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Journal Articles

Microscopic properties of the heavy-fermion superconductor PuCoIn$$_5$$ explored by nuclear quadrupole resonance

Koutroulakis, G.*; Yasuoka, Hiroshi; Chudo, Hiroyuki; Tobash, P. H.*; Mitchell, J. N.*; Bauer, E. D.*; Thompson, J. D.*

New Journal of Physics (Internet), 16, p.053019_1 - 053019_12, 2014/05

 Times Cited Count:6 Percentile:47.83(Physics, Multidisciplinary)

We report $$^{115}$$In nuclear quadrupolar resonance (NQR) measurements on the heavy-fermion superconductor PuCoIn$$_5$$, in the temperature range 0.29 K $$leq Tleq$$75 K. The NQR parameters for the two crystallographically inequivalent In sites are determined, and their temperature dependence is investigated. A linear shift of the quadrupolar frequency with lowering temperature below the critical value $$T_c$$ is revealed, in agreement with the prediction for composite pairing. The nuclear spin-lattice relaxation rate $$T_1^{-1}(T)$$ clearly signals a superconducting (SC) phase transition at $$T_c simeq $$ 2.3 K, with strong spin fluctuations, mostly in-plane, dominating the relaxation process in the normal state near to $$T_c$$. Analysis of the $$T_1^{-1}$$ data in the SC state suggests that PuCoIn$$_5$$ is a strong-coupling $$d$$-wave superconductor.

Journal Articles

Weak itinerant antiferromagnetism in PuIn$$_3$$ explored using $$^{115}$$In nuclear quadrupole resonance

Chudo, Hiroyuki; Koutroulakis, G.*; Yasuoka, Hiroshi; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Thompson, J. D.*

Journal of Physics; Condensed Matter, 26(3), p.036001_1 - 036001_5, 2014/01

 Times Cited Count:4 Percentile:75.11(Physics, Condensed Matter)

The results of $$^{115}$$In nuclear quadrupole resonance (NQR) measurements on PuIn$$_3$$ are reported. Three of the four NQR lines of $$^{115}$$In expected for nuclear spin $$I$$=9/2 are observed. The equal spacing of these lines at 20 K yields the NQR frequency of $$nu_{rm Q}$$=10.45 MHz, and the asymmetry parameter of the electric field gradient, $$eta$$=0. The NQR line profile and the nuclear spin-lattice relaxation rate $$1/T_1$$ display an abrupt change at 14 K, which is associated with the onset of long-range antiferromagnetic order. The temperature dependences of the staggered magnetization $$M_{rm Q}(T)$$, extracted from the NQR spectra, and $$1/T_1$$ below $$T_{rm N}$$=14 K are well explained by the self-consistent renormalization (SCR) theory for spin fluctuations. In addition, scaling between $$T_1T$$ and $$M_{rm Q}(T)/M_{rm Q}(0)$$ is also consistent with the predictions of SCR theory, providing further evidence that PuIn$$_3$$ is a weak itinerant antiferromagnet in which spin fluctuations around the antiferromagnetic wave vector play a major role in the system's behavior at finite temperatures.

Journal Articles

Shubnikov-de Haas oscillation in PuIn$$_3$$

Haga, Yoshinori; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Ayala-Valenzuela, O.*; McDonald, R. D.*; Mielke, C. H.*; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.380 - 382, 2013/08

 Times Cited Count:2 Percentile:76.54(Physics, Multidisciplinary)

Journal Articles

Test results of ITER conductors in the SULTAN facility

Bruzzone, P.*; Stepanov, B.*; Wesche, R.*; Mitchell, N.*; Devred, A.*; Nunoya, Yoshihiko; Tronza, V.*; Kim, K.*; Boutboul, T.*; Martovetsky, N.*; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03

Starting March 2007, over 60 ITER cable-in-conduit conductors (CICC) have been tested in the SULTAN test facility, Switzerland. For the NbTi CICC, the results confirm the prediction from the strand data, which are made taking the peak field over the conductor cross section as operating field. All the NbTi samples passed the supplier qualification phase. For the Nb$$_{3}$$Sn CICC, the performance prediction is not straightforward because of the irreversible degradation caused by filament damage occurring during cyclic loading. At the first run of the test campaign, the performance of all the Nb$$_{3}$$Sn samples largely meets the target for all the tested samples. Contrary to the NbTi CICC case, the n-index of the transition is substantially lower than in the strands, providing evidence of irreversible degradation. The performance loss upon load cycles and thermal cycles has a broad range among the various conductor samples.

