K. Tanaka, H. Kitaguchi, H. Kumakura, H. Yamada, M. Hirakawa, M. Okada
This paper reports on the fabrication and testing of a MgB2 coil made using a wind & react method. We made a 130m‐long Fe/Cu‐composite sheathed, SiC‐doped MgB2‐superconducting round wire using an in‐situ PIT method. Using a 92m‐long wire, we fabricated a solenoid coil with 722 turns. In the coil test, we measured the Ic of the coil under various external fields and temperatures. The Ic of the coil reached 162 A (Je = 340 A/mm2) at 4.2 K and in the external field of 2 T. The coil generated 2.2 T (the center magnetic field, Bo); thus the total field reached 4.2 T. The Je exceeded 100 A/mm2 in the external fields of 4 T, 2.5 T, and 1 T at 15 K, 20 K, and 25 K, respectively. The Jc of the coil was almost equal to that of the short sample. This indicates that the 92m‐long wire has a very homogeneous Jc distribution.
{"title":"Development of 2T‐Class MgB2 Solenoid Coil","authors":"K. Tanaka, H. Kitaguchi, H. Kumakura, H. Yamada, M. Hirakawa, M. Okada","doi":"10.1063/1.2192408","DOIUrl":"https://doi.org/10.1063/1.2192408","url":null,"abstract":"This paper reports on the fabrication and testing of a MgB2 coil made using a wind & react method. We made a 130m‐long Fe/Cu‐composite sheathed, SiC‐doped MgB2‐superconducting round wire using an in‐situ PIT method. Using a 92m‐long wire, we fabricated a solenoid coil with 722 turns. In the coil test, we measured the Ic of the coil under various external fields and temperatures. The Ic of the coil reached 162 A (Je = 340 A/mm2) at 4.2 K and in the external field of 2 T. The coil generated 2.2 T (the center magnetic field, Bo); thus the total field reached 4.2 T. The Je exceeded 100 A/mm2 in the external fields of 4 T, 2.5 T, and 1 T at 15 K, 20 K, and 25 K, respectively. The Jc of the coil was almost equal to that of the short sample. This indicates that the 92m‐long wire has a very homogeneous Jc distribution.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192408","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Kobayashi, T. Kato, K. Yamazaki, K. Ohkura, K. Fujino, J. Fujikami, E. Ueno, N. Ayai, M. Kikuchi, K. Hayashi, K. Sato, R. Hata
Progress in the performance of the controlled overpressure (CT‐OP) processed (Bi,Pb)2Sr2Ca2Cu3Ox (Bi2223) wire is reviewed. Optimization of the CT‐OP processing improved microstructure of Bi2223 wires and increased their critical current (Ic) by greater than 60% compared to normal pressure processing. The CT‐OP processing effectively removed pores and cracks. The SEM show CT‐OP wires had very dense, uniform, and well connected Bi2223 grain. Densification of the CT‐OP wires prevents liquid nitrogen penetration during long term exposure to liquid nitrogen of them for use in power cable applications. Ballooning caused by trapped nitrogen, that expands when warming up to room temperature, doesn’t occur in CT‐OP wires. These high performance levels in CT‐OP wires have enabled commercial level applications such as power cables, magnets and motors.
