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Sample records for situ processed mgb

  1. Enhancement of the low-field Jc properties of MgB2/Fe tapes by a modified in situ process

    NASA Astrophysics Data System (ADS)

    Jiang, C. H.; Kumakura, H.; Dou, S. X.

    2007-10-01

    The low-field Jc properties of MgB2/Fe tapes were significantly improved by a modified in situ process. The as-drawn MgB2/Fe wires were first pre-annealed to form MgB2, before they were further rolled into flat tapes and post-annealed. In comparison to the conventional in situ process, our modified process produced dense, homogeneous and well-connected MgB2 cores in the final tapes, which resulted in a significant improvement in the low-field Jc properties. This modified in situ process is very promising for the fabrication of long-length MgB2 tapes/wires with excellent Jc properties for low-field applications, such as magnetic resonance imaging (MRI) magnets.

  2. Improved critical current density in ex situ processed MgB2 tapes by the size reduction of grains and crystallites by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Fujii, Hiroki; Ishitoya, Akira; Itoh, Shinji; Ozawa, Kiyoshi; Kitaguchi, Hitoshi

    2017-03-01

    We have fabricated Fe-sheathed MgB2 tapes through an ex situ process in a powder-in-tube (PIT) technique using powders ball milled under various conditions. Although the ex situ processed wires and tapes using the high-energy ball milled MgB2 powders have been studied and the decrease of grain and crystallite sizes of MgB2 and the critical current density (Jc) improvement of those conductors were reported so far, the use of filling powders milled at a higher rotation speed than previously reported further decreases the crystallite size and improves the Jc properties. The improved Jc values at 4.2 K and 10 T were nearly twice as large as those previously reported. Those milled powders and hence as-rolled tapes easily receive contamination in air. Thus, the transport Jc properties are easily deteriorated and scattered unless the samples are handled with care. The optimized heat treatment temperature (Topt) of those tape samples at which best performance in the Jc property is obtained decreases by more than 100 °C, compared with that of tapes using the as-received MgB2 powder.

  3. Strongly connected ex situ MgB2 polycrystalline bulks fabricated by solid-state self-sintering

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroya; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ogino, Hiraku; Kishio, Kohji

    2012-11-01

    The transport current carrying capacity of ex situ processed MgB2 is expected to be greatly enhanced if a strong intergrain connectivity can be realized. Although percolation theory predicts that ex situ MgB2 samples should have a high connectivity of over 30% due to their high bulk density (P ≈ 75%), the reported connectivities of ex situ MgB2 bulks and wires are generally less than 10%. This is presumably because ex situ MgB2 has a much weaker intergrain connectivity than in situ MgB2. It is well known that heat treatment after cold working of ex situ MgB2 improves the connectivity and the critical current density. However, it is currently unclear whether such heat treatment induces self-sintering that results in the formation of necks, the elimination of pores, and an increase in contact area. In the present study, we investigated the microstructure, normal-state electrical connectivity, and critical current density of ex situ MgB2 polycrystalline bulks prepared by systematically varying the sintering conditions under low pressure. Samples heated at a high temperature of ˜900 °C for a long period showed an increased packing factor, a larger intergrain contact area, and a significantly enhanced electrical connectivity, all of which indicate solid-state self-sintering of MgB2. Sintered ex situ MgB2 bulks from a laboratory-made ball-milled powder exhibited a greatly enhanced connectivity of 28%, which is the highest connectivity of pressureless ex situ MgB2 bulks, wires, and tapes. Surprisingly, grain growth did not occur during long-duration (˜100 h) sintering in the sintered ex situ MgB2 bulks. This is in marked contrast to in situ processed MgB2 samples, for which significant grain growth occurred during heat treatment at ˜900 °C, producing grains that are several tens of times larger than the initial boron grains. Consequently, the critical current density as a function of the external magnetic field at 20 K progressively improved with sintering due

  4. In situ synthesis of superconducting MgB2 fibers within a magnesium matrix

    NASA Astrophysics Data System (ADS)

    DeFouw, John D.; Dunand, David C.

    2003-07-01

    Composite wires, consisting of several hundred continuous MgB2 fibers embedded within an Mg matrix, are produced by a casting method, whereby liquid Mg is pressure infiltrated into a preform of aligned B fibers which are subsequently reacted in situ to form MgB2 fibers. Despite defects in the form of small, unreacted B islands and radial cracks from volume expansion, the MgB2 fibers exhibit superconducting properties (Tc=39 K and Jc=360 kA/cm2 at 5 K) comparable to the best results published for bulk MgB2. The fibers are cylindrical and straight, allowing high packing densities within a mechanically tough, thermally dissipating, electrically conductive Mg matrix. The process is scalable to continuous lengths of superconducting Mg/MgB2 wires.

  5. The critical parameters in in-situ MgB2 wires and tapes with ex-situ MgB2 barrier after hot isostatic pressure, cold drawing, cold rolling and doping

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A. J.; Häßler, W.; Nenkov, K.; Rindfleisch, M. A.; Żuchowska, E.; Gajda, G.; Czujko, T.; Cetner, T.; Hossain, M. S. A.

    2015-05-01

    MgB2 precursor wires were prepared using powder in tube technique by Institute of High Pressure PAS in Warsaw. All samples were annealed under isostatic pressure generated by liquid Argon in the range from 0.3 GPa to 1 GPa. In this paper, we show the effects of different processing routes, namely, cold drawing (CD), cold rolling (CR), hot isostatic pressure (HIP) and doping on critical current density (Jc), pinning force (Fp), irreversible magnetic-field (Birr), critical temperature (Tc), n value, and dominant pinning mechanism in MgB2/Fe wires with ex situ MgB2 barrier. The results show that medium pressures (˜0.35 GPa) lead to high Jc in low and medium magnetic fields (0 T - 9 T). On the other hand, higher pressures (˜1 GPa) lead to enhanced Jc in high magnetic fields (above 9 T). Transport measurements show that CD, CR, and HIP have small effects on Birr and Tc, but CD, CR, HIP, and doping enhance Jc and Fp in in situ MgB2 wires with ex situ MgB2 barrier. Transport measurements on in situ undoped MgB2 wire with ex situ MgB2 barrier yield a Jc of about 100 A/mm2 at 4.2 K in 6 T, at 10 K in 4 T and at 20 K in 2 T. The results also show that cold drawing causes increase of n value.

  6. Comparison of critical current density in SiC-doped in situ MgB2 coils and straight wire samples processed by HIP

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A.; Cetner, T.; Małecka, M.; Presz, A.; Rindfleisch, M.; Tomsic, M.; Thong, C. J.; Surdacki, P.

    2013-11-01

    Unreacted MgB2 wires fabricated from SiC-doped precursor material by Hyper Tech Research, Inc. have been used to make small-diameter (14 mm) superconducting coils. All coils made of 500 mm length wires were subjected to hot isostatic pressure (HIP) treatment. The critical current density (Jc) parameters of coils were compared to straight samples characteristics. Both types of samples have been measured in perpendicular magnetic field configuration for Jc and pinning force density (Fp) evaluation. No significant Jc difference between the long wires on coils and straight wires was found. These results suggest that the critical current (Ic) for coils can be determined for straight samples (25 mm). SEM analysis indicated that a small diameter of the coil does not influence the structure of in situ MgB2 wire.

  7. Effect of cold high pressure deformation on the properties of ex situ MgB2 wires

    NASA Astrophysics Data System (ADS)

    Kulich, M.; Flükiger, R. L.; Senatore, C.; Tropeano, M.; Piccardo, R.

    2013-10-01

    A substantially different behaviour was observed between MgB2 wires produced either by in situ or ex situ processing after applying the recently developed technique of cold high pressure densification (or CHPD). In contrast to in situ wires, where densification at 1.5 GPa on binary and ternary alloyed in situ MgB2 wires causes an enhancement of mass density and a strong enhancement of Jc, ex situ wires up to 2 GPa show only a negligible enhancement of the MgB2 mass density, while a considerable enhancement of Jc is still observed. In both cases, this reflects an enhancement of grain connectivity, however in ex situ wires, the enhancement of Jc is connected to the partial disruption of the oxide layer around each MgB2 powder particle, in contrast to the enhancement of Jc in situ wires, which is correlated to a smaller void fraction and a larger contact area between neighbouring grains. It is well known that Jc of ex situ wires decreases after longer exposition times when exposed to air prior to annealing; after several months Jc falls to values ≤50% of the original value. After cold pressing, we have found that Jc of the same wire exceeded the original values, even after exposing the unreacted wire for >1 year to air. A lower electrical resistivity is measured on pressed ex situ MgB2 wires, which confirms the improvement of grain connectivity due to the breakage of the oxide layers. Thus, the application of high pressure at room temperature allows us to recover the values of Jc for ex situ wires even after they have been degraded either by low quality MgB2 precursors or by prolonged ageing of the already formed wire prior to the final heat treatment. The limits of the Jc enhancement in ex situ wires are discussed.

  8. Influence of intermediate annealing on the microstructure of in situ MgB 2/Fe wire

    NASA Astrophysics Data System (ADS)

    Jun, B.-H.; Kim, Y.-J.; Tan, K. S.; Kim, J. H.; Xu, X.; Dou, S. X.; Kim, C.-J.

    2008-09-01

    A two-step process with an intermediate annealing was used in an attempt to improve the critical current density ( Jc) through a core densification of in situ MgB 2/Fe wires. MgB 2/Fe wires were first drawn to an outer diameter of 1.9 mm, and heat-treated at 600 °C for 0.5, 1, 2 and 4 h in flowing Ar gas as an intermediate annealing (IA) step. In the cases of the wires heat-treated at 600 °C for 0.5-2 h, un-reacted Mg and MgB 2 phases coexisted. The sample heat-treated for 4 h showed a full MgB 2 formation through a solid state reaction. The intermediate-annealed wires were then further drawn to an outer diameter of 1.42 mm as an attempt to reduce the porosity. This second mechanical deformation crushed the superconducting grains into smaller pieces and mixed preformed MgB 2 phase with un-reacted Mg and B powders. And then, the second heat-treatment was performed at 650 °C for 0.5 h. The Jc values of the MgB 2 wires prepared with an intermediate annealing step were notably lower, over a wide range of magnetic fields, when compared to the reference sample heat-treated once at 650 °C for 0.5 h. The decrease in Jc is probably due to the introduction of a large amount of weak links between the grains.

  9. Filamentary MgB2 wires manufactured by different processes subjected to tensile loading and unloading

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Kulich, M.; Kopera, L.; Melišek, T.; Kováč, J.; Hušek, I.

    2017-06-01

    A reversible strain effect on the transport critical current (I c) of filamentary MgB2 wires manufactured by three different processes has been examined at 4.2 K and under an external field of 5 T. MgB2 wires with a Nb barrier and a Monel® outer sheath made by powder-in-tube ex situ, in situ and by diffusion of magnesium into the boron process, have been examined. The wire samples were loaded and partially unloaded at progressively higher strain levels to determine the irreversible strain limit (ε irr), which is defined as the ultimate strain where the critical current (I c) is still reversible. It was found that the strain tolerances of the tested MgB2 wires are affected by the production process. The highest annealing temperature (>900 °C), applied in the ex situ process, causes an apparent softening of the Monel® and, together with the poor grain connectivity of MgB2 filaments, leads to the lowest strain tolerance (ε irr = 0.20%). The best grain connectivity, in internal Mg diffusion (IMD)-made MgB2, combined with a stronger Monel® sheath (heat treated at a lower temperature ∼640 °C) results in the best strain tolerance (ε irr = 0.55%).

  10. Ex situ MgB2 barrier behavior of monofilament in situ MgB2 wires with Glidcop® sheath material

    NASA Astrophysics Data System (ADS)

    Kario, A.; Morawski, A.; Häßler, W.; Nenkov, K.; Schubert, M.; Herrmann, M.; Ringsdorf, B.; Schlachter, S. I.; Goldacker, W.; Holzapfel, B.; Schultz, L.

    2010-11-01

    Cost-effective MgB2 wires are highly sought after to replace the widely used NbTi conductors in superconducting magnets, e.g. for magnetic resonance imaging (MRI). One method of choice for lowering conductor costs is to use a less expensive barrier and sheath material. From this point of view copper is a good candidate for the sheath, and additionally has other advantageous properties, e.g. the best electrical and thermal conductivity at operating temperature. One major disadvantage of copper is its high chemical reactivity. This material reacts fast with magnesium and forms Mg-Cu alloys, removing the starting element necessary for MgB2 formation. To prevent this reaction, a special coaxial architecture was applied using ex situ MgB2 powder as a chemical barrier between the copper sheath and the in situ MgB2 powder core. The Glidcop® (dispersed strengthened copper) sheathed MgB2 wires with an ex situ barrier have been fabricated by the conventional powder in tube (PIT) method. Besides avoiding the reaction of Mg and Cu, the barrier also contributes to the superconducting core fraction and increases the filling factor up to 50%. The Glidcop® sheathed wires with an ex situ MgB2 commercial powder used as a barrier have been successfully drawn to a diameter of 1.2 mm and then a pressure-assisted heat treatment was applied. For our case of specified in situ and ex situ powders the pressure-assisted preparation of at least 0.15 GPa was found to be important for the densification of the ex situ barrier.

  11. In situ Pulsed Laser Deposition of C-Axis Oriented MgB2 Films and Their Characterization

    NASA Technical Reports Server (NTRS)

    Shinde, Sanjay; Lakew, Brook; Ogale, S. B.; Kulkarni, V. N.; Kale, S. N.; Venkatesan, T.

    2004-01-01

    The recent discovery of an intermetallic superconductor MgB2 has renewed interest in the area of superconductivity not only because of fundamental understanding of superconductivity but also due to its potential applicability in devices such as thermal detectors. Considerable amount of research has been devoted to obtain MgB2 films by an all in situ growth technique. We have grown MgB2 thin films by an all in situ pulsed laser deposition process from pure B and Mg targets. Ultrathin layers of B and Mg were deposited in a multilayer configuration. Hundreds of such Mg-B bilayers with a capping Mg layer on the top were deposited on sapphire substrate. These depositions were done in high vacuum (approx. 10(exp -7) Torr) and at room temperature. After deposition, such a configuration was annealed at high temperature for a short time in a forming gas (4% H2 in Ar). The best films, obtained by this procedure, showed superconducting transition temperature approx. 30 K. These films have been characterized by x-ray diffraction, Rutherford Backscattering Spectrometry, AC susceptibility-, resistivity- (with and without magnetic field) and 1/f noise-measurements. The physical properties of these films will be presented and discussed.

  12. In situ Pulsed Laser Deposition of C-Axis Oriented MgB2 Films and Their Characterization

    NASA Technical Reports Server (NTRS)

    Shinde, Sanjay; Lakew, Brook; Ogale, S. B.; Kulkarni, V. N.; Kale, S. N.; Venkatesan, T.

    2004-01-01

    The recent discovery of an intermetallic superconductor MgB2 has renewed interest in the area of superconductivity not only because of fundamental understanding of superconductivity but also due to its potential applicability in devices such as thermal detectors. Considerable amount of research has been devoted to obtain MgB2 films by an all in situ growth technique. We have grown MgB2 thin films by an all in situ pulsed laser deposition process from pure B and Mg targets. Ultrathin layers of B and Mg were deposited in a multilayer configuration. Hundreds of such Mg-B bilayers with a capping Mg layer on the top were deposited on sapphire substrate. These depositions were done in high vacuum (approx. 10(exp -7) Torr) and at room temperature. After deposition, such a configuration was annealed at high temperature for a short time in a forming gas (4% H2 in Ar). The best films, obtained by this procedure, showed superconducting transition temperature approx. 30 K. These films have been characterized by x-ray diffraction, Rutherford Backscattering Spectrometry, AC susceptibility-, resistivity- (with and without magnetic field) and 1/f noise-measurements. The physical properties of these films will be presented and discussed.

  13. Properties of hydrostatically extruded in situ MgB2 wires doped with SiC

    NASA Astrophysics Data System (ADS)

    Pachla, W.; Morawski, A.; Kovác, P.; Husek, I.; Mazur, A.; Lada, T.; Diduszko, R.; Melisek, T.; Strbík, V.; Kulczyk, M.

    2006-01-01

    In situ nano-SiC doped MgB2 wires were fabricated from MgH2 and B powders. Hydrostatic extrusion, followed by rotary swaging and two-axial rolling, were applied as the forming processes. The critical current Jc of MgB2 wires, made from MgH2 and B powders, was significantly improved by nano-SiC doping. Nano-SiC doping substantially increased the upper critical (irreversibility) field Bc 2 above 20 T. The maximum Jc values were measured for samples having 6 at.% SiC in low field and for those having 12 at.% SiC in high field, above 10 T. During the final sintering at 670 °C, the SiC decomposed and formed an Si-rich layer at the inner circumference of the Fe sheath. The composition of the core of SiC doped wires is more inhomogeneous in comparison to undoped ones, with MgO, Mg2Si and probably Mg2SiO4 as the major segregated phases. Strong segregation of Si within the MgB2 core was also observed. The highest Tc-mid = 39.3 K was measured for undoped wire. For the optimal SiC doping amount ~6 at.%, at high field, there was no difference in Jc between hydrostatically extruded and hydrostatically extruded plus two-axially rolled wire. This can be attributed to the beneficial effect of hydrostatic extrusion, which causes higher density of the core in comparison to traditional deformation processes.

  14. Preparation of SiC doped In-Situ MgB2 mono- and 7-filamentary wires by continuous tube forming and filling technique

    NASA Astrophysics Data System (ADS)

    Ma, L.; Suo, H. L.; Zhang, Z. L.; Gao, T. Y.; Liu, M.; Zhao, Y.; Zhou, M. L.; Flükiger, R.

    2008-02-01

    Long lengths of in-situ SiC doped MgB2/Fe mono- filamentary wires with high critical current densities and 7- filamentary MgB2/Nb/Cu/Fe wires with better thermal stability have been fabricated by either continuous tube forming & filling (CTFF) technique or combining both powder in tube (PIT) and CTFF process, respectively. Particular efforts were made in view of the optimization of the manufacturing and annealing processes of the wires. The as obtained wires were sintered under a vacuum furnace at different sintering temperatures and the optimized sintering of the MgB2 wires were investigated by the analysis of optical microscope, XRD, SEM, and the transport Jc measurements. The Jc value in a 8 at.% SiC doped MgB2/Fe mono- filamentary wire is more than 104A/cm2 at 4.2 K and a field of 11 T. While in doped 7- filamentary wire, the similar Jc value (104A/cm2) is obtained at 4.2 K and a field of 7.5 T. Moreover, the n factors are determined to be 33 and 10 at 11 T in the mono- and 7- filamentary MgB2wires with SiC doping, respectively, indicating the possibility to use the as fabricated MgB2 wires in the persistent mode for fields from 0.5 T to 10 T at 4.2 K.

  15. Copper sheath MgB 2 wires fabricated by an in situ PIT method

    NASA Astrophysics Data System (ADS)

    Shimura, S.; Machi, T.; Murakami, M.; Koshizuka, N.; Mochizuki, K.; Ishikawa, I.; Shibata, N.

    2004-10-01

    We investigated the applicability of Cu as sheath materials for MgB 2 wires prepared by in situ PIT (powder-in-tube) method in comparison with stainless steal. Since the critical current density of MgB 2 increases with TiH 2 doping, we prepared TiH 2 doped MgB 2 Cu sheath wires 40 m in length and ∅ 1.0 mm or 0.5 × 1.0 mm 2 in cross section by rotary swaging, drawing, and two-axial rolling under cold working. We then annealed the samples at 600-850 °C for 1-2 h in Ar gas atmosphere. The critical current of TiH 2 (6%) doped MgB 2/Cu short sample annealed at 650 °C reached 208 A ( Jc=230 kA/cm 2) at 4.2 K and self-field. We also fabricated several coils using these wires. The Ic value was ∼100 A at 4.2 K for a coil prepared with use of a 5 m length wire. These results suggest that it is possible to fabricate Cu sheathed MgB 2 wires with good performance by using the in situ PIT method.

  16. Electromagnetic properties and microstructures of in situ MgB2 wires made from three types of boron powders

    NASA Astrophysics Data System (ADS)

    Kodama, Motomune; Kotaki, Hiroshi; Yamamoto, Hiroyuki; Iwane, Tomohiro; Tanaka, Kazuhide; Tanaka, Hideki; Okishiro, Kenji; Okamoto, Kazutaka; Nishijima, Gen; Matsumoto, Akiyoshi; Kumakura, Hiroaki; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Kishio, Kohji

    2016-10-01

    In powder-in-tube processed MgB2 wires, the choice of boron powder as a starting material crucially affects their performance. In this paper, we prepared in situ MgB2 wires from three types of boron powders in various heat-treatment conditions and investigated their electromagnetic properties and microstructures. Their critical current density, J c, varied over a wide range from sample to sample. The difference in J c is understood to be caused by the effect of changes in the electrical connectivity, K, and intrinsic residual resistivity, ρ 0. Here, K represents the effective cross-sectional area for current, and ρ 0 reflects the degree of the charge carrier scattering caused by lattice defects. It was found that the use of boron powder with a large specific surface area leads to a large degree of lattice defects in MgB2 grains and enhances ρ 0, resulting in improving J c. The boron powder produced by thermal decomposition of B2H6 has a large specific surface area. Hence, this boron powder is the most suitable as a starting material for MgB2. Meanwhile, dry pulverization of low-cost boron powder, which is largely produced by active-metal reduction of B2O3, is also effective to increase its specific surface area without introducing impurities, resulting in the enhancement of J c in the entire magnetic field region. This finding broadens the choice of boron powder and contributes to realizing superconducting applications with excellent balance between performance and cost.

  17. Fast creation of dense MgB2 phase in wires made by IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kopera, L.; Kulich, M.

    2016-10-01

    Single-core MgB2 wires have been made by internal magnesium diffusion (IMD) into boron process. Heat treatments were performed at variable periods (4-90 min) for two adjusted temperatures 635 °C and 650 °C, with an overshoot of ≈20 °C after 5 min. Critical currents of differently treated MgB2/Ti/GlidCop wires have been measured and related with the MgB2 layers. The fast creation MgB2 compound has been observed after 8 min annealing at both temperatures and showing the critical current maxima. The less uniform MgB2 containing cracks was created for longer annealing periods (≥10 min), which resulted in lowered critical currents and worsened thermal stability. The fast creation of dense MgB2 allows it to utilize a continual and short heat treatment process for high current density wires made by IMD.

  18. In situ synthesis of MgB2 thin films for tunnel junctions

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Geerk, J.; Ratzel, F.; Linker, G.; Zaitsev, A. G.

    2004-11-01

    An approach to the in situ preparation of as-grown MgB2 thin films is presented. It comprises a conventional B sputter gun and a special Mg evaporator that provides a high Mg vapor pressure at the position of the substrate. Thin films deposited on r-plane sapphire substrates at a temperature of 440°C had a zero resistance Tc of 33K and a residual resistivity of 111μΩcm. Sandwich-type tunnel junctions with a natural MgB2 oxide as the potential barrier were prepared for superconducting tunneling spectroscopy. Voltage-dependent conductance measurements revealed estimates of the barrier thickness, height, and shape.

  19. Influence of nano-Cu additive on MgB2 phase formation, processing temperature, and transport properties

    NASA Astrophysics Data System (ADS)

    Varghese, Neson; Vinod, K.; Rahul, S.; Devadas, K. M.; Thomas, Syju; Pradhan, S.; Syamaprasad, U.

    2011-02-01

    Pure and nano-Cu doped MgB2/Fe superconducting wires were prepared by in situ powder-in-tube method at different temperatures (550-675 °C). The phase formation, microstructure, and transport critical current density of the wires were investigated as a function of the heat-treatment temperature. A small amount of nano-Cu addition (2.5 wt %) was found to dramatically decrease the reaction temperature of magnesium and boron, forming MgB2 without any degradation in the transport critical current. From x-ray diffraction and scanning electron microscopy analyses, it was found that the added Cu form a reacted phase Mg2Cu with Mg which melts at around 550 °C. This liquid phase helps the formation of MgB2 at a significant lower temperature with improved grain connectivity, grain size, and density. All Cu doped samples heat treated in the range of 550-650 °C exhibited a transport JC quite comparable to that of the pure sample processed at 650 °C, which shows that high quality MgB2 conductors can be produced even at 550 °C with minor Cu doping.

  20. Effect of various mechanical deformation processes on critical current density and microstructure in MgB2 tapes and wires

    NASA Astrophysics Data System (ADS)

    Zhou, Sihai; Pan, Alexey V.; Liu, Huakun; Horvat, Joseph; Dou, Shixue

    2002-11-01

    MgB2 tapes and wires have been prepared by the in situ reaction method. Two cycle drawing and groove-rolling were used for the mechanic deformation of the samples. The critical current density, Jc, as a function of applied magnetic field, Ba, was measured and compared for all the prepared samples. The influence of the different processing at its different stages on the MgB2 microstructure was studied by scanning electron microscopy. Weak links introduced in the superconducting core after the second cycle mechanical deformation could not be re-joined with a consecutive heat treatment. Accordingly, for these samples Jc(Ba) turned out to decrease significantly faster in an increasing field than for samples prepared with one-cycle processing.

  1. Multifilamentary MgB $_{2}$ 2 Wires Prepared by an In Situ Powder-in-Tube Method

    NASA Astrophysics Data System (ADS)

    Sobrero, C. E.; Vallejos, J. M.; San Martin, V.; Malachevsky, M. T.; Serquis, A. C.

    2015-04-01

    MgB has become a commercially attractive material for technological applications for its particular superconducting properties. However, due to its brittleness to obtain wires, a metallic sheath is needed for drawing. In the present work, grade 2 titanium has been used as sheath material, and several multifilamentary wires have been prepared. The powder-in-tube method has been used to prepare the wires with the in situ variant, where the sheath is filled with the unreacted precursor powders (Mg and B). Different thermal treatments have been investigated including several intermediate treatments during the drawing process in addition to the final one. This last treatment is necessary to accomplish the synthesis and heal the cracks generated during the cold work. The superconducting properties were determined by magnetization measurements on a SQUID magnetometer, and the microstructure evolution was followed by TEM and SEM microscopy. Mechanical behavior is also evaluated.

  2. Properties of seven-filament in situ MgB2/Fe composite deformed by hydrostatic extrusion, drawing and rolling

    NASA Astrophysics Data System (ADS)

    Kovác, P.; Hušek, I.; Pachla, W.; Kulczyk, M.

    2007-07-01

    Seven-filament MgB2/Fe wires and tapes were made by in situ processing using hydrostatic extrusion, rolling and drawing. Microhardness measurements have shown that the density of as-deformed cores reflects the applied deformation and follows the iron sheath hardness. The filament size was reduced from 245 µm down to 19 µm by rolling and the critical current densities of samples with different core sizes and deformation routes were compared. The highest current density was measured for the tape deformed by two-axial rolling and a filament size of 60 µm. Thinner filaments show lower Jc values due to hard inclusions present in low-purity boron powder (boron oxide), which reduce the transport current substantially. The obtained results show that a proper combination of extrusion and rolling deformations leads to high filament density in wires and tapes, which results in high transport current density.

  3. Low-temperature synthesis of MgB2 via powder metallurgy processing

    NASA Astrophysics Data System (ADS)

    Birol, Yucel

    2016-12-01

    Ball-milled Mg/B2O3 powder blends reveal interpenetrating layers of deformed magnesium and boron oxide grains that are increasingly refined with increasing milling time. Boron oxide is reduced by Mg and MgO thus formed reacts with the remaining B2O3 to produce Mg3(BO3)2 during ball milling for 30 min. Both B2O3 and Mg3(BO3)2 react with Mg to produce MgB2 upon further ball milling. An annealing treatment can be employed when ball milling is performed for less than 1 h as thermal exposure of the ball-milled Mg/B2O3 powder blends also leads to the formation of MgB2. The above reactions take place between 500 and 700 °C when the Mg/B2O3 powder blend is ball milled for 30 min, and between 450 and 550 °C, after ball milling for 1 h. This is a very attractive route owing to processing temperatures where the volatility of Mg is no longer a problem.

  4. In-situ study on growth units of Ba2Mg(B3O6)2 crystal

    NASA Astrophysics Data System (ADS)

    Lv, X. S.; Sun, Y. L.; Tang, X. L.; Wan, S. M.; Zhang, Q. L.; You, J. L.; Yin, S. T.

    2013-05-01

    BMBO (Ba2Mg(B3O6)2 crystal) is an excellent birefringent crystal and a potential stimulated Raman scattering (SRS) crystal. In this paper, high temperature Raman spectroscopy was used to in-situ study the melt structure near a BMBO crystal-melt interface. [B3O6]3- groups were found in this region. The result reveals that both of BaO bonds and MgO bonds are the weak bonds in the BMBO crystal structure. During the melting process, the crystal structure broke into Ba2+ ions, Mg2+ ions and [B3O6]3- groups. Our experimental results confirmed that the well-developed faces of BMBO crystals are the (001), (101) and (012) faces. Based on attachment energy theory, the crystal growth habit was discussed. The (001) (101) and (012) crystal faces linked by the weak BaO bonds and MgO bonds have smaller attachment energies and slower growth rates, and thus present in the final morphology. The (012) crystal face has a multi-terrace structure, which suggests that BMBO crystal grows with a layer-by-layer mode.

  5. Ex-situ manufacturing of SiC-doped MgB2 used for superconducting wire in medical device applications

    NASA Astrophysics Data System (ADS)

    Herbirowo, Satrio; Imaduddin, Agung; Sofyan, Nofrijon; Yuwono, Akhmad Herman

    2017-02-01

    Magnesium diboride (MgB2) is a superconductor material with a relatively high critical temperature. Due to its relatively high critical temperature, this material is promising and has the potential to replace Nb3Sn for wire superconducting used in many medical devices. In this work, nanoparticle SiC-doped MgB2 superconducting material has been fabricated through an ex-situ method. The doping of nanoparticle SiC by 10 and 15 wt% was conducted to analyze its effect on specific resistivity of MgB2. The experiment was started by weighing a stoichiometric amount of MgB2 and nanoparticles SiC. Both materials were mixed and grounded for 30 minutes by using an agate mortar. The specimens were then pressed into a 6 mm diameter stainless steel tube, which was then reduced until 3 mm through a wire drawing method. X-ray diffraction analysis was conducted to confirm the phase, whereas the superconductivity of the specimens was analyzed by using resistivity measurement under cryogenic magnetic system. The results indicated that the commercial MgB2 showed a critical temperature of 37.5 K whereas the SiC doped MgB2 has critical temperature of 38.3 K.

  6. Development and Properties of Advanced Internal Magnesium Infiltration (AIMI) Processed MgB2 Wires

    SciTech Connect

    Collings, Prof Edward William; Sumption, Prof Michael D; Li, Guangze; Susner, Michael A

    2016-01-01

    The development, processing, properties, and formation mechanisms of Advanced Internal Magnesium Infiltration (AIMI) MgB2 wires are discussed against a background of the related and original processes, Internal-Magnesium-Diffusion (IMD) and Magnesium-Reactive-Liquid-Infiltration (Mg-RLI). First reviewed are the formation, properties and applications of Mg-RLI bulks as basis for discussions of Mg-RLI-processed and IMD-processed wires. The transition from Mg-RLI- and IMD- to AIMI wires is explained, and the relative performances of powder-in-tube (PIT), IMD and AIMI wires are summarized in the form of an iso-Je diagram of Jc,nb versus Anb/ATOT in which ATOT, Anb, Jc,nb, and Je are, respectively, the wire s cross-sectional area, the area inside the chemical barrier, the critical current (Ic) normalized to Anb, and Ic normalized to ATOT. After the details of AIMI wire fabrication selection of starting powders, dopants, and reaction heat treatments are introduced the report goes on to describe in detail the development of high performance AIMI wires: layer Jcs, fill factors, Jes, and the effects of wire size, multifilamentarization, doping with C, and co-doping with C and Dy2O3. The two-stage mechanism of layer formation in AIMI wires is discussed: first the reactive infiltration of liquid Mg into a porous B pack, a process that terminates with the formation of a dense MgB2 layer; second the slow diffusion of Mg into any remaining B through that MgB2 layer. The report concludes with a brief general discussion of anisotropy, current percolation, and the Jc field dependence of MgB2 wires.

  7. Fabrication of MgB2 superconducting wires with a hybrid method combining internal-Mg-diffusion and powder-in-tube processes

    NASA Astrophysics Data System (ADS)

    Ye, ShuJun; Matsumoto, Akiyoshi; Togano, Kazumasa; Zhang, YunChao; Ohmura, Takahito; Kumakura, Hiroaki

    2014-05-01

    We have previously reported that the addition of Mg powder to the B powder layer (B layer) of internal-Mg-diffusion (IMD)-processed MgB2 wires can decrease the amount of unreacted B particles, and hence increase the critical current density (Jc). As the amount of Mg powder is increased, the diameter of the central Mg rod must be reduced in order to maintain an overall Mg:B molar ratio of 1:2, corresponding to stoichiometric MgB2. If this ratio is achieved by the Mg powder alone, then the required diameter of the Mg rod is zero, which means that the IMD process becomes the powder-in-tube (PIT) process. A hybrid process intermediate between the IMD and PIT processes is proposed as a new approach for fabricating MgB2 wires. In the present study, the critical current and microstructure of MgB2 wires fabricated using this method are investigated. It is found that the method yields a higher engineering critical current density (Je, = Jc × MgB2 area fraction, where the MgB2 area fraction corresponds to the ratio of the MgB2 cross-sectional area to the total cross-sectional area of the wire) than that for either the IMD or the PIT method. Compared with the IMD method, the MgB2 layer thickness (the thickness of the MgB2 layer in the transverse cross section) is increased and the diameter of the central hole is decreased, thus increasing the MgB2 area fraction The proposed method also achieves a much higher MgB2 layer density, and thus a much higher Jc, than is possible using the PIT method. The combination of these factors leads to the enhanced Je value of MgB2 wires.

  8. The effect of used deformation, metal sheath and heat treatment on the I-V curve of ex situ MgB 2 composite

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.

    2004-01-01

    Current-voltage characteristics of MgB 2 composite wires made of ex situ process using Cu, Fe and stainless steel (SS) sheaths have been measured at 4.2 K in the self-field and external magnetic field between 2 and 4 T. It was found that the used mode of deformation (drawing, rotary swaging and two-axial rolling) influences the slope of I-V curve due to affected grain connectivity. Final heat treatment at 950 °C/0.5 h improves grain connectivity apparently, which results in I-V characteristic with very high n-exponents. The n-exponents of multi-core wires measured in external field are apparently lower due to a current sharing among the non-uniform filaments surrounded by high resistance matrix.

  9. Recent developments in melt processed Gd-123 and MgB2 materials at RTRI

    NASA Astrophysics Data System (ADS)

    Muralidhar, M.; Fukumoto, Y.; Ishihara, A.; Suzuki, K.; Tomita, M.; Koblischka, M. R.; Yamamoto, A.; Kishio, K.

    2014-01-01

    In this contribution we will report on the current status, recent developments in GdBa2Cu3Oy "Gd-123" and MgB2 material processing, characterization, and applications at the Railway Technical Research Institute (RTRI). Batch-processing of Gd-123 bulk material grown in air was performed using novel thin film Nd-123 seeds grown on MgO crystals. In this way, we are able to fabricate materials with good quality, and uniform performance. We examined the technology of the uniform performance of the large 45 mm diameter, single grain Gd-123 bulks for use in application of NMR. For this purpose, four 5 mm thick pieces are cut vertically from a single grain Gd-123 material and the magnetic field distribution is measured using a scanning hall sensor. We found that all four pieces are single domain and exhibit a quite uniform field distribution. Furthermore, the batch-processed bulk materials are used for the construction of a chilled Maglev vehicle. On the other hand, to optimize the trapped field performance of bulk MgB2 material, several samples were prepared by solid state reaction at different temperatures ranging from 750 to 950 °C in pure argon atmosphere. X-ray diffraction results indicated that single phase and homogenous MgB2 bulks are produced when sintering them around 775 °C. Further, atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicated that an uniform grain size results by controlling the processing temperature. So, higher trapped fields can be achieved in sintered MgB2 material.

  10. Magnetization AC losses in MgB2 wires made by IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, J.; Šouc, J.; Kováč, P.; Hušek, I.

    2015-01-01

    Magnetization AC losses of MgB2 superconductors with one and four filaments made by an internal magnesium diffusion (IMD) into boron process were measured and analyzed. For AC loss measurement a system based on a calibration-free method was used. Short samples of MgB2 wires were exposed to an external magnetic field with amplitudes up to 0.07 T, frequencies up to 1200 Hz, and a temperature range between 15 K and 40 K. A strong effect of eddy current losses was found in single-core wire containing pure copper sheath, which was proved by the same wire measurement after Cu etching. The impact of coupling current losses in non-twisted four-filament wire and the decoupling effect after twisting were observed. Coupling current losses in a low-frequency region were effectively reduced in agreement with theoretical assumption. The degradation of transport currents due to torsion stress by twisting was taken into account and the normalized AC losses of MgB2 wires made by IMD and powder-in-tube processes were compared. It appears that the IMD process is more perspective for AC applications due to much higher current densities and smaller degradation of current-carrying capability by twisting.

  11. High temperature and low field regime vortex phase diagram of in-situ prepared stainless steel sheathed MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Rajput, Suchitra

    2017-04-01

    A magnetic field-temperature vortex phase diagram has been proposed for MgB2 on the basis of magnetoresistance studies performed on an in-situ prepared stainless steel sheathed MgB2 tapes. Thermally activated flux flow (TAFF) behavior is analyzed using Arrhenius relation. Low dissipative part of magnetoresistance with temperature is well described by vortex glass theory. Above critical region, the resistive behavior is influenced by fluctuation conductivity. In addition, a considerable vortex liquid region below HC2 is also observed but TAFF region is found to be quite narrow.

