A large amount of lead doping to Bi2212 superconductors is effective in decreasing their high electromagnetic anisotropy and introduces effective pinning sites, such as lamella structure interfaces due to compositional fluctuation of lead ions, resulting in greatly enhanced flux pinning properties up to high temperatures. Particularly in the high-Tc superconducting materials with lowered anisotropy, further improvement of critical current properties can be expected by doping a small amount of impurity elements, which generate locally weak superconducting regions. Based on this background, we have attempted to enhance flux pinning strength of Bi(Pb)2212 single crystals by 3d metal doping in the present study. Crystal boules with starting compositions of Bi1.6Pb0.6Sr1.8Ca(Cu1-xMx)2Oy (M = Fe, Co, Ni : x = 0, 0.001, 0.002, 0.005, 0.02) were grown by the floating zone method. Tc's of the single crystals annealed to be the carrier overdoped state were dramatically decreased with an increase of metal doping levels. Critical current performance of the 3d metal-doped Bi(Pb)2212 crystals was quite poor at high temperatures near Tc, The crystal with x= 0.001, 0.002, 0.005, however, showed improved Jc properties accompanied by larger second peak effects in their magnetization hysteresis loops when compared with the 3d metal free Bi(Pb)2212 crystal below 50 K. On the other hand, magneto-optical measurements revealed that anisotropy in the in-plane Jc properties (Jca > Jcb ) was systematically suppressed with an increase of the doping level x. These results suggested that a very small amount of 3d metal doping is an essentially effective method to enhance pinning strength of Bi-based superconductors due to their generation of point-defect-like pinning centers. 3d doping, however, does decrease the pinning strength at the lamella structure interfaces.
{"title":"3d遷移金属置換Bi(Pb)2212単結晶の磁束ピンニング特性","authors":"雅直 重森, 智史 内田, 滋 堀井, 淳一 下山, 光二 岸尾","doi":"10.2221/JCSJ.39.155","DOIUrl":"https://doi.org/10.2221/JCSJ.39.155","url":null,"abstract":"A large amount of lead doping to Bi2212 superconductors is effective in decreasing their high electromagnetic anisotropy and introduces effective pinning sites, such as lamella structure interfaces due to compositional fluctuation of lead ions, resulting in greatly enhanced flux pinning properties up to high temperatures. Particularly in the high-Tc superconducting materials with lowered anisotropy, further improvement of critical current properties can be expected by doping a small amount of impurity elements, which generate locally weak superconducting regions. Based on this background, we have attempted to enhance flux pinning strength of Bi(Pb)2212 single crystals by 3d metal doping in the present study. Crystal boules with starting compositions of Bi1.6Pb0.6Sr1.8Ca(Cu1-xMx)2Oy (M = Fe, Co, Ni : x = 0, 0.001, 0.002, 0.005, 0.02) were grown by the floating zone method. Tc's of the single crystals annealed to be the carrier overdoped state were dramatically decreased with an increase of metal doping levels. Critical current performance of the 3d metal-doped Bi(Pb)2212 crystals was quite poor at high temperatures near Tc, The crystal with x= 0.001, 0.002, 0.005, however, showed improved Jc properties accompanied by larger second peak effects in their magnetization hysteresis loops when compared with the 3d metal free Bi(Pb)2212 crystal below 50 K. On the other hand, magneto-optical measurements revealed that anisotropy in the in-plane Jc properties (Jca > Jcb ) was systematically suppressed with an increase of the doping level x. These results suggested that a very small amount of 3d metal doping is an essentially effective method to enhance pinning strength of Bi-based superconductors due to their generation of point-defect-like pinning centers. 3d doping, however, does decrease the pinning strength at the lamella structure interfaces.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131735075","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}
{"title":"特集「高温超電導電流リード」によせて","authors":"通隆 小野","doi":"10.2221/JCSJ.39.72","DOIUrl":"https://doi.org/10.2221/JCSJ.39.72","url":null,"abstract":"","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122014378","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}
This article focuses on Poynting’s vector which is defined by a vector product of electric and magnetic fields and plays an important role in considering a flow of electromagnetic energy between power supplies and various types of electromagnetic devices in electrical, electronical and information networks. Poynting’s vector is introduced from a law of energy conservation and its surface integral on an arbitrary domain is equal to the electromagnetic power inside it. This relation can be applied to any system in which there is an interest in the energy flow. Validity of the speculation that Poynting’s vector directly gives the energy flow is examined in various cases. It is pointed out that Poynting’s vector is not equal to the energy flow in some cases. Also discussed is the condition under which the equality holds.