{"title":"Controlled Overpressure Processed Bi2223 Wires for Power Applications","authors":"S. Kobayashi, T. Kato, K. Yamazaki, K. Ohkura, K. Fujino, J. Fujikami, E. Ueno, N. Ayai, M. Kikuchi, K. Hayashi, K. Sato, R. Hata","doi":"10.1063/1.2192411","DOIUrl":"https://doi.org/10.1063/1.2192411","url":null,"abstract":"Progress in the performance of the controlled overpressure (CT‐OP) processed (Bi,Pb)2Sr2Ca2Cu3Ox (Bi2223) wire is reviewed. Optimization of the CT‐OP processing improved microstructure of Bi2223 wires and increased their critical current (Ic) by greater than 60% compared to normal pressure processing. The CT‐OP processing effectively removed pores and cracks. The SEM show CT‐OP wires had very dense, uniform, and well connected Bi2223 grain. Densification of the CT‐OP wires prevents liquid nitrogen penetration during long term exposure to liquid nitrogen of them for use in power cable applications. Ballooning caused by trapped nitrogen, that expands when warming up to room temperature, doesn’t occur in CT‐OP wires. These high performance levels in CT‐OP wires have enabled commercial level applications such as power cables, magnets and motors.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192411","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59399444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Sumption, A. Contractor, S. Kawabata, E. Collings
AC loss measurements have been made on YBCO coated conductors in externally applied sinusoidal AC fields using the pick‐up coil method. Various arrangements of YBCO coated conductor have been measured at frequencies of 50 Hz, 75 Hz, 100 Hz, 150 Hz, and 200 Hz, with amplitudes ranging from 0 to 140 mT. Three different sets of IBAD‐based YBCO coated conductor were measured: (i) unfilamented conductors with Cu added either on one side only, or on both sides (as well as the edges), (ii) conductors with various numbers of filament, (iii) 4 mm wide conductors. All samples were 4 cm long and untwisted. The per cycle AC loss per unit length of conductor, displayed in the format Q/B (in J/T.m) vs. Bm. enabled separation of the eddy current and hysteretic components of the total loss, after which the results were analyzed and discussed. The resistivity of the interfilamentary connections were characterized and the results compared to expectation.
在外部正弦交流磁场中，用检波线圈法测量了YBCO涂层导体的交流损耗。在50hz, 75hz, 100hz, 150hz和200hz的频率范围内，测量了不同排列的YBCO涂层导体，幅度从0到140 mT。测量了三种不同的IBAD基YBCO涂层导体:(i)仅在一侧或两侧(以及边缘)添加Cu的无丝导体，(ii)具有不同数量的丝的导体，(iii) 4mm宽的导体。所有的样品都是4厘米长，没有扭曲。单位长度导体的每周期交流损耗，以Q/B (J/T.m) vs. Bm的格式显示。使总损耗的涡流和滞后分量分离，然后对结果进行分析和讨论。对纤维间连接的电阻率进行了表征，并与预期结果进行了比较。
{"title":"AC loss (50-200 Hz) in YBCO conductors with filaments and Cu stabilization","authors":"M. Sumption, A. Contractor, S. Kawabata, E. Collings","doi":"10.1063/1.2192437","DOIUrl":"https://doi.org/10.1063/1.2192437","url":null,"abstract":"AC loss measurements have been made on YBCO coated conductors in externally applied sinusoidal AC fields using the pick‐up coil method. Various arrangements of YBCO coated conductor have been measured at frequencies of 50 Hz, 75 Hz, 100 Hz, 150 Hz, and 200 Hz, with amplitudes ranging from 0 to 140 mT. Three different sets of IBAD‐based YBCO coated conductor were measured: (i) unfilamented conductors with Cu added either on one side only, or on both sides (as well as the edges), (ii) conductors with various numbers of filament, (iii) 4 mm wide conductors. All samples were 4 cm long and untwisted. The per cycle AC loss per unit length of conductor, displayed in the format Q/B (in J/T.m) vs. Bm. enabled separation of the eddy current and hysteretic components of the total loss, after which the results were analyzed and discussed. The resistivity of the interfilamentary connections were characterized and the results compared to expectation.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192437","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59400109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Walsh, V. Toplosky, Ke Han, P. Heitzenroeder, B. Nelson
The National Compact Stellerator Experiment (NCSX) is the first of a new class of stellarators. The modular superconducting coils in the NCSX have complex geometry that are manufactured on cast stainless steel (modified CF8M) winding forms. Although CF8M castings have been used before at cryogenic temperature there is limited data available for their mechanical properties at low temperatures. The fatigue life behavior of the cast material is vital thus a test program to generate data on representative material has been conducted. Fatigue test specimens have been obtained from key locations within prototype winding forms to determine the 77 K fatigue crack growth rate. The testing has successfully developed a representative database that ensures confident design. The measured crack growth rates are analyzed in terms of the Paris law parameters and the crack growth properties are related to the materials microstructure.