Journal Articles

ITER magnet systems; From qualification to full scale construction

Nakajima, Hideo; Hemmi, Tsutomu; Iguchi, Masahide; Nabara, Yoshihiro; Matsui, Kunihiro; Chida, Yutaka; Kajitani, Hideki; Takano, Katsutoshi; Isono, Takaaki; Koizumi, Norikiyo; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03

The ITER organization and 6 Domestic Agencies (DA) have been implementing the construction of ITER superconducting magnet systems. Four DAs have already started full scale construction of Toroidal Field (TF) coil conductors. The qualification of the radial plate manufacture has been completed, and JA and EU are ready for full scale construction. JA has qualified full manufacturing processes of the winding pack with a 1/3 prototype and made 2 full scale mock-ups of the basic segments of TF coil structure to optimize and industrialize the manufacturing process. Preparation and qualification of the full scale construction of the TF coil winding is underway by EU. Procurement of the manufacturing equipment is near completion and qualification of manufacturing processes has already started. The constructions of other components of the ITER magnet systems are also going well towards the main goal of the first plasma in 2020.

Journal Articles

Status of ITER conductor development and production

Devred, A.*; Backbier, I.*; Bessette, D.*; Bevillard, G.*; Gardner, M.*; Jewell, M.*; Mitchell, N.*; Pong, I.*; Vostner, A.*

IEEE Transactions on Applied Superconductivity, 22(3), p.4804909_1 - 4804909_9, 2012/06

 Times Cited Count:106 Percentile:2.5(Engineering, Electrical & Electronic)

The ITER magnet system is made up of 4 sets of coils: 18 Toroidal Field (TF) coils, 6 Poloidal Field (PF) coils, 6 Central Solenoid (CS) coils and 9 pairs of Correction Coils (CC's). All of them are wound from Cable-In-Conduit Conductors (CICC's) made up of superconducting and copper strands assembled into a multistage, rope-type cable inserted into a conduit of butt-welded austenitic steel tubes. The TF and CS conductors call for about 500 tons of Nb$$_3$$Sn strands while the PF and CC conductors need around 250 tons of NbTi strands. The required amount of Nb$$_3$$Sn strands far exceeds pre-existing industrial capacity and calls for a significant worldwide production scale up. After recalling the technical requirements defined by the ITER Internal Organization (IO), we detail the in-kind procurement sharing of the various conductor types among the 6 ITER Domestic Agencies (DA's) involved: China, Europe, Japan, South Korea, Russia, and the United States, and we present a status of ongoing productions. The most advanced production is that for the TF coils, where all 6 DAs have qualified suppliers and have already registered more than 30% of the expected production data into the web-based ITER Conductor Database developed by the IO.

Journal Articles

Technology development and mass production of Nb$$_{3}$$Sn conductors for ITER toroidal field coils in Japan

Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

Nuclear Fusion, 51(11), p.113015_1 - 113015_11, 2011/11

 Times Cited Count:10 Percentile:52.4(Physics, Fluids & Plasmas)

Japan Atomic Energy Agency is procuring the Nb$$_{3}$$Sn superconductors for Toroidal Field (TF) Coils under the ITER project. Because manufacturing amount of Nb$$_{3}$$Sn strands is quite large compared with the past experience and required superconducting performance is higher than that of the model coils which have been fabricated and tested in the ITER-EDA, quality control technique is very important for the manufacture of the strands. Sophisticated control technique is also required for the jacketing, in order to fabricate the conductors with the precise outer diameter and without leakage at welding part. This paper summarizes the technical developments leading to the first successful mass production of ITER TF conductors.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:22 Percentile:29.37(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:142 Percentile:0.63(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:49.68(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 Times Cited Count:137 Percentile:1.54(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Journal Articles

Technology development for the manufacture of Nb$$_{3}$$Sn conductors for ITER Toroidal Field coils

Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Japan Atomic Energy Agency is procuring the Nb$$_{3}$$Sn superconductors for Toroidal Field (TF) coils under the ITER project. Because manufacturing amount of Nb$$_{3}$$Sn strands is quite large compared with the past experience and required superconducting performance is higher than that of the model coils which have been fabricated and tested in the ITER-EDA, quality control technique is very important for the manufacture of the strands. Sophisticated control technique is also required for the jacketing, in order to fabricate the conductors with the precise outer diameter and without leakage at welding part. Cu dummy conductor with full length (760 m) has been fabricated successfully and all jacketing technology was confirmed through this fabrication. The fabrication of the Nb$$_{3}$$Sn conductor for TF coils will start in March 2010.

