Sr 2 CaCu 2 O 8+x superconducting wires: A modified descriptive strain model

December 5, 2011
Author(s)
Najib Cheggour, Xifeng Lu, T G. Holesinger, Theodore C. Stauffer, J Jiang, Loren F. Goodrich
A reversible strain effect on transport critical current I c was found in Bi 2Sr 2CaCu 2O 8+x (Bi-2212) high-temperature superconducting round wires. I c showed unambiguous reversibility at 4 K and 16 T up to an irreversible strain limit of about 0.3 % in

Development of a multifilament PIT V3Ga conductor for fusion applications

June 12, 2011
Author(s)
Najib Cheggour, Theodore C. Stauffer, Loren F. Goodrich, L. R. Motowidlo, J Distin, P. J. Lee, David C. Larbalestier, A. K. Ghosh
Previous studies on V3Ga assert its suitability for use in proposed fusion reactors. V3Ga may outperform Nb3Sn in a fusion reactor environment based on its relatively flat critical-current profile in the 15 T- 20 T range, resilience to applied strain, and

Method for determining the irreversible strain limit of Nb 3 Sn wires

June 6, 2011
Author(s)
Loren F. Goodrich, Najib Cheggour, Xifeng Lu, Jolene D. Splett, Theodore C. Stauffer, Bernard J. Filla
We have defined a rigorous and reliable method for determining the irreversible strain limit of Nb 3Sn wires. The critical current (I c) is measured as a function of applied longitudinal strain (ε), I c(ε), at one magnetic field and a temperature of 4.0 K

Strain and Magnetization Properties of High Subelement Count Tube-type Nb3Sn Strands

June 6, 2011
Author(s)
Najib Cheggour, X Peng, E Gregory, M Tomsic, M D. Sumption, A. K. Ghosh, Xifeng Lu, Theodore C. Stauffer, Loren F. Goodrich, Jolene D. Splett
Abstract—A tubular technique for economical production of Nb3Sn material with large numbers of subelements is being explored by Supergenics I LLC and Hyper Tech Research Inc. The number of subelements was increased to 919 (744 subelements plus 175 Cu

Evidence that the reversible strain effect on critical current density and flux pinning in Bi2Sr2Ca2Cu3Ox tapes is caused entirely by the pressure dependence of the critical temperature

December 23, 2010
Author(s)
Daniel C. van der Laan, J. F. Douglas, Cameron C. Clickner, Theodore C. Stauffer, Loren F. Goodrich, Hans J. van Eck
It is well known that the critical temperature of cuprate- and iron-based high-temperature superconductors changes with pressure. YBa 2Cu 3O 7-δ coated conductors, as well as Bi 2Sr 2CaCu 2O x and Bi 2Sr 2Ca 2Cu 3O x tapes and wires, show a clear

Effect of strain, magnetic field and field angle on the critical current density of YBa 2 Cu 3 O 7-d coated conductors

May 18, 2010
Author(s)
Daniel C. van der Laan, J. F. Douglas, John (Jack) W. Ekin, Loren F. Goodrich, Theodore C. Stauffer, Cameron C. Clickner
A large, magnetic-field-dependent, reversible reduction in critical current density with axial strain in YBa 2Cu 3O 7-δ coated conductors at 75.9 K has been measured. This effect may have important implications for the performance of YBa 2Cu 3O 7-δ coated

Influence of Ti and Ta doping on the irreversible strain limit of ternary Nb 3 Sn superconducting wires made by the restacked-rod process

April 1, 2010
Author(s)
Najib Cheggour, Loren F. Goodrich, Theodore C. Stauffer, Jolene D. Splett, Xifeng Lu, A. K. Ghosh, G. Ambrosio
Nb 3Sn superconducting wires made with restacked-rod process (RRP®) were found to have a dramatically improved resilience to axial tensile strain when alloyed with Ti as compared to Ta. Whereas Ta-alloyed Nb 3Sn in RRP wires showed permanent damage to its