  12. Microwave properties of MgB2 thin films prepared in situ by thermal evaporation combined with sputtering

    NASA Astrophysics Data System (ADS)

    Zaitsev, A. G.; Schneider, R.; Hott, R.; Ratzel, F.; Linker, G.; Geerk, J.

    2006-06-01

    Superconducting MgB2 thin films were prepared in situ using a combination of rf magnetron sputtering of B and thermal evaporation of Mg. The films exhibited Tc of up to 36 K. The microwave measurements were performed on 14 × 14 mm2 films using both Cu-shielded and Nb-shielded sapphire puck resonators at the frequency of 18.8 GHz. The hf surface resistance (RS) and the change of the hf surface reactance (ΔXS) were determined. The films exhibited low RS matching the literature results for high-quality MgB2 films. Below 3K RS reached 3-5 µΩ which was the resolution limit of our measurement. The temperature dependences of both RS and ΔXS were in good agreement with BCS theory. From the RS(T) dependence we obtained an energy gap Δ(0) ≈ 3 meV. The measured variation of the London penetration depth with temperature, ΔλL(T), was also in good agreement with the BCS model. Using the BCS relation between the energy gap and the penetration depth we fitted our experimental ΔλL(T) data and obtained λL(0) values, which ranged for different films from 85 to 100 nm.

  13. In situ deposition of MgB 2 thin films by magnetron cosputtering and sputtering combined with thermal evaporation

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Geerk, J.; Linker, G.; Ratzel, F.; Zaitsev, A. G.; Obst, B.

    2005-07-01

    We report on two approaches to the in situ synthesis of superconducting MgB2 thin films. In the first approach, Mg and B were simultaneously sputtered from two separate planar targets. The substrate temperature Ts was limited to a small range of 290-320 °C. The resulting films on sapphire substrates were c-axis textured with low growth quality. Their transition temperature Tc reached a maximum of 24 K with a transition width of 0.6 K. A short-time in situ annealing at 600 °C improved Tc to 28 K. In the second approach, the Mg sputter source was replaced by a specially designed Mg evaporator. Due to this intense Mg source Ts could be increased to 440 °C, and Tc of the "as-grown" films rose to 33 K. Short-time in situ annealing after the film deposition enhanced Tc to 36 K. For these films we also measured a high critical current density of 15 MA/cm2 at 6 K.

  14. Effect of boron particle size on microstructure and superconducting properties of in-situ Cu addition MgB2 multifilamentary wire

    NASA Astrophysics Data System (ADS)

    Hishinuma, Y.; Kikuchi, A.; Shimada, Y.; Hata, S.; Takeuchi, T.; Yamada, S.; Sagara, A.

    2014-05-01

    In previous studies, the secondary (impurity and non-reactive) phase and voids were observed in MgB2 matrix after the heat treatment, and then these are the lowering factors of critical current density (Jc) property. In order to improve Jc property by microstructure control of MgB2 matrix, the fine elemental boron powder as the raw material was carried out using the high-speed vibrated milling with tungsten carbide (WC) jar. The average particle size of metal boron powder was decreased from 1.14 μm to 0.20 μm by the high-speed vibrated milling. The various fine particle boron powders as the function of milling time were also prepared, and in-situ Cu addition MgB2 multifilamentary wires using these fine boron powders were fabricated. Critical transition temperature (Tc) value of Cu addition MgB2 wire using fine boron powder obtained to about 37 K. No change of the Tc property by the different particle sized boron powders was confirmed. In this paper, the comparisons of microstructure and superconducting properties between the different boron particle sizes were investigated.

  15. Influence of crystalline boron powders on superconducting properties of C-doped internal Mg diffusion processed MgB2 wires

    NASA Astrophysics Data System (ADS)

    Wang, Dongliang; Zhang, Xianping; Tang, Shaopu; Xu, Da; Yao, Chao; Dong, Chiheng; Xu, Zhongtang; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2015-10-01

    Monofilament MgB2/Fe wires or tapes were fabricated with two different purity crystalline boron powders, using internal magnesium diffusion (IMD) and in situ powder-in-tube (PIT) processes. To evaluate which method was more insensitive to the purity of the boron powders, a sensitivity factor was used. It was found that the IMD process was less sensitive to the purity of the boron powders, compared to the PIT method. Furthermore, J c values of the IMD-processed wires were higher than those of the PIT-processed samples. The reduced porosity and hence the increased density in the IMD-processed samples was thought to be the main reason. Although a number of B-rich particles remained in the MgB2 region, a layer J c as high as 4.8 × 104 A cm-2 at 4.2 K and 10 T was still obtained in the IMD-processed wire, which was comparable to that of IMD-processed wires fabricated using amorphous boron powders.

  16. Continuous- and batch-processed MgB 2/Fe strands--transport and magnetic properties

    NASA Astrophysics Data System (ADS)

    Collings, E. W.; Lee, E.; Sumption, M. D.; Tomsic, M.; Wang, X. L.; Soltanian, S.; Dou, S. X.

    2003-04-01

    The tube filling/forming powder-in-tube (PIT) technique was employed at Hyper Tech Research for the continuous processing of MgB 2/Fe composite strand. Demonstration lengths of up to 70 m of 1.2 mm diameter precursor strand--an Fe-clad Mg + B elemental powder mixture--have so far been produced. Short samples of this strand, heat treated for 3-30 min/800-950 °C, have yielded transport critical current densities ( Jc) of 2-3×10 4 A/cm 2 at 4 K/4 T, 4×10 4 A/cm 2 at 4 K/2 T, and at 4 K in self field an extrapolated Jc of at least 2×10 5 A/cm 2. Batch-processed PIT MgB 2/Fe strands and tapes were made at the University of Wollongong’s Institute for Superconducting and Electronic Materials. These were the focus of magnetization- and magnetic-shielding studies. Depending on the thickness of the Fe sheath, the superconducting core could be completely shielded at low fields (e.g. below 2 kOe). Taking this into account, the magnetic Jc is extracted, and found to be comparable to the extrapolated transport value.

  17. Superconducting MgB2 wires with vanadium diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hušek, I.; Kováč, P.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.; Szundiová, B.

    2017-10-01

    Single-core MgB2 wires with a vanadium barrier and Cu stabilization have been made by the in situ powder-in-tube (PIT) and internal magnesium diffusion (IMD) into boron processes. Heat treatment of PIT wires was done at the temperature range of 650 °C–850 °C/30 min. Critical currents of differently treated MgB2/V/Cu wires have been measured and related with the structure of MgB2. It was found that critical current density of MgB2/V wire annealed above 700 °C decreases rapidly. The obtained results clearly show that vanadium is a well formable metal and can be applied as an effective diffusion barrier for MgB2 wires heat-treated at temperatures ≤700 °C. This temperature limit is well applicable for MgB2 wires with high current densities made by PIT and also by the IMD process.

  18. Development of magnesium diboride (MgB 2) wires and magnets using in situ strand fabrication method

    NASA Astrophysics Data System (ADS)

    Tomsic, Michael; Rindfleisch, Matthew; Yue, Jinji; McFadden, Kevin; Doll, David; Phillips, John; Sumption, Mike D.; Bhatia, Mohit; Bohnenstiehl, Scot; Collings, E. W.

    2007-06-01

    Since 2001 when magnesium diboride (MgB 2) was first reported to have a transition temperature of 39 K, conductor development has progressed to where MgB 2 superconductor wire in kilometer-long piece-lengths has been demonstrated in magnets and coils. Work has started on demonstrating MgB 2 wire in superconducting devices now that the wire is available commercially. MgB 2 superconductors and coils have the potential to be integrated in a variety of commercial applications such as magnetic resonance imaging, fault current limiters, transformers, motors, generators, adiabatic demagnetization refrigerators, magnetic separation, magnetic levitation, energy storage, and high energy physics applications. This paper discusses the progress on MgB 2 conductor and coil development in the last several years at Hyper Tech Research, Inc.

  19. In Situ Processing.

    ERIC Educational Resources Information Center

    Edgar, T. F.; Schechter, R. S.

    1980-01-01

    Describes research on in situ processing to develop necessary theory and understanding of the underground process to facilitate commercialization of a wide range of mineral deposits. Goal is to produce laboratory and computer-based tools to allow site evaluation based on field and laboratory measurements of mineral and associated overburdens.…

  20. Graphite coating effects on the critical current characteristics of MgB 2/Cu wires fabricated by an in situ PIT method

    NASA Astrophysics Data System (ADS)

    Shimura, S.; Machi, T.; Nakao, K.; Koshizuka, N.; Tanaka, S.; Mochizuki, K.; Shibata, N.; Ushio, K.

    2005-10-01

    In order to improve the critical current characteristics of Cu sheathed MgB2 wires, we studied the carbon doping and coating effects on JC of wires prepared by an in situ powder-in-tube (PIT) method. Raw materials of Mg and B powders were mixed with a certain amount of MgB2 powder to increase the core density of wires in the heat treated samples. The pellets of these mixed powders were inserted into Cu sheaths and manufactured into wires by rotary swaging, two-axial rolling and drawing under cold-working. The wires were finally heat treated at 600 °C for 2 h in Ar gas atmosphere. The critical current IC of short samples of graphite 5 at.% doped MgB2/Cu with diameter of 1.0 mm reached 548 A (JC = 440 kA/cm2) at 4.2 K in self-field. The reaction of Mg with Cu decreased for graphite coating samples compared with non-coating ones. We obtained high performance MgB2/Cu wires by doping of diamond and graphite powder in the in situ PIT method. We found that the graphite coating on the inside surface of Cu sheath was effective for suppressing the reaction of Mg with Cu sheath. We also fabricated solenoid coils by wind and react method heat treated under the above conditions. The IC value was 230 A at 4.2 K for a coil produced by using a 16 m wire. This coil generated a magnetic field of 0.42 T at liquid He temperature.

  1. Improved transport properties and connectivity of in situ MgB 2 wires obtained by Cold High Pressure Densification (CHPD)

    NASA Astrophysics Data System (ADS)

    Flükiger, R.; Hossain, M. S. A.; Senatore, C.; Rindfleisch, M.

    2011-11-01

    The critical current density, Jc, of in situ MgB2 wires with C4H6O5 (malic acid) has been strongly enhanced by means of Cold High Pressure Densification (CHPD) at pressures up to 2.5 GPa prior to reaction. An increase in Jc by factors 2 and 8 was observed at 4.2 and 20 K, regardless of the applied field. Densified wires were found to exhibit a higher homogeneity due to enhanced connectivity. In addition, a higher C content was found, as shown by the lattice parameter change, the decrease of Tc, the shift of the calorimetric Tc distribution and a reduced anisotropy in tapes obtained from the same wires. The higher C content in densified wires is responsible for the observed enhancement of Birr by more than 1 T, up to 11 T at 20 K. Almost isotropic Jc values were obtained for C4H6O5 added square wires of 1 × 0.6 mm2 cross section, the values of Jc(4.2 K) = 1 × 104 A/cm2 for fields // and ⊥ to the wider surface being obtained at 13.8 and 13.1 T (1 μV/cm criterion), the values for 20 K being 6.4 and 6.2 T, respectively. The method was successfully applied to mono- and multifilamentary wires with lengths up to several meters, suggesting applicability for industrial lengths.

  2. Superconducting MgB2 thin films grown by pulsed laser deposition on Al2O3(0001) and MgO(100) substrates

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Dai, S. Y.; Zhou, Y. L.; Chen, Z. H.; Cui, D. F.; Xu, J. D.; He, M.; Lu, H. B.; Yang, G. Z.; Fu, G. S.; Han, L.

    2001-11-01

    Superconducting MgB2 thin films were fabricated on Al2O3(0001) and MgO(100) substrates by a two-step method. Boron thin films were deposited by pulsed laser deposition followed by an ex-situ annealing process. Resistance measurements of the deposited MgB2 films show a Tc of 38.6 K for MgB2/Al2O3 and 38.1 K for MgB2/MgO. Atomic force microscopy, scanning electron microscopy and x-ray diffraction were used to study the properties of the films. The results indicate that the MgB2/Al2O3 films consist of well-crystallized grains with a highly c-axis-oriented structure while the MgB2/MgO films have a dense uniform appearance with an unfixed orientation.

  3. Microstructure and superconducting properties of nanocarbon-doped internal Mg diffusion-processed MgB2 wires fabricated using different boron powders

    NASA Astrophysics Data System (ADS)

    Xu, Da; Wang, Dongliang; Li, Chen; Yuan, Pusheng; Zhang, Xianping; Yao, Chao; Dong, Chiheng; Huang, He; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-04-01

    MgB2/Nb/Monel monofilament wires were fabricated using four different boron powders by an internal Mg diffusion (IMD) process. The microstructure, morphology and the critical current density (J c) of the used boron powders and the formative MgB2 layers were analyzed and compared. It was found that the purity and particle size of the boron powder influence the superconducting properties of MgB2 wires; further that the optimized heat-treatment condition also depends on the quality of the boron powder. The highest J c was obtained in the MgB2 layer made using amorphous boron (AB) powder, although a certain amount of voids existed in the superconducting layer. The IMD-processed MgB2 layer fabricated using high-purity boron (HB) powder had also a high J c compared with the powder-in-tube (PIT) process and a few unreacted boron particles remained in it. MgB2 wire fabricated using low-purity boron (LB) powder had a high cost-performance ratio compared with the others, which is expected to allow the fabrication of large-scale and low-cost superconducting wires for practical application. However, the enhancement of the J c was not found in the MgB2 layer manufactured using the ball-milled LB (MLB) powder as expected due to the increased percentage of impurity.

  4. Significant improvement in the critical current density of MgB2 bulks in situ sintered at low temperature by excess Mg addition

    NASA Astrophysics Data System (ADS)

    Ma, Zongqing; Liu, Yongchang; Cai, Qi; Yu, Liming

    2014-01-01

    MgB2 bulks with excess Mg addition were rapidly synthesized by sintering at low temperature in present work. It is found that even after ball milling treatment of original powders, the reaction between Mg and B during subsequent low temperature sintering process was uncompleted within 5 h and there is still some residual Mg. On the other hand, the presence of residual Mg can make the sintering microstructure more homogeneous and dense, and also reduce lattice defects and mechanical strains. All the factors are contributed to the improvement of the grain connectivity in the samples with excess Mg addition sintered at low temperature compared to the reference MgB2 sample sintered at high temperature. Hence, Jc of these prepared samples is enhanced significantly across the whole measured fields. Especially, at 20 K, 2 T, the value of Jc in the 5 h-sintered MgB2 bulk with Mg addition is above 1 × 105 A cm-2. The technique developed in present work is an effective and low-cost way to further enhance Jc in the MgB2 superconductors without using expensive nanometer-size dopants.

  5. Optimization of vortex pinning at grain boundaries on ex-situ MgB2 bulks synthesized by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Naito, Tomoyuki; Endo, Yuri; Fujishiro, Hiroyuki

    2017-09-01

    Grain boundaries are well known to be the predominant pinning centers in MgB2 superconductors. To study the effects of grain boundaries on the trapped field properties of MgB2 bulk, we prepared MgB2 bulks by a spark plasma sintering method using a ball-milled starting powder. The trapped field was maximized for the bulk made from the ball-milled powder with crystallite size, τ, of 27 nm; the highest trapped field, {B}{{T}}, of 2.3 T achieved at 19.3 K was 1.2 times larger than that of the bulk made from the non ball-milled powder (τ = 50 nm). The degradation of the trapped field for the bulk from finer powder (τ = 6 nm) originated mainly from the lowered {T}{{c}}. The critical current density, {J}{{c}}, and the pinning force density, {F}{{p}}, were also maximized for the bulk from τ = 27 nm. The competition between the increase of the numerical density of grain boundaries and the degradation of superconductivity determined the vortex pinning properties for the MgB2 bulks with mechanically refined grains. The scaling analysis for the pinning force density suggested that the change in the dimension of the dominant pinning source from 2D (surface) to 0D (point) was induced by grain refining. Although the nanometric impurity particles such as MgB4, MgO and Mg-B-O were created in the bulk during both ball-milling and spark plasma sintering processes, we considered the point-contact between the refined grains was the predominant point pinning source.

  6. The effect of geometry of composite MgB 2/stainless-steel (SS) wires fabricated by PIT process on the superconducting properties

    NASA Astrophysics Data System (ADS)

    Song, K. J.; Kim, S. W.; Park, C.; Joo, J. H.; Choi, S. J.; Ko, R. K.; Ha, H. S.; Ha, D. W.; Oh, S. S.

    2004-08-01

    Single-, multi-, and two kinds of coaxial-filament composite MgB 2/SS-SS (stainless steel for both outer and inner tubes) and MgB 2/SS-Cu (stainless steel for outer tube and copper for inner tube) wires were successfully fabricated using powder-in-tube (PIT) process with swaging only. The effect of the geometries of the MgB 2 PIT wires has been studied comparatively. The isothermal magnetizations M( H) for both the sintered and the as-rolled single-, multi-, and coaxial-filament MgB 2 wires were measured at temperatures between 5 and 50 K in fields up to 5 T. The critical current density was estimated by the M( H) data using Bean model. The coaxial-filament composite MgB 2 wires showed much better Jc than both the single- and the multi-filament composite ones. The results of this study show that the superconducting properties of the MgB 2 PIT wires/tapes can improve by employing better geometries such as the coaxial-filament composite MgB 2/SS-SS wires.

  7. Multicore MgB 2 wires made by hydrostatic extrusion

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Pachla, W.; Hušek, I.; Kulczyk, M.; Melišek, T.; Holúbek, T.; Diduszko, R.; Reissner, M.

    2008-12-01

    Seven-filament MgB2/Fe and MgB2/Nb/Cu wires have been made by in situ process using hydrostatic extrusion, drawing and two-axial drawing deformation into the wire size of 1.1 × 1.1 mm2. The conductors were sintered at 650 °C/0.5 h and studied in terms of field-dependent transport critical current density and thermal stability. XRD, SEM and EDX analysis were applied for structural characterization. Transport current property and compositional/structural differences are compared and discussed in connection to used powders and metallic materials.

  8. Effect of Dy2O3 doping on phase formation and properties of MgB2 wires made by the modified internal magnesium diffusion process

    NASA Astrophysics Data System (ADS)

    Brunner, B.; Rosová, A.; Kováč, P.; Reissner, M.; Dobročka, E.

    2017-02-01

    A series of single-core MgB2 wires was produced by the modified internal magnesium diffusion process, starting with a Mg tube filled with carbon predoped boron powder, which resulted in an extractable MgB2 core allowing thorough investigation of superconducting properties. Carbon contained in the boron powder enhances critical current density (J c), however, it also reduces the reactivity of boron and thus acts as a MgB2 growth inhibitor. In order to compensate this negative effect, Dy2O3 nanopowder was added into boron powder and the composites were subjected to heat-treatment at increased temperature for a longer time. By this approach, the reactivity of carbon predoped boron was substantially improved, yielding wires with an increased amount of MgB2 of high phase purity with enhanced J c.

  9. Evolution of core connectivity in MgB 2 wires and tapes during PIT processing

    NASA Astrophysics Data System (ADS)

    Beilin, V.; Dul'kin, E.; Yashchin, E.; Galstyan, E.; Lapides, Y.; Tsindlekht, M.; Felner, I.; Roth, M.

    2004-05-01

    Critical current density, Jc, ac susceptibility, χ, and the core microhardness in Ni/MgB 2 wires and tapes were measured in as-deformed state at the various stages of the powder-in-tube process. We found that during a drawing process Jc reached a peak at some strain value, followed by rather steep degradation down to zero level with further strain growth. It was shown that the data of electrical and magnetic measurements correlated with the core microhardness during the deformation processes. χ vs. T measurements showed that Jc degradation was resulted from the deterioration of a core connectivity, that was confirmed by microhardness measurements. It was revealed that rolling the as-drawn wires restored a core connectivity and thus caused drastic Jc, growth. This effect was explained by differences in powder flow between drawing and rolling processes. XRD examination of MgB 2 cores showed that rolling the Ni/MgB 2 tapes resulted in gradual growth of the core c-axis texturing with the tape thickness reduction, though texture degree remained relatively low (21% at maximum).

  10. The enhanced Jc and Birr of in situ MgB2 wires and tapes alloyed with C4H6O5 (malic acid) after cold high pressure densification

    NASA Astrophysics Data System (ADS)

    Hossain, M. S. A.; Senatore, C.; Flükiger, R.; Rindfleisch, M. A.; Tomsic, M. J.; Kim, J. H.; Dou, S. X.

    2009-09-01

    Cold high pressure densification, a method recently introduced at GAP in Geneva, was applied for improving the transport critical current density, Jc, and the irreversibility field, Birr, of monofilamentary in situ MgB2 wires and tapes alloyed with 10 wt% C4H6O5 (malic acid). Tapes densified at 1.48 GPa exhibited after reaction an enhancement of Jc from 2 to 4 × 104 A cm-2 at 4.2 K/10 T and from 0.5 to 4 × 104 A cm-2 at 20 K/5 T, while the Birr was enhanced from 19.3 to 22 T at 4.2 K and from 7.5 to 10.0 T at 20 K. Cold densification also caused a strong enhancement of B(104), the field at which Jc takes the value 1 × 104 A cm-2. For tapes subjected to 1.48 GPa, B(10^{4})^{\\parallel } and B(10^{4})^{ \\perp } at 4.2 K were found to increase from 11.8 and 10.5 T to 13.2 and 12.2 T, respectively. Almost isotropic conditions were obtained for rectangular wires with aspect ratios a/b<2 subjected to 2.0 GPa, where B(10^{4})^{\\parallel }=12.7 and B(10^{4})^{ \\perp }=12.5 T were obtained. At 20 K, the wires exhibited an almost isotropic behavior, with B(10^{4})^{\\parallel }=5.9 T and B(10^{4})^{ \\perp }=5.75 T, Birr(20 K) being ~10 T. These values are equal to or higher than the highest values reported so far for isotropic in situ wires with SiC or other carbon based additives. Further improvements are expected on optimizing the cold high pressure densification process, which has the potential for fabrication of MgB2 wires of industrial lengths.

  11. High-performance dense MgB2 superconducting wire fabricated from mechanically milled powder

    NASA Astrophysics Data System (ADS)

    Kodama, Motomune; Suzuki, Takaaki; Tanaka, Hideki; Okishiro, Kenji; Okamoto, Kazutaka; Nishijima, Gen; Matsumoto, Akiyoshi; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Kishio, Kohji

    2017-04-01

    Owing to the relatively high critical temperature and the low manufacturing cost, MgB2 superconducting wires are promising for liquid helium-free superconducting applications. Today, commercially available MgB2 wires are manufactured by either an in situ or ex situ powder-in-tube process, the in situ process being more effective to obtain high critical current density. In in situ-processed wires, however, the critical current density is seriously suppressed by the high porosity of MgB2 filaments. To resolve this problem, we propose an innovative method of using precursor powder prepared by mechanical milling of magnesium, boron, and coronene powders. This precursor powder has a metal-matrix-composite structure, in which boron particles are dispersed in a magnesium matrix. The plastic deformation of the precursor powder through wire processing leads to compact packing, and a dense MgB2 filament is generated after heat treatment. As a result, the limitation of critical current density that occurs for the typical in situ process is overcome, and the practical critical current density of 103 A mm-2 is obtained at 10 K and 6.1 T, at 15 K and 4.8 T, and at 20 K and 3.3 T.

  12. Effects of Metal Powder Addition in Ni-Sheathed PIT MgB2 Tapes

    NASA Astrophysics Data System (ADS)

    Tachikawa, K.; Yamada, Y.; Katagiri, K.; Kumakura, H.; Iwamoto, A.; Watanabe, K.

    2004-06-01

    The effect of different metal powder additions on the transport current and stress/strain performance of ex-situ processed MgB2 tapes with Ni sheath has been studied. The metal powder added to the core exhibits elongated morphology after the fabrication. The addition of low melting point metal powder, e.g. In and Sn, produces an appreciable increase in the Jc of MgB2 core. An addition of 10 vol% In enhances Jc by a factor of 6 to 7 after the combination of rolling and annealing at 200 °C, up to the order of 105 A/cm2 at 0.5 T and 4.2 K. An addition of 10 vol% Sn enhances Jc by a factor of ˜ 3. The In and Sn additions also appreciably increase the n-value of the current-voltage transition. Both In and Sn metals infiltrate into gaps between MgB2 grains, improving the linkage of the grains. Current may transfer through the impregnated metal by the proximity effect. Furthermore, the metal powder addition appreciably improves the strain tolerance in MgB2 tapes. The low melting point metal powder addition is a relatively simple and easy approach to yield better transport current and stress/strain performance in ex-situ MgB2 tapes.

  13. Uniform transport performance of a 100 m-class multifilament MgB2 wire fabricated by an internal Mg diffusion process

    NASA Astrophysics Data System (ADS)

    Wang, Dongliang; Xu, Da; Zhang, Xianping; Yao, Chao; Yuan, Pusheng; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-06-01

    A 100 m long six-filament MgB2 wire was successfully fabricated using an internal magnesium diffusion (IMD) process. We investigated the transport properties and the uniformity of this long multifilament IMD wire. The MgB2 layer and the sub-filament region are regular, and the J c values have a fairly homogenous distribution throughout the wire, suggesting that there were no obvious defects along the length of the wire. The uniformity problem of long multifilament IMD MgB2 wires can be mitigated by optimizing the starting composite parameters, multifilament geometry, fabricating process and annealing conditions. A layer J c as high as 1.2 × 105 A cm-2 at 4.2 K and 8 T was obtained, which was comparable with the highest reported value for a short multifilament IMD wire. The transport layer J c, non-barrier J c and J e values are independent of the wire diameter. In addition, the analysis of the stress-strain characteristics and the n value of the IMD wire is also presented. These results indicate that the long multifilament IMD-processed MgB2 superconducting wire is suitable for practical applications.

  14. RAPID COMMUNICATION: Formation of MgB2 at ambient temperature with an electrochemical process: a plausible mechanism

    NASA Astrophysics Data System (ADS)

    Jadhav, A. B.; Subhedar, K. M.; Hyam, R. S.; Talaptra, A.; Sen, Pintu; Bandyopadhyay, S. K.; Pawar, S. H.

    2005-06-01

    The binary intermetallic MgB2 superconductor has been synthesized by many research groups. However, the mechanism of its formation is not clearly understood. In this communication, a comprehensive mechanism of the formation of MgB2 from Le Chatelier's principle of equilibrium reaction has been explained both for solid-state reaction and electrodeposition methods.

  15. Epitaxial growth of superconducting MgB2 thin films with a Mg buffer layer at 110 °C

    NASA Astrophysics Data System (ADS)

    Shishido, Hiroaki; Nakagami, Takatoshi; Yoshida, Takuya; Ishida, Takekazu

    2017-07-01

    Since the discovery of MgB2, its application to superconducting electronics has been limited by the absent of proper microfabrication techniques. In this study, we grew crystalline MgB2 thin films using molecular beam epitaxy at a low substrate temperature of 110 °C under ultra-high vacuum of about 10-6 Pa. MgB2 thin films were deposited with an epitaxial Mg buffer layer on c-plane 4H-SiC or sapphire substrates. In spite of the low growth temperature, superior crystallinity and surface flatness were confirmed by in situ reflection high-energy electron diffraction and X-ray diffraction measurements. Moreover, we successfully confirmed the occurrence of a sharp superconducting transition at 27 K. The present growth temperature was lower than any in prior reports on superconducting MgB2 thin films, and is lower than the applicable temperature of an organic-based lift-off resist. Our new MgB2 thin film growth process is promising for the development of an alternative nanofabrication technique for MgB2 thin films by means of a standard lift-off process with an organic resist.

  16. Current densities of thin filament MgB2/Ti/GlidCop® wire

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kopera, L.

    2011-10-01

    Fine-filamentary MgB2/Ti/GlidCop wire has been produced by an in situ process. Hydrostatic extrusion, drawing and two-axis rolling were used for wire deformation up to the size of 0.2 × 0.2 mm2. An averaged filament size of 7.6-14 µm was obtained for two-axis rolled wire and tape, which are the smallest MgB2 filaments known so far. Very short annealing periods (3-7 min) were used for the thinnest filaments, resulting in a critical current density of ≈12 000 A cm - 2 at 8 T and 4.2 K. The results presented demonstrate the ability to prepare uniform ≈10 µm size and high current density filamentary MgB2 wires in nonmagnetic sheaths, which can be applied for DC and AC coils.

  17. Enhancement of critical current of SiC and malic acid codoped MgB2/Fe wires

    NASA Astrophysics Data System (ADS)

    Li, W. X.; Chen, R. H.; Xu, X.; Hu, Y. M.; Zhu, M. Y.; Li, Y.; Dou, S. X.

    2015-09-01

    The influences of microstructure, connectivity, and disorder on the critical current density, Jc, are discussed to clarify the different mechanisms of Jc(H) in different magnetic field ranges for in situ and combined in situ/ex situ MgB2/Fe wires with nano SiC and malic acid codoping. Sintering temperature plays a very important role in the electromagnetic properties at different temperatures and under various magnetic fields. Connectivity, upper critical field, Hc2, and irreversibility field, Hirr, are studied to demonstrate the mechanism of Jc dependence on magnetic field. The combined in situ/ex situ process is proved to be a promising technique for fabrication of practical MgB2 wires.

  18. Combined Effect of Upper Critical Field and Flux Pinning on Enhancing Critical Current Density of In-situ MgB2/Fe Tapes with Various Carbon Sources Simultaneously Doped

    NASA Astrophysics Data System (ADS)

    Pan, Xifeng; Matsumoto, Akiyoshi; Kumakura, Hiroaki; Zhao, Yong; Yan, Guo; Feng, Yong

    2012-01-01

    MgB2/Fe tapes with various forms of mono- and co-doped C sources were prepared by an in-situ powder-in-tube (PIT) method to study the effect of different C sources on the transport critical current density Jc behavior of MgB2. A remarkable Jc improvement at 4.2 K under higher fields and a significant increase in the actual content of C substitution for B were achieved for the tapes with various C sources co-doped. For these co-doped tapes, both enhanced Hc2 and flux pinning properties are responsible for their Jc improvement in this work. Comparing the 4 wt % C9H11NO doped tape with the 20 wt % malic acid doped tape, the latter possesses much better in-field Jc performance at 4.2 K and 10 T and sharper field dependence of Jc, which suggests that the flux pinning plays a crucial role in determining its Jc behavior.

  19. High temperature heat treatment on boron precursor and PIT process optimization to improve the Jc performance of MgB2-based conductors

    NASA Astrophysics Data System (ADS)

    Vignolo, M.; Bovone, G.; Bernini, C.; Palenzona, A.; Kawale, S.; Romano, G.; Siri, A. S.

    2013-10-01

    The promising results reported in our previous works led us to think that the production process of boron plays a crucial role in MgB2 synthesis. A new method for boron preparation has been developed in our laboratory. This particular process is based on magnesiothermic reaction (Moissan’s process) with the addition of an initial step that gives boron powder with nano-metric grain size. In this paper we report our efforts regarding optimization of the powder-in-tube (PIT) method for these nano-metric powders, and the resolution of problems previously highlighted such as the difficulty in powder packaging and the high friction phenomena occurring during cold working. This increases cracking during the tape and wire manufacture, leading to failure. Packaging problems are related to the amorphous nature of boron synthesized in our laboratory, so a crystallization treatment was applied to improve the crystallinity of the boron. To prevent excessive friction phenomena we synthesized non-stoichiometric MgB2 and used magnesium as lubricant. Our goal is the Jc improvement, but a global physical-chemical characterization was also made to analyse the improvement given by our treatments: this characterization includes x-ray diffraction, ρ(T) measurement, and SEM imaging, besides magnetic and transport Jc measurements.

  20. Electro-mechanical characterization of MgB2 wires for the Superconducting Link Project at CERN

    NASA Astrophysics Data System (ADS)

    Konstantopoulou, K.; Ballarino, A.; Gharib, A.; Stimac, A.; Garcia Gonzalez, M.; Perez Fontenla, A. T.; Sugano, M.

    2016-08-01

    In previous years, the R & D program between CERN and Columbus Superconductors SpA led to the development of several configurations of MgB2 wires. The aim was to achieve excellent superconducting properties in high-current MgB2 cables for the HL-LHC upgrade. In addition to good electrical performance, the superconductor shall have good mechanical strength in view of the stresses during operation (Lorenz forces and thermal contraction) and handling (tension and bending) during cabling and installation at room temperature. Thus, the study of the mechanical properties of MgB2 wires is crucial for the cable design and its functional use. In the present work we report on the electro-mechanical characterization of ex situ processed composite MgB2 wires. Tensile tests (critical current versus strain) were carried out at 4.2 K and in a 3 T external field by means of a purpose-built bespoke device to determine the irreversible strain limit of the wire. The minimum bending radius of the wire was calculated taking into account the dependence of the critical current with the strain and it was then used to obtain the minimum twist pitch of MgB2 wires in the cable. Strands extracted from cables having different configurations were tested to quantify the critical current degradation. The Young’s modulus of the composite wire was measured at room temperature. Finally, all measured mechanical parameters will be used to optimize an 18-strand MgB2 cable configuration.

  1. Effect of cold isostatic pressing on the transport current of filamentary MgB2 wire made by the IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Pachla, W.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.

    2016-07-01

    This work describes the effect of cold isostatic pressing applied to as-drawn filamentary wires in a GlidCop and/or Cu sheath made by the internal magnesium diffusion process. Critical currents of as-drawn and isostatically pressed wires at high pressures up to 2.0 GPa followed by heat treatment at 640 °C for 40 min were measured. The obtained results show an improvement in boron powder density resulting in an increase of the critical current of MgB2 layers. The engineering current density increases by 4-13 times after the high-pressure treatment, and is influenced by the density of the boron powder and by the mechanical strength of the outer sheath.

  2. Microstructures and superconducting properties of high performance MgB2 thin films deposited from a high-purity, dense Mg-B target

    PubMed Central

    Li, G.Z.; Susner, M.A.; Bohnenstiehl, S.D.; Sumption, M.D.; Collings, E.W.

    2015-01-01

    High quality, c-axis oriented, MgB2 thin films were successfully grown on 6H-SiC substrates using pulsed laser deposition (PLD) with subsequent in situ annealing. To obtain high purity films free from oxygen contamination, a dense Mg-B target was specially made from a high temperature, high pressure reaction of Mg and B to form large-grained (10~50 µm) MgB2. Microstructural analysis via electron microscopy found that the resulting grains of the film were composed of ultrafine columnar grains of 19–30 nm. XRD analysis showed the MgB2 films to be c-axis oriented; the a-axis and c-axis lattice parameters were determined to be 3.073 ± 0.005 Å and 3.528 ± 0.010 Å, respectively. The superconducting critical temperature, Tc,onset, increased monotonically as the annealing temperature was increased, varying from 25.2 K to 33.7 K. The superconducting critical current density as determined from magnetic measurements, Jcm, at 5 K, was 105 A/cm2 at 7.8 T; at 20 K, 105 A/cm2 was reached at 3.1 T. The transport and pinning properties of these films were compared to “powder-in-tube” (PIT) and “internal-infiltration” (AIMI) processed wires. Additionally, examination of the pinning mechanism showed that when scaled to the peak in the pinning curve, the films follow the grain boundary, or surface, pinning mechanism quite well, and are similar to the response seen for C doped PIT and AIMI strands, in contrast to the behavior seen in undoped PIT wires, in which deviations are seen at high b (b = B/Bc2). On the other hand, the magnitude of the pinning force was similar for the thin films and AIMI conductors, unlike the values from connectivity-suppressed PIT strands. PMID:26417117

  3. Microstructures and superconducting properties of high performance MgB2 thin films deposited from a high-purity, dense Mg-B target.

    PubMed

    Li, G Z; Susner, M A; Bohnenstiehl, S D; Sumption, M D; Collings, E W

    2015-12-01

    High quality, c-axis oriented, MgB2 thin films were successfully grown on 6H-SiC substrates using pulsed laser deposition (PLD) with subsequent in situ annealing. To obtain high purity films free from oxygen contamination, a dense Mg-B target was specially made from a high temperature, high pressure reaction of Mg and B to form large-grained (10~50 µm) MgB2. Microstructural analysis via electron microscopy found that the resulting grains of the film were composed of ultrafine columnar grains of 19-30 nm. XRD analysis showed the MgB2 films to be c-axis oriented; the a-axis and c-axis lattice parameters were determined to be 3.073 ± 0.005 Å and 3.528 ± 0.010 Å, respectively. The superconducting critical temperature, Tc,onset , increased monotonically as the annealing temperature was increased, varying from 25.2 K to 33.7 K. The superconducting critical current density as determined from magnetic measurements, Jcm , at 5 K, was 10(5) A/cm(2) at 7.8 T; at 20 K, 10(5) A/cm(2) was reached at 3.1 T. The transport and pinning properties of these films were compared to "powder-in-tube" (PIT) and "internal-infiltration" (AIMI) processed wires. Additionally, examination of the pinning mechanism showed that when scaled to the peak in the pinning curve, the films follow the grain boundary, or surface, pinning mechanism quite well, and are similar to the response seen for C doped PIT and AIMI strands, in contrast to the behavior seen in undoped PIT wires, in which deviations are seen at high b (b = B/Bc2 ). On the other hand, the magnitude of the pinning force was similar for the thin films and AIMI conductors, unlike the values from connectivity-suppressed PIT strands.

  4. The roles of CHPD: superior critical current density and n-value obtained in binary in situ MgB2 cables

    NASA Astrophysics Data System (ADS)

    Hossain, M. S. A.; Motaman, A.; Barua, S.; Patel, D.; Mustapic, M.; Kim, J. H.; Maeda, M.; Rindfleisch, M.; Tomsic, M.; Cicek, O.; Melisek, T.; Kopera, L.; Kario, A.; Ringsdorf, B.; Runtsch, B.; Jung, A.; Dou, S. X.; Goldacker, W.; Kovac, P.