Journal Articles

Anisotropic spin fluctuations and superconductivity in "115" heavy fermion compounds; $$^{59}$$Co NMR study in PuCoGa$$_5$$

Baek, S.-H.*; Sakai, Hironori; Bauer, E. D.*; Mitchell, J. N.*; Kennison, J. A.*; Ronning, F.*; Thompson, J. D.*

Physical Review Letters, 105(21), p.217002_1 - 217002_4, 2010/11

 Times Cited Count:12 Percentile:36.55(Physics, Multidisciplinary)

We report results of $$^{59}$$Co nuclear magnetic resonance measurements on a single crystal of superconducting PuCoGa$$_5$$ in its normal state. The nuclear spin-lattice relaxation rates and the Knight shifts as a function of temperature reveal an anisotropy of spin fluctuations with finite wave vector ${it q}$. By comparison with the isostructural members, we conclude that antiferromagnetic ${it XY}$-type anisotropy of spin fluctuations plays an important role in mediating superconductivity in these heavy fermion materials.

Journal Articles

Status report on the toroidal field coils for the ITER project

Savary, F.*; Bonito Oliva, A.*; Gallix, R.*; Knaster, J.*; Koizumi, Norikiyo; Mitchell, N.*; Nakajima, Hideo; Okuno, Kiyoshi; Sborchia, C.*

IEEE Transactions on Applied Superconductivity, 20(3), p.381 - 384, 2010/06

 Times Cited Count:18 Percentile:29.93(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Installation and test programme of the ITER poloidal field conductor insert (PFCI) in the ITER test facility at JAEA Naka

Nunoya, Yoshihiko; Takahashi, Yoshikazu; Hamada, Kazuya; Isono, Takaaki; Matsui, Kunihiro; Oshikiri, Masayuki; Nabara, Yoshihiro; Hemmi, Tsutomu; Nakajima, Hideo; Kawano, Katsumi; et al.

IEEE Transactions on Applied Superconductivity, 19(3), p.1492 - 1495, 2009/06

 Times Cited Count:1 Percentile:86.94(Engineering, Electrical & Electronic)

The ITER Poloidal Field Conductor Insert (PFCI) was constructed to characterize the performance of selected cable-in-conduit NbTi conductors for the ITER Poloidal Field (PF) under relevant operating conditions. The PFCI was installed and tested inside the bore of the ITER CS model coil, which provides the background magnetic field. The PFCI is a single-layer solenoid, wound from about 50 m of a full-size ITER cable-in-conduit conductor. The winding diameter and height are about 1.5 m and 1 m, respectively. The nominal design current of the conductor is 45 kA at 6 T and 5 K. The main items in the PFCI test programme are current sharing temperature (Tcs) measurements, critical current (Ic) measurements and AC loss measurement. The key technology of the installation, the test methods and procedures, and some preliminary results of the testing campaigns are described and discussed in this paper.

Journal Articles

Stability and quench analysis of toroidal field coils for ITER

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Bessette, D.*; Shatil, N.*; Mitchell, N.*

IEEE Transactions on Applied Superconductivity, 17(2), p.2426 - 2429, 2007/06

 Times Cited Count:13 Percentile:40.74(Engineering, Electrical & Electronic)

The ITER TF coils consists of 18 D-shape coils. The operating current, the maximum field and the stored magnetic energy are 68 kA, 11.8 T and 41 GJ, respectively. A Nb$$_{3}$$Sn cable-in-conduit conductor with a central channel is used, with a cooling length of 380 m. An accurate prediction of the coil performance requires, in addition to assessments of the superconductor behavior, a thermohydraulic analysis of the supercritical He. The overall thermohydraulic conditions were simulated by the full-scale quasi three dimensional code VINCENTA. Analysis of stability and quench was carried out using one dimensional Gandalf electric and thermohydraulic code. An interface was written between these codes. The stability margin against the mechanical disturbance and due to a plasma disruption was estimated. In the quench analysis, the temperature rise during the fast discharge was calculated. According to these results, it is confirmed that the TF coils will be operated with the designed performance.

Journal Articles

Predictive analysis of the ITER poloidal field conductor insert (PFCI) test program

Zanino, R.*; Astrov, M.*; Bagnasco, M.*; Baker, W.*; Bellina, F.*; Ciazynski, D.*; Egorov, S. A.*; Kim, K.*; Kvitkovic, J. L.*; Lacroix, B.*; et al.