Delamination strength of YBCO coated conductors under transverse tensile stress

June 21, 2007
Author(s)
Daniel C. van der Laan, John (Jack) W. Ekin, Cameron C. Clickner, Theodore C. Stauffer
We present a new experimental technique to measure the delamination strength under transverse tensile stress of YBa 2Cu 3O 7-δ coated conductors for electric power applications. The delamination strength, defined as the tensile stress at which the ceramic

Critical-Current Measurements on ITER Nb3Sn Strands: Effect of Temperature

July 29, 2005
Author(s)
Loren F. Goodrich, Najib Cheggour, John (Jack) W. Ekin, Theodore C. Stauffer
Transport critical-current (II c) measurements were made on commercial multifilamentary Nb 3Sn strands at temperatures (T) from 4 to 17 K and magnetic fields (H) from 0 to 14 T. Samples investigated were taken from the stage 1 pre-production strand for the

Unexpected Effect of Field Angle in Magnetoresistance Measurements of High-Purity Nb

June 1, 2005
Author(s)
Loren F. Goodrich, Theodore C. Stauffer, Jolene Splett, Dominic F. Vecchia
We report on unexpected field-angle dependence of the magnetoresistance measurements of commercial, high-purity Nb discovered during our study of residual resistivity ratio ( RRR) measurements. The ( RRR) value indicates the purity and the low-temperature

Variable-Temperature Critical-Current Measurements on a Nb 3 Sn Wire

June 1, 2005
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We made variable-temperature critical-current (I c) measurements on a commercial multifilamentary Nb 3Sn wire for temperatures (T) from 4 to 17 K and magnetic fields (H) from 0 to 12 T using transport current. The sample had a diameter of 0.811 mm and a Cu

Measuring residual resistivity ratio of high-purity Nb

July 27, 2004
Author(s)
Loren F. Goodrich, Theodore C. Stauffer, Jolene Splett, Dominic F. Vecchia
We compared methods of measuring the residual resistivity ratio (RRR) of high-purity Nb using transport current. Our experimental study is intended to answer some fundamental questions about the best measurement for RRR and the biases that may exist among

Variable-temperature critical-current measurements on a Nb-Ti wire

July 27, 2004
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We made variable-temperature critical-current (I c) measurements on a commercial multifilamentary Nb-Ti wire for temperatures (T) from 4 to 9 K and magnetic fields (H) from 0 to 11.5 T using transport current. The measurements cover the whole range of

More Diamagnetism Demonstrations

February 1, 2003
Author(s)
Chris Conery, Loren F. Goodrich, Theodore C. Stauffer
The availability of very strong permanent magnets allows observation of phenomena previously difficult to see. The diamagnetism of water and diamagneticly stabilized magnetic levitation are now easy to demonstrate.

Variable mutual inductance in critical-current measurements

January 1, 2002
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We have investigated the mutual inductance observed on pairs of voltage tapes that are soldered to superconducting wires in order to measure the voltage-current (V-I) characteristics & determine the critical current. Measurements on a Nb-Ti superconductor

Hysteresis in transport critical-current measurements of oxide superconductors

May 31, 2001
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We investigated magnetic hysteresis in transport critical-current (I c) measurement of Ag-matrix (B i,Pb) 2Sr 2Ca 2Cu 3O^10-x^ *Bi-2223) and AgMg-matrix Bi 2Sr 2CaCu 2O 8+X (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current

Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors

March 1, 2001
Author(s)
Loren F. Goodrich, Theodore C. Stauffer
We have investigated magnetic hysteresis in transport critical-current (I c) measurements of Ag-matrix (Bi, Pb) 2Sr 2Ca 2Cu 3O 10-x (Bi-2223) and AgMg-matrix Bi 2Sr 2CaCu 2O 8+x (Bi-22-2212) tapes. I c hysteresis causes measurements with field, angle, and