    2014-09-01

    A binary magnesium diboride (MgB2) cable has been assembled by braiding six Nb/Monel sheathed monofilament strands around a central copper stabilizer for improving the operational environment. The total critical current (Ic) of the braided cable is obtained by multiplying the Ic of six single wires, without any dissipation. In this work, various mechanical deformations, i.e., swaging, two-axial rolling, groove rolling, and cold high-pressure densification (CHPD) at 1.8 GPa have been applied to the 6-stranded cable to obtain additional densification. The highest critical current density at both 4.2 and 20 K has been achieved in this work through the CHPD treated cable due to higher filament mass density. The present results are promising in view of the cable, particularly in power applications at industrial lengths that pave the way to seeking an optimal protocol to meet a practical functionality.

  5. Fabrication of superconducting MgB2 nanostructures by an electron beam lithography-based technique

    NASA Astrophysics Data System (ADS)

    Portesi, C.; Borini, S.; Amato, G.; Monticone, E.

    2006-03-01

    In this work, we present the results obtained in fabrication and characterization of magnesium diboride nanowires realized by an electron beam lithography (EBL)-based method. For fabricating MgB2 thin films, an all in situ technique has been used, based on the coevaporation of B and Mg by means of an e-gun and a resistive heater, respectively. Since the high temperatures required for the fabrication of good quality MgB2 thin films do not allow the nanostructuring approach based on the lift-off technique, we structured the samples combining EBL, optical lithography, and Ar milling. In this way, reproducible nanowires 1 μm long have been obtained. To illustrate the impact of the MgB2 film processing on its superconducting properties, we measured the temperature dependence of the resistance on a nanowire and compared it to the original magnesium diboride film. The electrical properties of the films are not degraded as a consequence of the nanostructuring process, so that superconducting nanodevices may be obtained by this method.

  6. Magnetic lenses using different MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Y.; Choi, S.; Matsumoto, S.; Teranishi, R.; Giunchi, G.; Figini Albisetti, A.; Kiyoshi, T.

    2012-02-01

    A magnetic lens allows the concentration of magnetic fields using the diamagnetism of superconductors. The important features of the magnetic lens are a tapered inner diameter from which the magnetic flux is extruded and a slit to suppress the circumference current that shields the magnetic flux. This concept was experimentally confirmed through the use of GdBaCuO bulks and a stack of NbTi/Nb/Cu sheets. We refer to this arrangement as a magnetic lens. The Mg-reactive liquid infiltration (Mg-RLI) process developed by Edison SpA is suitable for the production of large and high-density MgB2 bulks. Three MgB2 bulk magnetic lenses, each with a different microstructure, were fabricated following the Mg-RLI process. The properties of the MgB2 magnetic lenses were measured in a cryocooler system as well as in liquid helium. The results confirmed that the MgB2 bulk magnetic lenses could concentrate a magnetic field and that their field concentration properties were greatly affected by the temperature and the external field. In addition, the microstructure of the MgB2 bulk also had an influence on the magnetic properties at different external fields. The results indicated that the MgB2 lens might be utilized as a field amplifier in intermediate fields.

  7. Effects of three different homemade nanocarbons doping on the superconducting properties of MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Wang, Dongliang; Zhang, Haitao; Zhang, Xianping; Tang, Shaopu; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2015-01-01

    The doping effects of three different homemade nanocarbons on microstructure and superconducting properties of in situ powder-in-tube (PIT) processed MgB2/Fe tapes were studied. Compared with pure tapes, all homemade nano-carbon additions led to an order of magnitude enhancement of the supercurrent at 4.2 K, 10 T. Among them, hollow carbon nanoboxes doped samples exhibited the highest transport Jc-B properties, about 3.4 × 104 A cm-2 at 4.2 K, 10 T (Je ∼ 104 A cm-2). The large Jc improvements of doped samples are thought to be attributed to the enhancement of flux pinning force. It is also interesting that the change of microstructure and critical field of three nanocarbons doped MgB2 samples are not obvious, which mainly because that the performance parameters of these nanocarbons with different morphologies are almost same.

  8. Semiconductors: In Situ Processing of Photovoltaic Devices

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.

    1998-01-01

    Current proposals for developing an extended human presence on the Moon and Mars increasingly consider the processing of nonterrestrial materials essential for keeping the Earth launch burden reasonable. Utilization of in situ resources for construction of lunar and Mars bases will initially require assessment of resource availability followed by the development of economically acceptable and technically feasible extraction processes. In regard to materials processing and fabrication, the lower gravity level on the Moon (0.125 g) and Mars (0.367 g) will dramatically change the presently accepted hierarchy of materials in terms of specific properties, a factor that must be understood and exploited. Furthermore, significant changes are expected in the behavior of liquid materials during processing. In casting, for example, mold filling and associated solidification processes have to be reevaluated. Finally, microstructural development, and therefore material properties, presently being documented through ongoing research in microgravity science and applications, need to be understood and scaled to the reduced gravity environments.

  9. Structure, grain connectivity and pinning of as-deformed commercial MgB2 powder in Cu and Fe/Cu sheaths

    NASA Astrophysics Data System (ADS)

    Kovác, P.; Husek, I.; Pachla, W.; Melisek, T.; Diduszko, R.; Fröhlich, K.; Morawski, A.; Presz, A.; Machajdik, D.

    2002-07-01

    Single-core MgB2 wires and tapes have been made by the powder-in-tube (PIT) method using commercial MgB2 powder (Alfa Aesar). Composites have been made using the two-axial rolling process in Cu and/or Fe/Cu sheaths. Alternative deformations by wire drawing, rotary swaging and cold isostatic pressing have been applied to PIT wires and tapes. Current-voltage characteristics and transport current densities in the self-field and in the external field were measured. It was found that the grain connectivity of ex situ MgB2 is affected by the applied sheath and the mode of deformation. Two-axial rolling has generated the highest powder density resulting in the best grain connectivity. The highest transport current densities of 8700 A cm-2 and 55 830 A cm-2 were measured for Cu and Fe/Cu sheathed square wires, respectively. Cold isostatic pressing at 1.5 GPa has increased current density and n-exponent, which suggests an improvement in grain connectivity. It was found that the external pressure improves the inter-grain connectivity but decreases the pinning in MgB2 cores.

  10. In Situ Field Testing of Processes

    SciTech Connect

    J. Wang

    2001-12-14

    The purpose of this Analysis/Model Report (AMR) is to update and document the data and subsequent analyses from ambient field-testing activities performed in underground drifts of the Yucca Mountain Site Characterization Project (YMP). This revision updates data and analyses presented in the initial issue of this AMR. This AMR was developed in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' and ''Technical Work Plan for UZ Flow, Transport, and Coupled Processes Process Model Report. These activities were performed to investigate in situ flow and transport processes. The evaluations provide the necessary framework to: (1) refine and confirm the conceptual model of matrix and fracture processes in the unsaturated zone (UZ) and (2) analyze the impact of excavation (including use of construction water and effect of ventilation) on the UZ flow and transport processes. This AMR is intended to support revisions to ''Conceptual and Numerical Models for UZ Flow and Transport'' and ''Unsaturated Zone Flow and Transport Model Process Model Report''. In general, the results discussed in this AMR are from studies conducted using a combination or a subset of the following three approaches: (1) air-injection tests, (2) liquid-release tests, and (3) moisture monitoring using in-drift sensors or in-borehole sensors, to evaluate the impact of excavation, ventilation, and construction-water usage on the surrounding rocks. The liquid-release tests and air-injection tests provide an evaluation of in situ fracture flow and the competing processes of matrix imbibition. Only the findings from testing and data not covered in the ''Seepage Calibration Model and Seepage Testing Data'' are analyzed in detail in the AMR.

  11. An innovative technique to synthesize C-doped MgB2 by using chitosan as the carbon source

    NASA Astrophysics Data System (ADS)

    Bovone, G.; Vignolo, M.; Bernini, C.; Kawale, S.; Siri, A. S.

    2014-02-01

    Here, we report a new technique to synthesize carbon-doped MgB2 powder. Chitosan was innovatively used as the carbon source during the synthesis of boron from boron oxide. This allowed the introduction of local defects, which later on served as pinning centers in MgB2, in the boron lattice itself, avoiding the traditional and time consuming ways of ex situ MgB2 doping (e.g. ball milling). Two volume percentages of C-doping have been tried and its effect on the superconducting properties, evaluated by magnetic and transport measurements, are discussed here. Morphological analysis by scanning electron microscopy revealed nano-metric grains’ distribution in the boron and MgB2 powder. Mono-filamentary MgB2 wires have been fabricated by an ex situ powder-in-tube technique by using the thus prepared carbon-doped MgB2 and pure MgB2 powders. Transport property measurements on these wires were made and compared with MgB2 wire produced using commercial boron.

  12. Natural attenuation processes during in situ capping.

    PubMed

    Himmelheber, David W; Pennell, Kurt D; Hughes, Joseph B

    2007-08-01

    Chlorinated solvents are common groundwater contaminants that threaten surface water quality and benthic health when present in groundwater seeps. Aquatic sediments can act as natural biobarriers to detoxify chlorinated solvent plumes via reductive dechlorination. In situ sediment capping, a remedial technique in which clean material is placed at the sediment-water interface, may alter sedimentary natural attenuation processes. This research explores the potential of Anacostia River sediment to naturally attenuate chlorinated solvents under simulated capping conditions. Results of microcosm studies demonstrated that intrinsic dechlorination of dissolved-phase PCE to ethene was possible, with electron donor availability controlling microbial activity. A diverse microbial community was present in the sediment, including multiple Dehalococcoides strains indicated by the amplification of the reductive dehalogenases tceA, vcrA, and bvcA. An upflow column simulating a capped sediment bed subject to PCE-contaminated groundwater seepage lost dechlorination activity with time and only achieved complete dechlorination when microorganisms present in the sediment were provided electron donor. Increases in effluent chloroethene concentrations during the period of biostimulation were attributed to biologically enhanced desorption and the formation of less sorptive dechlorination products. These findings suggest that in situ caps should be designed to account for reductions in natural biobarrier reactivity and for the potential breakthrough of groundwater contaminants.

  13. Characterization of MgB2 Conductors for Coil Development

    NASA Astrophysics Data System (ADS)

    Aslanoglu, Z.; Arda, L.; Akin, Y.; Sumption, M. D.; Tomsic, M.; Hascicek, Y. S.

    2004-06-01

    The effects of the heat treatment conditions on microstructure and the transport critical current density of MgB2 wires, which were fabricated by the Continuous Tube Forming and Filling (CTFF) process, have been investigated. Two types of MgB2 conductors, Fe/MgB2 and Cu/MgB2, were studied. It was found that the sheath materials affect the optimum annealing profile of MgB2 conductor. The annealing temperature for Cu/MgB2 conductors was lower than that for the Fe/MgB2 conductors. The critical current density, Jc was measured to be 1.1×105 A/cm2 at 20 K in-self field for Cu/MgB2 conductor of 1.25 mm in diameter. The processing, microstructure and superconducting properties are presented.

  14. Superconducting characteristics of short MgB2 wires of long level sensor for liquid hydrogen

    NASA Astrophysics Data System (ADS)

    Takeda, M.; Inoue, Y.; Maekawa, K.; Matsuno, Y.; Fujikawa, S.; Kumakura, H.

    2015-12-01

    To establish the worldwide storage and marine transport of hydrogen, it is important to develop a high-precision and long level sensor, such as a superconducting magnesium diboride (MgB2) level sensor for large liquid hydrogen (LH2) tanks on board ships. Three 1.7- m-long MgB2 wires were fabricated by an in situ method, and the superconducting characteristics of twenty-four 20-mm-long MgB2 wires on the 1.7-m-long wires were studied. In addition, the static level-detecting characteristics of five 500-mm-long MgB2 level sensors were evaluated under atmospheric pressure.

  15. Neutron scattering studies of superconducting MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Bellingeri, E.; Malagoli, A.; Modica, M.; Braccini, V.; Siri, A. S.; Grasso, G.

    2003-02-01

    The capability of manufacturing long superconducting MgB2 wires with already remarkable critical currents makes this material a very promising candidate for future applications. Tapes are prepared by the powder-in-tube technique. After the cold working procedure typically carried out by wire drawing and cold rolling, it has been found that a final sintering step carried out in argon atmosphere is a key process for further improving the superconducting properties of the conductors. To study the effect of the deformation and heat treatment processes, we performed neutron scattering experiment. Due to the high penetration depth of neutron inside matter, it was possible to analyse the MgB2 phase still wrapped in the Ni sheath. Our studies were carried out by a full spectra refinement by the Rietveld method. In the starting superconducting powder a large Mg deficiency was observed. In the tapes we found that the large forces applied during the cold working induced a large MgB2 lattice deformation, and that it is partly relaxed during the final sintering process. An important correlation of the residual stress with the critical temperature and the pinning properties was pointed out. We also observed the appearance of detrimental secondary phases during the sintering process. In particular, the MgB2 phase reacted with the nickel sheath and MgB2Ni2.5 was formed at temperatures higher than 850 °C. These results are of basic importance for a further optimization of the transport properties at moderate fields where applications of MgB2 tapes are already envisageable.

  16. Note: Progress on the use of MgB2 superconducting joint technique for the development of MgB2 magnets for magnetic resonance imaging (MRI).

    PubMed

    Kim, Y G; Song, J B; Kim, J C; Kim, J M; Yoo, B H; Yun, S B; Hwang, D Y; Lee, H G

    2017-08-01

    This note presents a superconducting joint technique for the development of MgB2 magnetic resonance imaging (MRI) magnets. The MgB2 superconducting joint was fabricated by a powder processing method using Mg and B powders to establish a wire-bulk-wire connection. The joint resistance measured using a field-decay method was <10(-14) Ω, demonstrating that the proposed joint technique could be employed for developing "next-generation" MgB2 MRI magnets operating in the persistent current mode.

  17. Note: Progress on the use of MgB2 superconducting joint technique for the development of MgB2 magnets for magnetic resonance imaging (MRI)

    NASA Astrophysics Data System (ADS)

    Kim, Y. G.; Song, J. B.; Kim, J. C.; Kim, J. M.; Yoo, B. H.; Yun, S. B.; Hwang, D. Y.; Lee, H. G.

    2017-08-01

    This note presents a superconducting joint technique for the development of MgB2 magnetic resonance imaging (MRI) magnets. The MgB2 superconducting joint was fabricated by a powder processing method using Mg and B powders to establish a wire-bulk-wire connection. The joint resistance measured using a field-decay method was <10-14 Ω, demonstrating that the proposed joint technique could be employed for developing "next-generation" MgB2 MRI magnets operating in the persistent current mode.

  18. In situ vitrification: Process and products

    SciTech Connect

    Kindle, C.; Koegler, S.

    1991-06-01

    In situ vitrification (ISV) is an electrically powered thermal treatment process that converts soil into a chemically inert and stable glass and crystalline product. It is similar in concept to bringing a simplified glass manufacturing process to a site and operating it in the ground, using the soil as a glass feed stock. Gaseous emissions are contained, scrubbed, and filtered. When the process is completed, the molten volume cools producing a block of glass and crystalline material that resembles natural obsidian commingled with crystalline phases. The product passes US Environmental Protection Agency (EPA) leach resistance tests, and it can be classified as nonhazardous from a chemical hazard perspective. ISV was developed by the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE) for application to contaminated soils. It is also being adapted for applications to buried waste, underground tanks, and liquid seepage sites. ISV's then-year development period has included tests on many different site conditions. As of January 1991 there have been 74 tests using PNL's ISV equipment; these tests have ranged from technology development tests using nonhazardous conditions to hazardous and radioactive tests. 2 refs., 6 figs., 7 tabs.

  19. Support Routines for In Situ Image Processing

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Pariser, Oleg; Yeates, Matthew C.; Lee, Hyun H.; Lorre, Jean

    2013-01-01

    This software consists of a set of application programs that support ground-based image processing for in situ missions. These programs represent a collection of utility routines that perform miscellaneous functions in the context of the ground data system. Each one fulfills some specific need as determined via operational experience. The most unique aspect to these programs is that they are integrated into the large, in situ image processing system via the PIG (Planetary Image Geometry) library. They work directly with space in situ data, understanding the appropriate image meta-data fields and updating them properly. The programs themselves are completely multimission; all mission dependencies are handled by PIG. This suite of programs consists of: (1)marscahv: Generates a linearized, epi-polar aligned image given a stereo pair of images. These images are optimized for 1-D stereo correlations, (2) marscheckcm: Compares the camera model in an image label with one derived via kinematics modeling on the ground, (3) marschkovl: Checks the overlaps between a list of images in order to determine which might be stereo pairs. This is useful for non-traditional stereo images like long-baseline or those from an articulating arm camera, (4) marscoordtrans: Translates mosaic coordinates from one form into another, (5) marsdispcompare: Checks a Left Right stereo disparity image against a Right Left disparity image to ensure they are consistent with each other, (6) marsdispwarp: Takes one image of a stereo pair and warps it through a disparity map to create a synthetic opposite- eye image. For example, a right eye image could be transformed to look like it was taken from the left eye via this program, (7) marsfidfinder: Finds fiducial markers in an image by projecting their approximate location and then using correlation to locate the markers to subpixel accuracy. These fiducial markets are small targets attached to the spacecraft surface. This helps verify, or improve, the

  20. MgB2 superconductors with abnormally improved Jc sintered after autoxidation of milled original powders

    NASA Astrophysics Data System (ADS)

    Ma, Zongqing; Liu, Yongchang; Huo, Jie; Gao, Zhiming

    2009-12-01

    An autoxidation treatment of short-time milled original powders was introduced for the synthesis of MgB2 superconductors and the critical current density Jc of the sintered MgB2 bulks was measured. It is unusually found that the undoped MgB2 bulks sintered with those autoxided milled original powder exhibit abnormally excellent Jc (above 1×104 A cm-2 even at 3.5 T, 20 K). Combined with the investigation of sintering process, it was found that the autoxidation treatment of the milled powders affects the subsequent sintering process dramatically and finally leads to the formation of MgB2 nanocrystalline with lots of dislocation and self-generated MgO nanoinclusions embedded in them. This unique microstructure brought up a significant improvement of Jc at high fields. Besides, the formation mechanism of this unique microstructure during the sintering process was also discussed in detail. It suggested that the MgO preformed by the reaction between Mg and B2O3 in the interface between Mg particles and B particles might serve as nuclei for the heterogeneous nucleation of the MgB2 phase and finally be included in the MgB2 grains as they grew up. The present method provides possible windows for the development of practical MgB2 superconductors without adopting expensive nanodopants.

  1. Development of hot-electron THz bolometric mixers using MgB2 thin films

    NASA Astrophysics Data System (ADS)

    Cunnane, Daniel; Kawamura, Jonathan; Karasik, Boris S.; Wolak, Matthaeus A.; Xi, X. X.

    2014-07-01

    Terahertz high-resolution spectroscopy of interstellar molecular clouds greatly relies on hot-electron superconducting bolometric (HEB) mixers. Current state-of-the-art receivers use mixer devices made from ultrathin (~ 3-5 nm) films of NbN with critical temperature ~ 9-11 K. Such mixers have been deployed on a number of groundbased, suborbital, and orbital platforms including the HIFI instrument on the Hershel Space Observatory. Despite its good sensitivity and well-established fabrication process, the NbN HEB mixer suffers from the narrow intermediate frequency (IF) bandwidth ~ 2-3 GHz and is limited to operation at liquid Helium temperature. As the heterodyne receivers are now trending towards "high THz" frequencies, the need in a larger IF bandwidth becomes more pressing since the same velocity resolution for a Doppler shifted line at 5 THz requires a 5-times greater IF bandwidth than at 1 THz. Our work is focusing on the realization of practical HEB mixers using ultrathin (10-20 nm) MgB2 films. They are prepared using a Hybrid Physical-Chemical Vapor Deposition (HPCVD) process yielding ultrathin films with critical temperature ~ 37-39 K. The expectation is that the combination of small thickness, high acoustic phonon transparency at the interface with the substrate, and very short electron-phonon relaxation time may lead to IF bandwidth ~ 10 GHz or even higher. SiC continues to be the most favorable substrate for MgB2 growth and as a result, a study has been conducted on the transparency of SiC at THz frequencies. FTIR measurements show that semi-insulating SiC substrates are at least as transparent as Si up to 2.5 THz. Currently films are passivated using a thin (10 nm) SiO2 layer which is deposited ex-situ via RF magnetron sputtering. Micron-sized spiral antenna-coupled HEB mixers have been fabricated using MgB2 films as thin as 10 nm. Fabrication was done using contact UV lithography and Ar Ion milling, with E-beam evaporated Au films deposited for the

  2. Improving magnetic properties of MgB2 bulk superconductors by synthetic engine oil treatment

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Yanmaz, E.

    2016-08-01

    The present study focuses on the effects of standby time of the MgB2 samples immersed in synthetic engine oil on the critical current density (Jc(H)), magnetic field dependence of the pinning force density fp(b) and Tc performances of MgB2 bulk superconductors. Synthetic engine oil was used as a product which is cheap and a rich carbon source. Manufactured MgB2 pellet samples were immersed at different standby time of 30 min, 120 min, 300 min and 1440 min in synthetic engine oil after the first heating process. Finally, MgB2 samples immersed in synthetic engine oil were sintered at 1000 °C and kept for 15 min in Ar atmosphere. The critical current density of all of MgB2 samples immersed at different standby time in engine oil in whole field range was better than that of the pure MgB2 sample because of the number of the pinning centers. The MgB2 sample immersed at 300 min standby time in synthetic engine oil has the best performance compared to other samples. The Jc value for the pure sample is 2.0 × 103 A/cm2, whereas for the MgB2 sample immersed at 300 min standby time in engine oil the Jc is enhanced to 4.8 × 103A/cm2 at 5 K and 3 T. The superconducting transition temperature (Tc) did not change with the increasing standby time of the samples in synthetic engine oil at all. The best diamagnetic property was obtained from the sample which kept in synthetic engine oil for 300 min. Synthetic engine oil treatment results in remarkable improvement of the critical current density and pinning force performances of MgB2 superconductors. It was found that all MgB2 samples have a different pinning property at different measuring temperatures. Using synthetic engine oil as a product which is cheap and a rich carbon source in MgB2 bulk superconductors makes MgB2 samples immersed in synthetic engine oil a good candidate for industrial applications.

  3. IN SITU FIELD TESTING OF PROCESSES

    SciTech Connect

    J.S.Y. YANG

    2004-11-08

    The purpose of this scientific analysis report is to update and document the data and subsequent analyses from ambient field-testing activities performed in underground drifts and surface-based boreholes through unsaturated zone (UZ) tuff rock units. In situ testing, monitoring, and associated laboratory studies are conducted to directly assess and evaluate the waste emplacement environment and the natural barriers to radionuclide transport at Yucca Mountain. This scientific analysis report supports and provides data to UZ flow and transport model reports, which in turn contribute to the Total System Performance Assessment (TSPA) of Yucca Mountain, an important document for the license application (LA). The objectives of ambient field-testing activities are described in Section 1.1. This report is the third revision (REV 03), which supercedes REV 02. The scientific analysis of data for inputs to model calibration and validation as documented in REV 02 were developed in accordance with the Technical Work Plan (TWP) ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (BSC 2004 [DIRS 167969]). This revision was developed in accordance with the ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 1.2.4) for better integrated, consistent, transparent, traceable, and more complete documentation in this scientific analysis report and associated UZ flow and transport model reports. No additional testing or analyses were performed as part of this revision. The list of relevant acceptance criteria is provided by ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654]), Table 3-1. Additional deviations from the TWP regarding the features, events, and processes (FEPs) list are discussed in Section 1.3. Documentation in this report includes descriptions of how, and under what conditions, the tests were conducted. The descriptions and

  4. Superconductivity, critical current density, and flux pinning in MgB2-x(SiC)x/2 superconductor after SiC nanoparticle doping

    NASA Astrophysics Data System (ADS)

    Dou, S. X.; Pan, A. V.; Zhou, S.; Ionescu, M.; Wang, X. L.; Horvat, J.; Liu, H. K.; Munroe, P. R.

    2003-08-01

    We investigated the effect of SiC nanoparticle doping on the crystal lattice structure, critical temperature Tc, critical current density Jc, and flux pinning in MgB2 superconductor. A series of MgB2-x(SiC)x/2 samples with x=0-1.0 were fabricated using an in situ reaction process. The contraction of the lattice and depression of Tc with increasing SiC doping level remained rather small most likely due to the counterbalancing effect of Si and C co-doping. The high level Si and C co-doping allowed the creation of intragrain defects and highly dispersed nanoinclusions within the grains which can act as effective pinning centers for vortices, improving Jc behavior as a function of the applied magnetic field. The enhanced pinning is mainly attributable to the substitution-induced defects and local structure fluctuations within grains. A pinning mechanism is proposed to account for different contributions of different defects in MgB2-x(SiC)x/2 superconductors.

  5. Connectivity, Doping, and Anisotropy in Highly Dense Magnesium Diboride (MgB2)

    NASA Astrophysics Data System (ADS)

    Li, Guangze

    Magnesium diboride (MgB2) is a superconducting material which can be potentially used in many applications such as magnetic resonance imaging system (MRI), wind turbine generators and high energy physics facilities. The major advantages of MgB2 over other superconductors include its relatively high critical temperature of about 39 K, its low cost of raw materials, its simple crystal structure, and its round multifilament form when in the form of superconducting wires. Over the past fourteen years, much effort has been made to develop MgB2 wires with excellent superconducting properties, particularly the critical current density J c. However, this research has been limited by technical difficulties such as high porosity and weak connectivity in MgB2, relatively small flux pinning strength, low upper critical field B c2 and relatively high anisotropy. The goal of this dissertation is to understand the relationship between superconducting properties, microstructure, and reaction mechanisms in MgB 2. In particular, the influences of connectivity, B c2, anisotropy and flux pinning were investigated in terms of the effects of these variables on the Jcs and n-values of MgB2 superconducting wires (n-value is a parameter which indicates the sharpness of resistive V-I transition). The n -values of traditional "Powder in Tube (PIT)" processed MgB2 wires were improved by optimizing precursor species after the identification of microstructural defects such as so-called "sausaging problems". Also, it was found that "high porosity and weak connectivity" was one of the most critical issues which limited the J c performance in typical MgB2. To overcome this problem, highly dense, well-connected MgB2 conductors were successfully fabricated by adopting an innovative "Advanced Internal Magnesium Infiltration (AIMI)" process. A careful study on the reaction kinetics together with the microstructural evidence demonstrated how the MgB2 layer was formed as the infiltration process

  6. Low temperature decomposition of metal borohydride drives autogenous synthesis of MgB2

    NASA Astrophysics Data System (ADS)

    Mackinnon, I. D. R.; Shahbazi, M.; Alarco, J. A.; Talbot, P. C.

    2017-05-01

    We describe a low temperature, autogenous pressure method to synthesise mm-scale MgB2 aggregates with highly connected grains. The decomposition of metal borohydrides such as NaBH4 and KBH4 at low temperature (i.e. < 150 °C) in the presence of Mg provides reactive boron species at pressure and subsequent formation of MgB2 in high yield. Optimum synthesis conditions include heating to 250 °C for > 30 min then a ramp to 450 °C < T max < 500 °C and 1.4 MPa < P max < 2.2 MPa. Reactions with KBH4 release reactive boron species at higher temperature (˜130 °C) than reactions with NaBH4 (˜80 °C-100 °C). Alkali metal solubility in MgB2 is at ˜ppm levels. The onset superconducting transition temperature, T c, for MgB2 produced by these syntheses ranges between 38.3 and 38.5 K. Magnetic measurements of MgB2 aggregates show a grain connectivity comparable to powders produced at higher temperature (> 800 °C) and suggests that this synthesis approach may be effective for ex situ wire production.

  7. Properties of carbon nanotubes-doped Fe-sheath MgB2 for superconducting wires

    NASA Astrophysics Data System (ADS)

    Herbirowo, Satrio; Sofyan, Nofrijon; Saragih, Risuliniko; Imaduddin, Agung; Hendrik, Sebleku, Pius; Yuwono, Akhmad Herman

    2017-03-01

    Magnesium diboride (MgB2) is a potential superconductor materials that could be applied as superconducting wires due to its relatively high critical temperature. To study the influence of carbon nanotubes (CNT) on MgB2 wire manufacture, CNT-doped MgB2 superconducting wires have been fabricated from MgB2 and CNT powders sheathed in a SS304 stainless steel tube. In the process, the mixtures of MgB2 and CNT powders were inserted into the SS304 tubes and then were rolled and drawn. The properties of the fabricated superconducting wires were then analyzed through the crystal structure, surface morphology and temperature dependence of resistivity. The addition of CNT did not seem to have a significant influence on the crystal structure of Magnesium diboride. However, the addition of CNT caused the particle size of MgB2 became smaller. The temperature dependence of resistivity results showed that the critical temperatures were shifting linearly toward low temperatures due to the addition of CNT.

  8. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... contamination of ground and surface waters, damage to fish, wildlife and related environmental values, and threats to the public health and safety. (d) Each person who conducts in situ processing activities shall... processing activities shall restore the quality of affected ground water in the permit area and adjacent area...

  9. Semiconductors: In Situ Processing of Photovoltaic Devices

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.

    1998-01-01

    The possible processing of semiconductor photovoltaic devices is discussed. The requirements for lunar PV cells is reviewed, and the key challenges involved in their manufacturing are investigated. A schematic diagram of a passivated emitter and rear cell (PERC) is presented. The possible fabrication of large photovoltaic arrays in space from lunar materials is also discussed.

  10. Design, control and in situ visualization of gas nitriding processes.

    PubMed

    Ratajski, Jerzy; Olik, Roman; Suszko, Tomasz; Dobrodziej, Jerzy; Michalski, Jerzy

    2010-01-01

    The article presents a complex system of design, in situ visualization and control of the commonly used surface treatment process: the gas nitriding process. In the computer design conception, analytical mathematical models and artificial intelligence methods were used. As a result, possibilities were obtained of the poly-optimization and poly-parametric simulations of the course of the process combined with a visualization of the value changes of the process parameters in the function of time, as well as possibilities to predict the properties of nitrided layers. For in situ visualization of the growth of the nitrided layer, computer procedures were developed which make use of the results of the correlations of direct and differential voltage and time runs of the process result sensor (magnetic sensor), with the proper layer growth stage. Computer procedures make it possible to combine, in the duration of the process, the registered voltage and time runs with the models of the process.

  11. Design, Control and in Situ Visualization of Gas Nitriding Processes

    PubMed Central

    Ratajski, Jerzy; Olik, Roman; Suszko, Tomasz; Dobrodziej, Jerzy; Michalski, Jerzy

    2010-01-01

    The article presents a complex system of design, in situ visualization and control of the commonly used surface treatment process: the gas nitriding process. In the computer design conception, analytical mathematical models and artificial intelligence methods were used. As a result, possibilities were obtained of the poly-optimization and poly-parametric simulations of the course of the process combined with a visualization of the value changes of the process parameters in the function of time, as well as possibilities to predict the properties of nitrided layers. For in situ visualization of the growth of the nitrided layer, computer procedures were developed which make use of the results of the correlations of direct and differential voltage and time runs of the process result sensor (magnetic sensor), with the proper layer growth stage. Computer procedures make it possible to combine, in the duration of the process, the registered voltage and time runs with the models of the process. PMID:22315536

  12. Adaptation of in-situ microscopy for crystallization processes

    NASA Astrophysics Data System (ADS)

    Bluma, A.; Höpfner, T.; Rudolph, G.; Lindner, P.; Beutel, S.; Hitzmann, B.; Scheper, T.

    2009-08-01

    In biotechnological and pharmaceutical engineering, the study of crystallization processes gains importance. An efficient analytical inline sensor could help to improve the knowledge about these processes in order to increase efficiency and yields. The in-situ microscope (ISM) is an optical sensor developed for the monitoring of bioprocesses. A new application for this sensor is the monitoring in downstream processes, e.g. the crystallization of proteins and other organic compounds. This contribution shows new aspects of using in-situ microscopy to monitor crystallization processes. Crystals of different chemical compounds were precipitated from supersaturated solutions and the crystal growth was monitored. Exemplified morphological properties and different forms of crystals could be distinguished on the basis of offline experiments. For inline monitoring of crystallization processes, a special 0.5 L stirred tank reactor was developed and equipped with the in-situ microscope. This reactor was utilized to carry out batch experiments for crystallizations of O-acetylsalicyclic acid (ASS) and hen egg white lysozyme (HEWL). During the whole crystallization process, the in-situ microscope system acquired images directly from the crystallization broth. For the data evaluation, an image analysis algorithm was developed and implemented in the microscope analysis software.

  13. Master of Puppets: Cooperative Multitasking for In Situ Processing

    SciTech Connect

    Morozov, Dmitriy; Lukic, Zarija

    2016-01-01

    Modern scientific and engineering simulations track the time evolution of billions of elements. For such large runs, storing most time steps for later analysis is not a viable strategy. It is far more efficient to analyze the simulation data while it is still in memory. Here, we present a novel design for running multiple codes in situ: using coroutines and position-independent executables we enable cooperative multitasking between simulation and analysis, allowing the same executables to post-process simulation output, as well as to process it on the fly, both in situ and in transit. We present Henson, an implementation of our design, and illustrate its versatility by tackling analysis tasks with different computational requirements. This design differs significantly from the existing frameworks and offers an efficient and robust approach to integrating multiple codes on modern supercomputers. The techniques we present can also be integrated into other in situ frameworks.

  14. Evaluation of persistent-mode operation in a superconducting MgB2 coil in solid nitrogen

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; See, Khay Wai; Qiu, Wenbin; Kobayashi, Hiroki; Ma, Zongqing; Kim, Seong Jun; Hong, Jonggi; Park, Jin Yong; Choi, Seyong; Maeda, Minoru; Shahabuddin, Mohammed; Rindfleisch, Matt; Tomsic, Mike; Xue Dou, Shi; Kim, Jung Ho

    2016-04-01

    We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to obtain the persistent-current mode. After a heat treatment, the whole coil was installed in the SN2 chamber. During operation, the resultant total circuit resistance was estimated to be <7.4 × 10-14 Ω at 19.5 K ± 1.5 K, which meets the technical requirement for magnetic resonance imaging application.

  15. Fine-Filament MgB2 Superconductor Wire

    NASA Technical Reports Server (NTRS)

    Cantu, Sherrie

    2015-01-01

    Hyper Tech Research, Inc., has developed fine-filament magnesium diboride (MgB2) superconductor wire for motors and generators used in turboelectric aircraft propulsion systems. In Phase I of the project, Hyper Tech demonstrated that MgB2 multifilament wires (<10 micrometers) could reduce alternating current (AC) losses that occur due to hysteresis, eddy currents, and coupling losses. The company refined a manufacturing method that incorporates a magnesium-infiltration process and provides a tenfold enhancement in critical current density over wire made by a conventional method involving magnesium-boron powder mixtures. Hyper Tech also improved its wire-drawing capability to fabricate fine multifilament strands. In Phase II, the company developed, manufactured, and tested the wire for superconductor and engineering current density and AC losses. Hyper Tech also fabricated MgB2 rotor coil packs for a superconducting generator. The ultimate goal is to enable low-cost, round, lightweight, low-AC-loss superconductors for motor and generator stator coils operating at 25 K in next-generation turboelectric aircraft propulsion systems.

  16. Stress/strain characteristics of Cu-alloy sheath MgB 2 superconducting wires

    NASA Astrophysics Data System (ADS)

    Katagiri, Kazumune; Kasaba, Koichi; Shoji, Yoshitaka; Yamakage, Daisuke; Obara, Takeshi; Shimura, Satoshi; Koshizuka, Naoki; Watanabe, Kazuo

    2007-04-01

    The mechanical properties of Cu and Cu-alloy (Cu-Zr, Cu-Be and Cu-Cr) sheath in situ PIT-processed MgB 2 superconducting wires were studied at room temperature (RT) and 4.2 K. The effects of stress/strain on the critical current ( Ic) of the wires have also been studied at 4.2 K and in magnetic fields up to 5 T. Alloying the Cu sheath significantly increased the yield stress of the wires. The 0.5% flow stresses of the Cu-alloy sheath wires were 147-237 MPa, whereas that of Cu was 55 MPa. At RT, the serration in the stress-strain curves corresponding to the multiple cracking was observed around a strain of 0.4% and the curve almost saturated beyond that point. The strain dependence of Ic prior to the critical strain ( ɛirr) was different depending on the magnetic field; being almost constant at 2 T and increased with strain at 5 T. The Ic decreased beyond ɛirr, which was much larger for Cu-alloy sheath wires as compared with Cu sheath wire. The magnitude of ɛirr is due to the difference in the thermal compressive strain in the MgB 2 core, which was relaxed by yielding in the sheath materials. The transverse compression tests revealed that the Ic of the Cu-alloy sheath wire did not degrade up to about 95 MPa, which is also higher than that of Cu sheath wire.

  17. Raman spectroscopy for in-situ monitoring of electrode processes

    SciTech Connect

    Varma, R; Cook, G M; Yao, N P

    1982-04-01

    The theoretical and experimental applications of Raman spectroscopic techniques to the study of battery electrode processes are described. In particular, the potential of Raman spectroscopy as an in-situ analytical tool for the characterization of the structure and composition of electrode surface layers at electrode-electrolyte interfaces during electrolysis is examined. It is anticipated that this understanding of the battery electrode processes will be helpful in designing battery active material with improved performance. The applications of Raman spectroscopy to the in-situ study of electrode processes has been demonstrated in a few selected areas, including: (1) the anodic corrosion of lead in sulfuric acid and (2) the anodization and sulfation of tetrabasicleadsulfate in sulfuric acid. Preliminary results on the anodization of iron and on the electrochemical behavior of nickel positive-electrode active material in potassium hydroxide electrolytes are presented in the Appendix.