IEEE Transactions on Applied Superconductivity, 17(2), p.1353 - 1357, 2007/06

 Times Cited Count:4 Percentile:68.77(Engineering, Electrical & Electronic)

The PFCI will be tested at JAEA Naka, inside the bore of the ITER Central Solenoid Model Coil. The main test program are the DC characterization of the conductor, the measurement of AC losses in conductor, the hydraulic characterization, the stability and the quench propagation, and the effects of cycling electromagnetic load. Based on and in support of this test program, an extensive campaign of predictive analysis has been initiated on a subset of the above-mentioned test program items and the results of the comparison of selected predictions from different laboratories will be presented and discussed. A sudden quench at 5.7-6.2 K and 45 kA is predicted. The computed temperature increase at the winding outlet is about 0.5 K for the pulse. These results will be compared with the experiment and used for an accurate prediction of the PF coil performance.

Journal Articles

Simulation of quench tests of the central solenoid insert coil in the ITER central solenoid model coil

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Nabara, Yoshihiro; Edaya, Masahiro*; Mitchell, N.*

IEEE Transactions on Applied Superconductivity, 16(2), p.783 - 786, 2006/06

 Times Cited Count:7 Percentile:57.12(Engineering, Electrical & Electronic)

To investigate the conductor behavior during a quench, quench tests of Center Solenoid (CS) insert coils were carried out with various initial conditions in DC and pulse modes. The conductor has very similar configuration and parameters. The inductive heater, attached at the center of the length, initiated an artificial quench in DC mode. A quench has also occurred during the pulse operation with the ramping rate of 0.4-2 T/s. Simulations of electric, thermal and hydraulic behaviors of the conductor during the quench tests in both modes were carried out by using the thermohydraulic simulation code. The experimental results were compared with the simulation and good agreement was obtained. These results are described and the implication for quench detection in ITER is discussed in this paper. The voltage tap method will be used for the quench detection for the CS, and the sensitivity of the detection and the maximum temperature of the conductor during a quench are described. It is shown that the detection system could be designed with high enough detection sensitivity.

Journal Articles

Implications of NbTi short-sample test results and analysis for the ITER Poloidal Field Conductor Insert (PFCI)

Zanino, R.*; Bagnasco, M.*; Baker, W.*; Bellina, F.*; Bruzzone, P.*; della Corte, A.*; Ilyin, Y.*; Martovetsky, N.*; Mitchell, N.*; Muzzi, L.*; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.886 - 889, 2006/06

 Times Cited Count:7 Percentile:57.12(Engineering, Electrical & Electronic)

As the test of the PFCI is foreseen at JAERI Naka, Japan, it is essential to consider in detail the lessons learned from the short NbTi sample tests, as well as the issues left open after them, in order to develop a suitable test program of the PFCI aimed at bridging the extrapolation gap between measured strand and future PF coil performance. Here we consider in particular the following issues: (1) the actual possibility to quench the PFCI conductor in the TCS tests before quenching the intermediate joint, (2) the question of the so-called sudden or premature quench, based on SULTAN sample results, applying a recently developed multi-solid and multi-channel extension of the Mithrandir code to a short sample analysis; (3) the feasibility of the AC losses calorimetry in the PFCI. These results show that Tcs measurement and the calorimetric measurement of AC losses will be carried out successfully. However, we need further analytic works for the problem of the sudden quench.

Journal Articles

Updating the design of the feeder components for the ITER magnet system

Yoshida, Kiyoshi; Takahashi, Yoshikazu; Isono, Takaaki; Mitchell, N.*

Fusion Engineering and Design, 75-79, p.241 - 247, 2005/11

 Times Cited Count:10 Percentile:39.62(Nuclear Science & Technology)

The ITER superconducting magnet system stores energy of 50 GJ during plasma operation, and generates an average heat load of 23 kW at 4 K to cryoplant. The helium is distributed to the coil through 30 separate feeder lines. The feeders also contain the electrical supplies to the coil and are integrated into the current lead transition to room temperature. The interface components between the coils and the service facilities (power supply and cryogenic plant) consist of the in-cryostat feeders, the cryostat feedthroughs, and the coil terminal boxes (CTBs). The cryostat feedthroughs with S-bend boxes allow thermal contraction of the magnet system. The layout of the in-cryostat feeders takes into consideration routing restrictions in the cryostat and initial assembly with other Tokamak components. The forced-flow-cooled current leads with a conventional copper heat exchanger in the CTBs are adapted to fit in the limited space in the building. This paper presents the latest design concept and parameters of the feeder components.

28 (Records 1-20 displayed on this page)