{"title":"電磁気学こぼれ話—超伝導応用のための電磁気学の問題 第2話—","authors":"照男 松下, 和夫 船木","doi":"10.2221/JCSJ.39.2","DOIUrl":"https://doi.org/10.2221/JCSJ.39.2","url":null,"abstract":"This article focuses on Poynting’s vector which is defined by a vector product of electric and magnetic fields and plays an important role in considering a flow of electromagnetic energy between power supplies and various types of electromagnetic devices in electrical, electronical and information networks. Poynting’s vector is introduced from a law of energy conservation and its surface integral on an arbitrary domain is equal to the electromagnetic power inside it. This relation can be applied to any system in which there is an interest in the energy flow. Validity of the speculation that Poynting’s vector directly gives the energy flow is examined in various cases. It is pointed out that Poynting’s vector is not equal to the energy flow in some cases. Also discussed is the condition under which the equality holds.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122944357","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}
Shinpei Nakagiri, M. Iino, S. Murase, N. Nanato, H. Kumakura, A. Matsumoto
The measurement and analysis of AC transport current loss (self-field loss) in MgB2 superconducting composites were studied. In experimental results, the normalized Ic dependency of AC loss in the MgB2 deviated from Norris' theoretical curve. Then a numerical analysis was performed by taking into consideration the model of a round superconducting wire that consisted of three concentric layers. The analysis clearly showed the experimentally obtained results, such as that the phenomenon originated in the inhomogeneity of the critical current density in the wire rod section.
{"title":"Self-field Loss in AC Transport Current Loss of MgB_2 Superconducting Composites","authors":"Shinpei Nakagiri, M. Iino, S. Murase, N. Nanato, H. Kumakura, A. Matsumoto","doi":"10.2221/JCSJ.38.615","DOIUrl":"https://doi.org/10.2221/JCSJ.38.615","url":null,"abstract":"The measurement and analysis of AC transport current loss (self-field loss) in MgB2 superconducting composites were studied. In experimental results, the normalized Ic dependency of AC loss in the MgB2 deviated from Norris' theoretical curve. Then a numerical analysis was performed by taking into consideration the model of a round superconducting wire that consisted of three concentric layers. The analysis clearly showed the experimentally obtained results, such as that the phenomenon originated in the inhomogeneity of the critical current density in the wire rod section.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115531166","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}
Kazuhide Tanaka, M. Okada, H. Kumakura, H. Kitaguchi
This paper reports on the successful fabrication and testing of a MgB2 coil. We have fabricated a 15 m-long MgB2/stainless steel mono-core tape using a mixture of commercial MgB2 powder and tin powder (10wt% of MgB2 powder) using the PIT method. The tape is made applying an ex-situ process without any heat treatment during the processing procedure. The MgB2 superconducting tapes show good uniformity, with a high Jc value (180-290 A/mm2 at 4.2 K and 3 T) along the tape's length, as well as good bending tolerance. Ic degradation of the tape occurred at a bending strain of as high as 1.3%. Using wire over 12 m-long, we made a small solenoid coil, 48.5 mm in outer diameter and 40 mm height, and tested it at 4.2 K and self-field. The highest Ic value we obtained was 255 A, which generated a central field of 0.5 T, and a maximum magnetic field of 0.575 T.