  18. Effect of fabrication route on density and connectivity of MgB2 filaments

    NASA Astrophysics Data System (ADS)

    Viljamaa, J.; Kováč, P.; Hušek, I.; Melišek, T.; Štrbík, V.; Dobročka, E.

    2010-06-01

    Series of samples was manufactured to test the effect of fabrication route on the density of the polycrystalline core, the connectivity between MgB2 grains and also the critical current density of undoped MgB2 conductors. All the samples had titanium sheaths and were manufactured using the Powder-in-Tube method. The Ti tubes were filled with either in situ, ex situ, or 60%-40% mixture of in situ and ex situ powders. After powder packing, the samples went through different deformation steps such as rotary swaging, two-axial rolling, pressing, cold isostatic pressing, or some combination of these, to form monofilamentary tapes. The core density was qualitatively estimated by measuring the Vickers microhardness from several locations of the ceramic filament. The changes in connectivity, or effective cross-section, were evaluated by performing resistivity measurements on the MgB2 cores after removal of the metallic sheath. The Jc characteristics were measured at 4.2 K and at variable external magnetic flux densities.

  19. 30 CFR 933.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... CAROLINA § 933.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  20. 30 CFR 912.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... § 912.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  1. 30 CFR 933.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... CAROLINA § 933.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  2. 30 CFR 922.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... § 922.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  3. 30 CFR 910.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... § 910.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  4. 30 CFR 922.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... § 922.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  5. 30 CFR 939.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... ISLAND § 939.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  6. 30 CFR 912.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... § 912.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  7. 30 CFR 941.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... DAKOTA § 941.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  8. 30 CFR 947.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... § 947.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  9. 30 CFR 941.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... DAKOTA § 941.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  10. 30 CFR 939.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... ISLAND § 939.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  11. 30 CFR 921.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ... MASSACHUSETTS § 921.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  12. 30 CFR 910.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ... § 910.828 Special performance standards—in situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts in situ...

  13. Fabrication and radio frequency test of large-area MgB2 films on niobium substrates

    NASA Astrophysics Data System (ADS)

    Ni, Zhimao; Guo, Xin; Welander, Paul B.; Yang, Can; Franzi, Matthew; Tantawi, Sami; Feng, Qingrong; Liu, Kexin

    2017-04-01

    Magnesium diboride (MgB2) is a promising candidate material for superconducting radio frequency (RF) cavities because of its higher transition temperature and critical field compared with niobium. To meet the demand of RF test devices, the fabrication of large-area MgB2 films on metal substrates is needed. In this work, high quality MgB2 films with 50 mm diameter were fabricated on niobium by using an improved HPCVD system at Peking University, and RF tests were carried out at SLAC National Accelerator Laboratory. The transition temperature is approximately 39.6 K and the RF surface resistance is about 120 μΩ at 4 K and 11.4 GHz. The fabrication processes, surface morphology, DC superconducting properties and RF tests of these large-area MgB2 films are presented.

  14. Fabrication and radio frequency test of large-area MgB2 films on niobium substrates

    DOE PAGES

    Ni, Zhimao; Guo, Xin; Welander, Paul B.; ...

    2017-01-19

    Magnesium diboride (MgB2) is a promising candidate material for superconducting radio frequency (RF) cavities because of its higher transition temperature and critical field compared with niobium. To meet the demand of RF test devices, the fabrication of large-area MgB2 films on metal substrates is needed. Here, in this work, high quality MgB2 films with 50 mm diameter were fabricated on niobium by using an improved HPCVD system at Peking University, and RF tests were carried out at SLAC National Accelerator Laboratory. The transition temperature is approximately 39.6 K and the RF surface resistance is about 120 μΩ at 4 Kmore » and 11.4 GHz. Finally, the fabrication processes, surface morphology, DC superconducting properties and RF tests of these large-area MgB2 films are presented.« less

  15. Elimination of bubbles and improvement of the superconducting properties in MgB2 films annealed using electron beam

    NASA Astrophysics Data System (ADS)

    Xu, Zhuang; Kong, Xiangdong; Han, Li; Pang, Hua; Wu, Yue; Gao, Zhaoshun; Li, Xiaona

    2017-03-01

    MgB2 superconducting films can be readily obtained using the electron-beam annealing method. However, many bubbles existing in the film severely damage the surface morphology, which is known as the deleterious current-limiting mechanism. Based on morphology images and energy-dispersive spectroscopy spectra, we found that, during the annealing process, solid Mg-rich layers evaporate to form Mg vapour in the precursor film, resulting in bubbles in the film. By reducing the cycle thickness of the precursor film, we obtained MgB2 films with better properties. The root-mean-square surface roughness was 2.7 nm over a 10 × 10 μm area for a 100 nm-thick film, and the critical current density at 20 K was increased to 3.8 × 106 A cm‑2. These MgB2 films are suitable for fabricating MgB2 superconducting devices.

  16. The phase analysis of spark plasma sintered MgB2 after ball milling.

    PubMed

    Kang, Deuk-Kyun; Kim, Dong-Woong; Kim, Cheol-Jin; Ahn, In-Shup

    2010-01-01

    Mg and amorphous B powders below 10 and 3 micro meter were used as raw materials, and mixed by planetary-mill for 9 hours at argon atmosphere. MgB2 bulk was fabricated at the various temperatures by Spark Plasma Sintering. In the sintering process, mixed powders were sintered in graphite mold, at the pressure of 55 Mpa. The fabricated MgB2 samples were evaluated with XRD, EDS, FE-SEM, PPMS. MgB2, MgO and Fe phases were observed from XRD result. In the results, MgO and Fe were impurity which may affect superconducting properties of MgB2 samples, and it's distribution could be confirmed from EDS mapping result. In order to confirm the formation of MgB2 phase, DTA was used as heating rate of 10 degrees C/min at Ar atmosphere from room temperature to 1200 degrees C. In the PPMS result, the Tc (critical temperature) was about 21 K, and the density of spark plasma sintered samples increased to 1.87 g/cm3 by increasing sintering temperature.

  17. Critical current density and grain connectivity of Bi-2223 added MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Dey, T. K.

    2014-04-01

    Polycrystalline MgB2 with addition of 0, 1, 3, and 5 wt. % of Bi-2223(Bi1.8Pb0.26Sr2Ca2Cu3O10+x) powder has been synthesized by solid reaction process. The effect of Bi-2223 addition on current transport and superconducting properties of polycrystalline MgB2 superconductor is discussed. Four probe DC resistivity measurement shows that low level of Bi-2223 addition hardly affects the superconducting transition temperature, Tc of MgB2. The modified Bloch- Gruneisen (B-G) analysis of normal state resistivity data reveals a decrease in intergrain connectivity and increase in intragrain connectivity of MgB2 by Bi-2223 addition. The critical current density of present set of samples is estimated from M- H hysteresis loop in the light of Bean's model. MgB2 added with 1 wt. % of Bi- 2223 added gives the best performance (˜ 2 times enhancement in Jc) amongst the studied samples.

  18. Scaling considerations for modeling the in situ vitrification process

    SciTech Connect

    Langerman, M.A.; MacKinnon, R.J.

    1990-09-01

    Scaling relationships for modeling the in situ vitrification waste remediation process are documented based upon similarity considerations derived from fundamental principles. Requirements for maintaining temperature and electric potential field similarity between the model and the prototype are determined as well as requirements for maintaining similarity in off-gas generation rates. A scaling rationale for designing reduced-scale experiments is presented and the results are assessed numerically. 9 refs., 6 figs.

  19. Structure and stability of superconducting core of single-core MgB2/Cu,Nb tube composite with a high critical current

    NASA Astrophysics Data System (ADS)

    Krinitsina, T. P.; Kuznetsova, E. I.; Blinova, Yu. V.; Rakov, D. N.; Belotelova, Yu. N.; Sudareva, S. V.; Degtyarev, M. V.; Romanov, E. P.

    2014-06-01

    The core of a single-core MgB2/Cu,Nb composite, which has been prepared by the ex-situ technique and exhibits a high critical current equal to 427 A (at 0 T and 4.2 K, j c ≥ 105 A/cm2), has been studied using various structural methods. Two kinds of MgB2 crystals were observed; those of the first kind is large, highly dense crystals characterized by a low oxygen content (2-8 at %) and the others are fine, weakly coupled crystallites characterized by high oxygen content (4-21 at %). To perform a comparative analysis of the structures, we have also studied an MgB2 bulk sample synthesized at 1000°C. It was found that two phases with the same lattice are formed; they differ in the magnesium and boron contents (within the homogeneity range), impurity oxygen content and microstructure as well but differ slightly in the lattice parameters. The two-phase state of MgB2 bulk sample is due to the mechanism of its formation, which includes the melting of magnesium, the dissolution of solid boron in it, and the crystallization of MgB2 from the melt with the formation of dendrite-like structure characterized by corresponding redistribution of components and impurities. To a certain degree, the two-phase structure of MgB2 bulk sample is inherited by the MgB2/Cu,Nd composite prepared by ex-situ technique (annealing of composite at 700°C). It was shown that oxygen in the MgB2 compound is the destabilizing factor and leads to the transformation of the superconductor into MgO.

  20. Comparative study of mono- and multi-filament MgB2 wires with different boron powders and malic acid addition

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Heo, Yoon-Uk; Matsumoto, A.; Kumakura, H.; Rindfleisch, M.; Tomsic, M.; Dou, S. X.

    2010-07-01

    We evaluated the effects of different boron (B) powders and of malic acid (C4H6O5) addition on the critical current density (Jc) of mono- and multi-filament MgB2 wires. We found that Jc of the wires made from the amorphous B showed the best performance. Low sintering processing keeps the grain size small, which leads to strong flux pinning. From transmission electron microscopy (TEM) observations, we confirmed that the crystalline B powders supplied by SMI and Tangshan had a β-rhombohedral structure as a main phase. These two powders also had numerous defects, such as twin and stacking faults inside the powder particles. However, these defects are not enough to promote the full reaction between magnesium (Mg) and B crystalline powder when sintered at low temperatures, and brings about low Jc values. Even though the morphologies of the two crystalline B powders appeared somewhat different, Jc for the two wires had similar quantitative values. For the malic acid doped wires, Jc of the wire made from the amorphous B was estimated to be above 100 000 A cm - 2 at 6 T and 4.2 K. This value is comparable to the low temperature superconductor Nb-Ti. In addition, the Jc was 25 000 A cm - 2 at 10 T and 4.2 K. This performance is the best Jc reported so far in in situ processed MgB2 wires. Interestingly, the low-field Jc performance of malic acid doped wire fabricated with crystalline B is higher than that of the pure wire fabricated with amorphous B. At 20 K, enhanced performance of Jc by malic acid doping is much higher than that of the pure MgB2 wire. The Jc at 5 T and 20 K was estimated to be 13 000 A cm - 2.

  1. A defect detection method for MgB2 superconducting and iron-based Ba(Fe,Co)2As2 wires

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A.; Yamamoto, A.; Cetner, T.

    2016-04-01

    In this article, a method allowing for the detection of damage in iron-based superconducting bulks and MgB2 wires is presented. MgB2 wires were made of in situ material with ex situ MgB2 barrier. The iron superconductor studied was Ba(Fe,Co)2As2. This material was surrounded by Nb barrier and placed inside an iron tube. All samples were annealed in the isostatic pressure of 1 GPa. Transport measurements were made using a four-contact probe. The transition of Nb and ex situ MgB2 barrier from superconducting into resistive state (first transition) was observed at a temperature range from 5 K to 10 K and can be attributed to damage in either the Nb or ex situ MgB2 barrier in these samples. For samples with a damaged barrier, it was not possible to determine the critical current density of the wires. The analysis indicates that annealing at 1 GPa leads to the Ba(Fe,Co)2As2 material with critical temperatures of 27 K and 21.5 K at upper critical flux density (Bc2) of 14 T.

  2. Fabrication and superconducting properties of MgB2 composite wiresby the PIT method

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Zhao, Y.; Pradhan, A. K.; Zhou, L.; Zhang, P. X.; Liu, X. H.; Ji, P.; Du, S. J.; Liu, C. F.; Wu, Y.; Koshizuka, N.

    2002-01-01

    Dense MgB2/Cu wires with Ta as a buffer layer were successfully fabricated by the powder-in-tube (PIT) method. The microstructure was investigated by optical microscopy. Magnetization measurements were carried out by using a superconducting quantum interference device (SQUID) magnetometer at magnetic fields up to 7 T from 5 K to 35 K. The transition temperature of the MgB2 wire is around 38.4 K and the irreversibility field is 6.6 T at 5 K. The critical current density as high as 105 A cm-2 (5 K, self-field) and 104 A cm-2 (20 K, 1 T) has been obtained. The results suggest that the powder-in-tube (PIT) process is promising in preparing high-quality MgB2 wires.

  3. Fabrication and transport properties of MgB 2 wire and coil

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Okada, M.; Kumakura, H.; Kitaguchi, H.; Togano, K.

    2002-11-01

    The paper reports the first successful fabrication and test of a MgB 2 coil. We have fabricated 15 m long MgB 2-superconducting wires by a powder-in-tube method using Ni-sheath without any heat treatments during the processing. The MgB 2/Ni tape has a good uniformity of high Jc value (500-600 A/mm 2 at 4.2 K and 0 T) along the tape length as well as a nice bending tolerance. Ic degradation of the tape occurred at the bending strain of as high as 1%. Using a 10 m long Ni-sheath tape, we have made a small solenoidal coil with 80 turns to be tested in liquid helium. The coil showed a typical training effect, Ic increasing by repeating the excitation, and the highest Ic value we obtained was 105 A, which generated the central field of 0.13 T.

  4. Development of the integrated in situ lasagna process

    SciTech Connect

    Ho, S.; Athmer, C.; Sheridan, P.

    1995-10-01

    Contamination in deep, low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in uniform delivery of treatment reagents have rendered existing in-situ methods such as bioremediation, vapor extraction, and pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites. Recently the use of electrokinetics as an in situ method for soil remediation has received increasing attention due to its unique applicability to low-permeability soils. Electrokinetics includes the transport of water (electroosmosis) as well as ions (electromigration) as a result of an applied electric field. For remedial applications, water is typically introduced into the soil at the anode to replenish the water flowing towards the cathode due to electroosmosis. The water flow is utilized to flush organic contaminants from the subsurface soil to the ground surface at the cathode region for further treatment or disposal. This report describes a treatment process under development termed the LASAGNA process which incorporates electrokinetics, along with the establishment of degradation zones, for pollutant removal.

  5. Process for forming an in situ oil shale retort

    SciTech Connect

    Knepper, J.C.

    1984-05-08

    A process is provided for forming an in situ oil shale retort which minimizes channeling, explosion gas turbulence and flame front tilting. In the process, explosives are detonated in an underground formation of oil shale to blast the oil shale into a permeable rubblized mass defining a retort, and gases emitted from the explosion are symmetrically vented. In the preferred form, the gases are vented through vertical vent holes and blast holes which extend through the top of the retort, as well as through a lateral access tunnel which extends into the bottom of the retort.

  6. In situ aeration: Air sparging, bioventing, and related remediation process

    SciTech Connect

    Hinchee, R.E.; Miller, R.N.; Johnson, P.C.

    1995-12-31

    This volume is part of a ten volume set of papers derived from the Third International In Situ and On-Site Bioreclamation Symposium which was held in San Diego, California, in April 1995. The purpose of the conference was to provide a multidisciplinary forum for exchange of state-of-the-art information on bioremediation. This volume focuses on the use of air sparging, bioventing, and other aeration processes to remediate hydrocarbon-contaminated soils and groundwater. Individual papers have been processed separately for inclusion in the appropriate data bases.

  7. Enhanced critical fields and superconducting properties of pre-doped B powder-type MgB2 strands

    NASA Astrophysics Data System (ADS)

    Susner, M. A.; Yang, Y.; Sumption, M. D.; Collings, E. W.; Rindfleisch, M. A.; Tomsic, M. J.; Marzik, J. V.

    2011-01-01

    Conventional doping methods that directly add C or a C-bearing species to Mg + B powder have the disadvantage of adding C inhomogeneously, yielding either under-reacted regions or, in some cases, secondary phases which may be either beneficial or detrimental. Alternatively, pre-doped B powder provides a more homogeneous distribution of the C dopant in MgB2. In this work, powders containing varying amounts of C were used to produce in situ MgB2 strands which showed high values of Bc2, Birr and transport Jc (104 A cm - 2 at 13.3 T). Compared to SiC-added and malic-acid-treated strands the pre-doped MgB2 showed high values of Birr primarily due to more efficient C substitution into the B sublattice and a concomitant increase in transport Jc.

  8. Temperature effect on microstructure and electromagnetic performance of polycarbosilane and sugar-doped MgB2 wires

    NASA Astrophysics Data System (ADS)

    Shcherbakov, A. V.; Horvat, J.; Shcherbakova, O. V.; Novosel, N.; Babić, E.; Dou, S. X.

    2010-06-01

    The effect of processing temperature on structural and superconducting properties of 10 wt.% sugar- and 10 wt.% PCS-doped MgB2 wires is systematically investigated. It is demonstrated that these dopants significantly enhance the electromagnetic performance of Fe-clad MgB2 superconductor and increase its potential for practical application. The enhancement of in-field critical current density (Jc(Ba)) and upper critical field (Bc2) is due to formation of a large amount of lattice defects caused by impurities and C substitution into the MgB2 crystal lattice. High temperature sintering of sugar-doped sample results in as high Bc2 value as 37 T (at 5 K), which correlates with higher level of C substitution into MgB2 crystal lattice in this sample. In contrast, for PCS doped MgB2 wire higher Bc2 value (32 T at 5 K) is observed at lower sintering temperatures. In spite of the fact that the level of C in the crystal lattice and Bc2 value are higher in the sugar doped MgB2 sample, this sample has lower Jc(Ba) when compared to the sample with PCS addition. We speculate that it is due to a higher level of MgO impurities in the sugar doped sample (18.6 wt.% compared to 9.15 wt.% in the PCS doped sample), which results in the dissipation of supercurrent flowing through this sample.

  9. Compositions produced using an in situ heat treatment process

    DOEpatents

    Roes, Augustinus Wilhelmus Maria; Nair, Vijay; Munsterman, Erwin Hunh; Van Bergen, Petrus Franciscus; Van Den Berg, Franciscus Gondulfus Antonius

    2013-05-28

    Methods for treating a subsurface formation and compositions produced therefrom are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

  10. Compositions produced using an in situ heat treatment process

    DOEpatents

    Roes, Augustinus Wilhelmus Maria; Nair, Vijay; Munsterman, Erwin Henh; Van Bergen, Petrus Franciscus; Van Den Berg, Franciscus Gondulfus Antonius

    2009-10-20

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

  11. Treatment of gas from an in situ conversion process

    DOEpatents

    Diaz, Zaida [Katy, TX; Del Paggio, Alan Anthony [Spring, TX; Nair, Vijay [Katy, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX

    2011-12-06

    A method of producing methane is described. The method includes providing formation fluid from a subsurface in situ conversion process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. At least the olefins in the first gas stream are contacted with a hydrogen source in the presence of one or more catalysts and steam to produce a second gas stream. The second gas stream is contacted with a hydrogen source in the presence of one or more additional catalysts to produce a third gas stream. The third gas stream includes methane.

  12. Superconductivity in MgB 2

    NASA Astrophysics Data System (ADS)

    Akimitsu, Jun; Muranaka, Takahiro

    2003-05-01

    We recently discovered that the intermetallic compound magnesium diboride (MgB2) exhibits the highest superconducting transition temperature (Tc=39 K) of all the metallic superconductors. In this paper we report on the basic superconducting characteristics of MgB2 and the current status of the research for the unanswered problem in this superconductivity. Especially, we review the several reports for the superconducting gap (Δ) by the spectroscopic measurements. Moreover we introduce the research into its anisotropic parameter (γ), which is important for the understanding of this superconducting states in this material.

  13. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-In situ... § 903.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, applies to any person who conducts surface coal mining...

  14. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-In situ... § 903.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, applies to any person who conducts surface coal mining...

  15. 30 CFR 905.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-In situ... § 905.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts surface coal...

  16. 30 CFR 905.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-In situ... § 905.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts surface coal...

  17. 30 CFR 942.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-In situ... § 942.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts surface coal...

  18. 30 CFR 942.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-In situ... § 942.828 Special performance standards—In situ processing. Part 828 of this chapter, Special Permanent Program Performance Standards—In Situ Processing, shall apply to any person who conducts surface coal...

  19. In situ studies of microbial inactivation during high pressure processing

    NASA Astrophysics Data System (ADS)

    Maldonado, Jose Antonio; Schaffner, Donald W.; Cuitiño, Alberto M.; Karwe, Mukund V.

    2016-01-01

    High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization.

  20. The Effect of High-energy Ball Milling on the Microstructure and Properties of Ti-doped MgB2 Bulks and Wires

    NASA Astrophysics Data System (ADS)

    Yang, F.; Yan, G.; Wang, Q. Y.; Xiong, X. M.; Li, S. Q.; liu, G. Q.; Feng, J. Q.; Pang, Y. C.; Li, C. S.; Feng, Y.; Zhang, P. X.

    MgB2 bulks were prepared by high-energy ball milling of Mg, B and Ti powders at ambient temperatures. The mixed powders were ball-milled for 0-10 h using a ball-to-powder mass ratio of 10 and sintered at 750 °C for 2 h. The phase and microstructure of MgB2 were characterized by means of X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD results reveal the appearance of a small amount of MgO impurity, and the relative percentage composition of MgO phase is gradually increased with prolonged the milling time. It proved that the sample milled 5 h has the best homogeneity in grain size. The milled 5 h powders were further processed to wires. The wire samples were fabricated by the in-situ powder-in-tube (PIT) method. The mechanical properties were analyzed by stress-strain measurements at room temperature and the superconducting behaviors are investigated by electrical tests at 4.2 K. The critical engineering current Ic reaches above 330 A (Jce exceeding 2.2×104 A/cm2) at 4.2 K and 2 T.

  1. Fabrication and superconducting properties of multifilamentary MgB2 conductors for AC purposes: twisted tapes and wires with very thin filaments

    NASA Astrophysics Data System (ADS)

    Malagoli, A.; Bernini, C.; Braccini, V.; Fanciulli, C.; Romano, G.; Vignolo, M.

    2009-10-01

    In order to use MgB2 conductors for AC applications, research and development efforts have to be carried out on their architecture and sheath material to minimize the AC losses. This paper will present the fabrication and characterization of two types of ex situ powder-in-tube processed pure MgB2 conductors with properties making them good candidates for AC industrial applications: a multifilamentary tape with 12 filaments with a twisting pitch down to 17 mm and a 361-filament wire with an average single-filament size of about 30 µm. Concerning the twisted tapes we will present values of critical current density of about 105 A cm-2 at 4.2 K and 2 T and we will show that it is possible to achieve a proper compromise between the tape size, the twisting pitch length and the critical current density to face a reduction of the critical current density as a consequence of the strain on the filaments. Concerning the 361-multifilamentary wire we will show appreciable values of critical current density of about 5 × 104 A cm-2 at 4.2 K and 2.5 T which, together with the advantages given by the high number of very thin filaments and the non-magnetic matrix, could justify their employment.

  2. Physical property characterization of bulk MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Awana, V. P. S.; Vajpayee, A.; Mudgel, M.; Ganesan, V.; Awasthi, A. M.; Bhalla, G. L.; Kishan, H.

    2008-04-01

    We report synthesis, structure/micro-structure, resistivity under magnetic field [ρ(T)H], Raman spectra, thermoelectric power S(T), thermal conductivity κ(T), and magnetization of ambient pressure argon annealed polycrystalline bulk samples of MgB2, processed under identical conditions. The compound crystallizes in hexagonal structure with space group P6/mmm. Transmission electron microscopy ( TEM) reveals electron micrographs showing various types of defect features along with the presence of 3 4 nm thick amorphous layers forming the grain boundaries of otherwise crystalline MgB2. Raman spectra of the compound at room temperature exhibited characteristic phonon peak at 600 cm-1. Superconductivity is observed at 37.2 K by magnetic susceptibility χ(T), resistivity ρ(T), thermoelectric power S(T), and thermal conductivity κ(T) measurements. The power law fitting of ρ(T) give rise to Debye temperature (ΘD) at 1400 K which is found consistent with the theoretical fitting of S(T), exhibiting Θ D of 1410 K and carrier density of 3.81 × 1028/m3. Thermal conductivity κ(T) shows a jump at 38 K, i.e., at Tc, which was missing in some earlier reports. Critical current density (Jc) of up to 105 A/cm2 in 1 2 T (Tesla) fields at temperatures (T) of up to 10 K is seen from magnetization measurements. The irreversibility field, defined as the field related to merging of M(H) loops is found to be 78, 68 and 42 kOe at 4, 10 and 20 K respectively. The superconducting performance parameters viz. irreversibility field (Hirr) and critical current density Jc(H) of the studied MgB2 are improved profoundly with addition of nano-SiC and nano-diamond. The physical property parameters measured for polycrystalline MgB2 are compared with earlier reports and a consolidated insight of various physical properties is presented.

  3. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  4. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas; Fowlkes, Jason Davidson; Rack, Prof. Philip; Moore, Tom; Magel, Greg; Hartfield, Cheryl

    2012-01-01

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {micro}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  5. Reactive spark plasma sintering of MgB2 in nitrogen atmosphere for the enhancement of the high-field critical current density

    NASA Astrophysics Data System (ADS)

    Badica, P.; Burdusel, M.; Popa, S.; Pasuk, I.; Ivan, I.; Borodianska, H.; Vasylkiv, O.; Kuncser, A.; Ionescu, A. M.; Miu, L.; Aldica, G.

    2016-10-01

    High density bulks (97%-99%) of MgB2 were prepared by spark plasma sintering (SPS) in nitrogen (N2) atmosphere for different heating rates (10, 20 and 100 °C min-1) and compared with reference samples processed in vacuum and Ar. N2 reacts with MgB2 and forms MgB9N along the MgB2 grain boundaries. The high-field critical current density is enhanced for the sample processed in N2 with a heating rate of 100 °C min-1. At 2-35 K, this sample shows the strongest contribution of the grain boundary pinning (GBP). All samples are in the point pinning (PP) limit and by increasing temperature the GBP contribution decreases.

  6. Influence of Ball-Milling Treatment of B Original Powder on the Phase Formation and Critical Current Density of Graphite Doped MgB

    NASA Astrophysics Data System (ADS)

    Su, Xiaocheng; Jiang, Qingguo; Zuo, Anying

    2014-10-01

    In present work, the sintering process and superconducting properties of graphite doped MgB prepared with milled B original powder were investigated. It is found that ball milling treatment of B original powder obviously suppresses the solid-solid reaction between Mg and B, whereas it enhances their liquid-solid reaction during the subsequent sintering process of these graphite doped MgB bulks. Ball milling treatment of B original powder can also promote C substitution for B sites in MgB crystal lattice in the graphite-doped samples, and thus obviously increase their values of at high fields. Moreover, ball milling also refines MgB grains, enhancing grain boundary pinning and at high fields.

  7. Energy from true in situ processing of Antrim oil shale: initial in situ extraction trials

    SciTech Connect

    McNamara, P.H.

    1980-04-01

    This report covers the three in situ extraction trials performed at The Dow Chemical Company's existing oil shale site near Peck, Michigan, from August 11, 1977 to May 24, 1978 and the subsequent analysis. The trials were conducted at a depth of 1200 to 1300 feet for a total operating time of 109 days. Ignition was achieved by an electric heater and by a propane burner using coal and charcoal to increase the input of energy. Gas having an energy value of 50 to 55 Btu/scf was prodcued. The energy recovered in the third and most productive trial compared to the energy used for ignition reached a ratio of 4.8. A cyclic operation, called Huff and Puff, gave a 47 to 65% improvement in energy recovery compared to a single forward combustion. No sulfur compounds were detected in the production gas. Particulate measurement was not of value in monitoring the burning process. The trials reported, and the information gathered for them, provide a basis for a trial at a new site adjacent to the existing site.

  8. Understanding the thermal sciences in the electron beam melting process through in-situ process monitoring

    NASA Astrophysics Data System (ADS)

    Raplee, J.; Plotkowski, A.; Kirka, M. M.; Dinwiddie, R.; Dehoff, R. R.; Babu, S. S.

    2017-04-01

    Additive Manufacturing provides the opportunity to fabricate components of nearly limitless complexity compared to that of traditional manufacturing techniques. However, thermal gyrations imparted into the material from the passing of the heat source cause challenges in fabricating complex structures with the proper process parameters. While the thermal history of the material can be simulated, validating the simulations requires access to thermal data generated through in-situ process monitoring. While generation of in-situ thermal data seems trivial, acquiring and developing reliable calibrations for metallic materials is difficult due to the physical state of the material transitioning from powder to liquid to a solid. To be discussed is the methodology taken to integrate IR in-situ process monitoring within the electron beam melting process and the approach developed to accurately correlate a materials emissivity to temperature during the build process. Further the wealth of information contained within the thermal data will be discussed in the context of understanding of microstructural evolutions within the material during the build process, identification of material defects, and ability to determining the similarity/repeatability of builds fabricated with identical processing parameters as based only on the thermal signature of the build.

  9. Modeling of the in-situ vitrification process

    SciTech Connect

    Koegler, S.S.; Kindle, C.H.

    1990-04-01

    In situ vitrification (ISV) is a thermal treatment process that converts contaminated soil into a durable, leach-resistant product similar to obsidian or basalt. The process, which was developed by Pacific Northwest Laboratory (PNL) for remediation of contaminated soil, is now in the field demonstration and implementation stage. Demonstration tests using the US Department of Energy (DOE)-owned large-scale system are underweight or planned for applications at Hanford and other DOE sites, including the Idaho National Engineering Laboratory, Oak Ridge National Laboratory, and the Savannah River Site. In addition, a private company, Geosafe Corporation, is beginning remediation of commercial contaminated soil sites. A mathematical and computer model has been developed at PNL as a predictive tool to assist engineers and researchers in the application of ISV to different sites. The model, currently configured on a Macintosh personal computer, predicts vitrification time, depth, width, and electrical consumption based on user inputs of electrode configuration, soil parameters, and molten glass characteristics. The model time and depth predications are useful for operations planning, cost estimates, and site selection. Additionally, the depth and width predictions will be used to direct ISV operations to ensure that the contaminated area is completely vitrified and to help mitigate the effect of ISV on adjacent structures. 1 ref., 8 figs.

  10. Development of the integrated in situ Lasagna process

    SciTech Connect

    Ho, S.; Athmer, C.; Sheridan, P.

    1995-12-31

    Contamination in deep, low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in uniform delivery of treatment reagents have rendered existing in-situ methods such as bioremediation, vapor extraction, and pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites.

  11. Second-phase segregation and micro strain/lattice parameter dependent transition temperature in polycrystalline MgB2

    NASA Astrophysics Data System (ADS)

    Cai, Qi; Liu, Yongchang; Guo, Qianying; Ma, Zongqing; Li, Huijun

    2016-10-01

    Un-doped, metal-doped, and carbon-doped MgB2 samples were prepared by furnace cooling and quenching to investigate the second phase behavior and the resultant critical current density J c performance under different heat treatment processes, which is infrequently mentioned, and to explore the strain/lattice parameter dependence of the superconducting transition temperature. To release the residual stress, quenching induced second-phase segregation in these MgB2 samples shows a negative effect on the J c. Nevertheless, the dislocations and the lattice distortion assisted the enhancement of the high-field J c in the un-doped and metal-doped MgB2 samples, which indicated that quenching could be technically applied for the fabrication of metal-sheathed MgB2 wires and tapes to obtain excellent J c. After evaluating the micro strain and the lattice parameters’ (c and a for hexagonal lattice) variation, a dome was observed in the illustration of the strain/lattice parameter c/a dependence of T c, which differed from the reported linear relation in previous work. This suggests that the c/a ratio and the strain may be the predominant parameters for scaling of the superconducting dome width in the superconducting phase diagram of MgB2.

  12. Superior high-field current density in slightly Mg-deficient MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Jiang, C. H.; Nakane, T.; Kumakura, H.

    2005-12-01

    A series of Fe-clad MgxB2 tapes with x varying from 0.5 to 1.2 was prepared by the in situ powder-in-tube method. Slightly Mg-deficient samples showed higher Jc in high magnetic fields, whereas samples with stoichiometric Mg or a slight excess of Mg exhibited better Jc in the low-field region. The sample with x =0.9 showed the best Jc in the applied magnetic field. The MgB2 core was porous in Mg-deficient tapes but with smaller grain sizes than the samples with a slight Mg excess due to insufficient grain growth. Some fine nanometer size grains were also observed in the B-rich samples. The enhanced grain boundary pinning due to the smaller grain size may explain the superior high-field Jc property of the slightly Mg-deficient MgB2 tapes. Our results indicate that preparing MgB2 samples with a slight excess of Mg may not be advantageous when developing devices for high-field applications.

  13. In situ characterization of metal matrix composites processing

    NASA Astrophysics Data System (ADS)

    Munger, Gareth Torrey

    1999-11-01

    The high temperatures and pressures used for the processing of fiber reinforced metal matrix composites (MMC's) can result in the bending and fracture of fibers, and the development of residual stresses in both the fibers and surrounding metal matrix. These phenomena adversely affect the properties of MMC's. Methods for their nondestructive measurement are therefore needed both to better understand the process induced damage mechanisms and to ensure that composites are not placed into service with unacceptable fiber damage and/or residual stresses. A fiber optic luminescence approach based upon the frequency shift of the R lines emission of doped sapphire fibers was used to determine the residual stresses in both Ti/Al2O3 and Ti/SiC composites. To investigate the significance of the creep relaxation effects, residual stresses were measured for sapphire fibers embedded in Ti-6Al-4V plates that had been cooled at different rates. The compressive stresses in the fiber are consistent with the coefficients of thermal expansion (CTE) of sapphire being less than Ti-6Al-4V. A multiple concentric cylinder model was used to predict the residual stress state. The model results confirmed that the creep relaxation was induced responsible for the lower stress in the slowly cooled samples and suggest that cooling rate is important to control during processing. To test the notion of the use of a sapphire fiber as a 'witness to' the stress state in an MMC, a sapphire fiber was inserted into a Ti-6Al-4V coated SIGMA (SiC) fiber bundle prior to its consolidation. A generalized method of cells (GMC) model was used to develop a relationship between the stress state within the sapphire witness fiber and that of the surrounding Ti-6Al-4V matrix and the SIGMA fibers. Fiber fracture during the hot isostatic processing (HIP) consolidation of titanium matrix composite was measured using an in-situ acoustic emission approach. For process cycles in which pressure was applied prior to

  14. Demonstration of a Conduction Cooled React and Wind MgB2 Coil Segment for MRI Applications

    PubMed Central

    Kim, H. S.; Kovacs, C.; Rindfleisch, M.; Yue, J.; Doll, D.; Tomsic, M.; Sumption, M. D.; Collings, E. W.

    2016-01-01

    This study is a contribution to the development of technology for an MgB2-based, cryogen-free, superconducting magnet for an MRI system. Specifically, we aim to demonstrate that a react and wind coil can be made using high performance in-situ route MgB2 conductor, and that the conductor could be operated in conduction mode with low levels of temperature gradient. In this work, an MgB2 conductor was used for the winding of a sub-size, MRI-like coil segment. The MgB2 coil was wound on a 457 mm ID 101 OFE copper former using a react-and-wind approach. The total length of conductor used was 330 m. The coil was epoxy impregnated and then instrumented for low temperature testing. After the initial cool down (conduction cooling) the coil Ic was measured as a function of temperature (15-30 K), and an Ic of 200 A at 15 K was measured. PMID:27857508

  15. Demonstration of a Conduction Cooled React and Wind MgB2 Coil Segment for MRI Applications.

    PubMed

    Kim, H S; Kovacs, C; Rindfleisch, M; Yue, J; Doll, D; Tomsic, M; Sumption, M D; Collings, E W

    2016-06-01

    This study is a contribution to the development of technology for an MgB2-based, cryogen-free, superconducting magnet for an MRI system. Specifically, we aim to demonstrate that a react and wind coil can be made using high performance in-situ route MgB2 conductor, and that the conductor could be operated in conduction mode with low levels of temperature gradient. In this work, an MgB2 conductor was used for the winding of a sub-size, MRI-like coil segment. The MgB2 coil was wound on a 457 mm ID 101 OFE copper former using a react-and-wind approach. The total length of conductor used was 330 m. The coil was epoxy impregnated and then instrumented for low temperature testing. After the initial cool down (conduction cooling) the coil Ic was measured as a function of temperature (15-30 K), and an Ic of 200 A at 15 K was measured.

  16. In situ remediation process using divalent metal cations

    DOEpatents

    Brady, Patrick V.; Khandaker, Nadim R.; Krumhansl, James L.; Teter, David M.

    2004-12-14

    An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu.sup.2+ or Zn.sup.2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO.sub.4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.

  17. In situ characterization of nanoscale catalysts during anodic redox processes

    SciTech Connect

    Sharma, Renu; Crozier, Peter; Adams, James

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  18. Electrical and structural properties of MgB2 films prepared by sequential deposition of B and Mg on the NbN-buffered Si(100) substrate

    NASA Astrophysics Data System (ADS)

    Chromik, Š.; Gaži, Š.; Štrbík, V.; Španková, M.; Vávra, I.; Beňačka, Š.; van der Beek, C. J.; Gierlowski, P.