{"title":"77 K Fatigue Crack Growth Rate of Modified CF8M Stainless Steel Castings","authors":"R. Walsh, V. Toplosky, Ke Han, P. Heitzenroeder, B. Nelson","doi":"10.1063/1.2192344","DOIUrl":"https://doi.org/10.1063/1.2192344","url":null,"abstract":"The National Compact Stellerator Experiment (NCSX) is the first of a new class of stellarators. The modular superconducting coils in the NCSX have complex geometry that are manufactured on cast stainless steel (modified CF8M) winding forms. Although CF8M castings have been used before at cryogenic temperature there is limited data available for their mechanical properties at low temperatures. The fatigue life behavior of the cast material is vital thus a test program to generate data on representative material has been conducted. Fatigue test specimens have been obtained from key locations within prototype winding forms to determine the 77 K fatigue crack growth rate. The testing has successfully developed a representative database that ensures confident design. The measured crack growth rates are analyzed in terms of the Paris law parameters and the crack growth properties are related to the materials microstructure.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192344","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59396545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Problems involved in using coated conductors for an all superconducting aircraft generator are summarized. The biggest remaining problem is transposition of the filaments produced by striating the superconducting film. Various ways of performing the transposition are discussed.
{"title":"Problems Which Must Be Solved in Using Superconducting Coated Conductors in Aircraft Generators","authors":"W. J. Carr","doi":"10.1063/1.2192380","DOIUrl":"https://doi.org/10.1063/1.2192380","url":null,"abstract":"Problems involved in using coated conductors for an all superconducting aircraft generator are summarized. The biggest remaining problem is transposition of the filaments produced by striating the superconducting film. Various ways of performing the transposition are discussed.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Potanina, G. Vedernikov, A. Shikov, I. Gubkin, N. Salunin, V. Korpusov, E. Plashkin, H. Khodzhibagiyan, A. Kovalenko, S. Novikov, M. Novikov
A new hollow high current cable was designed at JINR for the magnets of the GSI accelerator ring SIS 100. To increase both the structural current density and the operating current it was proposed to replace the superconducting wires with a round cross section (0.5 mm in diameter) by wires having a keystoned or trapezoidal (in the first approximation) cross section.Trapezoidal fine filament superconducting wire based on NbTi alloy, intended for operating at fields having sweep rate from 1 up to 4 T/s, has been developed and manufactured by Bochvar Institute (VNIINM). The wire with 10374 filaments and Cu/non Cu of 1.8 was fabricated by a single stacking method. Each filament was surrounded by a matrix of commercial MN‐5 alloy (Cu‐5wt.%Ni). The trapezoidal shape was formed by two steps drawing of a round 1.01 mm wire at a final stage of production. The optimized cross section is 0.73 × 1.08 mm at the medium line.The critical current density is more than 2700 A/mm2 at 5 T, 4.2 K. The current carrying capacity...
{"title":"Trapezoidal Wire for the Hollow Superconducting Cable Designed for Fast Cycling Synchrotron Magnets","authors":"L. Potanina, G. Vedernikov, A. Shikov, I. Gubkin, N. Salunin, V. Korpusov, E. Plashkin, H. Khodzhibagiyan, A. Kovalenko, S. Novikov, M. Novikov","doi":"10.1063/1.2192381","DOIUrl":"https://doi.org/10.1063/1.2192381","url":null,"abstract":"A new hollow high current cable was designed at JINR for the magnets of the GSI accelerator ring SIS 100. To increase both the structural current density and the operating current it was proposed to replace the superconducting wires with a round cross section (0.5 mm in diameter) by wires having a keystoned or trapezoidal (in the first approximation) cross section.Trapezoidal fine filament superconducting wire based on NbTi alloy, intended for operating at fields having sweep rate from 1 up to 4 T/s, has been developed and manufactured by Bochvar Institute (VNIINM). The wire with 10374 filaments and Cu/non Cu of 1.8 was fabricated by a single stacking method. Each filament was surrounded by a matrix of commercial MN‐5 alloy (Cu‐5wt.%Ni). The trapezoidal shape was formed by two steps drawing of a round 1.01 mm wire at a final stage of production. The optimized cross section is 0.73 × 1.08 mm at the medium line.The critical current density is more than 2700 A/mm2 at 5 T, 4.2 K. The current carrying capacity...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192381","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We measured voltage versus magnetic field (V‐H) on commercial Nb3Sn wires. Typically voltage‐current (V‐I) at constant field is measured to determine the critical current (Ic). Recently, V‐H at constant or ramping current is being measured to assess the relative stability of Nb3Sn wires. Our low‐noise measurements were made with the same equipment, apparatus, and sample mount as used in Ic measurements. High‐performance Nb3Sn wires exhibit flux‐jump instabilities at low magnetic fields, and low‐noise V‐H curves on these wires show indications of flux jumps. Two nominal 0.8 mm diameter Nb3Sn wires were measured: a high‐performance wire with an Ic of 750 A at 12 T and a stable wire with an Ic of 150 A at 12 T. V‐H measurements also reveal that less stable wires will quench (abrupt and irreversible transition to the normal state) at currents much smaller than Ic at the lower magnetic fields. The measured V‐H curves and quench currents of these two wires are contrasted.