{"title":"Transport Properties of PIT-processed MgB_2 Wire and Coil","authors":"Kazuhide Tanaka, M. Okada, H. Kumakura, H. Kitaguchi","doi":"10.2221/JCSJ.38.623","DOIUrl":"https://doi.org/10.2221/JCSJ.38.623","url":null,"abstract":"This paper reports on the successful fabrication and testing of a MgB2 coil. We have fabricated a 15 m-long MgB2/stainless steel mono-core tape using a mixture of commercial MgB2 powder and tin powder (10wt% of MgB2 powder) using the PIT method. The tape is made applying an ex-situ process without any heat treatment during the processing procedure. The MgB2 superconducting tapes show good uniformity, with a high Jc value (180-290 A/mm2 at 4.2 K and 3 T) along the tape's length, as well as good bending tolerance. Ic degradation of the tape occurred at a bending strain of as high as 1.3%. Using wire over 12 m-long, we made a small solenoid coil, 48.5 mm in outer diameter and 40 mm height, and tested it at 4.2 K and self-field. The highest Ic value we obtained was 255 A, which generated a central field of 0.5 T, and a maximum magnetic field of 0.575 T.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133476381","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}
A. Minoda, Y. Mizuno, Y. Muramoto, Naohiro Nozumi, M. Nagao, M. Kosaki
Superconducting power cables are one of the promising ways for handling large volumes of electric power efficiently in the future. The authors have proved that ethylene-propylene rubber (EPR) is suitable for use as the solid electrical insulating material of superconducting cable due to its excellent mechanical and electrical properties at cryogenic temperature. It is therefore imperative to study EPR resistance to treeing in view of long-term reliability as a cable insulator. The objectives of this study were to examine EPR resistance to treeing both at liquid nitrogen and room temperatures and the effect of fillers on resistance to treeing. The results show that EPR has sufficient resistance to AC treeing at liquid nitrogen temperature and the fillers improve resistance to AC treeing slightly.
{"title":"Treeing Characteristic of EPR for Solid Insulated Superconducting Cable","authors":"A. Minoda, Y. Mizuno, Y. Muramoto, Naohiro Nozumi, M. Nagao, M. Kosaki","doi":"10.2221/JCSJ.38.554","DOIUrl":"https://doi.org/10.2221/JCSJ.38.554","url":null,"abstract":"Superconducting power cables are one of the promising ways for handling large volumes of electric power efficiently in the future. The authors have proved that ethylene-propylene rubber (EPR) is suitable for use as the solid electrical insulating material of superconducting cable due to its excellent mechanical and electrical properties at cryogenic temperature. It is therefore imperative to study EPR resistance to treeing in view of long-term reliability as a cable insulator. The objectives of this study were to examine EPR resistance to treeing both at liquid nitrogen and room temperatures and the effect of fillers on resistance to treeing. The results show that EPR has sufficient resistance to AC treeing at liquid nitrogen temperature and the fillers improve resistance to AC treeing slightly.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"195 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123011278","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}
A SQUID system for application to the biological immunoassay process is shown. In this system, the biological binding-reaction between an antigen and its antibody is detected using a magnetic marker and a SQUID magnetometer; that is, the binding reaction is detected by measuring the magnetic field from the marker. A so-called SQUID microscope was used in order to achieve a close distance between the cooled SQUID and the room-temperature sample. Three methods have so far been developed for measurement: susceptibility, relaxation and remanence. The measurement method is chosen by the properties of the magnetic marker. It is pointed out that a marker that is optimized for the immunoassay should be developed. For this purpose, we have developed a new marker made of an Fe3O4 particle having a diameter of 25 nm. Since the new marker can keep a remanence after a field of 0.1 T is applied, we use the remanent field of the marker to detect the binding reaction. We conducted an experiment to detect an antigen called Interleukin 8 (IL8). It was shown that the present system can detect IL8 at a weight of 0.1 pg.
{"title":"Biological Immunoassay with a SQUID Magnetometer","authors":"K. Enpuku","doi":"10.2221/jcsj.38.469","DOIUrl":"https://doi.org/10.2221/jcsj.38.469","url":null,"abstract":"A SQUID system for application to the biological immunoassay process is shown. In this system, the biological binding-reaction between an antigen and its antibody is detected using a magnetic marker and a SQUID magnetometer; that is, the binding reaction is detected by measuring the magnetic field from the marker. A so-called SQUID microscope was used in order to achieve a close distance between the cooled SQUID and the room-temperature sample. Three methods have so far been developed for measurement: susceptibility, relaxation and remanence. The measurement method is chosen by the properties of the magnetic marker. It is pointed out that a marker that is optimized for the immunoassay should be developed. For this purpose, we have developed a new marker made of an Fe3O4 particle having a diameter of 25 nm. Since the new marker can keep a remanence after a field of 0.1 T is applied, we use the remanent field of the marker to detect the binding reaction. We conducted an experiment to detect an antigen called Interleukin 8 (IL8). It was shown that the present system can detect IL8 at a weight of 0.1 pg.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132722404","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}
N. Koizumi, K. Okuno, H. Nakajima, T. Ando, H. Tsuji
The Japan Atomic Energy Research Institute has been involved in developing Nb3Al conductors since the middle of 1980s based on the consideration that Nb3Al conductors are capable of producing a higher magnetic field than Nb3Sn conductors owing to the extremely high critical current density in high magnetic fields. At the beginning of the development work, a fabrication technique for Nb3Al strands using a Jelly-roll process was established. This process requires heat treatment at 750°C for 50 h instead of a temperature of more than 1,800°C as required by the conventional method. Using this technique, about 1 ton of strands was produced and a 150-m Nb3Al cable-in-conduit conductor was fabricated. For the next step, to demonstrate the applicability of the Nb3Al conductor to a large coil, a coil 1.5-m in diameter, called the Nb3Al Insert, was manufactured. A react-and-wind method was tried for the production process as it simplifies the fabrication of large coils such as an ITER-TF coil. Performance tests of the Nb3Al Insert were conducted in 2002. The Nb3Al Insert could be charged to the designed point of 13 T and 46 kA without showing any instability. Thus, the world's first large superconducting coil using a Nb3Al conductor was successfully developed, thus indicating the possibility of producing fusion magnets that can operate in higher magnetic fields than those used with Nb3Sn conductors.