    2004-10-01

    We introduce a simple method of a MgB2 film preparation using a sequential electron-beam evaporation of B-Mg bilayer (followed by in-situ annealing) on the NbN-buffered Si(100) substrate. The transmission electron microscopy analyses confirm a growth of homogeneous nanogranular MgB2 films without the presence of crystalline MgO. A sensitive measurement of temperature dependence of microwave losses shows a presence of intergranular weak links close to the superconducting transition only. The MgB2 films obtained, about 200-nm thick, exhibit a maximum zero resistance critical temperature of 36K and a critical current density of 3×107A /cm2 at 13.2K.

  19. Gas injection to inhibit migration during an in situ heat treatment process

    SciTech Connect

    Kuhlman, Myron Ira; Vinegar; Harold J.; Baker, Ralph Sterman; Heron, Goren

    2010-11-30

    Methods of treating a subsurface formation are described herein. Methods for treating a subsurface treatment area in a formation may include introducing a fluid into the formation from a plurality of wells offset from a treatment area of an in situ heat treatment process to inhibit outward migration of formation fluid from the in situ heat treatment process.

  20. Improvement in microstructure and superconducting properties of single-filament powder-in-tube MgB2 wires by cold working with a swaging machine

    NASA Astrophysics Data System (ADS)

    Saito, Yusuke; Murakami, Masato; Matsumoto, Akiyoshi; Kumakura, Hiroaki

    2017-06-01

    We investigated the influence of the mechanical deformation method of wire fabrication on the microstructure and superconducting properties of single-filament in situ powder-in-tube (PIT) MgB2 wires. We employed three deformation methods to fabricate the wires: only swaging, groove rolling + roller drawing, and groove rolling + conventional drawing. We found that cold working by swaging has three advantages over the groove rolling + drawing method: (1) improved uniformity of the MgB2 core along the longitudinal direction; (2) higher mass density of the Mg + B (MgB2) core before (after) heat treatment (HT); and (3) well-developed fiber structures of Mg (MgB2) before (after) HT. These three factors greatly enhanced the critical current density (J c) values of PIT MgB2 wires. The highest J c values were obtained through mechanical deformation by swaging for both pure and carbon-doped wires. A J c value of 3.5 × 104 A cm-2 and an engineering critical current density (J e) of 1.1 × 104 A cm-2 were recorded at 4.2 K and 10 T for a swaged wire of 4.5%-carbon-coated boron powder heat-treated at 600 °C for 1 h.

  1. Electron microscopy observations of MgB 2 wire prepared by an internal Mg diffusion method

    NASA Astrophysics Data System (ADS)

    Shimada, Y.; Kubota, Y.; Hata, S.; Ikeda, K.; Nakashima, H.; Matsumoto, A.; Togano, K.; Kumakura, H.

    2011-11-01

    Microstructure in a high-density MgB2 wire fabricated by an internal Mg diffusion (IMD) process has been investigated by electron microscopy imaging and analysis at different scales. In the IMD process, a pure Mg rod was used as Mg source, and nanosized SiC powders were mixed with amorphous B powders. In the case of a heat treatment at 640 °C for 1 h carried out after rolling and drawing processes, the wire has two microstructural features that degrade critical current density: uncrystallized zones composed mainly of unreacted B and SiC powders, and cracks partly filled with course Mg2Si crystals. Those cracks were formed in the uncrystallized zones as well as in crystallized MgB2 zones. It indicate that the cracks formed by the mechanical milling and drawing remain after the heat treatment.

  2. Martian Air Separation for In-Situ Resource Utilization Processes

    NASA Astrophysics Data System (ADS)

    MacArthur, J. R.; Way, J. D.; Baldwin, R. M.; Mason, L. W.

    2002-01-01

    We will introduce the concept of using synthetic organic and inorganic membranes for the separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The class of applications targeted in this project are known as In Situ Resource Utilization (ISRU). ISRU involves the use of resources present on Mars, such as atmospheric gases, a concept that will dramatically reduce the amount of material that must be transferred from Earth to support a mission. ISRU technologies will provide many of the consumables required for a manned mission, such as rocket propellant, water, oxygen and buffer gases. The Martian atmosphere is primarily CO2, and also contains a few percent nitrogen and argon. Martian CO2 is a principal component of several ISRU processes that may be used in a manned Mars mission. For example, the Sabatier/Electrolysis (SE) process reacts atmospheric CO2 with hydrogen to produce methane (fuel), water, and oxygen. Pure gas and mixed gas permeation tests with CO2, Ar, N2, and O2 were performed over the temperature range 243 K to 295 K with a several candidate membrane materials including rubbery polymers (silicone rubber and PEBAX) and supported faujasite zeolite membranes. In experiments with commercially available silicone rubber membranes, the pure gas CO2 permeance (flux/driving force) increases from 460 GPUs to 655 GPUs as the temperature decreases from 295 K to 243 K. A GPU is a commonly used unit of permeance and is defined as 10-6 cm3(STP)/cm2-s-cm Hg. The ideal carbon dioxide/nitrogen separation factor (ratio of pure gas permeances) increases from 7.5 to 17.5 over the same temperature range. However, in mixed gas experiments, the CO2/N2 separation factor was much lower, increasing from 4.5 to 6 as the temperature decreased from 295 K to 243 K. This difference was attributed to plasticization of the rubbery polymer membrane by CO2.

  3. Raman spectroscopy - in situ characterization of growth and surface processes

    NASA Astrophysics Data System (ADS)

    Perkins, James Robert

    The goal of this thesis is to expand on the usefulness of Raman spectroscopy as an in situ probe to aid in the growth and implementation of electronic, optical, and biodetection materials. We accomplish this goal by developing two diverse optical characterization projects. In the first project, an autoclave similar to those used in solvothermal growth which has been outfitted with an optical window is used to collect vibrational spectra of solvents and mineralizers commonly used in the ammonothermal growth of gallium nitride. Secondly, novel silver nanowires created by ferroelectric lithography are evaluated by surface enhanced micro-Raman spectroscopy for use as surface enhanced substrates for low detection limit or single molecule bio-detectors. Raman spectroscopy is already a widely accepted method to characterize and identify a wide variety of materials. Vibrational spectra can yield much information on the presence of chemical species as well as information regarding the phase and interactive properties. Because Raman spectroscopy is a generally non-intrusive technique it is ideal for analysis of hazardous or far-from-ambient liquids, gases, or solids. This technique is used in situ to characterize crystal growth and surface enhanced photochemistry. The phenomenon of Surface Enhanced Raman Spectroscopy (SERS) has been observed in many systems but some fundamental understanding is still lacking and the technique has been slow to transition from the laboratory to the industry. Aggregated colloids and lithographically created islands have shown the best success as reproducible substrates for SERS detection. These techniques, however, lack control over shape, size, and position of the metal nanoparticles which leave them reliant on hotspots. Because of the potential for control of the position of aggregates, ferroelectric lithographically created silver nanowires are evaluated as a potential SERS substrate using pyridine, benzoic acid, and Rhodamine 6g. Surface

  4. Effects of Bi-2212 addition on the levitation force properties of bulk MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Guner, S. B.; Celik, S.

    2016-02-01

    We present a detailed investigation of the effects of Bi2Sr2Ca1Cu2O8+κ (Bi-2212) adding on the levitation force and magnetic properties of bulk MgB2 obtained by hot press method. The amount of Bi-2212 was varied between 0 and 10 wt% (0, 2, 4, 6, 10 wt%) of the total MgB2. Moreover, we present MgB2 bulk samples fabricated by using different production methods including hot pressing method to our knowledge. All samples were prepared by using elemental magnesium (Mg) powder, amorphous nano-boron (B) powder and Bi-2212 powder which are produced by hot press method. As a result of hot press process, compact pellet samples were manufactured. The vertical and lateral levitation force measurements were executed at the temperatures of 20, 24 and 28 K under zero-field-cooled (ZFC) and field-cooled (FC) regimes for samples with various adding levels. At 24 K and 28 K under ZFC regime, the 2 wt% Bi-2212 added sample exhibits a higher vertical levitation force than the pure sample. Bi-2212 added MgB2 samples compared to the pure sample have lower attractive force values in FC regime. The magnetic field dependence of the critical current density J c was calculated from the M-H loops for Bi-2212 added MgB2 samples. The 2 wt% Bi-2212 added sample has the best levitation and critical current density performance compared to other samples. The critical temperature ( T c ) has slightly dropped from 37.8 K for the pure MgB2 sample to 36.7 K for the 10 wt% of Bi-2212 added sample. The transition temperature slightly decreases when Bi-2212 adding level is increased.

  5. Electrochemical atomic force microscopy: In situ monitoring of electrochemical processes

    NASA Astrophysics Data System (ADS)

    Reggente, Melania; Passeri, Daniele; Rossi, Marco; Tamburri, Emanuela; Terranova, Maria Letizia

    2017-08-01

    The in-situ electrodeposition of polyaniline (PANI), one of the most attractive conducting polymers (CP), has been monitored performing electrochemical atomic force microscopy (EC-AFM) experiments. The electropolymerization of PANI on a Pt working electrode has been observed performing cyclic voltammetry experiments and controlling the evolution of current flowing through the electrode surface, together with a standard AFM image. The working principle and the potentialities of this emerging technique are briefly reviewed and factors limiting the studying of the in-situ electrosynthesis of organic compounds discussed.

  6. SITE TECHNOLOGY CAPSULE: IN SITU STEAM ENHANCED RECOVERY PROCESS

    EPA Science Inventory

    The SERP technology is designed to treat soils contaminated with VOCs and SVOCs in situ. Steam injection and vacuum extraction are used to remove the organic compounds from the soil and concentrate them for disposal or recycling. A full-scale demonstration of SERP was conducted a...

  7. SITE TECHNOLOGY CAPSULE: IN SITU STEAM ENHANCED RECOVERY PROCESS

    EPA Science Inventory

    The SERP technology is designed to treat soils contaminated with VOCs and SVOCs in situ. Steam injection and vacuum extraction are used to remove the organic compounds from the soil and concentrate them for disposal or recycling. A full-scale demonstration of SERP was conducted a...

  8. Plasmons in MgB2

    NASA Astrophysics Data System (ADS)

    Chow, Paul; Caliebe, Wolfgang; Kao, Chi-Chang; Friedman, Barry

    2002-03-01

    Due to an apparent anomalously small effective coulomb interaction , it has been suggested [1] that there is a novel charge response from MgB2 in the form of acoustic plasmons. This has motivated at least two detailed calculations of plasmons in MgB2 [2,3]. Although these calculations find no indication of acoustic plasmons, there is a very interesting calculated charge response in the form of a very broad plasmon at ~20eV and an extremely sharp collective excitation with energy between 2-5 eV. Using inelastic X-ray scattering (IXS) we measured the collective charge excitations in MgB2 from oriented thin films and powder samples. The inelastic scattering from the oriented thin film was too weak to be measured, most likely indicating that the film was not sufficiently thick. The conventional plasmons near 20eV were measured in the powder sample for several values of q. In apparent disgreement with calculations [2] these plasmons persist for q of at least 1. /angstrom. We found no evidence of the calculated sharp lower energy excitation, possibly due to the low weight, insufficient resolution or directional averaging of the powder. Research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, [1] K. Voelker, V.I. Anisimov, and T.M. Rice, cond-mat/0103082 5 March 2001. [2] W. Ku, W.E. Pickett, R.T. Scalettar, and A.G. Eguiluz, cond-mat/0105389, 20 May 2001. [3] V.P. Zhukov, V.M. Silkin, E.V. Chulkov, P.M. Echenique, cond-mat/0105461, 23 May 2001.

  9. Evaluation of Select Surface Processing Techniques for In Situ Application During the Additive Manufacturing Build Process

    NASA Astrophysics Data System (ADS)

    Book, Todd A.; Sangid, Michael D.

    2016-07-01

    Although additive manufacturing offers numerous performance advantages for different applications, it is not being used for critical applications due to uncertainties in structural integrity as a result of innate process variability and defects. To minimize uncertainty, the current approach relies on the concurrent utilization of process monitoring, post-processing, and non-destructive inspection in addition to an extensive material qualification process. This paper examines an alternative approach by evaluating the application of select surface process techniques, to include sliding severe plastic deformation (SPD) and fine particle shot peening, on direct metal laser sintering-produced AlSi10Mg materials. Each surface processing technique is compared to baseline as-built and post-processed samples as a proof of concept for surface enhancement. Initial results pairing sliding SPD with the manufacture's recommended thermal stress relief cycle demonstrated uniform recrystallization of the microstructure, resulting in a more homogeneous distribution of strain among the microstructure than as-built or post-processed conditions. This result demonstrates the potential for the in situ application of various surface processing techniques during the layerwise direct metal laser sintering build process.

  10. A MgB2 12.5 kVA superconductor transformer

    NASA Astrophysics Data System (ADS)

    Hascicek, Y. S.; Akin, Y.; Baldwin, T. W.; Rindfleisch, M. M.; Yue, J.; Sumption, M. D.; Tomsic, M.

    2009-06-01

    A 12.5 kVA, MgB2 superconductor transformer was designed as five alternating stacked coils between the primary and the secondary windings. Hyper Tech Research Inc. (Hyper Tech) manufactured multifilament MgB2 superconductor wire by using a patented process called the continuous tube filling and forming (CTFF) process. The CTFF MgB2 conductor was insulated with yttrium-stabilized zirconia (YSZ) using the chemical solution coating process. An all-copper former was designed and fabricated with an OD of 71 mm, ID of 42 mm and heights of 12 mm and 8 mm for primary and secondary coils, respectively. Two primary and three secondary coils were fabricated using the sol-gel insulated MgB2 wire using the W&R coil technology. One of the primary coils was tested at 4.2 K which showed better than 250 A engineering critical current. These five coils were then stacked as in the design in alternating fashion and connected and instrumented for testing. The transformer was cooled in He gas first then in liquid helium. The tests showed that the individual coils, the primary and the secondary windings performed better than the design currents. Also the open-circuit tests of the transformer showed that 1:1 transfer was achieved. This article was originally submitted for the special issue 'Selected papers from the International Conference on Superconductivity and Magnetism (ICSM2008) (Side, Turkey, 25-29 August 2008)', Superconductor Science and Technology, volume 22, issue 3.

  11. Method of rubblization for in-situ oil shale processing

    NASA Technical Reports Server (NTRS)

    Yang, Lien C. (Inventor)

    1985-01-01

    A method that produces a uniformly rubblized oil shale bed of desirable porosity for underground, in-situ heat extraction of oil. Rubblization is the generation of rubble of various sized fragments. The method uses explosive loadings lying at different levels in adjacent holes and detonation of the explosives at different levels in sequence to achieve the fracturing and the subsequent expansion of the fractured oil shale into excavated rooms both above and below the hole pattern.

  12. In Situ Investigations of Ion Exchange Processes in Microporous Materials

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Parise, J. B.; Hanson, J. C.

    2001-12-01

    The mechanism by which ions exchange in microporous and layered solids, such as zeolites and clays for example, has important implications in areas as diverse as soil fertility and environmental remediation. A detailed characterization of the ion-exchange pathway, the structural consequences of ion exchange and the specific sites involved in the course of exchange, is desirable. A probe that is both time- and structure-sensitive allows resolution of which specific sites are involved, along with the effects of different cation types on the uptake and release of ions. In order to discern the mechanism of ion exchange, it is necessary not only to observe the course of the reaction, which can now be done routinely using energy dispersive X-ray diffraction at synchrotron sources, but also to collect dynamic diffraction data of sufficient quality to allow structure refinement using Rietveld structure refinement techniques. This at present requires the collection of monochromatic data. Tradeoffs between time-resolution, peak-to-background discrimination and structural resolution are often required and depend on the problem at hand. We have developed a number of strategies for in situ ion exchange techniques that probe both structural and kinetic information from dynamic solid media. Examples include investigations of the site-specific ion-exchange mechanism in zeolite LSX using a combination of ex situ and in situ time-resolved synchrotron X-ray powder diffraction, Iterative Target Transformation Factor Analysis (ITTFA) and Rietveld structural refinements. Measurement of competitive ion depletion curves showed that the newly synthesized gallosilicate TsG-1 is more selective for Sr than mineral clinoptilolite, and the structural pathway of Sr-exchange in TsG-1 was monitored by in situ and ex situ synchrotron X-ray powder diffraction. In those cases where full structure refinement is desirable using less than optimal powder diffraction data, we found it necessary to first

  13. IN SITU STEAM ENHANCED RECOVERY PROCESS - HUGHES ENVIRONMENTAL SYSTEMS, INC. - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This Innovative Technology Evaluation report summarizes the findings of an evaluation of the in situ Steam Enhanced Recovery Process (SERP) operated by Hughes Environmental Systems, Inc. at the Rainbow Disposal facility in Huntington Beach, California. he technology demonstration...

  14. IN SITU STEAM ENHANCED RECOVERY PROCESS - HUGHES ENVIRONMENTAL SYSTEMS, INC. - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This Innovative Technology Evaluation report summarizes the findings of an evaluation of the in situ Steam Enhanced Recovery Process (SERP) operated by Hughes Environmental Systems, Inc. at the Rainbow Disposal facility in Huntington Beach, California. he technology demonstration...

  15. Evaluating Acoustic Emission Signals as an in situ process monitoring technique for Selective Laser Melting (SLM)

    SciTech Connect

    Fisher, Karl A.; Candy, Jim V.; Guss, Gabe; Mathews, M. J.

    2016-10-14

    In situ real-time monitoring of the Selective Laser Melting (SLM) process has significant implications for the AM community. The ability to adjust the SLM process parameters during a build (in real-time) can save time, money and eliminate expensive material waste. Having a feedback loop in the process would allow the system to potentially ‘fix’ problem regions before a next powder layer is added. In this study we have investigated acoustic emission (AE) phenomena generated during the SLM process, and evaluated the results in terms of a single process parameter, of an in situ process monitoring technique.

  16. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-07-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  17. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    PubMed Central

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-01-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning. PMID:27406904

  18. Influence of nanocrystalline boron precursor powder on superconductivity in MgB2 bulk.

    PubMed

    Zhang, Yun; Lu, Cheng; Zhou, Sihai; Joo, Jinho

    2009-12-01

    In this report, high-purity nanocrystalline boron powders processed by ball-milling were used as the precursor powders to fabricate MgB2 superconductor. The transport properties and the critical current density in the samples made from ball-milled boron powders and as-supplied boron powders were investigated. It was found that the ball-milled boron powders led to a significant enhancement of the critical current density in MgB2 sintered at 650 degrees C. The reason can be attributed to the small MgB2 grain size caused by the ball-milled boron precursor powders. The resistivity of the samples made from the ball-milled boron powder was lower than that of the sample from as-supplied boron powder. As the sintering temperature increased, both resistivity and upper critical field decreased in the samples using the ball-milled boron powders as a precursor. Poor connectivity and large strain are responsible for the high resistivity.

  19. Al addition effect of bulk MgB 2 superconductor

    NASA Astrophysics Data System (ADS)

    Shinohara, K.; Ikeda, H.; Yoshizaki, R.

    2007-10-01

    The properties of transport and magnetization have been investigated for bulk MgB2Alx superconductor with Al addition (x = 0, 0.5, 1 wt%). MgB2 bulk samples sintered at different temperatures at 650-740 °C were prepared in the undoped state. The temperature and applied field dependencies of resistivity and magnetization were measured for the samples. The sample sintered at 690 °C exhibited the highest critical current density (Jc) and the lowest resistivity. This undoped sample was chosen as a criterion sample, and the effect of Al addition on the MgB2 bulk was studied from the transport and magnetization properties in a magnetic field. For MgB2Alx bulk samples sintered at 690 °C, the resistivity increased and Jc decreased as amount of Al was increased.

  20. Properties of as-deformed and post-annealed MgB2/Fe(Fe-alloy) composite wires

    NASA Astrophysics Data System (ADS)

    Kovác, P.; Husek, I.; Grovenor, Ch; Salter, Ch

    2003-02-01

    Composite MgB2 wires have been made by the powder-in-tube method using commercial MgB2 powder (Alfa Aesar) in Fe and Fe-alloy (stainless steel (SS)) sheaths. Different deforming processes have been used. Two-axial rolling (TAR) produces the highest powder density leading to the best Jc (0 T, 4.2 K) of 55000 A cm-2 in as-deformed wire. Therefore, four-core wire has also been made by TAR. The short samples were subjected to annealing at temperatures from 850 to 1100 °C for 30 min in argon, which leads to apparently improved Jc values, 25000 A cm-2 at 4 T and around 106 A cm-2 in the self-field (at 4.2 K). An interdiffusion layer between MgB2 and the Fe or SS sheath was observed and analysed. The SS sheath reacts more intensely than Fe due to the presence of Ni and Cr elements. Transport currents were measured at temperatures 4.2-25 K and an external magnetic field B = 0-8 T. The engineering current density level of 104 A cm-2 is used to estimate the magnetic field possibly generated by coils wound from MgB2 composite wires.

  1. An evaluation of in-situ bioremediation processes

    SciTech Connect

    Cole, L.L.; Rashidi, M.

    1996-08-01

    Remediation of petroleum hydrocarbons in groundwater was the primary focus in the initial application of in-situ bioremediation which, from its development in the 1970s, has grown to become one of the most promising technologies for the degradation of a wide variety of organic contaminants. The degradation of contaminants in subsurface soils is the current new focus of the technology. While the need for improvements in the technology does exist, the indisputable fact remains that this technology is by far the least expensive and that it has the capability to provide long term reduced levels of contaminants or long term complete remediation of contaminated sites. The aim of this paper is to disclose pertinent information related to current conditions and current feelings in the area of new research, novel applications, new government regulations, and an overview of new topics on the horizon that relate to the overall technology.

  2. In situ conversion process utilizing a closed loop heating system

    SciTech Connect

    Sandberg, Chester Ledlie; Fowler, Thomas David; Vinegar, Harold J.; Schoeber, Willen Jan Antoon Henri

    2009-08-18

    An in situ conversion system for producing hydrocarbons from a subsurface formation is described. The system includes a plurality of u-shaped wellbores in the formation. Piping is positioned in at least two of the u-shaped wellbores. A fluid circulation system is coupled to the piping. The fluid circulation system is configured to circulate hot heat transfer fluid through at least a portion of the piping to form at least one heated portion of the formation. An electrical power supply is configured to provide electrical current to at least a portion of the piping located below an overburden in the formation to resistively heat at least a portion of the piping. Heat transfers from the piping to the formation.

  3. Urine Stasis Predisposes to Urinary Tract Infection by an Opportunistic Uropathogen in the Megabladder (Mgb) Mouse.

    PubMed

    Becknell, Brian; Mohamed, Ahmad Z; Li, Birong; Wilhide, Michael E; Ingraham, Susan E

    2015-01-01

    Urinary stasis is a risk factor for recurrent urinary tract infection (UTI). Homozygous mutant Megabladder (Mgb-/-) mice exhibit incomplete bladder emptying as a consequence of congenital detrusor aplasia. We hypothesize that this predisposes Mgb-/- mice to spontaneous and experimental UTI. Mgb-/-, Mgb+/-, and wild-type female mice underwent serial ultrasound and urine cultures at 4, 6, and 8 weeks to detect spontaneous UTI. Urine bacterial isolates were analyzed by Gram stain and speciated. Bladder stones were analyzed by x-ray diffractometry. Bladders and kidneys were subject to histologic analysis. The pathogenicity of coagulase-negative Staphylococcus (CONS) isolated from Mgb-/- urine was tested by transurethral administration to culture-negative Mgb-/- or wild-type animals. The contribution of urinary stasis to CONS susceptibility was evaluated by cutaneous vesicostomy in Mgb-/- mice. Mgb-/- mice develop spontaneous bacteriuria (42%) and struvite bladder stones (31%) by 8 weeks, findings absent in Mgb+/- and wild-type controls. CONS was cultured as a solitary isolate from Mgb-/- bladder stones. Bladders and kidneys from mice with struvite stones exhibit mucosal injury, inflammation, and fibrosis. These pathologic features of cystitis and pyelonephritis are replicated by transurethral inoculation of CONS in culture-negative Mgb-/- females, whereas wild-type animals are less susceptible to CONS colonization and organ injury. Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys. CONS is an opportunistic uropathogen in the setting of urinary stasis, leading to enhanced UTI incidence and severity in Mgb-/- mice.

  4. Processing of In-Situ Al-AlN Metal Matrix Composites via Direct Nitridation Method

    DTIC Science & Technology

    1998-04-01

    The role of Mg in the present in-situ nitridation process could be different from that in the DIMOX process [13,17]. Further study is clearly...however, that the addition of Si suppresses the formation of A1N during the DIMOX process [10]. It is, therefore, important to examine the effect of Si

  5. Kinematic analysis of in situ measurement during chemical mechanical planarization process

    SciTech Connect

    Li, Hongkai; Wang, Tongqing; Zhao, Qian; Meng, Yonggang; Lu, Xinchun

    2015-10-15

    Chemical mechanical planarization (CMP) is the most widely used planarization technique in semiconductor manufacturing presently. With the aid of in situ measurement technology, CMP tools can achieve good performance and stable productivity. However, the in situ measurement has remained unexplored from a kinematic standpoint. The available related resources for the kinematic analysis are very limited due to the complexity and technical secret. In this paper, a comprehensive kinematic analysis of in situ measurement is provided, including the analysis model, the measurement trajectory, and the measurement time of each zone of wafer surface during the practical CMP process. In addition, a lot of numerical calculations are performed to study the influences of main parameters on the measurement trajectory and the measurement velocity variation of the probe during the measurement process. All the efforts are expected to improve the in situ measurement system and promote the advancement in CMP control system.

  6. Kinematic analysis of in situ measurement during chemical mechanical planarization process

    NASA Astrophysics Data System (ADS)

    Li, Hongkai; Wang, Tongqing; Zhao, Qian; Meng, Yonggang; Lu, Xinchun

    2015-10-01

    Chemical mechanical planarization (CMP) is the most widely used planarization technique in semiconductor manufacturing presently. With the aid of in situ measurement technology, CMP tools can achieve good performance and stable productivity. However, the in situ measurement has remained unexplored from a kinematic standpoint. The available related resources for the kinematic analysis are very limited due to the complexity and technical secret. In this paper, a comprehensive kinematic analysis of in situ measurement is provided, including the analysis model, the measurement trajectory, and the measurement time of each zone of wafer surface during the practical CMP process. In addition, a lot of numerical calculations are performed to study the influences of main parameters on the measurement trajectory and the measurement velocity variation of the probe during the measurement process. All the efforts are expected to improve the in situ measurement system and promote the advancement in CMP control system.

  7. Kinematic analysis of in situ measurement during chemical mechanical planarization process.

    PubMed

    Li, Hongkai; Wang, Tongqing; Zhao, Qian; Meng, Yonggang; Lu, Xinchun

    2015-10-01

    Chemical mechanical planarization (CMP) is the most widely used planarization technique in semiconductor manufacturing presently. With the aid of in situ measurement technology, CMP tools can achieve good performance and stable productivity. However, the in situ measurement has remained unexplored from a kinematic standpoint. The available related resources for the kinematic analysis are very limited due to the complexity and technical secret. In this paper, a comprehensive kinematic analysis of in situ measurement is provided, including the analysis model, the measurement trajectory, and the measurement time of each zone of wafer surface during the practical CMP process. In addition, a lot of numerical calculations are performed to study the influences of main parameters on the measurement trajectory and the measurement velocity variation of the probe during the measurement process. All the efforts are expected to improve the in situ measurement system and promote the advancement in CMP control system.

  8. SIMULATING THE IN SITU CONDENSATION PROCESS OF SOLAR PROMINENCES

    SciTech Connect

    Xia, C.; Keppens, R.; Antolin, P.; Porth, O.

    2014-09-10

    Prominences in the solar corona are a hundredfold cooler and denser than their surroundings, with a total mass of 10{sup 13} up to 10{sup 15} g. Here, we report on the first comprehensive simulations of three-dimensional, thermally and gravitationally stratified magnetic flux ropes where in situ condensation to a prominence occurs due to radiative losses. After a gradual thermodynamic adjustment, we witness a phase where runaway cooling occurs while counter-streaming shearing flows drain off mass along helical field lines. After this drainage, a prominence-like condensation resides in concave upward field regions, and this prominence retains its overall characteristics for more than two hours. While condensing, the prominence establishes a prominence-corona transition region where magnetic field-aligned thermal conduction is operative during the runaway cooling. The prominence structure represents a force-balanced state in a helical flux rope. The simulated condensation demonstrates a right-bearing barb, as a remnant of the drainage. Synthetic images at extreme ultraviolet wavelengths follow the onset of the condensation, and confirm the appearance of horns and a three-part structure for the stable prominence state, as often seen in erupting prominences. This naturally explains recent Solar Dynamics Observatory views with the Atmospheric Imaging Assembly on prominences in coronal cavities demonstrating horns.

  9. Effect of Mg/B ratio on the superconductivity of MgB2 bulk with SiC addition

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Dou, S. X.; Lu, C.; Zhou, S. H.; Li, W. X.

    2010-03-01

    To improve the self-field critical current density (Jc) and critical temperature (Tc) in SiC-doped MgB2 , optimization of the nominal Mg/B mixing ratio has been performed. The effects of the nominal Mg/B mixing ratio (x:2) on the superconductivity, Raman spectra, current transport properties, and flux pinning mechanisms in MgB2 with 10 wt.% SiC doping were investigated systematically, with x varied from 1 to 1.2. It has been found that the sample with the Mg/B ratio of 1.15:2 exhibited the best Jc performance for all fields (0-8.5 T), and its Tc was also enhanced. The optimized Mg/B ratio diminished the interband scattering caused by Mg or B vacancies, and in turn, increased Tc . The connectivity and disorder were increased in the Mg1.15B2 sample. Both of these were responsible for the improved Jc under all the fields examined.

  10. The effect of boron powder on the microstructure of MgB2 filaments prepared by the modified internal magnesium diffusion technique

    NASA Astrophysics Data System (ADS)

    Rosová, A.; Kulich, M.; Kováč, P.; Brunner, B.; Scheiter, J.; Häßler, W.

    2017-05-01

    We have analyzed the microstructure of MgB2 prepared by the modified internal magnesium diffusion technique resulting in filaments without a central hole. Three different amorphous boron powders with a nominal purity of 98.5%-99.0% and a different particle size were used. It was shown that the real purity of the powders was different from the nominal purity, and the microstructure as well as the critical current densities of the MgB2 were affected by using boron. Larger B particles with a size of 400-500 nm led to the presence of large B-rich grains inside the MgB2 matrix. For one wire series, boron powder containing residual chlorine from the boron preparation process was used. It was found that just a small quantity of chlorine in the B powder caused significant MgB2 filament inhomogeneity, an apparent decrease in the critical current density and high reactivity with air. We estimated the ideal packing density for achieving a large volume of dense MgB2.

  11. Superconducting tunnel junctions on MgB2 using MgO and CaF2 as a barrier

    NASA Astrophysics Data System (ADS)

    Sakoda, Masahito; Aibara, Masato; Mede, Kazuya; Kikuchi, Motoyuki; Naito, Michio

    2016-11-01

    We report the fabrication of superconducting tunnel junctions, both of superconductor-insulator-normal metal (SIN) and superconductor-insulator-superconductor (SIS), on MgB2 using MgO and CaF2 as a barrier. The SIN junctions fabricated using an MgO barrier showed excellent quasi-particle characteristics, including a large superconducting gap (Δ) of 2.5-3 meV and a low zero-bias conductance. We have also fabricated SIS junctions with an MgO barrier, but the quasi-particle characteristics of the SIS junctions are not as good as those of the SIN junctions, namely a reduced superconducting gap and a high zero-bias conductance. It appears that top MgB2 electrodes do not grow well on an MgO barrier, which is also suggested from in-situ RHEED observation. The SIN junctions fabricated using a CaF2 barrier showed less sharp quasi-particle characteristics than using an MgO barrier. However, the SIS junctions using a CaF2 barrier showed a fairly large IcRN value at 4.2 K over 1 mV and also exhibited finite Josephson current up to almost the film's Tc (∼30 K). The RHEED observation revealed that top MgB2 electrodes grow well on a CaF2 barrier.

  12. Strong enhancement of high-field critical current properties and irreversibility field of MgB2 superconducting wires by coronene active carbon source addition via the new B powder carbon-coating method

    NASA Astrophysics Data System (ADS)

    Ye, Shu Jun; Matsumoto, Akiyoshi; Chao Zhang, Yun; Kumakura, Hiroaki

    2014-08-01

    We report an effective carbon-containing additive, coronene (C24H12), for MgB2 superconducting wires. We used B powder coated with C24H12 to fabricate MgB2 wires using the powder-in-tube (PIT) and internal Mg diffusion (IMD) processes. The in-field critical current properties are strongly enhanced for both PIT- and IMD-processed MgB2 wires. For PIT MgB2 wires, a critical current density (Jc) value of 1.8 × 104 A cm-2 is obtained at 4.2 K and 10 T. For IMD MgB2 wires, we obtained a Jc of 1.07 × 105 A cm-2 and an engineering Jc (Je) of 1.12 × 104 A cm-2 at 4.2 K and 10 T. These Jc and Je values are similar to the highest values reported for MgB2 wires thus far. Furthermore, the irreversibility field, Birr, determined with a current density criterion of 100 A cm-2, is strongly enhanced to 25 T at 4.2 K, which is also the highest value reported for MgB2 superconducting wires thus far. Coronene is an active carbon source for MgB2 superconducting wires because (1) coronene has a high carbon content (96 wt%) with a small amount of hydrogen (impurity), (2) the decomposition temperature for coronene is near the reaction temperature between Mg and B, and (3) uniform dispersion of coronene on the B surface can be obtained due to the melting point of coronene being lower than the decomposition temperature. Carbon substitution for B caused by the coronene active carbon source is mainly responsible for the high field critical current properties and the high Birr obtained in this work.

  13. Investigation of the Geokinetics horizontal in-situ oil-shale-retorting process

    NASA Astrophysics Data System (ADS)

    Costimiris, E. C.

    1982-07-01

    The objective of the Geokinetics in situ shale oil project is to develop a true in situ process for recovering shale oil using a fire front moving in a horizontal direction. The project is conducted at a field site, Kamp Kerogen, Utah. During 1981, one full sized retort was blasted and the following three retorts were processed: (1) retort No. 24 operations were continued until July 23; (2) retort No. 23 was ignited and processed during the calendar year; (3) retort No. 25 was ignited and burned for 77 days during 1981.

  14. Wireless sensor technology for in-situ plasma process monitoring

    NASA Astrophysics Data System (ADS)

    Gahan, David

    2015-09-01

    There is an increasing demand for plasma measurement and control solutions to cope with the growing complexity of integrated circuit manufacture in the semiconductor industry. Standard plasma diagnostic instruments used in research, such as the Langmuir probe, are not suitable for use in the production environment for myriad reasons - contamination of the process being one of the main concerns. Silicon wafer based wireless sensors, which measure temperature during the process, have gained the most traction with tool manufacturers and chip makers - albeit during process development or the PM cycle rather than live production. In this presentation we will discuss two novel wireless technologies that have the potential for use in process tools. The first is an ion detector embedded in a silicon wafer. The sensor measures the average ion flux and the maximum ion energy during the process. This information is stored and is downloaded later for analysis. The second technology consists of a wireless sensor that sits inside the process and communicates data in real time to a detector installed on the rf power line. This platform is similar to RFID technology and can be combined with various sensor types to transmit data to the user during the process.

  15. 30 CFR 785.22 - In situ processing activities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Delineation of proposed holes and wells and production zone for approval of the regulatory authority; (2..., health, safety or environmental hazard caused by the mining and recovery process; and (4) Plans for...

  16. Process control of MOCVD growth for LEDs by in-situ photoluminescence

    NASA Astrophysics Data System (ADS)

    Prall, C.; Haberland, K.; Kaspari, C.; Brunner, F.; Weyers, M.; Rueter, D.

    2016-03-01

    Development and manufacturing of LED structures is still driven by production cost reduction and performance improvements. Therefore, in-situ monitoring during the epitaxial process plays a key role in view of further yield improvement and process optimization. With the continuing trend towards larger wafers, stronger bow and increased aspherical curvature are additional challenges the growers have to face, leading to non-uniform LED-emission. Compared to traditional in-situ metrology like curvature measurement and near UV pyrometry, in-situ photoluminescence measurements can provide a more direct access to the quantum well emission already during growth. In this paper we show how in-situ photoluminescence measurements can be used in a production type multi-wafer MOCVD system to characterize the quantum well emission already during growth. We also demonstrate how deviations from the desired wavelength can be detected and corrected in the same growth run. Since the method is providing spatially resolved line-scans across the wafer, also the uniformity of the emission wavelength can be characterized already during growth. Comparison of in-situ and ex-situ photoluminescence data show excellent agreement with respect to wavelength uniformity on 4 inch wafers.

  17. High transport critical current density in Cu-clad multifilament MgB2 tape

    NASA Astrophysics Data System (ADS)

    Liu, C. F.; Du, S. J.; Yan, G.; Fu, B. Q.; Feng, Y.; Ji, P.; Wang, J. R.; Liu, X. H.; Zhang, P. X.; Wu, X. Z.; Zhou, L.; Cao, L. Z.; Ruan, K. Q.; Wang, C. Y.; Li, X. G.; Zhou, G. E.; Zhang, Y. H.

    2002-05-01

    Cu-clad multifilament MgB2 tapes with Ta or NbZr buffer have been fabricated by using a powder-in-tube (PIT). Mg+2B mixture powder was used as the central conductor core in single filament with Cu sheath and Ta or NbZr buffer wall. The composite tapes with 18 filaments were heat-treated in pure Ar atmosphere at 600-1000 °C for 1-10 h, and reacted in-situ to form MgB2. The phase composition and microstructure in the samples were examined by using X-ray diffraction and optical microscopy. Transport critical current was measured by a standard four-probe technique at different magnetic fields and temperatures. The sample with 18 filaments and NbZr buffer shows a high transport critical current density of 8×104 A/cm2 (10 K, 0 T) and 1.36×104 A/cm2 (10 K, 1 T).

