B. Zeitlin, E. Gregory, J. Marte, M. Benz, R. Scanlan, D. Dietderich
MEIT conductors fabricated with Nb‐1at%Zr filaments are evaluated as to the effect of the additions of Oxygen and Titanium introduced through the tin core. The effects as a function of time and temperature are evaluated through reaction area and grain size. Current density in the reaction layer is evaluated as a function of magnetic field and the reaction variables. In the temperature range of 850 °C to 900°C the addition of oxygen yielded the best results with layer current density of 1877 A/mm2 at 12 T. Fabrication experience with Nb‐1at%ZrOx filaments and solutions are also discussed.
{"title":"The Effect on the Superconducting Properties of the Addition of Oxygen and Titanium to (Nb‐1Zr)3Sn Mono Element Internal Tin (MEIT) Conductors","authors":"B. Zeitlin, E. Gregory, J. Marte, M. Benz, R. Scanlan, D. Dietderich","doi":"10.1063/1.2192389","DOIUrl":"https://doi.org/10.1063/1.2192389","url":null,"abstract":"MEIT conductors fabricated with Nb‐1at%Zr filaments are evaluated as to the effect of the additions of Oxygen and Titanium introduced through the tin core. The effects as a function of time and temperature are evaluated through reaction area and grain size. Current density in the reaction layer is evaluated as a function of magnetic field and the reaction variables. In the temperature range of 850 °C to 900°C the addition of oxygen yielded the best results with layer current density of 1877 A/mm2 at 12 T. Fabrication experience with Nb‐1at%ZrOx filaments and solutions are also discussed.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":"824 1","pages":"513-519"},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192389","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398212","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}
K. Miyoshi, S. Awaji, H. Oguro, G. Nishijima, K. Watanabe
We found that critical current Ic, upper critical field Bc2 and critical temperature Tc are greatly enhanced by pre‐bending treatment for bronze route Nb3Sn superconductors, called the pre‐bending effect. The superconducting properties of Nb3Sn superconductor are sensitive to strain. However, a pre‐bending treatment of the Nb3Sn wire enhances the properties. This is because the treatment causes relaxation of the residual strain in the Nb3Sn layer in the wire.Interestingly, the pre‐bending effect also makes the Nb3Sn wire stronger against strain. By using this effect, the react‐and‐wind (R&W) method is expected to be applicable for the fabrication of the Nb3Sn superconducting coil. In this paper, the development of Nb3Sn coils made by the R&W method with the pre‐bending effect is described, and the efficiency of the cable assembled by the reacted Nb3Sn strands is discussed.
{"title":"Ic Enhancement Effect in Nb3Sn Coils Fabricated by the React‐and‐Wind Method","authors":"K. Miyoshi, S. Awaji, H. Oguro, G. Nishijima, K. Watanabe","doi":"10.1063/1.2192392","DOIUrl":"https://doi.org/10.1063/1.2192392","url":null,"abstract":"We found that critical current Ic, upper critical field Bc2 and critical temperature Tc are greatly enhanced by pre‐bending treatment for bronze route Nb3Sn superconductors, called the pre‐bending effect. The superconducting properties of Nb3Sn superconductor are sensitive to strain. However, a pre‐bending treatment of the Nb3Sn wire enhances the properties. This is because the treatment causes relaxation of the residual strain in the Nb3Sn layer in the wire.Interestingly, the pre‐bending effect also makes the Nb3Sn wire stronger against strain. By using this effect, the react‐and‐wind (R&W) method is expected to be applicable for the fabrication of the Nb3Sn superconducting coil. In this paper, the development of Nb3Sn coils made by the R&W method with the pre‐bending effect is described, and the efficiency of the cable assembled by the reacted Nb3Sn strands is discussed.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":"53 1","pages":"536-543"},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192392","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59398272","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":"824 1","pages":"688-695"},"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. Hennessy, E. Mueller, O. Mueller, J. Park, R. R. Neal
Several cryogenic power converter modules were built and tested, including a low‐voltage, high‐power series based on Cryo‐MOSFETs and a high‐voltage, high‐power series based on Cryo‐IGBTs. Half‐bridge modules were manufactured and demonstrated in liquid nitrogen. The hardware is such that several half‐bridge modules can be interconnected to form a multiphase full bridge. Conduction losses in the MOSFET modules were reduced by more than an order of magnitude. Switching powers up to 340 kW were achieved in the MOSFET modules, and 720 kW was demonstrated in the IGBT series. These modules can be utilized in fully integrated, megawatt‐level cryogenic power systems.
{"title":"Cryogenic Power Converter Module Performance","authors":"M. Hennessy, E. Mueller, O. Mueller, J. Park, R. R. Neal","doi":"10.1063/1.2192373","DOIUrl":"https://doi.org/10.1063/1.2192373","url":null,"abstract":"Several cryogenic power converter modules were built and tested, including a low‐voltage, high‐power series based on Cryo‐MOSFETs and a high‐voltage, high‐power series based on Cryo‐IGBTs. Half‐bridge modules were manufactured and demonstrated in liquid nitrogen. The hardware is such that several half‐bridge modules can be interconnected to form a multiphase full bridge. Conduction losses in the MOSFET modules were reduced by more than an order of magnitude. Switching powers up to 340 kW were achieved in the MOSFET modules, and 720 kW was demonstrated in the IGBT series. These modules can be utilized in fully integrated, megawatt‐level cryogenic power systems.","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":"824 1","pages":"367-374"},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192373","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59397636","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}
Different applications of superconductors require different material properties. In this paper a short account is given of the relevant properties of the main materials of interest, BSCCO, MgB2 and YBCO. While BSCCO tapes are well established, the low irreversibility field limits their use at 77K while at 30K where they can stand reasonably high magnetic fields, the cheapness and ease of manufacture of MgB2 makes this new material a serious competitor. Bulk YBCO is also well developed and can produce high fields, but coated YBCO conductors have more applications if the cost can be brought down. AC losses are central to many applications. Since the loss/vol is proportional to Jc, but the volume of material required for a given magnet is inversely proportional to Jc the loss is independent of the material used and depends only on the width of the conductor. However using fine filaments requires that they be decoupled, and is in conflict with the need to avoid high angle grain boundaries across the current p...
{"title":"Superconducting Materials for Practical Applications","authors":"A. Campbell","doi":"10.1063/1.2192376","DOIUrl":"https://doi.org/10.1063/1.2192376","url":null,"abstract":"Different applications of superconductors require different material properties. In this paper a short account is given of the relevant properties of the main materials of interest, BSCCO, MgB2 and YBCO. While BSCCO tapes are well established, the low irreversibility field limits their use at 77K while at 30K where they can stand reasonably high magnetic fields, the cheapness and ease of manufacture of MgB2 makes this new material a serious competitor. Bulk YBCO is also well developed and can produce high fields, but coated YBCO conductors have more applications if the cost can be brought down. AC losses are central to many applications. Since the loss/vol is proportional to Jc, but the volume of material required for a given magnet is inversely proportional to Jc the loss is independent of the material used and depends only on the width of the conductor. However using fine filaments requires that they be decoupled, and is in conflict with the need to avoid high angle grain boundaries across the current p...","PeriodicalId":80359,"journal":{"name":"Advances in cryogenic engineering","volume":"824 1","pages":"395-415"},"PeriodicalIF":0.0,"publicationDate":"2006-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1063/1.2192376","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59397937","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":"824 1","pages":"138-144"},"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":"824 1","pages":"440-447"},"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":"824 1","pages":"448-454"},"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":"824 1","pages":"520-527"},"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":"824 1","pages":"617-624"},"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}
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