{"title":"Development of a Nb_3AI Conductor to be Applied to a Fusion Reactor and Its Application to a Large Superconducting Coil","authors":"N. Koizumi, K. Okuno, H. Nakajima, T. Ando, H. Tsuji","doi":"10.2221/JCSJ.38.391","DOIUrl":"https://doi.org/10.2221/JCSJ.38.391","url":null,"abstract":"The Japan Atomic Energy Research Institute has been involved in developing Nb3Al conductors since the middle of 1980s based on the consideration that Nb3Al conductors are capable of producing a higher magnetic field than Nb3Sn conductors owing to the extremely high critical current density in high magnetic fields. At the beginning of the development work, a fabrication technique for Nb3Al strands using a Jelly-roll process was established. This process requires heat treatment at 750°C for 50 h instead of a temperature of more than 1,800°C as required by the conventional method. Using this technique, about 1 ton of strands was produced and a 150-m Nb3Al cable-in-conduit conductor was fabricated. For the next step, to demonstrate the applicability of the Nb3Al conductor to a large coil, a coil 1.5-m in diameter, called the Nb3Al Insert, was manufactured. A react-and-wind method was tried for the production process as it simplifies the fabrication of large coils such as an ITER-TF coil. Performance tests of the Nb3Al Insert were conducted in 2002. The Nb3Al Insert could be charged to the designed point of 13 T and 46 kA without showing any instability. Thus, the world's first large superconducting coil using a Nb3Al conductor was successfully developed, thus indicating the possibility of producing fusion magnets that can operate in higher magnetic fields than those used with Nb3Sn conductors.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122654362","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}
The ITER Central Solenoid (CS) model coil, CS Insert and Nb3Al Insert were developed and tested from 2000 to 2002. The AC loss performances of these coils were investigated in various experiments. In addition, the AC losses of the CS and Nb3Al Insert conductors were measured using short CS and Nb3Al Insert conductors before the coil tests. The coupling time constants of these conductors were estimated to be 30 and 120 ms, respectively. On the other hand, the test results of the CS and Nb3Al Inserts show that the coupling currents induced in these conductors had multiple decay time constants. In fact, the existence of the coupling currents with long decay time constants, the order of which was in the thousands of seconds, was directly observed with hall sensors and voltage taps. Moreover, the AC loss test results show that electromagnetic force decreases coupling losses with exponential decay constants. This is because the weak sinter among the strands, which originated during heat treatment, was broken due to the electromagnetic force, and then the contact resistance among strands increased. It was found that this exponential decay constant was the function of a gap (i.e., a mechanical property of the cable) created between the cable and conduit due to electromagnetic force. The gap can be estimated by pressure drop, measured under the electromagnetic force. The pressure drop can easily be measured at an initial trial charge, and then it is possible to estimate the exponential decay constant before normal coil operation. Accordingly, it is possible to predict promptly how many times the trial operations are necessary to decrease the coupling losses to the designed value by measuring the coupling losses and the pressure drop during the initial coil operation trial.