  18. MgB2 magnetometer with a directly coupled pick-up loop

    NASA Astrophysics Data System (ADS)

    Portesi, C.; Mijatovic, D.; Veldhuis, D.; Brinkman, A.; Monticone, E.; Gonnelli, R. S.

    2006-05-01

    In this work, we show the results obtained in the fabrication and characterization of an MgB2 magnetometer with a directly coupled pick-up loop. We used an all in situ technique for fabricating magnesium diboride films, which consists of the co-evaporation of B and Mg by means of an e-gun and a resistive heater respectively. Consequently, we realized the superconducting device, which incorporates two nanobridges as weak links in a superconducting loop. The nanobridges were realized by focused ion beam milling; they were 240 nm wide and had a critical current density of 107 A cm-2. The magnetometer was characterized at different temperatures and also measurements of the noise levels have been performed. The device shows Josephson quantum interference up to 20 K and the calculated effective area at low temperatures was 0.24 mm2. The transport properties of the magnetometer allow determining fundamental materials properties of the MgB2 thin films, such as the penetration depth.

  19. SITE DEMONSTRATION BULLETIN - ENHANCED IN-SITU BIOREMEDIATION PROCESS, EARTH TECH, INC.

    EPA Science Inventory

    The USEPA conducted an evaluation of the Enhanced In-situ Bioremediation process, a biostimulation technology developed by the USDOE at the Westinghouse Savannah River Plant site in Aiken, SC. DOE has licensed the process to Earth Tech, Inc. The evaluation described in this bulle...

  20. EARTH TECH INC.'S ENHANCED IN-SITU BIOREMEDIATION PROCESS; INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    The USEPA conducted an evaluation of the Enhanced In-situ Bioremediation process, a biostimulation technology developed by the USDOE at the Westinghouse Savannah River Plant site in Aiken, SC. DOE has licensed the process to Earth Tech, Inc. The evaluation described in this bulle...

  1. EPA SITE DEMONSTRATION OF THE INTERNATIONAL WASTE TECHNOLOGIES/GEO-CON IN SITU STABILIZATION/ SOLIDIFICATION PROCESS

    EPA Science Inventory

    This paper presents an EPA evaluation of the first field demonstration of an in situ stabilization/solidification process for contaminated soil under the EPA Superfund Innovative Technology Evaluation (SITE) program. Demonstration of this process was a joint effort of two vendors...

  2. Experimental Investigation and High Resolution Simulator of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Anthony Kovscek

    2007-03-31

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this current and fourteenth report, we report on our continued numerical experimentation with the Virtual Kinetic Cell and our continuing experimental program.

  3. Experimental Investigation and High Resolution Simulator of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2006-12-31

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this current and thirteenth report, we report on our continuing development of a Virtual Kinetic Cell model and our continuing experimental program.

  4. Process defects and in situ monitoring methods in metal powder bed fusion: a review

    NASA Astrophysics Data System (ADS)

    Grasso, Marco; Colosimo, Bianca Maria

    2017-04-01

    Despite continuous technological enhancements of metal Additive Manufacturing (AM) systems, the lack of process repeatability and stability still represents a barrier for the industrial breakthrough. The most relevant metal AM applications currently involve industrial sectors (e.g. aerospace and bio-medical) where defects avoidance is fundamental. Because of this, there is the need to develop novel in situ monitoring tools able to keep under control the stability of the process on a layer-by-layer basis, and to detect the onset of defects as soon as possible. On the one hand, AM systems must be equipped with in situ sensing devices able to measure relevant quantities during the process, a.k.a. process signatures. On the other hand, in-process data analytics and statistical monitoring techniques are required to detect and localize the defects in an automated way. This paper reviews the literature and the commercial tools for in situ monitoring of powder bed fusion (PBF) processes. It explores the different categories of defects and their main causes, the most relevant process signatures and the in situ sensing approaches proposed so far. Particular attention is devoted to the development of automated defect detection rules and the study of process control strategies, which represent two critical fields for the development of future smart PBF systems.

  5. EPA SITE DEMONSTRATION OF THE INTERNATIONAL WASTE TECHNOLOGIES/GEO-CON IN SITU STABILIZATION/ SOLIDIFICATION PROCESS

    EPA Science Inventory

    This paper presents an EPA evaluation of the first field demonstration of an in situ stabilization/solidification process for contaminated soil under the EPA Superfund Innovative Technology Evaluation (SITE) program. Demonstration of this process was a joint effort of two vendors...

  6. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., and follow after approval, a plan that ensures that all acid-forming, toxic-forming, or radioactive... processing activities shall restore the quality of affected ground water in the permit area and adjacent area, including ground water above and below the production zone, to the approximate premining levels or better...

  7. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... contamination of ground and surface waters, damage to fish, wildlife and related environmental values, and... processing activities shall restore the quality of affected ground water in the permit area and adjacent area, including ground water above and below the production zone, to the approximate premining levels or...

  8. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Avoiding discharge of fluids into holes or wells, other than as approved by the regulatory authority; (2... regulatory authority; (3) Avoiding annular injection between the wall of the drill hole and the casing; and... processing activities shall restore the quality of affected ground water in the permit area and adjacent...

  9. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) Avoiding discharge of fluids into holes or wells, other than as approved by the regulatory authority; (2... regulatory authority; (3) Avoiding annular injection between the wall of the drill hole and the casing; and... processing activities shall restore the quality of affected ground water in the permit area and adjacent...

  10. Biodegradation Rates Assessment For An In Situ Bioremediation Process

    NASA Astrophysics Data System (ADS)

    Troquet, J.; Poutier, F.

    Bioremediation methods seem a promising way of dealing with soil and subsoil con- tamination by organic substances. The biodegradation process is supported by micro- organisms which use the organic carbon from the pollutants as energy source and cells building blocks. However, bioremediation is not yet universally understood and its success is still an intensively debated issue because all soils and groundwater are not able to sustain biological growth and, then, cannot be successfully bioremediated. The outcome of each degradation process depends on several factors, which, such as oxygen transfer and pollutant bio-availability, can be controlled and are therefore key variables of such bioremediation processes. Then, it is essential to carry out a fea- sibility study based on pilot-testing before starting a remediation project in order to determine the best formulation of nutrients and bacteria to use for the specific condi- tions encountered. The scope of this work is to study the main parameters of the process and its physi- cal limiting steps in order to determine the biodegradation rates in a specific case of contamination. Several ground samples from an actual petroleum hydrocarbon con- taminated site have been laboratory tested. Five fixed bed column reactors, enabling the study of the influence of the different op- erating variables on the biodegradation kinetics, are used. The stoichiometric equation for bacteria growth and pollutant degradation has been established, allowing the de- termination of mass balances. Biodegradation monitoring is achieved by continuously measuring the emissions of carbon dioxide production and intermittently by analysing residual hydrocarbons. Results lead to the knowledge of biodegradation rates which allow to determine the treatment duration and cost.

  11. Pressure-induced phase transition and electronic properties of MgB2C2

    NASA Astrophysics Data System (ADS)

    Zheng, Baobing

    2017-05-01

    Two thermodynamically stable new high-pressure phases of MgB2C2 with P-3m1 and I4 cm structure were uncovered through first principles crystal structure search based on unbiased evolutionary simulations. Compared with oC80-MgB2C2 and oP10-MgB2C2 phases, the theoretically predicted hP5-MgB2C2 and tI20-MgB2C2 phases show an intriguing three-dimensional (3D) sp3 B-C bonded network, instead of original 2D sp2 B-C layers, which has been confirmed with the analysis of their structures and partial densities of states. The phase transitions of oC80-MgB2C2 → oP10-MgB2C2, oP10-MgB2C2 → hP5-MgB2C2, and hP5-MgB2C2 → tI20-MgB2C2 occur at 4.6 GPa, 18.9 GPa, and 247.5 GPa, respectively, which have been determined according to the examination of enthalpy differences curves. Electronic band structure calculations suggest that the oC80-MgB2C2, oP10-MgB2C2 and hP5-MgB2C2 phases are indirect band gap semiconductor, while the tI20-MgB2C2 phase changes to direct band gap semiconductor.

  12. MgB2 tunnel junctions with native or thermal oxide barriers

    NASA Astrophysics Data System (ADS)

    Singh, R. K.; Gandikota, R.; Kim, J.; Newman, N.; Rowell, J. M.

    2006-07-01

    MgB2 tunnel junctions (MgB2/barrier/MgB2) were fabricated using a native oxide grown on the bottom MgB2 film as the tunnel barrier. Such barriers therefore survive the deposition of the second electrode at 300°C, even over junction areas of ˜1mm2. Studies of such junctions and those of the type MgB2/native or thermal oxide/metal (Pb, Au, or Ag) show that tunnel barriers grown on MgB2 exhibit a wide range of barrier heights and widths.

  13. Optical method for in situ monitoring of electrospinning process and porosity characterization of microporous membrane

    NASA Astrophysics Data System (ADS)

    Chen, Chung-Han; Huang, Chieh-Tse; Fuh, Yiin-Kuen

    2017-04-01

    We present an optical-based, rapid method for the in situ porosity measurement of membranes through the electrospinning process. The method was developed by combining an optical method with in situ monitoring of the porosity of the electrospun membranes based on the measured reflected power density. The results showed that the area of bright and dark ratio is consistently proportional to the porosity of the electrospun membranes, which can potentially be used for actual characterization of the membranes. In addition, the effect of different incident angles of a laser beam was performed and compared. The porosity ratio of the electrospun membranes can be empirically evaluated as the determination coefficient R2=0.9945 to 0.9876 can be obtained. The proposed method is successfully demonstrated and validated by the SEM images of the binary method. The potential applications include the in situ monitoring of the electrospinning process for the bioassembly and biomimicking of a human tissue with a great accuracy.

  14. Study on the in-situ coupling process of fermentation, extraction and distillation for biobutanol production: process analysis

    NASA Astrophysics Data System (ADS)

    Jin, Fuqiang; Zhang, Xiaodong; Hua, Dongliang; Xu, Haipeng; Li, Yan; Mu, Hui

    2017-01-01

    The transfer process of the in-situ coupling process of fermentation, extraction and distillation for biobutanol production was discussed from a theoretical point of view. The existence of temperature gradient in the extraction section was proved. The force of solute in the extracted liquid was discussed. And the mass transfer mechanism and impetus of the FEDIC process was analyzed. The theoretical analysis could provide a foundation for the following research.

  15. Experimental Investigation and High Resolution Simulator of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2006-07-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this current and eleventh report, we report on the development of a virtual kinetic cell (VKC) that aids the study of the interaction between kinetics and phase behavior. The VKC also provides an excellent tool for developing and testing specialized solvers for the stiff kinetics encountered in ISC processes.

  16. Experimental Investigation and High Resolution Simulation of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Tony Kovscek

    2008-04-30

    This final technical report describes work performed for the project 'Experimental Investigation and High Resolution Numerical Simulator of In-Situ Combustion Processes', DE-FC26-03NT15405. In summary, this work improved our understanding of in-situ combustion (ISC) process physics and oil recovery. This understanding was translated into improved conceptual models and a suite of software algorithms that extended predictive capabilities. We pursued experimental, theoretical, and numerical tasks during the performance period. The specific project objectives were (i) identification, experimentally, of chemical additives/injectants that improve combustion performance and delineation of the physics of improved performance, (ii) establishment of a benchmark one-dimensional, experimental data set for verification of in-situ combustion dynamics computed by simulators, (iii) develop improved numerical methods that can be used to describe in-situ combustion more accurately, and (iv) to lay the underpinnings of a highly efficient, 3D, in-situ combustion simulator using adaptive mesh refinement techniques and parallelization. We believe that project goals were met and exceeded as discussed.

  17. In-situ characterization of colloidal soft solution processes.

    SciTech Connect

    Tallant, David Robert; Rodriguez, Mark Andrew; Bell, Nelson Simmons

    2003-11-01

    The purpose of this program was to investigate methods to characterize the colloidal stability of nanoparticles during the synthesis reaction, and to characterize their organization related to interparticle forces. Studies were attempted using Raman spectroscopy and ultrasonic attenuation to observe the nucleation and growth process with characterization of stability parameters such as the zeta potential. The application of the techniques available showed that the instrumentation requires high sensitivity to the concentration of the system. Optical routes can be complicated by the scattering effects of colloidal suspensions, but dilution can cause a lowering of signal that prevents collection of data. Acoustic methods require a significant particle concentration, preventing the observation of nucleation events. Studies on the dispersion of nanoparticles show that electrostatic routes are unsuccessful with molecular surfactants at high particle concentration due to electrostatic interaction collapse by counterions. The study of molecular surfactants show that steric lengths on the order of 2 nm are successful for dispersion of nanoparticle systems at high particle concentration, similar to dispersion with commercial polyelectrolyte surfactants.

  18. In-situ steam drive oil recovery process

    SciTech Connect

    Vanmeurs, P.; Waxman, M.H.; Vinegar, H.J.

    1987-02-03

    A process is described for heating a subterranean oil and water-containing reservoir formation, comprising: completing at least one each of heat-injecting and fluid-producing wells into a treatment interval of the formation which is at least about 100 feet thick, contains both oil and water, and is both undesirably impermeable and non-productive in response to injections of oil recovery fluids; arranging the wells to have boreholes which, substantially throughout the treatment interval, are substantially parallel and are separated by substantially equal distances of at least about 20 feet; in each heat-injecting well, substantially throughout the treatment interval, sealing the face of the reservoir formation with a solid material which is relatively heat-conductive and substantially fluid impermeable; in each fluid-producing well, substantially throughout the treatment interval, establishing fluid communication between the wellbore and the reservoir formation and arranging the well for producing fluid from the reservoir formation; and heating the interior of each heat-injecting well, at least substantially throughout the treatment interval, at a rate or rates capable of (a) increasing the temperature within the borehole interior to at least about 600/sup 0/C. and (b) maintaining a borehole interior temperature of at least about 600/sup 0/C. without causing it to become high enough to thermally damage equipment within the borehole while heat is being transmitted away from the borehole at a rate not significantly faster than that permitted by the thermal conductivity of the reservoir formation.

  19. EBSD analysis of MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Inoue, K.; Muralidhar, M.; Berger, K.; Noudem, J.

    2016-04-01

    The grain orientation, the texture and the grain boundary misorientations are important parameters for the understanding of the magnetic properties of the bulk MgB2 samples intended for super-magnet applications. Such data can be provided by electron backscatter diffraction (EBSD) analysis. However, as the grain size (GS) of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique working in reflection operates properly only on highly dense samples. In order to achieve a reasonably good Kikuchi pattern quality on all samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to several bulk MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analyzed within the SEM, operating with a specific sample holder. We present several EBSD mappings of samples prepared with different techniques and at various reaction temperatures.

  20. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    DOE PAGES

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; ...

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipactingmore » issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.« less

  1. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    SciTech Connect

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; Neustadt, Thomas S.; Saunders, Jeffrey W.; Tyagi, Puneet V.; Vandygriff, Daniel J.; Vandygriff, David M.; Ball, Jeffrey Allen; Blokland, Willem; Crofford, Mark T.; Lee, Sung-Woo; Stewart, Stephen; Strong, William Herb

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.

  2. DEMONSTRATION BULLETIN: COLD TOP EX-SITU VITRIFICATION PROCESS - GEOTECH DEVELOPMENT CORPORATION

    EPA Science Inventory

    The Cold Top Vitrification process, developed by Geotech Development Corporation, is an ex-situ, submerged-electrode, resistance-melting technology. The technology is designed to transform heavy metal contaminated soil into a glassy, amorphous, non-leachable mass composed of inte...

  3. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE ARIZONA...

  4. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE ARIZONA...

  5. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE ARIZONA...

  6. 30 CFR 937.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-in situ processing. 937.828 Section 937.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  7. 30 CFR 937.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-in situ processing. 937.828 Section 937.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  8. 30 CFR 937.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ processing. 937.828 Section 937.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  9. 30 CFR 937.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-in situ processing. 937.828 Section 937.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  10. 30 CFR 921.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ processing. 921.828 Section 921.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE MASSACHUSETTS § 921.828 Special...

  11. 30 CFR 912.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-in situ processing. 912.828 Section 912.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE IDAHO...

  12. 30 CFR 912.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-in situ processing. 912.828 Section 912.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE IDAHO...

  13. 30 CFR 912.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Special performance standards-in situ processing. 912.828 Section 912.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE IDAHO...

  14. DEMONSTRATION BULLETIN: COLD TOP EX-SITU VITRIFICATION PROCESS - GEOTECH DEVELOPMENT CORPORATION

    EPA Science Inventory

    The Cold Top Vitrification process, developed by Geotech Development Corporation, is an ex-situ, submerged-electrode, resistance-melting technology. The technology is designed to transform heavy metal contaminated soil into a glassy, amorphous, non-leachable mass composed of inte...

  15. EPA SITE DEMONSTRATION OF THE TERRA VAC IN SITU VACUUM EXTRACTION PROCESS IN GROVELAND, MASSACHUSETTS

    EPA Science Inventory

    This paper presents an EPA evaluation of the patented Terra Vac, Inc.'s in situ vacuum extraction process that was field-demonstrated on a trichloroethylene (TCE) contaminated soil in Groveland, MA, under the EPA Superfund Innovative Technology Evaluation (SITE) program. he Terra...

  16. XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

    EPA Science Inventory

    Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

  17. 30 CFR 947.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-in situ processing. 947.828 Section 947.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE WASHINGTON...

  18. 30 CFR 947.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-in situ processing. 947.828 Section 947.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE WASHINGTON...

  19. 30 CFR 947.828 - Special performance standards-in situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-in situ processing. 947.828 Section 947.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE WASHINGTON...

  20. In situ heat treatment process utilizing a closed loop heating system

    SciTech Connect

    Vinegar, Harold J.; Nguyen, Scott Vinh

    2010-12-07

    Systems and methods for an in situ heat treatment process that utilizes a circulation system to heat one or more treatment areas are described herein. The circulation system may use a heated liquid heat transfer fluid that passes through piping in the formation to transfer heat to the formation. In some embodiments, the piping may be positioned in at least two of the wellbores.

  1. 30 CFR 942.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-In situ processing. 942.828 Section 942.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE TENNESSEE...

  2. 30 CFR 942.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-In situ processing. 942.828 Section 942.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE TENNESSEE...

  3. XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

    EPA Science Inventory

    Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

  4. EPA SITE DEMONSTRATION OF THE TERRA VAC IN SITU VACUUM EXTRACTION PROCESS IN GROVELAND, MASSACHUSETTS

    EPA Science Inventory

    This paper presents an EPA evaluation of the patented Terra Vac, Inc.'s in situ vacuum extraction process that was field-demonstrated on a trichloroethylene (TCE) contaminated soil in Groveland, MA, under the EPA Superfund Innovative Technology Evaluation (SITE) program. he Terra...

  5. DEMONSTRATION BULLETIN: IN SITU STEAM ENHANCED RECOVERY PROCESS - HUGHES ENVIRONMENTAL SYSTEMS, INC.

    EPA Science Inventory

    The Steam Enhanced Recovery Process (SERP) is designed to remove volatile compounds such as halogenated solvents and petroleum hydrocarbons, and semi-volatile compounds from contaminated soils in situ. The vapor pressures of most contaminants will increase by the addition of ste...

  6. Enhancement of lower critical field in thin MgB2 films and MgB2/MgO multilayers

    NASA Astrophysics Data System (ADS)

    Tan, Teng; Johnson, Evan; Acharya, Narendra; Hambe, Michael; Chen, Ke; Krick, Alex; May, Steven; Xi, Xiaoxing

    2013-03-01

    Magnesium diboride is a conventional superconductor with a high Tc of 39 K, a low residual resistivity of < 0.1 μΩ cm (at 42 K), and higher thermodynamic critical field Hc values than Nb. These properties make MgB2 a promising superconductor as an alternative to Nb for future SRF cavities. However, the lower critical field Hc 1 of MgB2 is low, and vortex dissipation above Hc 1 can lead to degradation of the quality factor and low RF breakdown field. Here, we report an enhancement of Hc 1 in thin MgB2 films and MgB2/MgO multilayers. The value of Hc 1(5K) is increased from 40 mT in a 300 nm-thick MgB2 film to 180 mT when the MgB2 layer thickness is 100 nm either in a single-layer film or in a MgB2/MgO multilayer with a total MgB2 layer thickness of 300 nm. Superconducting MgB2 thin films have been coated in-situon the inner wall of a SRF cavity using the hybrid physical chemical vapor deposition (HPCVD) technique. The characterization of the coating will be presented.

  7. The Levitation Characteristics of MGB2 Plates on Tracks of Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Perini, E.; Bassani, E.; Giunchi, G.

    2010-04-01

    The bulk MgB2 can be manufactured in large plates by an innovative process: the reactive liquid Mg infiltration (Mg-RLI). According to this process it is possible to produce, even at lab scale, plates of 10÷20 cm in lateral dimensions. The superconducting material resulting is very dense and, even if it is in polycrystalline form, it levitates with respect to Permanent Magnets (PM), like the textured YBCO samples, up to 35 K. In order to control the levitation forces and stiffnesses of an MgB2 plate (10×10×1 cm3) moving with respect to a track of PM's (NdFeB bars arranged in 4 lines according to an Halbach disposition and separated by Iron flux concentrators), we have used an instrumented Cryogenic Levitation Apparatus (CLA). We have studied different kind of movements of the PM's track with respect to the MgB2 plate. First, we consider the vertical movement, assumed z direction, which describes the properly levitation characteristics. Secondly, we consider two kinds of lateral movements of the track, assumed x direction, with the long size of the magnets either perpendicular or parallel to the movement direction. The resulting configurations simulate the main movements that a superconducting levitating vehicle will do in a real track, either of axial or of guidance type. The levitation axial forces, measured in Field Cooling or Zero Field Cooling conditions, indicate that at the distance between superconducting plate and PM's of 4 mm it is possible to have an overall levitating pressure of 7 N/cm2.

  8. The principles of dielectric measurements for in situ monitoring of composite processing

    NASA Astrophysics Data System (ADS)

    Mijovic, Jovan; Kenny, Jose M.; Maffezzoli, Alfonso; Trivisano, Antonio; Bellucci, Francesco; Nicolais, Luigi

    The fundamental concepts of dielectric behavior of polymers and the utilization of dielectric measurements for in situ monitoring of cure of polymers and composites are discussed. Information is presented on currently used dielectric sensors and the procedure for calculation of dielectric parameters from the monitored signal. The review is written to accommodate both the fundamental and the pragmatic aspects of dielectric monitoring of cure. In the final part of the review, a critical assessment is offered of the advantages and disadvantages of dielectric measurements for the in situ monitoring of processing of polymers and composites.

  9. Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels: Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors

    SciTech Connect

    Dutta, Abhijit; Sahir, A. H.; Tan, Eric; Humbird, David; Snowden-Swan, Lesley J.; Meyer, Pimphan A.; Ross, Jeff; Sexton, Danielle; Yap, Raymond; Lukas, John

    2015-03-01

    This report was developed as part of the U.S. Department of Energy’s Bioenergy Technologies Office’s efforts to enable the development of technologies for the production of infrastructure-compatible, cost-competitive liquid hydrocarbon fuels from biomass. Specifically, this report details two conceptual designs based on projected product yields and quality improvements via catalyst development and process integration. It is expected that these research improvements will be made within the 2022 timeframe. The two conversion pathways detailed are (1) in situ and (2) ex situ upgrading of vapors produced from the fast pyrolysis of biomass. While the base case conceptual designs and underlying assumptions outline performance metrics for feasibility, it should be noted that these are only two of many other possibilities in this area of research. Other promising process design options emerging from the research will be considered for future techno-economic analysis. Both the in situ and ex situ conceptual designs, using the underlying assumptions, project MFSPs of approximately $3.5/gallon gasoline equivalent (GGE). The performance assumptions for the ex situ process were more aggressive with higher distillate (diesel-range) products. This was based on an assumption that more favorable reaction chemistry (such as coupling) can be made possible in a separate reactor where, unlike in an in situ upgrading reactor, one does not have to deal with catalyst mixing with biomass char and ash, which pose challenges to catalyst performance and maintenance. Natural gas was used for hydrogen production, but only when off gases from the process was not sufficient to meet the needs; natural gas consumption is insignificant in both the in situ and ex situ base cases. Heat produced from the burning of char, coke, and off-gases allows for the production of surplus electricity which is sold to the grid allowing a reduction of approximately 5¢/GGE in the MFSP.

  10. Epitaxial MgB2 thin films on ZrB2 buffer layers: structural characterization by synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Ferrando, V.; Tarantini, C.; Bellingeri, E.; Manfrinetti, P.; Pallecchi, I.; Marré, D.; Plantevin, O.; Putti, M.; Felici, R.; Ferdeghini, C.

    2004-12-01

    Structural and superconducting properties of magnesium diboride thin films grown by pulsed laser deposition on zirconium diboride buffer layers were studied. We demonstrate that the ZrB2 layer is compatible with the MgB2 two step deposition process. Synchrotron radiation measurements, in particular anomalous diffraction measurements, allowed us to separate MgB2 peaks from ZrB2 ones and revealed that both layers have a single in plane orientation with a sharp interface between them. Moreover, the buffer layer avoids oxygen contamination from the sapphire substrate. The critical temperature of this film is near 37.6 K and the upper critical field measured at the Grenoble High Magnetic Field Laboratory up to 20.3 T is comparable with the highest ones reported in literature.

  11. The distribution of elements in sequentially prepared MgB2 on SiC buffered Si substrate and possible pinning mechanisms

    NASA Astrophysics Data System (ADS)

    Chromik, Š.; Nishida, A.; Štrbík, V.; Gregor, M.; Espinós, J. P.; Liday, J.; Durný, R.

    2013-03-01

    MgB2 thin films are prepared by sequential evaporation of boron and magnesium bilayers on SiC buffered Si substrates followed by an in situ annealing. Precursor Mg-B bilayers are deposited by electron beam evaporation at room temperature. The amount of B is varied so as to result in different thickness (15 nm and 50 nm) of stoichiometric MgB2 final film after an in situ reaction with the excess Mg top layer in the vacuum. We show the distribution of the elements through the film. X-ray photoelectron spectroscopy analyses have shown that carbon is not free in the films (except the surface of the film) and silicon is in the compound form, too. In the case of the 15 nm thick films we see a strong interdiffusion of the elements (C, B) and we observe a suppression of TC of the film to 20 K. We register different slope of the H(T) dependence - the lowest temperature value of H for the 15 nm thick film exceeds the one for the 50 nm thick film in spite of lower TC. We suppose that δl pinning mechanism is dominant for the 15 nm thick film.

  12. Numerical investigations on the characteristics of thermomagnetic instability in MgB2 bulks

    NASA Astrophysics Data System (ADS)

    Xia, Jing; Li, Maosheng; Zhou, Youhe

    2017-07-01

    This paper presents the characteristics of thermomagnetic instability in MgB2 bulks by numerically solving the macroscopic dynamics of thermomagnetic interaction governed by the coupled magnetic and heat diffusion equations in association with a modified E-J power-law relationship. The finite element method is used to discretize the system of partial differential equations. The calculated magnetization loops with flux jumps are consistent with the experimental results for MgB2 slabs bathed in a wide range of ambient temperatures. We reveal the evolution process of the thermomagnetic instability and present the distributions of the magnetic field, temperature, and current density before and after flux jumps. A 2D axisymmetric model is used to study the thermomagnetic instability in cylindrical MgB2 bulks. It is found that the number of flux jumps monotonously reduces as the ambient temperature rises and no flux jump appears when the ambient temperature exceeds a certain value. Moreover, the flux-jump phenomenon exists in a wide range of the ramp rate of the applied external field, i.e. 10-2-102 T s-1. Furthermore, the dependences of the first flux-jump field on the ambient temperature, ramp rate, and bulk thickness are investigated. The critical bulk thicknesses for stability are obtained for different ambient temperatures and sample radii. In addition, the influence of the capability of the interfacial heat transfer on the temporal response of the bulk temperature is discussed. We also find that the prediction of thermomagnetic instability is sensitive to the employment of the flux creep exponent in the simulations.

  13. Phase 1 Final Technical Report - MgB2 Synthesis for High Field Performance

    SciTech Connect

    Mohit Bhatia; Peter McIntyre

    2009-11-02

    boron results in the formation of parasitic phases such as MgB4, MgB7, etc. Such parasitic phases are a primary element of the connectivity problem, in which even though a sample powder may contain grains of high-quality MgB2, adjacent grains are surrounded by intergrowths of parasitic phases so that current trans-port is badly degraded. The best results to date have been obtained using boron powder produced long ago for a rocket propellant development project. The synthesis process was complex and is now largely lost, and the manufacturing equipment has long since been scrapped. The last batch of the powder has been used during recent years to support MgB2 R&D at several labs, but supplies are dwindling. ATC has identified a first application of its plasma torch to synthesize phase-pure amorphous boron flake using a rapid-quench splat technique. Inexpensive technical-grade boron would be purified of contaminants, then dispersed as an aerosol in inert gas and passed through the plasma torch to melt it into a spray. The spray would be splat-condensed on a rotating drum to form pure amorphous flake. The process would begin with technical-grade boron powder, having good stoichiometric purity, nanoscale particles, but significant contamination of MgO and crystalline boron. We used wet chemistry to remove B2O3 completely and reduced the MgO impurity, and analyzed the particle size distribution using a Coulter counter and the phase composition using X-ray diffrac-tion (XRD). The next step will be to build an rf plasma torch with a recirculating single-component aerosol feed and the cooled splat drum and collector, and undertake process devel-opment for amorphous boron powder. This revised goal has two benefits. First, it is an easier technology than our ultimate goal of a multi-component laminar flow torch. We have been counseled by those experienced in plasma torch technology that our ultimate goal will require a torch that should be feasible but has never been attempted. It

  14. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2005-04-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this sixth quarter of our DoE funded research, we continued the development of our new simulation tool which is based on an efficient Cartesian Adaptive Mesh Refinement technique. This methodology allows much higher grid densities to be used near typical fronts than current simulators. We improved the upscaling strategy on these grids, and derived an effective way to generate upscaled permeabilities that preserve local fluxes. We have started more in-depth research into splitting methods for stiff PDEs such as those found in in-situ combustion simulation. We will report on these new developments extensively in the next quarterly report. This quarterly report, we focus on experimental work. On the experimental side, we have fleshed out a mechanism of improved in-situ combustion with aqueous metallic salts using scanning electron microscopy (SEM) and the transport phenomenon of such additives through porous media. Based on the observations from SEM analysis, we propose cation exchange of metallic salts with clay as a mechanism to create activated sites that enhance combustion reactions between oil and oxygen. Moreover, the empirical ranking of the success of metallic ions as catalytic additives for in-situ combustion is interpreted as originating from three factors: cation replacing power, distribution of metallic additive adsorption sites, and cation catalytic power for oxidation and cracking of hydrocarbon.

  15. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2004-10-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this third quarterly report of our DoE funded research, we continue the discussion of the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. Also, we discuss the possibility of using Strang splitting for handling the large disparity in time-scales between the kinetics and transport in the in-situ combustion process. On the experimental side, we show results of experiments with our scanning electron microscope (SEM) to investigate the sand-clay-salt mixtures that are used for combustion in which we focus on grain sizes, shapes, orientations, characteristic inter-structures, and element analysis. SEM is shown to be a very effective tool in studying these mixtures.

  16. Highly enhanced in-field critical current density of MgB 2 superconductor by combined addition of burned rice husk and nano Ho 2O 3

    NASA Astrophysics Data System (ADS)

    Vinod, K.; Varghese, Neson; Sundaresan, A.; Syamaprasad, U.

    2010-04-01

    With the aim of improving flux pinning and in-field critical current density [ JC( H)], two physically and chemically different additives - burned rice husk (BRH) and nano Ho 2O 3 were introduced into in situ MgB 2 superconductor. The effects of the above two additives were studied individually and combinedly. Ho 2O 3 decomposed and reacted with B to form HoB 4, without any substitution. BRH caused considerable amount of C substitution at B site and formed Mg 2Si and Mg 2C 3 secondary phases. Addition of Ho 2O 3 improved the JC( H) only marginally, but BRH improved the JC( H) strongly. Combined addition of Ho 2O 3 with BRH was found to be much more effective than their solo addition for the enhancement of JC( H) of MgB 2.

  17. In situ treatment of chromium VI with an iron reduction process

    SciTech Connect

    Brown, R.A.; Crosbie, J.; O`Neil, S.

    1994-12-31

    Chromium VI is a fairly soluble compound and a known human carcinogen. Consequently, groundwater contamination with Chromium VI often represents a sensitive environmental issue. Removal of Chromium VI from groundwater has most often required long term and expensive pump and treat systems. Chromium III, on the other hand, is an essential nutrient and is, in most forms, highly insoluble. The conversion of Chromium VI, the soluble carcinogenic form, to the non-hazardous, insoluble Chromium III is the basis of many of the commercial water treatment processes such as the Andco{trademark} process or the Unocal, Unipure{trademark} process. Both processes are based on the reaction of Chromium VI with ferrous iron (Fe{sup +2}) to give Chromium III and Iron III, both of which are highly insoluble. This same technology -- iron reduction and precipitation of Chromium VI -- was successfully applied in situ to treat a perched aquifer contaminated with Chromium VI at a former industrial facility. The site was located on the Delaware River in an ecologically sensitive area. Groundwater concentrations of {approximately}85 ppm Chromium VI were successfully reduced to below 50 ppb across most of the site and discharge of Chromium VI into the Delaware River was stopped by the injection of a ferrous sulfate solution. This paper will discuss the selection, laboratory testing, regulatory approval, design and implementation of this in situ iron reduction process. The alternative to this in situ approach is a multi-year pump and treat operation involving high capital expenditure.

  18. MgB2UltrathinFilms Fabricated by Hybrid Physical Chemical Vapor Deposition and Subsequent Ion Milling

    NASA Astrophysics Data System (ADS)

    Acharya, Narendra; Wolak, Matthaeus; Tan, Teng; Cunnane, Daniel; Karasik, Boris; Xi, Xiaoxing

    Hot electron bolometer (HEB) mixers are a great tool for measuring high-resolution spectroscopy at Terahertz frequencies. MgB2offers a higher critical temperature (39 K) compared to commonly used Nb and NbN and boasts a shorter intrinsic electron-phonon relaxation time, giving rise to a broader intermediate frequency (IF) bandwidth. We have fabricated high quality ultrathin MgB2films using hybrid physical-chemical vapor deposition (HPCVD) and employing ion milling to achieve thickness down to 2 nm. The thinnest achieved films show high Tc of 28 K with residual resistivity below 28 µ Ωcm and high critical current Jcof 1x106 A/cm2at 20 K. As a result of the employed low angle ion milling process, the films remain well connected even after being thinned down since the initial thick films offer a better connectivity than as-grown thin films. The established process offers a way to realize MgB2 based HEB mixers of extremely low thickness and therefore small local oscillator power requirements and increased IF bandwidth.

  19. Synthesis of gold and silver nanoparticle S-ovalbumin protein conjugates by in situ conjugation process

    NASA Astrophysics Data System (ADS)

    Joshi, Deepti; Soni, R. K.

    2015-05-01

    Pure gold and silver nanoparticle (NP) generation and their conjugation with protein S-ovalbumin using in situ conjugation process have been reported. The in situ conjugation involves nanosecond pulse laser ablation of pure metal target in the protein S-ovalbumin solution. Transmission electron microscopy (TEM) and UV-Visible absorption results show decrease in mean NP size along with narrow particle size distribution on ablation in S-ovalbumin solution as compared to ablation in water for both Au and Ag NPs. Also, the NP size reduction was found to be dependent on the concentration of S-ovalbumin. For AuNPs, spherical NPs of mean size 4 nm with particle size distribution 2-6 nm were obtained at 300 nM S-ovalbumin concentration. Further, it has been observed that the resultant in situ-conjugated colloid gold and silver NP solutions were quite stable even in the presence of NaCl at physiological salt concentration (0.15 M). On post-laser irradiation (532 nm, 15 mJ) for 20 min, 9 nm red shift in surface plasmon resonance peak (SPR), along with increased broadening towards longer wavelength, was observed in the AuNPs-S-ovalbumin sample. Further increase in the time of irradiation showed shift in AuNPs-S-ovalbumin SPR towards lower wavelength. On laser irradiation (532 nm, 15 mJ) for 20 min, no significant change was observed in the line shape of the plasmon absorption band of the AgNPs-S-ovalbumin conjugate. FTIR spectra revealed that S-ovalbumin peptide backbone and secondary structure remain unchanged on laser irradiation during in situ conjugation process. Thus, integrity of S-ovalbumin does not get affected, and no degradation of S-ovalbumin takes place on laser-induced in situ conjugation. Raman results confirm that both Au and Ag NPs interact with S-ovalbumin via thiol-bearing cysteine residues of the disulfide bond.

  20. In-situ real time monitoring of the polymerization in gel-cast ceramic processes

    SciTech Connect

    Ahuja, S.; Dieckman, S.L.; Bostrom, G.A.; Waterfield, L.G.; Raptis, A.C.; Omatete, O.O.

    1996-08-01

    Gelcasting requires making a mixture of a slurry of ceramic powder in a solution of organic monomers and casting it in a mold. Gelcasting is different from injection molding in that it separates mold filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging were used for in-situ monitoring of the gelation process and gelcasting of alumina. {sup 1}H NMR spectra and images are obtained during polymerization of a mixture of soluble reactive acrylamide monomers. Polymerization was initiated by adding an initiator and an accelerator to form long- chain, crosslinked polymers. Multidimensional NMR imaging was used for in-situ monitoring of the process and for verification of homogeneous polymerization. Comparison of the modeled intensities with acquired images shows a direction extraction of T{sub 1} data from the images.