{"title":"Voltage Versus Magnetic Field Measurements on Nb3Sn Wires","authors":"L. Goodrich","doi":"10.1063/1.2192390","DOIUrl":"https://doi.org/10.1063/1.2192390","url":null,"abstract":"We measured voltage versus magnetic field (V‐H) on commercial Nb3Sn wires. Typically voltage‐current (V‐I) at constant field is measured to determine the critical current (Ic). Recently, V‐H at constant or ramping current is being measured to assess the relative stability of Nb3Sn wires. Our low‐noise measurements were made with the same equipment, apparatus, and sample mount as used in Ic measurements. High‐performance Nb3Sn wires exhibit flux‐jump instabilities at low magnetic fields, and low‐noise V‐H curves on these wires show indications of flux jumps. Two nominal 0.8 mm diameter Nb3Sn wires were measured: a high‐performance wire with an Ic of 750 A at 12 T and a stable wire with an Ic of 150 A at 12 T. V‐H measurements also reveal that less stable wires will quench (abrupt and irreversible transition to the normal state) at currents much smaller than Ic at the lower magnetic fields. The measured V‐H curves and quench currents of these two wires are contrasted.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192390","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Supercon has recently investigated the fabrication of magnesium diboride wires and tapes. The primary purpose of the study was to determine the efficacy of a combined ex‐situ and in‐situ approach, but included impurity doping in order to develop flux pinning sites. A matrix of conductor processing steps was explored. Microstructures were characterized and critical current densities were measured. The ultimate goal of the effort was to develop fabrication methods for high performance magnesium diboride conductors. Such conductors have the potential for use in a wide range of applications, including cryocooled magnets for magnetic resonance imaging systems, hydrogen cooled power systems, and high field magnets operating at liquid helium temperature, possibly as a replacement for Nb3Sn superconductors. Current results of the development effort will be discussed and conductor performance characteristics will be given.