{"title":"ケーブル・イン・コンジット導体の交流損失特性","authors":"邦浩 松井, 良和 高橋, 徳潔 小泉, 高明 礒野, 一弥 濱田, 嘉彦 布谷, CSモデル・コイル実験グループ","doi":"10.2221/JCSJ.38.410","DOIUrl":"https://doi.org/10.2221/JCSJ.38.410","url":null,"abstract":"The ITER Central Solenoid (CS) model coil, CS Insert and Nb3Al Insert were developed and tested from 2000 to 2002. The AC loss performances of these coils were investigated in various experiments. In addition, the AC losses of the CS and Nb3Al Insert conductors were measured using short CS and Nb3Al Insert conductors before the coil tests. The coupling time constants of these conductors were estimated to be 30 and 120 ms, respectively. On the other hand, the test results of the CS and Nb3Al Inserts show that the coupling currents induced in these conductors had multiple decay time constants. In fact, the existence of the coupling currents with long decay time constants, the order of which was in the thousands of seconds, was directly observed with hall sensors and voltage taps. Moreover, the AC loss test results show that electromagnetic force decreases coupling losses with exponential decay constants. This is because the weak sinter among the strands, which originated during heat treatment, was broken due to the electromagnetic force, and then the contact resistance among strands increased. It was found that this exponential decay constant was the function of a gap (i.e., a mechanical property of the cable) created between the cable and conduit due to electromagnetic force. The gap can be estimated by pressure drop, measured under the electromagnetic force. The pressure drop can easily be measured at an initial trial charge, and then it is possible to estimate the exponential decay constant before normal coil operation. Accordingly, it is possible to predict promptly how many times the trial operations are necessary to decrease the coupling losses to the designed value by measuring the coupling losses and the pressure drop during the initial coil operation trial.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127113868","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}
AC losses in multi-strand superconducting cables, utilized in large-scale applications such as fusion machines, are governed by the contact resistance between strands. Especially, in cable twisted at multiple-stages, a variety of magnetic field diffusion time constants exist and these correspond to the quantity of inter-strand coupling loss in each cabling stage. The rate of magnetic field change is less than several T/s in an average fusion machine. Under this condition, the magnetic field penetrates the cable well and the coupling current circuit with the larger time constant causes larger AC loss. Here, the time constant is equal to the leakage inductance divided by the resistance along the coupling current loop. Therefore, by evaluating the coupling current in the larger loop, which consists of a higher twisting stage (e.g., usually the final cabling stage), the loss in the entire cable can be determined. The leakage inductance between sub-cables can be estimated by considering the electrical centers. On the other hand, inter-sub-cable contact resistance was not previously evaluated due to its complexity. In this study, we established an inter-sub-cable contact resistance model that allows the AC loss in cable with multiple twisting stages to be evaluated numerically. The modeling of contact resistance between sub-cables is discussed in detail.
{"title":"Modeling of a Distributed Constant Electric Circuit considering Contact Resistance and Coupling Loss Analyses for Cable Twisted at Multiple Stages","authors":"K. Seo, K. Fukuhara, M. Hasegawa","doi":"10.2221/jcsj.38.348","DOIUrl":"https://doi.org/10.2221/jcsj.38.348","url":null,"abstract":"AC losses in multi-strand superconducting cables, utilized in large-scale applications such as fusion machines, are governed by the contact resistance between strands. Especially, in cable twisted at multiple-stages, a variety of magnetic field diffusion time constants exist and these correspond to the quantity of inter-strand coupling loss in each cabling stage. The rate of magnetic field change is less than several T/s in an average fusion machine. Under this condition, the magnetic field penetrates the cable well and the coupling current circuit with the larger time constant causes larger AC loss. Here, the time constant is equal to the leakage inductance divided by the resistance along the coupling current loop. Therefore, by evaluating the coupling current in the larger loop, which consists of a higher twisting stage (e.g., usually the final cabling stage), the loss in the entire cable can be determined. The leakage inductance between sub-cables can be estimated by considering the electrical centers. On the other hand, inter-sub-cable contact resistance was not previously evaluated due to its complexity. In this study, we established an inter-sub-cable contact resistance model that allows the AC loss in cable with multiple twisting stages to be evaluated numerically. The modeling of contact resistance between sub-cables is discussed in detail.","PeriodicalId":285677,"journal":{"name":"Teion Kogaku (journal of The Cryogenic Society of Japan)","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115139669","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：