  1. In-situ laser material process monitoring using a cladding power detection technique

    NASA Astrophysics Data System (ADS)

    Su, Daoning; Norris, Ian; Peters, Chris; Hall, Denis R.; Jones, Julian D. C.

    Progress in laser material processing may require real-time monitoring and process control for consistent quality and productivity. We report a method of in-situ monitoring of laser metal cutting and drilling using cladding power monitoring of an optical fibre beam delivery system—a technique which detects the light reflected or scattered from the workpiece. The light signal carries information about the quality of the process. Experiments involving drilling and cutting of two samples, a thin aluminum foil and a 2-mm thick stainless steel plate, confirmed the effectiveness of this method.

  2. Interfacial reactions and oxygen distribution in MgB2 wires in Fe, stainless steel and Nb sheaths

    NASA Astrophysics Data System (ADS)

    Grovenor, C. R. M.; Goodsir, L.; Salter, C. J.; Kovac, P.; Husek, I.

    2004-03-01

    Superconducting MgB2 wires have been made by powder-in-tube (PIT) processing of commercial MgB2 powder in Fe, stainless steel and composite metallic sheaths using annealing temperatures from 850 to 1100 °C. Technologically interesting Jc values around 106 A cm-2 in the self-field at 4.2 K have been achieved. However, as the annealing temperature is increased, substantial chemical reactions have been observed at the MgB2/sheath interface. We report on a detailed study using electron probe microanalysis of the reaction products in the interfacial region and the distribution of oxygen in the core. Iron and chromium borides are formed at the core/sheath interface in Fe and stainless steel sheaths respectively, with consequent depletion of B from the superconducting core. A similar effect is caused by the formation of a solid solution of B in Nb sheaths. Milling the starting powder before wire manufacture results in a very significant increase in the oxygen content of the core, which probably explains the relatively poor performance of these wires.

  3. In situ manufacture of magnetic tunnel junctions by a direct-write process

    NASA Astrophysics Data System (ADS)

    Costanzi, Barry N.; Riazanova, Anastasia V.; Dan Dahlberg, E.; Belova, Lyubov M.

    2014-06-01

    In situ construction of Co/SiO2/Co magnetic tunnel junctions using direct-write electron-beam-induced deposition is described. Proof-of-concept devices were built layer by layer depositing the specific components one at a time, allowing device manufacture using a strictly additive process. The devices exhibit a magnetic tunneling signature which agrees qualitatively with the Slonczewski model of magnetic tunneling.

  4. From Alloy Processing to Performance: An In Situ Experimental and Modeling Effort

    SciTech Connect

    Clarke, Amy Jean; Tourret, Damien; Gibbs, John W.; Imhoff, Seth D.; Lebensohn, Ricardo A.; Patterson, Brian M.; Mertens, James CE.; Henderson, Kevin C.

    2016-04-15

    Solidification is present in almost all materials. It is influenced by grain size and shape, chemical homogeneity, defect type and density, and mechanical properties. During micro-mechanical testing, the following occur: 1) Micro-CT (as processed) - Map Initial 3D Microstructure 2) Nano-Radiography (In situ under Tension) - Observe of Damage Initiation/Propagation 3) Micro-CT (Post Mortem) - Global Fracture Study 4) Nano-CT (Post Mortem) - High-Resolution Fracture Study.

  5. In Situ Infrared Spectroscopic Studies of Molecular Layer Deposition and Atomic Layer Etching Processes

    NASA Astrophysics Data System (ADS)

    DuMont, Jaime Willadean

    In this thesis, in situ Fourier transform infrared (FTIR) spectroscopy was used to study: i) the growth and pyrolysis of molecular layer deposition (MLD) films. ii) the surface chemistry of atomic layer etching (ALE) processes. Atomic layer processes such as molecular layer deposition (MLD) and atomic layer etching (ALE) are techniques that can add or remove material with atomic level precision using sequential, self-limiting surface reactions. Deposition and removal processes at the atomic scale are powerful tools for many industrial and research applications such as energy storage and semiconductor nanofabrication. The first section of this thesis describes the chemistry of reactions leading to the MLD of aluminum and tin alkoxide polymer films known as "alucone" and "tincone", respectively. The subsequent pyrolysis of these films to produce metal oxide/carbon composites was also investigated. In situ FTIR spectroscopy was conducted to monitor surface species during MLD film growth and to monitor the films background infrared absorbance versus pyrolysis temperature. Ex situ techniques such as transmission electron microscopy (TEM), four-point probe and X-ray diffraction (XRD) were utilized to study the properties of the films post-pyrolysis. TEM confirmed that the pyrolyzed films maintained conformality during post-processing. Four-point probe monitored film resistivity versus pyrolysis temperature and XRD determined the film crystallinity. The second section of this thesis focuses on the surface chemistry of Al2O3 and SiO2 ALE processes, respectively. Thermal ALE processes have been recently developed which utilize sequential fluorination and ligand exchange reactions. An intimate knowledge of the surface chemistry is important in understanding the ALE process. In this section, the competition between the Al2O3 etching and AlF 3 growth that occur during sequential HF (fluorinating agent) and TMA (ligand exchange) exposures is investigated using in situ FTIR

  6. A quantitative framework for understanding complex interactions between competing interfacial processes and in situ biodegradation.

    PubMed

    Johnson, Mark A; Song, Xin; Seagren, Eric A

    2013-03-01

    In situ bioremediation of contaminated groundwater is made technologically challenging by the physically, chemically, and biologically heterogeneous subsurface environment. Subsurface heterogeneities are important because of influences on interfacial mass transfer processes that impact the availability of substrates to microorganisms. The goal of this study was to perform a "proof-of-concept" evaluation of the utility of a quantitative framework based on a set of dimensionless coefficients for evaluating the effects of competing physicochemical interfacial and biokinetic processes at the field scale. First, three numerical modeling experiments were completed, demonstrating how the framework can be used to identify the rate-limiting process for the overall bioremediation rate, and to predict what engineered enhancements will alleviate the rate-limiting process. Baseline conditions for each scenario were established to examine intrinsic biodegradation with a given rate-limiting process (either dispersion, biokinetics, or sorption). Then different engineering treatments were examined. In each case, the treatment predicted to be appropriate for addressing the overall rate-limiting process based on the quantitative framework alleviated the limitation more successfully, and enhanced the in situ biodegradation rate more than the alternative enhancements. Second, the quantitative framework was applied to a series of large-scale laboratory and field-scale experiments, using reported parameter estimates to calculate the relevant dimensionless coefficients and predict the rate-limiting process(es). Observations from the studies were then used to evaluate those predictions.

  7. Improvement of critical properties of undoped, multifilamentary MgB2 wires in Nb/Cu after annealing under high gas pressure

    NASA Astrophysics Data System (ADS)

    Cetner, T.; Morawski, A.; Adamczyk, K.; Rindfleisch, M.; Tomsic, M.; Zaleski, A.; Gajda, D.; Presz, A.

    2012-09-01

    Raw MgB2 wires have been manufactured by Hyper Tech Inc. Each of their 18 cores contained undoped in situ powder surrounded by an Nb barrier and placed in a Cu sheath, and cores were coated in a common Monel sheath. Wires of diameters 0.63 and 0.83 mm were annealed under high argon pressure (up to 1 GPa). Parameters of such HIP process (temperature, time, and pressure) were varied in order to determine their optimal values. Superconducting properties of such samples were investigated by means of four-probe critical current j c measurement. Bitter magnet producing magnetic field up to 14 T was used. It provided place for samples 70 mm long in parallel field and 20 mm long in perpendicular field. Results include critical current j c and pinning force density F p dependencies on magnetic field as well as Kramer plots. Critical current of 104 A/cm 2 was achieved at 12 T magnetic field. SEM pictures of wire cross sections were also taken to determine quality of Nb barrier and microstructure of superconducting material.

  8. Ultrafast laser processing of transparent materials supported by in-situ diagnostics

    NASA Astrophysics Data System (ADS)

    Kumkar, M.; Kaiser, M.; Kleiner, J.; Grossmann, D.; Flamm, D.; Bergner, K.; Nolte, S.

    2016-03-01

    For the development of industrial NIR ultrafast laser processing of transparent materials, the absorption inside the bulk material has to be controlled. Applications we aim for are front and rear side ablation, drilling and inscription of modifications for cleaving and selective laser etching of glass and sapphire in sheet geometry. We applied pump probe technology and in situ stress birefringence microscopy for fundamental studies on the influence of energy and duration (100 fs - 20 ps), temporal and spatial spacing, focusing and beam shaping of the laser pulses. Applying pump probe technique we are able to visualize differences of spatio-temporal build up of absorption, self focusing, shock wave generation for standard, multispot and beam shaped focusing. Incubation effects and disturbance of beam propagation due to modifications or ablation can be observed. In-situ imaging of stress birefringence gained insight in transient build up of stress with and without translation. The results achieved so far, demonstrate that transient stress has to be taken into account in scaling the laser machining throughput of brittle materials. Furthermore it points out that transient stress birefringence is a good indicator for accumulation effects, supporting tailored processing strategies. Cutting results achieved for selective laser etching by single pass laser modification exemplifies the benefits of process development supported by in situ diagnostics.

  9. Combining In-situ and In-transit Processing to Enable Extreme-Sscale Scientific Analysis

    SciTech Connect

    Bennett, Janine C.; Abbasi, Hasan; Bremer, Peer-Timo; Grout, Ray; Gyulassy, Attila; Jin, Tong; Klasky, Scott A; Kolla, Hemanth; Parashar, Manish; Pascucci, Valerio; Pebay, Philippe; Thompson, David; Yu, Hongfeng; Zhang, Fan; Chen, Jacqueline H

    2012-01-01

    With the onset of extreme-scale computing, I/O constraints make it increasingly difficult for scientists to save a sufficient amount of raw simulation data to persistent storage. One potential solution is to change the data analysis pipeline from a post-process centric to a concurrent approach based on either in-situ or in-transit processing. In this context computations are considered in-situ if they utilize the primary compute resources, while in-transit processing refers to offloading computations to a set of secondary resources using asynchronous data transfers. In this paper we explore the design and implementation of three common analysis techniques typically performed on large-scale scientific simulations: topological analysis, descriptive statistics, and visualization. We summarize algorithmic developments, describe a resource scheduling system to coordinate the execution of various analysis workflows, and discuss our implementation using the DataSpaces and ADIOS frameworks that support efficient data movement between in-situ and in-transit computations. We demonstrate the efficiency of our lightweight, flexible framework by deploying it on the Jaguar XK6 to analyze data generated by S3D, a massively parallel turbulent combustion code. Our framework allows scientists dealing with the data deluge at extreme scale to perform analyses at increased temporal resolutions, mitigate I/O costs, and significantly improve the time to insight.

  10. Development of a liquid hydrogen transfer pump system with MgB2 wires

    NASA Astrophysics Data System (ADS)

    Kajikawa, Kazuhiro; Kuga, Hirotsugu; Inoue, Takuro; Watanabe, Kazuki; Uchida, Yushi; Nakamura, Taketsune; Kobayashi, Hiroaki; Hongo, Motoyuki; Kojima, Takayuki; Taguchi, Hideyuki; Naruo, Yoshihiro; Wakuda, Tsuyoshi; Tanaka, Kazuhide

    An electric pump composed of an MgB2 motor is combined with superconducting level sensors using thin CuNi-sheathed MgB2 wires to transfer liquid hydrogen. An impeller is attached to the lower end of a rotating shaft on the MgB2 motor and covered with an outer casing to form a centrifugal pump. Then, the MgB2 motor and impeller are placed vertically inside a cryostat with an infill of liquid hydrogen. A glass Dewar vessel is prepared to receive the liquid hydrogen transferred from the cryostat containing the MgB2 motor. The MgB2 sensors are used not only to detect the level of liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube.

  11. Geophysical Characterization of in situ Serpentinization Processes at the Coast Range Ophiolite Microbial Observatory (CROMO)

    NASA Astrophysics Data System (ADS)

    Ortiz, E.; Tominaga, M.; Cardace, D.; Schrenk, M. O.; Hoehler, T. M.; Kubo, M. D.

    2016-12-01

    Electrical and magnetic remote sensing both on land and at sea have emerged as a powerful approach to characterize in situ serpentinization and carbonation processes in time and space. We conducted 2D Electrical Resistivity Tomography (ERT) surveys to investigate in situ geological and hydrogeological architecture within the rock formation of the Jurassic age tectonic mélange portion of the Coast Range Ophiolite Microbiological Observatory (CROMO) where serpentinization processes are thought to facilitate an active deep biosphere. We acquired ERT imagery during both wet and dry seasons, along 9 survey tracks traversing two previously drilled wells, CSW1.1 and QV1.1, at different lateral and horizontal resolutions, yielding imagery with depth of 6.9 - 41m. Integrating ERT inversion models with wire-line and core data, we successfully documented temporal changes in the in situ hydrological properties at CROMO, i.e. the lateral and vertical water table boundaries (unconfined aquifer), non-permeable zones (confining bed), and possible confined aquifers that are juxtaposed within three dominant lithological units of serpentinite top soil, serpentinite gravel with clay, and serpentinite basement formation. We conducted rock magnetic experiments on core samples from drilled sites, including Magnetic Property Measurement System (MPMS) measurements, to better understand the connection between these hydrogeological properties and in situ serpentinization processes. Based on the observed downhole distribution of magnetite in correlation with ERT results and lithostratigraphy, we proposed that, at CROMO: (i) zones enriched in ferromagnetic minerals, correspond to in situ serpentinite formation with both high and low resistivity, suggesting that resistivity zones represent in situ architecture of consolidated serpentinite confining beds and possible fractured serpentinite aquifers, respectively; and (ii) zones (e.g. 14 - 31m at CSW site) enriched in superparamagnetic size

  12. Description and capabilities of the large-scale in situ vitrification process

    SciTech Connect

    Buelt, J.L.; Carter, J.G.

    1986-01-01

    An emerging thermal treatment process known as in situ vitrification is being developed to immobilize selected portions of radioactively contaminated soils. The process is a permanent remedial action that destroys solid and liquid organic contaminants and incorporates radionuclides and heavy metals into a glass and crystalline form. The process's flexibility in design and broad capabilities make it potentially adaptable to mixed and chemical wastes, as well. The process consists of an electrical power system for vitrifying contaminated soil, a hood to contain gaseous effluents, an off-gas treatment system, an off-gas cooling system, and a process control station. The process is mounted in three transportable trailers that can be easily moved from site to site. The process is capable of treating contaminated soils at least 13 m deep. The system components are designed to accommodate waste inclusions in the soil such as metals, combustibles, and large voids. Selectively applied to the more troublesome radioactively contaminated soils, in situ vitrification provides a potentially useful and permanent tool for remedial action.

  13. In-situ guidance of individual neuronal processes by wet femtosecond-laser processing of self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hideaki; Okano, Kazunori; Demura, Takanori; Hosokawa, Yoichiroh; Masuhara, Hiroshi; Tanii, Takashi; Nakamura, Shun

    2011-10-01

    In-situ guidance of neuronal processes (neurites) is demonstrated by applying wet femtosecond-laser processing to an organosilane self-assembled monolayer (SAM) template. By scanning focused laser beam between cell adhesion sites, on which primary neurons adhered and extended their neurites, we succeeded in guiding the neurites along the laser-scanning line. This guidance was accomplished by multiphoton laser ablation of cytophobic SAM layer and subsequent adsorption of cell adhesion molecule, laminin, onto the ablated region. This technique allows us to arbitrarily design neuronal networks in vitro.

  14. Thermographic In-Situ Process Monitoring of the Electron Beam Melting Technology used in Additive Manufacturing

    SciTech Connect

    Dinwiddie, Ralph Barton; Dehoff, Ryan R; Lloyd, Peter D; Lowe, Larry E; Ulrich, Joseph B

    2013-01-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  15. In situ monitoring of biomolecular processes in living systems using surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Altunbek, Mine; Kelestemur, Seda; Culha, Mustafa

    2015-12-01

    Surface-enhanced Raman scattering (SERS) continues to strive to gather molecular level information from dynamic biological systems. It is our ongoing effort to utilize the technique for understanding of the biomolecular processes in living systems such as eukaryotic and prokaryotic cells. In this study, the technique is investigated to identify cell death mechanisms in 2D and 3D in vitro cell culture models, which is a very important process in tissue engineering and pharmaceutical applications. Second, in situ biofilm formation monitoring is investigated to understand how microorganisms respond to the environmental stimuli, which inferred information can be used to interfere with biofilm formation and fight against their pathogenic activity.

  16. Infrared Fiber Evanescent Wave Spectroscopy For In-Situ Monitoring Of Chemical Processes

    NASA Astrophysics Data System (ADS)

    Margalit, Eli; Dodiuk, H.; Kosower, Edward M.; Katzir, Abraham

    1989-06-01

    A silver halide infrared fiber-optic evanescent wave spectroscopic technique for in-situ monitoring of chemical processes and surface analysis is described. Samples are spread onto a fiber contained in a teflon-lined cell. Attenuated total internal reflectance (AIR) measurement with a Fourier transform infrared (FTIR) spectrometer yields spectra at various stages of a process (for example, the monitoring of adhesive curing and coupling agent polymerization). Changes in known spectroscopic features may be recognized in films as thin as a monolayer. The advantages and limitations of this surface analysis technique are discussed.

  17. Hydrocarbon recovery process using an in situ silicate/polymer gel

    SciTech Connect

    Norton, C.J.

    1986-01-14

    This patent describes a process for treating a porous earthen mix with a silicate/polymer gel. The process consists of two steps. The first step is the injection into the matrix of an undried, water-soluble silicate and a gelling agent selected from water-soluble strong acids or water-soluble salts of strong acids. The second step consists of reacting a mixture of the partially hydrolyzed polyacrylamide, silicate and gelling agent in the matrix to form the silicate/polymer gel in situ.

  18. Instrumentation and process control development for in situ coal gasification. Quarterly report, December 1979-March 1980

    SciTech Connect

    Glass, R.E.

    1980-06-01

    The analysis of data for the Hanna IV and Hoe Creek in situ coal gasification tests raised questions concerning the fundamental controlling mechanisms of the process. The two main areas of concern are: (1) the air flow patterns; and (2) the initial cavity growth. Sandia National Laboratories is addressing these concerns by developing models of these processes. Results to date are in qualitative agreement with known phenomena. There have also been developments in data handling capability. These include improved data presentation ability and development of routine storage, access and back up methods.

  19. In-situ materials processing systems and bioregenerative life support systems interrelationships

    NASA Technical Reports Server (NTRS)

    Mignon, George V.; Frye, Robert J.

    1992-01-01

    The synergy and linkages between bioregenerative life support systems and the materials produced by in-situ materials processing systems was investigated. Such systems produce a broad spectrum of byproducts such as oxygen, hydrogen, processed soil material, ceramics, refractory, and other materials. Some of these materials may be utilized by bioregenerative systems either directly or with minor modifications. The main focus of this project was to investigate how these materials can be utilized to assist a bioregenerative life support system. Clearly the need to provide a sustainable bioregenerative life support system for long term human habitation of space is significant.

  20. Preparing for in situ processing on upcoming leading-edge supercomputers

    DOE PAGES

    Kress, James; Churchill, Randy Michael; Klasky, Scott; ...

    2016-10-01

    High performance computing applications are producing increasingly large amounts of data and placing enormous stress on current capabilities for traditional post-hoc visualization techniques. Because of the growing compute and I/O imbalance, data reductions, including in situ visualization, are required. These reduced data are used for analysis and visualization in a variety of different ways. Many of he visualization and analysis requirements are known a priori, but when they are not, scientists are dependent on the reduced data to accurately represent the simulation in post hoc analysis. The contributions of this paper is a description of the directions we are pursuingmore » to assist a large scale fusion simulation code succeed on the next generation of supercomputers. Finally, these directions include the role of in situ processing for performing data reductions, as well as the tradeoffs between data size and data integrity within the context of complex operations in a typical scientific workflow.« less

  1. Preparing for in situ processing on upcoming leading-edge supercomputers

    SciTech Connect

    Kress, James; Churchill, Randy Michael; Klasky, Scott; Kim, Mark; Childs, Hank; Pugmire, David

    2016-10-01

    High performance computing applications are producing increasingly large amounts of data and placing enormous stress on current capabilities for traditional post-hoc visualization techniques. Because of the growing compute and I/O imbalance, data reductions, including in situ visualization, are required. These reduced data are used for analysis and visualization in a variety of different ways. Many of he visualization and analysis requirements are known a priori, but when they are not, scientists are dependent on the reduced data to accurately represent the simulation in post hoc analysis. The contributions of this paper is a description of the directions we are pursuing to assist a large scale fusion simulation code succeed on the next generation of supercomputers. Finally, these directions include the role of in situ processing for performing data reductions, as well as the tradeoffs between data size and data integrity within the context of complex operations in a typical scientific workflow.

  2. Theoretical and Experimental Evidence for a Nodal Energy Gap in MgB2

    DTIC Science & Technology

    2017-02-17

    1   Theoretical and Experimental Evidence for a Nodal Energy Gap in MgB2 Y. Dan Agassia and Daniel E. Oatesb aConsultant, Jerusalem, Israel bMIT...the smaller of the two energy gaps in MgB2, the so-called  gap, contains nodal lines with a six-fold symmetry (i-wave). The model also indicates that...in MgB2 and the Coulomb repulsion. It is based on a phononic pairing mechanism and assumes no coupling between the two energy gaps in MgB2 at zero

  3. Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bateni, Ali; Erdem, Emre; Repp, Sergej; Weber, Stefan; Somer, Mehmet

    2016-05-01

    Undoped and aluminum (Al) doped magnesium diboride (MgB2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB2. Above a certain level of Al doping, enhanced conductive properties of MgB2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  4. Phase formation of MgB2 superconducting materials fabricated by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Kang, Deuk Kyun; Kim, Dong Woong; Choi, Sung Hyun; Kim, Chul Jin; Ahn, In Shup

    2009-02-01

    Much research on MgB2 has been carried out because MgB2 has a higher transition temperature (Tc) of 39 K than that of other metallic superconductors and because the bulk form of MgB2 has exhibited high current density. In this study, Mg powder of less than 10 μm and B powder of less than 3 μm with equivalent MgB2 composition were mixed simply under argon atmosphere. In order to consider the effect of a pinning element on the superconducting properties, activated carbon of 5 at.% was added to mixed powders. The MgB2 bulk was fabricated with mixed powders in graphite molds at the various temperatures by spark plasma sintering. The formation of the MgB2 phase was confirmed with Differential Thermal Analysis (DTA) at 550 °C. The relative density of sintered MgB2 was 97 %, which increased as the sintering temperature increased. The sintering proceeded initially in the solid state and then by liquid phase sintering with increasing temperature without abnormal grain growth. In the Physical Property Measurement System (PPMS) result, the Tc was about 37 K in the carbon-added sintered sample. The 300 nm size MgB2 grains of hexagonal shape were formed after spark plasma sintering, but the MgB4 phase did not produce precise Tc.

  5. Superconducting MgB2 flowers: growth mechanism and their superconducting properties

    NASA Astrophysics Data System (ADS)

    Seong, Won Kyung; Ranot, Mahipal; Lee, Ji Yeong; Yang, Cheol-Woong; Lee, Jae Hak; Oh, Young Hoon; Ahn, Jae-Pyoung; Kang, Won Nam

    2016-04-01

    We report for the first time the growth and the systematic study of the growth mechanism for flower-like MgB2 structures fabricated on the substrates for solid-state electronics by the hybrid physical-chemical vapor deposition (HPCVD) technique. The MgB2 flower has a width of 30 μm and a height of 10 μm. The superconductivity of MgB2 flowers was confirmed by a magnetization measurement, and the transition temperature is 39 K, which is comparable with high-quality bulk samples. The excellent current-carrying capability was demonstrated by MgB2 flowers. To understand the nucleation and growth mechanism of MgB2 flowers a very systematic study was performed by a high-resolution transmission electron microscope (HRTEM) and atom probe (AP) microscopy. The HRTEM revealed that the seed grain of a MgB2 flower has a [101¯0] direction, and the flower is composed of micro-columnar MgB2 grains having pyramidal tips and which are grown along the (0001) plane. A clear understanding of the growth mechanism for MgB2 flowers could lead to the growth of other low-dimensional MgB2 structures for superconducting electronic devices.

  6. In-situ FT-IR monitoring of a solar flux induced chemical process

    SciTech Connect

    Markham, J.R.; Cosgrove, J.E.; Nelson, C.M.; Bonanno, A.S.; Schlief, R.E.; Stoy, M.A.; Glatzmaier, G.C.; Bingham, C.E.; Lewandowski, A.A.

    1997-08-01

    The capability to perform in-situ, on-line monitoring of processes induced by concentrated solar flux will enhance the development and utilization of solar technologies. Temperature measurements and chemical concentration measurements provide an understanding of the ongoing chemistry, process limits, and process reproducibility. A Fourier transform infrared (FT-IR) spectrometer was optically coupled to a quartz flow reactor at the High Flux Solar Furnace of the National Renewable Energy Laboratory in Golden, CO. In-situ emission/transmission spectroscopy was utilized to simultaneously monitor steam temperature and the concentration of formed hydrogen bromide during the solar flux induced reaction of steam and bromine. The photochemical process is being investigated for the production of industrial quantities of hydrogen and oxygen, where downstream electrolysis of the formed hydrogen bromide provides the hydrogen and regenerates bromine. Steam temperature was measured to increase upon the addition of bromine to the reactor. Gas temperature increases of 200 C to 400 C were observed. Hydrogen bromide concentrations up to ten percent of the reactor gas volume was measured. The FT-IR system provided quantitative information of two critical parameters of the measured process and serves to accelerate this technology area.

  7. Robotic-Controlled, Autonomous Friction Stir Welding Processes for In-Situ Fabrication, Maintenance, and Repair

    NASA Astrophysics Data System (ADS)

    Zhou, W.

    NASA s new vision of human and robotic missions to the Moon Mars and beyond will demand large and permanent infrastructures on the Moon and other planets including power plants communication towers human and biomass habitats launch and landing facilities fabrication and repair workshops and research facilities so that material utilization and product development can be carried out and subsisted in-situ The conventional approach of transporting pre-constructed fabricated structures from earth to the Moon planets will no longer be feasible due to limited lifting capacity and extremely high transportation costs associated with long duration space travel To minimize transport of pre-made large structures between earth and the Moon planets minimize crew time for the fabrication and assembly of infrastructures on the Moon planets and to assure crew safety and maintain quality during the operation there is a strong need for robotic capabilities for in-situ fabrication maintenance and repair Clearly development of innovative autonomous in-situ fabrication maintenance and repair technologies is crucial to the success of both NASA s unmanned preparation missions and manned exploration missions In-space material joining is not new to NASA Many lessons were learned from NASA s International Space Welding Experiment which employed the Electron Beam Welding process for space welding experiments Significant safety concerns related to high-energy beams arcing spatter elecromagnetic fields and molten particles were

  8. InSitu-Eye: oceanological and atmospheric data processing and analyzing system

    NASA Astrophysics Data System (ADS)

    Stepochkin, Igor E.; Salyuk, Pavel A.; Shmirko, Konstantin A.; Golik, Irina A.; Burov, Denis V.

    2014-11-01

    In this study we introduce brief description and the main approaches used in system development. System is devising with a participation of Pacific Oceanological Institute (FEB RAS), Institute of Automation and Control Processes (FEB RAS) and also Maritime State University, n.a. G.I. Nevelskoy. For many years research team of these institutions carried out a lot of field measurements and collected a lot of remote sensing data, using spectrophotometers, LIDARs, fluorometers. The primary goal of this development - bring all this data together to integrated database and design user-friendly interface to work with. "InSitu-Eye" will perform standard routine operations, such as sampling data according to certain parameters; gridding and timing of data; filtering and quality check of data; visualization. After setting system up and testing it will provide a benefit. At first it gives 24/7 access to "clean", checked "in-situ" data, ready for further research. Also presence of such system gives "converse effect" - it will become necessary to develop strict protocols for measurements carrying out and increase their quality. In future, "InSitu-Eye" can become a platform, connecting research teams for data keeping and exchange.

  9. In-situ TEM on the coalescence of birnessite manganese dioxides nanosheets during lithiation process

    SciTech Connect

    Cao, Ke; Kuang, Min; Zhang, Yuxin; Liu, Jiabin; Wang, Hongtao; Meng, Liang

    2016-07-15

    Highlights: • Evolution of MnO{sub 2} nanosheets during lithiation was in situ observed. • MnO{sub 2} was reacted with Li to form Mn and LiO{sub 2}. • Nanosheets expanded and aggregated due to lithiation. - Abstract: Nanostructure is believed to produce great benefits for anode materials in lithium ion batteries (LIBs) by enhancing lithium ion transfer, accommodating large volume change and increasing surface area. Whether the nanostructure (especially the porous nanostructure) could be well held during charging/discharging process is one of the most commonly concerned issues in LIBs research. The dynamic evolution of birnessite manganese dioxides nanosheets during lithiation process is investigated by in-situ transmission electron microscopy (TEM) for the first time. The TiO{sub 2}@MnO{sub 2} core-shell nanowires are used as the anode and Li metal as the counter electrode inside the TEM. Interestingly, the lithiation process is confirmed as MnO{sub 2} and Li converting to Li{sub 2}O and Mn. The original porous structure of the nanosheets is hard to preserve during lithiation process due to lithiation-induced contact flattening.

  10. Scattering effect of the well-ordered MgB4 impurity phase in two-step sintered polycrystalline MgB2 with glycine addition

    NASA Astrophysics Data System (ADS)

    Cai, Qi; Liu, Yongchang; Guo, Qianying; Ma, Zongqing

    2017-04-01

    Glycine-doped MgB2 bulk was prepared by two-step sintering in this study, first at 750 °C and then 900 °C. The MgB4 particles are induced to precipitate where the dislocations concentrated after C substitution or along the steps of screw dislocation during crystal growth, forming ordered MgB4 arrays throughout the MgB2 grain. By means of atomic force microscope, the detected magnetic domains are arranged in agreement with the ordered MgB4 particles after the measurement of magnetic hysteresis loop, which supported that the nano-scale MgB4 domain structure brought strong scattering effects and indicated that atomic force microscopy could test the role of the impurities. As a result, the extrapolating upper critical field H c2(0 K) is enhanced to 22.8 T for the sample with ordered MgB4, while only 18.1 T for the un-doped sample underwent the same sintering program. Besides, carbon substitution contributed to the enhancement of H c2 as well.

  11. In situ Resource Utilization for Processing of Metal Alloys on Lunar and Mars Bases

    NASA Astrophysics Data System (ADS)

    Stefanescu, D. M.; Grugel, R. N.; Curreri, P. A.

    1998-01-01

    Current plans for practical missions leading to a sustained human presence on our Moon and Mars rely on utilizing their in situ resources. Initially, resource availability must be assessed followed by the development of economically acceptable and technically feasible extractive processes. In regard to metals processing and fabrication, the lower gravity level on the Moon (0.125 g) and Mars (0.369 g) will dramatically change the presently accepted hierarchy of materials in terms of specific properties, a factor which must be understood and exploited. Furthermore, significant changes are expected in the behavior of liquid metals during processing. In metal casting, for example, mold filling and associated solidification processes have to be reevaluated. Finally, microstructural development and therefore material properties, presently being documented through ongoing research in microgravity science and applications, needs to be understood and scaled to the reduced gravity environments. These and other issues are addressed in this paper.

  12. In Situ Vitrification: Recent test results for a contaminated soil melting process

    SciTech Connect

    Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.

    1988-06-01

    In Situ Vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy and other clients for the stabilization of soils and sludges contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product that is similar to obsidian. In June 1987, a large-scale test of the process was completed at a transuranic- contaminated soil site. This constituted the first full-scale demonstration of the ISV process at an actual site. This paper summarizes the preliminary results of this test and describes the processes' potential adaptation to radioactive and hazardous chemical waste contaminated soils. 10 refs., 10 figs.

  13. Literature survey of in situ processes for application to the US tar sand resource

    SciTech Connect

    Johnson, Jr., L. A.

    1989-08-01

    Tar sands in the United States and worldwide are a large potential source of hydrocarbon liquids that has yet to be sufficiently developed. The development of the US tar sand resource lags the worldwide development and poses a challenge that has not been eagerly accepted by the petroleum industry. This paper reviews the developmental status of in situ enhanced oil recovery techniques that have been proposed for the production of heavy oils or bitumen and determines which process or processes are in the forefront for application to the US resource. Also noted is what developmental work, if any, remains to be accomplished before field testing of the process(es). The review used only information available in the public domain. 196 refs., 1 fig., 2 tabs.

  14. Neutron Microtomography of MgB2 Superconducting Multifilament Wire

    NASA Astrophysics Data System (ADS)

    Trtik, Pavel; Scheuerlein, Christian; Alknes, Patrick; Meyer, Michael; Schmid, Florian; Lehmann, Eberhard

    Neutron imaging of sub-10-micrometres spatial resolution has been recently achieved in 2D mode within the framework of the Neutron Microscope project at the Paul Scherrer Institut. Here we report on the development of the PSI Neutron Microscope instrument and the results of the first microtomographic imaging experiment of multifilament superconducting MgB2 wire. The sample of MgB2 superconducting 37 multifilaments embedded in copper-nickel matrix was investigated -in microtomographic mode- with the scientific interest regarding the distribution of boron within the individual superconducting filaments (about 40 μm in diameter). The resulting tomographic dataset revealed the distribution of boron within the entire 0.8 mm thick multifilamental wire with the isotropic voxel size of 2.6 micrometres.

  15. Active Protection of an MgB2 Test Coil

    PubMed Central

    Park, Dong Keun; Hahn, Seungyong; Bascuñán, Juan; Iwasa, Yukikazu

    2011-01-01

    This paper presents results of a study, experimental and computational, of a detect-and-activate-the-heater protection technique applied to a magnesium diboride (MgB2) test coil operated in semi-persistent mode. The test coil with a winding ID of 25 cm and wound with ~500-m long reacted MgB2 wire was operated at 4.2 K immersed in a bath of liquid helium. In this active technique, upon the initiation of a “hot spot” of a length ~10 cm, induced by a “quench heater,” a “protection heater” (PH) of ~600-cm long planted within the test coil is activated. The normal zone created by the PH is large enough to absorb the test coil’s entire initial stored energy and still keeps the peak temperature within the winding below ~260 K. PMID:22081754

  16. Substitution Effects on MgB2 Superconductivity

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Zhao, Yuan; Yi, Lin

    2008-02-01

    With the help of supercell method, the first-principle calculations were performed for the study of doping crystal Mg1-xAlxB2 and Mg(B1-yCy)2. Analyzing the variations of the charge distribution and the partial densities of states, we found that the compounds with doping Al to MgB2 compound and/or replacing boron by carbon exhibit new covalent bond effects and unexpected electronic properties, related to superconductivity. The study of the density of states indicates that superconductivity decreases with the increase of Al fraction and carbon concentration. There exists a transition of superconductor to non-superconductor with the change of Al doping fraction. The substitution of boron by carbon results in the decrease of the transition temperature since the decrease of the electron concentration and the lattice constant. The theoretical predictions agree with experimental observations.

  17. Attempts at doping indium in MgB2

    NASA Astrophysics Data System (ADS)

    Grivel, J.-C.

    2016-12-01

    Indium (In) doped MgB2 polycrystalline samples were prepared by solid-liquid phase reaction in Ar. After reaction at 800 °C, less than 1 at.% Mg was replaced by In in the MgB2 phase, without significant influence on its lattice parameters and only a slight decrease of its superconducting transition temperature. For all studied In concentrations in the nominal composition, the formation of InMg was evidenced by X-ray diffraction. The critical current density and accommodation field of the wires are decreased in the samples containing In. The flux pinning mechanism can be described by surface pinning in both the doped and undoped samples.

  18. Experimental Investigation of MGB2 Switching with Magnetic Pulses

    NASA Astrophysics Data System (ADS)

    Ishmael, S. A.; Leveque, J.; Netter, D.; Meinke, R. B.; Masson, P. J.

    2010-04-01

    Superconducting machines require DC current excitation in the rotor usually achieved using brushless exciters relying on solid state components for current rectification. The use of solid state components limits the amount of current allowable and imposes a large inductance in the rotor. MgB2 allows for "close to" superconducting splicing enabling development of large current rotors where solid state devices could be advantageously replaced by superconducting switches and used with a flux pump excitation system. For certain applications, such as a synchronous condenser, the dynamics of the excitation system is important as well as imposing fast switching and fast recovery. Switches driven by magnetic pulses are expected to exhibit a very limited temperature increase leading to fast recovery and also to contribute to very good system dynamics. This paper covers the experimental investigation of the response of MgB2 conductors subjected to magnetic pulses. The dependence of the resistance vs. J/Jc and operating temperature are discussed.

  19. In Situ Optical Observation of High-Temperature Geological Processes With the Moissanite Cell

    NASA Astrophysics Data System (ADS)

    Walte, N.; Keppler, H.