{"title":"Magnesium Diboride Conductor Development at Supercon, Inc.","authors":"M. Rudziak, W. Nachtrab, T. Wong","doi":"10.1063/1.2192402","DOIUrl":"https://doi.org/10.1063/1.2192402","url":null,"abstract":"Supercon has recently investigated the fabrication of magnesium diboride wires and tapes. The primary purpose of the study was to determine the efficacy of a combined ex‐situ and in‐situ approach, but included impurity doping in order to develop flux pinning sites. A matrix of conductor processing steps was explored. Microstructures were characterized and critical current densities were measured. The ultimate goal of the effort was to develop fabrication methods for high performance magnesium diboride conductors. Such conductors have the potential for use in a wide range of applications, including cryocooled magnets for magnetic resonance imaging systems, hydrogen cooled power systems, and high field magnets operating at liquid helium temperature, possibly as a replacement for Nb3Sn superconductors. Current results of the development effort will be discussed and conductor performance characteristics will be given.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192402","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hysteresis and magnetic relaxation measurements have been performed on MgB2/Fe tapes in parallel and perpendicular magnetic field in order to investigate the correlation between the anisotropy of the transport current density and the texturing recently analysed by Lezza et al.. Volume pinning forces FP have been obtained from the current densities Jc as a function of the dc magnetic field up to 9 T in the temperature range 5–35 K. The reduced pinning forces do not scale with temperature in the parallel field configuration. It has been shown that this could be explained considering that the texturing occurs mainly at the surface of the sample. The scaling is recovered in perpendicular field for temperature higher than 20 K and the scaled pinning curves have been compared to theoretical predictions. Furthermore, the anisotropy of the pinning properties has been investigated using the present relaxation measurements. The magnetization was found to decrease linearly with ln(t). This allows calculation of the pinning potential energy U0 by using the relationship U0 = kT/{dM/[M0 dln(t)]}. The resulting variation of U0 in field and temperature is not related to the field orientation. The relaxation rate of MgB2 has been compared to other superconducting compounds, i.e. Bi‐2223 and Nb3Sn.
{"title":"Critical Current Anisotropy, Pinning Properties and Relaxation Rate of “Ex‐situ” MgB2/Fe Tapes","authors":"C. Senatore, P. Lezza, R. Flukiger","doi":"10.1063/1.2192407","DOIUrl":"https://doi.org/10.1063/1.2192407","url":null,"abstract":"Hysteresis and magnetic relaxation measurements have been performed on MgB2/Fe tapes in parallel and perpendicular magnetic field in order to investigate the correlation between the anisotropy of the transport current density and the texturing recently analysed by Lezza et al.. Volume pinning forces FP have been obtained from the current densities Jc as a function of the dc magnetic field up to 9 T in the temperature range 5–35 K. The reduced pinning forces do not scale with temperature in the parallel field configuration. It has been shown that this could be explained considering that the texturing occurs mainly at the surface of the sample. The scaling is recovered in perpendicular field for temperature higher than 20 K and the scaled pinning curves have been compared to theoretical predictions. Furthermore, the anisotropy of the pinning properties has been investigated using the present relaxation measurements. The magnetization was found to decrease linearly with ln(t). This allows calculation of the pinning potential energy U0 by using the relationship U0 = kT/{dM/[M0 dln(t)]}. The resulting variation of U0 in field and temperature is not related to the field orientation. The relaxation rate of MgB2 has been compared to other superconducting compounds, i.e. Bi‐2223 and Nb3Sn.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192407","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59399089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In AC loss measurements of superconductors using the four‐terminal method, the voltage measured consists of two components. The loss voltage component is in phase with transport current while the inductive voltage is out of phase with transport current. Here we report on the use of a compensation coil to nearly cancel the inductive voltage. The loss voltage was amplified by a transformer amplifier and observed on a digital oscilloscope. The waveform of the measured voltage was compared with that of a calculated signal. The loss voltage was analytically calculated for a round wire using the critical state model. The effects of frequency on the waveform of the loss voltage are also studied. Finally, a comparison between waveforms of loss voltages obtained with sine‐wave and triangle‐wave transport currents are presented.
{"title":"Waveform of Loss Voltage in Ag‐Sheathed Bi2223 Superconducting Tape Carrying AC Transport Current","authors":"D. Nguyen, P. Sastry, J. Schwartz","doi":"10.1063/1.2192435","DOIUrl":"https://doi.org/10.1063/1.2192435","url":null,"abstract":"In AC loss measurements of superconductors using the four‐terminal method, the voltage measured consists of two components. The loss voltage component is in phase with transport current while the inductive voltage is out of phase with transport current. Here we report on the use of a compensation coil to nearly cancel the inductive voltage. The loss voltage was amplified by a transformer amplifier and observed on a digital oscilloscope. The waveform of the measured voltage was compared with that of a calculated signal. The loss voltage was analytically calculated for a round wire using the critical state model. The effects of frequency on the waveform of the loss voltage are also studied. Finally, a comparison between waveforms of loss voltages obtained with sine‐wave and triangle‐wave transport currents are presented.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192435","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59400420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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