    2005-12-01

    A major drawback of existing techniques in experimental earth and material sciences is the inability to observe ongoing high-temperature processes in situ during an experiment. Examples for important time-dependent processes include the textural development of rocks and oxide systems during melting and crystallization, solid-state and melt-present recrystallization and Ostwald ripening, and bubble nucleation and growth during degassing of glasses and melts. The investigation of these processes by post-mortem analysis of a quenched microstructure is time consuming and often unsatisfactory. Here, we introduce the moissanite cell that allows optical in situ observation of long-term experiments at high temperatures. Moissanite is a transparent gem-quality type of SiC that is characterized by its hardness and superior chemical and thermal resistance. Two moissanite windows with a thickness and diameter of several millimeters are placed into sockets of fired pyrophyllite and fixed onto two opposite metal plates. The sockets are wrapped with heating wire and each window is connected to a thermocouple for temperature control. The sample is placed directly between the moissanite windows and the cell is assembled similarly to a large diamond anvil cell. In situ observation of the sample is done with a microscope through observation windows and movies are recorded with an attached digital camera. Our experiments with the new cell show that temperatures above 1200°C can be maintained and observed in a sample for several days without damaging the cell nor the windows. Time-lapse movies of melting and crystallizing natural and synthetic rocks and of degassing glasses and melts will be presented to show the potential of the new technique for experimental earth and material science.

  20. Methods of producing alkylated hydrocarbons from an in situ heat treatment process liquid

    DOEpatents

    Roes, Augustinus Wilhelmus Maria [Houston, TX; Mo, Weijian [Sugar Land, TX; Muylle, Michel Serge Marie [Houston, TX; Mandema, Remco Hugo [Houston, TX; Nair, Vijay [Katy, TX

    2009-09-01

    A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation.

  1. In-situ EXAFS study of nucleation process of CdSe nanocrystals

    NASA Astrophysics Data System (ADS)

    Sun, Z. H.; Oyanagi, H.; Uehara, M.; Yamashita, K.; Fukano, A.; Maeda, H.

    2009-11-01

    An in-situ EXAFS method is developed to study the nucleation and growth processes of nanocrystals by using a microfluidic reactor which converts the time-dependent kinetics to position-dependence. As an example, we measured the Se K-edge EXAFS spectra for CdSe nanocrystals along a microfluidic reactor channel and indicated strong time-dependence of the nucleation and growth at the beginning of the reaction. A rapid increase of the reaction yield within several seconds was observed. It is found that after injection of starting materials, the nucleation occurs abruptly and the CdSe nuclei concentration reaches the maximum and then declines rapidly.

  2. Experimental Analysis and Characterization on Thermal Imprint Process via In-situ Observation

    NASA Astrophysics Data System (ADS)

    Saito, Takushi; Kawaguchi, Tatsuya; Satoh, Isao

    In this study, an experimental system for in-situ observation of the thermal imprint process was constructed, and the material behavior from the initiation of transcription to product removal was precisely studied. Based on the results obtained, effect of the temperature and pressure on the transcription behavior and the shape accuracy was investigated, and the principles to obtain good replication were discussed. In addition, the exfoliation behavior of the material from substrate in the cooling stage after the transcription was observed and its characteristics were discussed.

  3. Rapid thermal processing chamber for in-situ x-ray diffraction

    SciTech Connect

    Ahmad, Md. Imteyaz; Van Campen, Douglas G.; Yu, Jiafan; Pool, Vanessa L.; Van Hest, Maikel F. A. M.; Toney, Michael F.; Fields, Jeremy D.; Parilla, Philip A.; Ginley, David S.

    2015-01-15

    Rapid thermal processing (RTP) is widely used for processing a variety of materials, including electronics and photovoltaics. Presently, optimization of RTP is done primarily based on ex-situ studies. As a consequence, the precise reaction pathways and phase progression during the RTP remain unclear. More awareness of the reaction pathways would better enable process optimization and foster increased adoption of RTP, which offers numerous advantages for synthesis of a broad range of materials systems. To achieve this, we have designed and developed a RTP instrument that enables real-time collection of X-ray diffraction data with intervals as short as 100 ms, while heating with ramp rates up to 100 °Cs{sup −1}, and with a maximum operating temperature of 1200 °C. The system is portable and can be installed on a synchrotron beamline. The unique capabilities of this instrument are demonstrated with in-situ characterization of a Bi{sub 2}O{sub 3}-SiO{sub 2} glass frit obtained during heating with ramp rates 5 °C s{sup −1} and 100 °C s{sup −1}, revealing numerous phase changes.

  4. Effect of Heavy Carbon Doping of MgB_2

    NASA Astrophysics Data System (ADS)

    Kasinathan, Deepa; Pickett, W. E.

    2003-03-01

    Superconductivity in MgB2 seems to be beginning to be understood, but behavior under changes of hole concentration remain to be established and understood. Recently Ribeiro, Bud'ko, Petrovic, and Canfield (cond-mat/0210530) have reported MgB_2-xC_x, where Tc ˜ 20 K for x 0.1 -- 0.2. Rigid band arguments would say that the σ-band hole states in MgB2 should be filled by x=1/6, with no superconductivity. We have carried all-electron, full potential LAPW studies [WIEN2K] of ordered supercells corresponding to x=1/6 and 1/8 to assess the effects of the C, whose potential is more attractive and size is smaller than B, on the structure and the electronic bands and density of states. The behavior is non-rigid-band in important ways. We report on the magnitude of B atom relaxation around the C impurities, the effect that the relaxation has on the band filling, and the degree to which the experimental data can be accounted for.

  5. In situ vitrification: Test results for a contaminated soil-melting process

    SciTech Connect

    Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.

    1989-10-01

    In situ vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy to stabilize soils and sludges that are contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product similar to obsidian and basalt. In June 1987, a large-scale test of the process was completed at a transuranic-contaminated soil site. The test constituted the first full-scale demonstration of ISV at an actual site. This paper summarizes the results of that test and describes the potential adaptation of the process to radioactive and hazardous chemical waste-contaminated soils. 15 refs., 9 figs., 3 tabs.

  6. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2004-01-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this first quarterly report of our DoE funded research, we discuss the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. The formulation presented here for a first one-dimensional simulator will serve as the foundation for the development of a three-dimensional simulator that can handle realistic permeability heterogeneity. The development of the simulation tool will be supported by extensive laboratory experiments conducted to provide validation data, and to study effective variants of the combustion process. The preliminary investigation reported here shows how metallic salt additives can promote and sustain combustion by enhancing the oxidation and cracking of hydrocarbons.

  7. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2004-07-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this third quarterly report of our DoE funded research, we continue the discussion of the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. Also, we show preliminary results for the one-dimensional in-situ combustion simulator, which will serve as the foundation for the development of a three-dimensional simulator that can handle realistic permeability heterogeneity. On the experimental side, the combustion kinetic apparatus and the combustion tube are now fully operational, and a series of successful combustion tube runs were performed that clearly showed additives allow combustion of poorly reactive oils. We have also started scanning electron microscope (SEM) analysis to investigate the sand-clay-salt mixtures that are used for combustion in which we focus on grain sizes, shapes, orientations, characteristic inter-structures, and element analysis.

  8. Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

    SciTech Connect

    Doshi, P.; Rohatgi, A.; Ropp, M.; Chen, Z.; Ruby, D.; Meier, D.L.

    1995-01-01

    Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J{sub 0}), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J{sub 0}.

  9. Discrete magic angle turning system, apparatus, and process for in situ magnetic resonance spectroscopy and imaging

    DOEpatents

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Wind, Robert A.

    2009-05-19

    Described are a "Discrete Magic Angle Turning" (DMAT) system, devices, and processes that combine advantages of both magic angle turning (MAT) and magic angle hopping (MAH) suitable, e.g., for in situ magnetic resonance spectroscopy and/or imaging. In an exemplary system, device, and process, samples are rotated in a clockwise direction followed by an anticlockwise direction of exactly the same amount. Rotation proceeds through an angle that is typically greater than about 240 degrees but less than or equal to about 360 degrees at constant speed for a time applicable to the evolution dimension. Back and forth rotation can be synchronized and repeated with a special radio frequency (RF) pulse sequence to produce an isotropic-anisotropic shift 2D correlation spectrum. The design permits tubes to be inserted into the sample container without introducing plumbing interferences, further allowing control over such conditions as temperature, pressure, flow conditions, and feed compositions, thus permitting true in-situ investigations to be carried out.

  10. [Extradural en bloc removal and in situ replacement of the anterior clinoid process].

    PubMed

    Shigeno, Taku; Kumai, Junichiro; Horikawa, Hiroshi; Naemura, Kazuaki; Aihara, Kouki; Ishikawa, Osamu; Nishido, Hajime; Sakamoto, Masaki; Oya, Soichi; Endo, Masaru

    2010-04-01

    Extradural removal of the anterior clinoid process (ACP) is useful and essential for approaching aneurysmal and tumor lesions in and around the cavernous sinus. A safe, rapid and less invasive technique is beneficial for this basic skull base surgery. We developed a new technique by sharply cutting the ACP together with the part of the sphenoid ridge bone followed by complete replacement. A series of patients with either basilar top or internal carotid artery aneurysms underwent the present technique. After frontotemporal craniotomy, the lateral frontal and anterior middle cranial fossae are exposed extradurally. The bone was cut using a cutting steel burr from the sphenoid ridge to the superior orbital fissure and to the optic canal. By sharply separating the meningo-orbital band between the dura propria and the periorbital fascia, the ACP is exposed. The cutting burr runs underneath the ACP. By leaving a very thin sheet of bone, the entire bone piece was elevated after fracturing the thin bone using a chisel. By severing the carotid ring, the internal carotid artery is freed and mobile either laterally or medially to obtain an ample basal cistern. After operation, the once removed clinoid process is replaced in situ using a titanium plate screw. Extradural en bloc removal and in situ replacement of the ACP can be safely done by this cutting procedure. This can provide a good cosmetic result without causing enophthalmos or transient oculomotor palsy.

  11. In situ remediation of hydrocarbon contamination using an injection-extraction process

    SciTech Connect

    Ross, A.; Tremblay, C.; Boulanger, C.

    1995-12-31

    Ecosite Inc. has developed a soil treatment technology to be applied in situ using an injection-extraction system (IES). This new restoration process uses custom-designed equipment for recovering free-phase hydrocarbons and for injection/recovery of different treatment solutions through cyclic manipulation of the water table level. Process development applied the basic principles of soil washing with improved distribution of the washing solution and improved hydraulic control using air sparging and vacuum capability. In this case study, free-phase recovery and soil washing have been used successfully to remediate the site. During the fall and winter of 1993--94, in situ restoration of soil contaminated with cutting oil below a machine shop was begun. The contamination extended from 1.83 to 4.27 m underneath the concrete slab. This represents a volume of 1,800 m{sup 3} of oil-laden soil with concentrations reaching 200,000 mg/kg. Moreover, free-floating phase hydrocarbons up to 1 m thick were observed. To clean the site, 400 injection/recovery points were arranged into three networks. A data collection system was used to monitor the water table level. A total of 160,000 kg of oil was extracted from the subsoil in less than 110 days of operation.

  12. A combined process coupling phytoremediation and in situ flushing for removal of arsenic in contaminated soil.

    PubMed

    Yan, Xiulan; Liu, Qiuxin; Wang, Jianyi; Liao, Xiaoyong

    2017-07-01

    Phytoremediation and soil washing are both potentially useful for remediating arsenic (As)-contaminated soils. We evaluated the effectiveness of a combined process coupling phytoremediation and in situ soil flushing for removal of As in contaminated soil through a pilot study. The results showed that growing Pteris vittata L. (P.v.) accompanied by soil flushing of phosphate (P.v./Flushing treatment) could significantly decrease the total As concentration of soil over a 37day flushing period compared with the single flushing (Flushing treatment). The P.v./Flushing treatment removed 54.04% of soil As from contaminated soil compared to 47.16% in Flushing treatment, suggesting that the growth of P. vittata was beneficial for promoting the removal efficiency. We analyzed the As fractionation in soil and As concentration in soil solution to reveal the mechanism behind this combined process. Results showed that comparing with the control treatment, the percent of labile arsenate fraction significantly increased by 17% under P.v./Flushing treatment. As concentration in soil solution remained a high lever during the middle and later periods (51.26-56.22mg/L), which was significantly higher than the Flushing treatment. Although soil flushing of phosphate for more than a month, P. vittata still had good accumulation and transfer capacity of As of the soil. The results of the research revealed that combination of phytoremediation and in situ soil flushing is available to remediate As-contaminated soils. Copyright © 2016. Published by Elsevier B.V.

  13. Study on in situ and real-time observation during process of SCN crystal growth

    NASA Astrophysics Data System (ADS)

    Lei, Songhe; Chen, Changle; Duan, Mengmeng

    2006-02-01

    Crystal growth is dynamic coupling of transportation process and growth process between interfaces. Convection during crystal growth will tend to changes of liquation component and the defect of impurity stripe. The convection and stability should further be studied to obtain the crystal of high quality. It is necessary to obtain surface configuration and distribution of temperature around liquation phase and solute concentration. The technique of in-situ and real-time observation is a brand new technique, which is widely applied to production and scientific research. Information of crystal growth will be obtained from the observation. But the in-situ and real-time observation is uncharitableness for the experiment equipment, some conditions matched to the character of crystal must be provided. In the paper a design with ingenious and cheap crystal growth cell and circulation system of constant-temperature water which is suitable for the experiment of observation is developed, and a combined light path based on the technique of flowing visualization is designed to match to the crystal cell. The combined light path which is made up of the schlieren method and the principle of Mach-zehnder interference is non destructive, high sensitivity and observable, so it is an effective method to study the crystal growth.

  14. In situ observation of elementary growth processes of protein crystals by advanced optical microscopy.

    PubMed

    Sazaki, Gen; Van Driessche, Alexander E S; Dai, Guoliang; Okada, Masashi; Matsui, Takuro; Otálora, Fermin; Tsukamoto, Katsuo; Nakajima, Kazuo

    2012-07-01

    To start systematically investigating the quality improvement of protein crystals, the elementary growth processes of protein crystals must be first clarified comprehensively. Atomic force microscopy (AFM) has made a tremendous contribution toward elucidating the elementary growth processes of protein crystals and has confirmed that protein crystals grow layer by layer utilizing kinks on steps, as in the case of inorganic and low-molecular-weight compound crystals. However, the scanning of the AFM cantilever greatly disturbs the concentration distribution and solution flow in the vicinity of growing protein crystals. AFM also cannot visualize the dynamic behavior of mobile solute and impurity molecules on protein crystal surfaces. To compensate for these disadvantages of AFM, in situ observation by two types of advanced optical microscopy has been recently performed. To observe the elementary steps of protein crystals noninvasively, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) was developed. To visualize individual mobile protein molecules, total internal reflection fluorescent (TIRF) microscopy, which is widely used in the field of biological physics, was applied to the visualization of protein crystal surfaces. In this review, recent progress in the noninvasive in situ observation of elementary steps and individual mobile protein molecules on protein crystal surfaces is outlined.

  15. Monitoring in situ retorting processes of oil shale by reflected and transmitted electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Hong, S. H.; DuBow, J. B.

    1980-07-01

    A theoretical model for an in situ oil shale retort with three distinct vertical zones, all surrounded by a wall of oil shale, overburden and underburden, is considered for the study of potential electromagnetic monitoring of the progression of retorting processes using wave propagation techniques. The overall power reflection and transmission coefficients for both transverse electric and transverse magnetic waves are used for finding the position of a combustion zone in the retort, based upon the assumption of straight-line propagation of monochromatic plane waves through layered lossy dielectric media characterized by the dielectric constants and loss tangents. The behavior of each power coefficient is discussed as a function of burn front positions and signal frequencies. As a result of the relatively moderate signal power for each coefficient required for detection, and the one-to-one correspondence between each power coefficient and burn front position at typical conditions, the feasibility of using low radio-frequency waves to monitor relatively large scale in situ retorting process is established.

  16. Why in situ, real-time characterization of thin film growth processes?

    SciTech Connect

    Auciello, O.; Krauss, A.R.

    1995-08-01

    Since thin-film growth occurs at the surface, the analytical methods should be highly surface-specific. although subsurface diffusion and chemical processes also affect film properties. Sampling depth and ambient-gas is compatibility are key factors which must be considered when choosing in situ probes of thin-film growth phenomena. In most cases, the sampling depth depends on the mean range of the exit species (ion, photon, or electron) in the sample. The techniques that are discussed in this issue of the MRS Bulletin (1) have been chosen because they may be used for in situ, real-time analysis of film-growth phenomena in vacuum and in the presence of ambient gases resulting either from the deposition process or as a requirement for the production of the desired chemical phase. A second criterion for inclusion is that the instrumentation be sufficiently compact and inexpensive to permit use as a dedicated tool in a thin-film deposition system.

  17. Utilization of the PHOSter {trademark} process to improve in situ bioremediation of petroleum hydrocarbons

    SciTech Connect

    Looney, B.B.; Easton, S.; Haselow, J.; Klemm, D.

    1996-12-31

    PHOSter{trademark} is a patented gas-phase nutrient delivery system that can be used to control the addition of vapor phase phosphorus and improve in situ bioremediation processes. PHOSter{trademark} can be easily and cost-effectively added to most existing biosparging or bioventing systems to provide the phosphorus that is often lacking for an optimally healthy microbial environment. Traditional approaches for adding phosphate to sites are based on addition of liquid fertilizer or phosphoric acid vapors. Such systems have been shown to influence very small areas and often result in overstimulation of the microbial population, which can lead to undesirable effects such as formation clogging. The PHOSter{trademark} system uses a relatively safe form of organic phosphate, triethylphosphate or TEP. TEP is added to an air injection stream by contacting or infusing the vapors from the liquid. With PHOSter{trademark}, the presence of the ethyl groups on the phosphate reduces the nutrient`s dissolution rate into water and provides a {open_quotes}time released{close_quotes} stimulation and prevents clogging, and because the phosphorus is in a gas form, it is more readily dispersed in the formation. PHOSter{trademark} has been successfully utilized in three states (South Carolina, Michigan, and New York) on petroleum hydrocarbon and trichloroethane contamination. A goal of a fourth test that is underway in Panama City, Florida at a gasoline distribution terminal is to improve the in situ remediation of BTEX and eliminate fugitive emissions from a multipoint airsparging process.

  18. Utilization of the PHOSter [trademark] process to improve in situ bioremediation of petroleum hydrocarbons

    SciTech Connect

    Looney, B.B. ); Easton, S. ); Haselow, J. ); Klemm, D. )

    1996-01-01

    PHOSter[trademark] is a patented gas-phase nutrient delivery system that can be used to control the addition of vapor phase phosphorus and improve in situ bioremediation processes. PHOSter[trademark] can be easily and cost-effectively added to most existing biosparging or bioventing systems to provide the phosphorus that is often lacking for an optimally healthy microbial environment. Traditional approaches for adding phosphate to sites are based on addition of liquid fertilizer or phosphoric acid vapors. Such systems have been shown to influence very small areas and often result in overstimulation of the microbial population, which can lead to undesirable effects such as formation clogging. The PHOSter[trademark] system uses a relatively safe form of organic phosphate, triethylphosphate or TEP. TEP is added to an air injection stream by contacting or infusing the vapors from the liquid. With PHOSter[trademark], the presence of the ethyl groups on the phosphate reduces the nutrient's dissolution rate into water and provides a [open quotes]time released[close quotes] stimulation and prevents clogging, and because the phosphorus is in a gas form, it is more readily dispersed in the formation. PHOSter[trademark] has been successfully utilized in three states (South Carolina, Michigan, and New York) on petroleum hydrocarbon and trichloroethane contamination. A goal of a fourth test that is underway in Panama City, Florida at a gasoline distribution terminal is to improve the in situ remediation of BTEX and eliminate fugitive emissions from a multipoint airsparging process.

  19. Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels. Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors

    SciTech Connect

    Dutta, Abhijit; Sahir, Asad; Tan, Eric; Humbird, David; Snowden-Swan, Lesley J.; Meyer, Pimphan; Ross, Jeff; Sexton, Danielle; Yap, Raymond; Lukas, John Lukas

    2015-03-01

    This report was developed as part of the U.S. Department of Energy’s Bioenergy Technologies Office’s efforts to enable the development of technologies for the production of infrastructurecompatible, cost-competitive liquid hydrocarbon fuels from biomass. Specifically, this report details two conceptual designs based on projected product yields and quality improvements via catalyst development and process integration. It is expected that these research improvements will be made within the 2022 timeframe. The two conversion pathways detailed are (1) in situ and (2) ex situ upgrading of vapors produced from the fast pyrolysis of biomass. While the base case conceptual designs and underlying assumptions outline performance metrics for feasibility, it should be noted that these are only two of many other possibilities in this area of research. Other promising process design options emerging from the research will be considered for future techno-economic analysis.

  20. Reactivity of carbides in synthesis of MgB 2 bulks

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ueda, Shinya; Horii, Shigeru; Kishio, Kohji

    2006-10-01

    The reactivity of various carbides (B4C, Al4C3, SiC, TiC, ZrC, NbC, Mo2C, HfC and WC) with magnesium and boron in synthesis of MgB2 was systematically studied. Decreases in the a-axis length and transition temperature were observed in all the carbide doped MgB2 bulks, reflecting a certain amount of carbon substituted for boron site in MgB2. The reactivity of each carbide estimated by the carbon content in MgB2 was found to be different depending on the chemical stability. Our results suggest that carbon content in MgB2 lattice can be controlled to its optimal doping level by adjusting synthesis conditions and selection of doping reagents.

  1. Evaluation Of In Situ Steam-Injection Processes For Reduction Of Petroleum Compounds Within An Abandoned Canal

    EPA Science Inventory

    A conceptual approach of a novel application of in-situ thermal processes that would either use a steam injection process or a steam/surfactant injection process was considered to remediate petroleum contaminated sediment residing in an abandoned canal. Laboratory tests were c...

  2. Evaluation Of In Situ Steam-Injection Processes For Reduction Of Petroleum Compounds Within An Abandoned Canal

    EPA Science Inventory

    A conceptual approach of a novel application of in-situ thermal processes that would either use a steam injection process or a steam/surfactant injection process was considered to remediate petroleum contaminated sediment residing in an abandoned canal. Laboratory tests were c...

  3. In Situ 3D Synchrotron Imaging of Failure Processes in Engineering Materials

    NASA Astrophysics Data System (ADS)

    Mostafijur Rahman, K. M.; Szpunar, Jerzy; Belev, George

    2013-03-01

    The micrometer range resolution of Synchrotron Radiation Tomography has developed an important technique for characterizing the three dimensional (3D) microstructure of materials. This technique was used for imaging Aluminum-alumina composites, porous aluminum and AA 6061 alloy under different loading conditions. The experimental set-up was installed at the Biomedical Imaging and Therapy (BMIT)'s 05B1-1 beamline at Canadian Light Source (CLS). The experimental stage has been designed for conducting the in-situ experiments. The unique feature of this experimental stage is that the sample can be rotated torsion free for taking the images for Computed Tomography imaging during any loading conditions. The developed experimental system and technique allows deciphering the internal structures of composites, porous materials, multiphase alloys and to observe the failure processes such as crack initiation, crack propagation, void formation, void coalescence and the fracture process during loading of materials.

  4. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators.

    PubMed

    Tremsin, Anton S; Makowska, Małgorzata G; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C; Losko, Adrian S; Strobl, Markus; Kuhn, L Theil; Bizarri, Gregory A; Bourret-Courchesne, Edith D

    2016-06-01

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g. while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studied in situ during the melting and solidification processes with a temporal resolution of 5-7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ∼50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (∼0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging for in situ diagnostics and the optimization of crystal-growth procedures.

  5. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

    PubMed Central

    Tremsin, Anton S.; Makowska, Małgorzata G.; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V.; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C.; Losko, Adrian S.; Strobl, Markus; Kuhn, L. Theil; Bizarri, Gregory A.; Bourret-Courchesne, Edith D.

    2016-01-01

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g. while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studied in situ during the melting and solidification processes with a temporal resolution of 5–7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ∼50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (∼0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging for in situ diagnostics and the optimization of crystal-growth procedures. PMID:27275133

  6. Nanomaterial processing for multifunctional patterned composites for in situ sensing applications

    NASA Astrophysics Data System (ADS)

    Melrose, Zachary R.

    The increasing performance demands on composite materials have stimulated the development of new approaches and manufacturing techniques to integrate various system functionalities within the composite structure. Opportunity exists to produce smart, self-sensing composites, by altering the microstructure of the composite where sensors can be patterned for assessing damage locality and severity. Introduction of nanomaterials into continuous fiber-reinforced composites either at the fiber/matrix interface or within the polymer matrix enables further tailoring of mechanical and electrical properties. Carbon nanotubes have been studied extensively for modifying the mechanical and physical properties of fiber composites. Recently graphene has generated scientific and technical interest due to potential lower raw material costs and ease of processing. This work studies graphene nano-platelet processing parameters to determine the suitability of graphene nanocomposites for in situ sensing applications. Processing parameters for optimizing the piezoresistive response of graphene nano-platelet composites for in situ sensing applications are determined and applied in for the development of a patterning media suitable for deposition onto glass fibers. A new approach to selectively modify the electrical properties of composite fibers is employed to selectively deposit carbon nanotube and graphene nano-platelet enhanced patterning media through an adapted screen printing process. These nano-modified depositions create hierarchical patterns of piezoresistive sensors as fully integrated components and form a distributed sensor network at the fiber/matrix interface. New analysis tools for resistance based sensing techniques are applied to nanocomposites and patterned unidirectional hybrid nanocomposites to assess damage onset and accumulation. The sensitivity of the electrical response for the graphene nano-platelet is compared with the electrical response of the carbon nanotube

  7. AC losses and transverse resistivity in filamentary MgB 2 tape with Ti barriers

    NASA Astrophysics Data System (ADS)

    Polák, M.; Demenčík, E.; Hušek, I.; Kopera, L.; Kováč, P.; Mozola, P.; Takács, S.

    2011-07-01

    We measured and analyzed AC losses of MgB 2 tape with 19 filaments surrounded by Ti barriers and embedded in copper stabilization, exposed to external magnetic field with frequencies from 30 mHz up to 1.4 Hz and amplitudes up to 0.8 T at 4.2 K. Using the measured frequency dependence of the total AC losses we determined the contribution of hysteresis and coupling losses. The transverse resistivity determined from the coupling losses is considerably higher than that corresponding to the resistivity of copper stabilization before the tape processing due to diffusion of Ti. From the measured penetration field critical current densities were determined using results of theories for circular as well as rectangular filaments.

  8. STANFORD IN-SITU HIGH RATE YBCO PROCESS: TRANSFER TO METAL TAPES AND PROCESS SCALE UP

    SciTech Connect

    Malcolm R. Beasley; Robert H.Hammond

    2009-04-14

    Executive Summary The materials science understanding of high rate low cost processes for Coated Conductor will benefit the application to power utilities for low loss energy transportation and power generation as well for DOD applications. The research in this program investigated several materials processing approaches that are new and original, and are not being investigated elsewhere. This work added to the understanding of the material science of high rate PVD growth of HTSC YBCO assisted by a liquid phase. A new process discovered uses amorphous glassy precursors which can be made at high rate under flexible conditions of temperature and oxygen, and later brought to conditions of oxygen partial pressure and temperature for rapid conversion to YBCO superconductor. Good critical current densities were found, but further effort is needed to optimize the vortex pinning using known artificial inclusions. A new discovery of the physics and materials science of vortex pinning in the HTSC system using Sm in place of Y came at growth at unusually low oxygen pressure resulting in clusters of a low or non superconducting phase within the nominal high temperature phase. The driving force for this during growth is new physics, perhaps due to the low oxygen. This has the potential for high current in large magnetic fields at low cost, applicable to motors, generators and transformers. The technical demands of this project were the motivation for the development of instrumentation that could be essential to eventual process scale up. These include atomic absorption based on tunable diode lasers for remote monitoring and control of evaporation sources (developed under DARPA support), and the utility of Fourier Transform Infrared Reflectivity (FTIR) for aid in the synthesis of complex thin film materials (purchased by a DURIP-AFOSR grant).

  9. Understanding aquatic microbial processes using EEM's and in-situ fluorescence sensors

    NASA Astrophysics Data System (ADS)

    Fox, Bethany; Attridge, John; Rushworth, Cathy; Cox, Tim; Anesio, Alexandre; Reynolds, Darren

    2015-04-01

    The diverse origin of dissolved organic matter (DOM) in aquatic systems is well documented within the literature. Previous literature indicates that coloured dissolved organic matter (CDOM) is, in part, transformed by aquatic microbial processes, and that dissolved organic material derived from a microbial origin exhibits tryptophan-like fluorescence. However, this phenomenon is not fully understood and very little data is available within the current literature. The overall aim of our work is to reveal the microbial-CDOM interactions that give rise to the observed tryptophan-like fluorescence. The work reported here investigates the microbial processes that occur within freshwater aquatic samples, as defined by the biochemical oxygen demand (BOD) test, as a function of the T1 peak (λex/em 280/330-370 nm). A series of standard water samples were prepared using glucose, glutamic acid, BOD dilution water and a bacterial seed (Cole-Parmer BOD microbe capsules). Samples were spiked with CDOM (derived from an environmental water body) and subjected to time resolved BOD analysis and as excitation-emission fluorescence spectroscopy. All EEM spectral data was interrogated using parallel factor analysis (PARAFAC) in an attempt to determine the presence and dominance (relative intensities) of the CDOM-related and T1-related fluorophores within the samples. In-situ fluorescence sensors (Chelsea Technologies Group Ltd.) were also used to monitor the T1 fluorescence peak (UviLux Tryptophan) and the CDOM fluorescence peak (UviLux CDOM) during experiments. Tryptophan-like fluorescence was observed (albeit transient) in both spiked and un-spiked standard water samples. By furthering our understanding of aquatic organic matter fluorescence, its origin, transformation, fate and interaction with aquatic microbiological processes, we aim to inform the design of a new generation in-situ fluorescence sensor for the monitoring of aquatic ecosystem health.

  10. Focused beam reflectance measurement as a tool for in situ monitoring of the lactose crystallization process.

    PubMed

    Pandalaneni, K; Amamcharla, J K

    2016-07-01

    Lactose accounts for about 75 and 85% of the solids in whey and deproteinized whey, respectively. Production of lactose is usually carried out by a process called crystallization. Several factors including rate of cooling, presence of impurities, and mixing speed influence the crystal size characteristics. To optimize the lactose crystallization process parameters to maximize the lactose yield, it is important to monitor the crystallization process. However, efficient in situ tools to implement at concentrations relevant to the dairy industry are lacking. The objective of the present work was to use a focused beam reflectance measurement (FBRM) system for in situ monitoring of lactose crystallization at supersaturated concentrations (wt/wt) 50, 55, and 60% at 20 and 30°C. The FBRM data were compared with Brix readings collected using a refractometer during isothermal crystallization. Chord length distributions obtained from FBRM in the ranges of <50 µm (fine crystals) and 50 to 300 µm (coarse crystals) were recorded and evaluated in relation to the extent of crystallization and rate constants deduced from the refractometer measurements. Extent of crystallization and rate constants increased with increasing supersaturation concentration and temperature. The measured fine crystal counts from FBRM increased at higher supersaturated concentration and temperature during isothermal crystallization. On the other hand, coarse counts were observed to increase with decreasing supersaturated concentration and temperature. Square weighted chord length distribution obtained from FBRM showed that as concentration increased, a decrease in chord lengths occurred at 20°C and similar observations were made from microscopic images. The robustness of FBRM in understanding isothermal lactose crystallization at various concentrations and temperatures was successfully assessed in the study.

  11. The influence of heating rate on superconducting characteristics of MgB2 obtained by spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    Aldica, G.; Burdusel, M.; Popa, S.; Enculescu, M.; Pasuk, I.; Badica, P.

    2015-12-01

    Superconducting bulks of MgB2 were obtained by the Spark Plasma Sintering (SPS) technique. Different heating rates of 20, 100, 235, 355, and 475 °C/min were used. Samples have high density, above 95%. The onset critical temperature Tc, is about 38.8 K. There is an optimum heating rate of ∼100 °C/min to maximize the critical current density Jc0, the irreversibility field Hirr, the product (Jc0 x μ0Hirr), and to partially avoid formation of undesirable flux jumps at low temperatures. Significant microstructure differences were revealed for samples processed with low and high heating rates in respect to grain boundaries.

  12. A 2-D Array of Superconducting Magnesium Diboride (MgB2) Far-IR Thermal Detectors for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Lakew, Brook

    2009-01-01

    A 2-D array of superconducting Magnesium Diboride(MgB2) far IR thermal detectors has been fabricated. Such an array is intended to be at the focal plane of future generation thermal imaging far-IR instruments that will investigate the outer planets and their icy moons. Fabrication and processing of the pixels of the array as well as noise characterization of architectured MgB2 thin films will be presented. Challenges and solutions for improving the performance of the array will be discussed.

  13. A 2-D Array of Superconducting Magnesium Diboride (MgB2) Far-IR Thermal Detectors for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Lakew, Brook

    2009-01-01

    A 2-D array of superconducting Magnesium Diboride(MgB2) far IR thermal detectors has been fabricated. Such an array is intended to be at the focal plane of future generation thermal imaging far-IR instruments that will investigate the outer planets and their icy moons. Fabrication and processing of the pixels of the array as well as noise characterization of architectured MgB2 thin films will be presented. Challenges and solutions for improving the performance of the array will be discussed.

  14. Time-Resolved Photoexcitation of the Superconducting Two-Gap State in MgB2 Thin Films

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Khafizov, M.; Satrapinsky, L.; Kúš, P.; Plecenik, A.; Sobolewski, Roman

    2003-11-01

    Femtosecond pump-probe studies show that carrier dynamics in MgB2 films is governed by the sub-ps electron-phonon (e-ph) relaxation present at all temperatures, the few-ps e-ph process well pronounced below 70K, and the sub-ns superconducting relaxation below Tc. The amplitude of the superconducting component versus temperature follows the superposition of the isotropic dirty gap and the three-dimensional π gap dependences, closing at two different Tc values. The time constant of the few-ps relaxation exhibits a double divergence at temperatures corresponding to the Tc's of the two gaps.

  15. Modeling and Analysis of the Reverse Water Gas Shift Process for In-Situ Propellant Production

    NASA Technical Reports Server (NTRS)

    Whitlow, Jonathan E.

    2000-01-01

    This report focuses on the development of mathematical models and simulation tools developed for the Reverse Water Gas Shift (RWGS) process. This process is a candidate technology for oxygen production on Mars under the In-Situ Propellant Production (ISPP) project. An analysis of the RWGS process was performed using a material balance for the system. The material balance is very complex due to the downstream separations and subsequent recycle inherent with the process. A numerical simulation was developed for the RWGS process to provide a tool for analysis and optimization of experimental hardware, which will be constructed later this year at Kennedy Space Center (KSC). Attempts to solve the material balance for the system, which can be defined by 27 nonlinear equations, initially failed. A convergence scheme was developed which led to successful solution of the material balance, however the simplified equations used for the gas separation membrane were found insufficient. Additional more rigorous models were successfully developed and solved for the membrane separation. Sample results from these models are included in this report, with recommendations for experimental work needed for model validation.

  16. Hydrous pyrolysis/oxidation process for in situ destruction of chlorinated hydrocarbon and fuel hydrocarbon contaminants in water and soil

    DOEpatents

    Knauss, Kevin G.; Copenhaver, Sally C.; Aines, Roger D.

    2000-01-01

    In situ hydrous pyrolysis/oxidation process is useful for in situ degradation of hydrocarbon water and soil contaminants. Fuel hydrocarbons, chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, petroleum distillates and other organic contaminants present in the soil and water are degraded by the process involving hydrous pyrolysis/oxidation into non-toxic products of the degradation. The process uses heat which is distributed through soils and water, optionally combined with oxygen and/or hydrocarbon degradation catalysts, and is particularly useful for remediation of solvent, fuel or other industrially contaminated sites.

  17. In situ vitrification: Numerical studies of coupled heat transfer and viscous flow processes

    SciTech Connect

    Carey, G.F.; MacKinnon, R.J.; Murray, P.E.

    1990-09-01

    This report describes the formulation, results and conclusions of a series of numerical studies performed to support the Idaho National Engineering Laboratory (INEL) In Situ Vitrification (ISV) treatability study. These studies were designed to explore some of the questions related to the dominant physical phenomena associated with the coupled electric field, heat transfer, and fluid flow processes. The work examines the case of a 3-D axisymmetric problem with a central electrode. Such issues as the form of an electric heating model, choice of boundary conditions, latent heat effects, and conductive and convective transport are considered. Some important conclusions and recommendations are made in relation to the convective effects, determination of property parameters, and the issue of a valid electrical heating model. 4 refs., 100 figs., 1 tab.

  18. In situ observation of deformation processes in nanocrystalline face-centered cubic metals.

    PubMed

    Kobler, Aaron; Brandl, Christian; Hahn, Horst; Kübel, Christian

    2016-01-01

    The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline Pd x Au1- x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin-twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains.

  19. Fundamental Processes Responsible for Continuous Dynamic Recrystallization: An In-Situ Tem Study

    SciTech Connect

    Dougherty, Lisa M.; Robertson, Ian M.; Vetrano, John S.; Z. Jin, A. Beaudoin, T. A. Bieler and B. Radhakrishnan

    2003-05-10

    Material from interrupted superplastic deformation tests of an Al-4Mg-0.3Sc alloy have been restrained in situ in the transmission electron microscope at nominally the superplastic forming temperature. In material pre-deformed to 0.2 true strain the migration of subgrain boundaries, their interaction and trapping at Al3Sc particles, and their disintegration were observed dynamically. The dislocations released during the disintegration of the subgrain boundaries moved rapidly through the matrix and were incorporated into the bounding grain boundaries. The resulting increase in grain boundary energy caused rupture and annihilation of a grain boundary triple point. This process was accompanied by a large volume rotation, resulting in a common orientation. The interaction of subgrain boundaries with Al3Sc particles, and the bypass mechanism have also been observed. These observations will be discussed in relation to the macroscopic response of the material.

  20. In-situ monitoring the realkalisation process by neutron diffraction: Electroosmotic flux and portlandite formation

    SciTech Connect

    Castellote, Marta . E-mail: martaca@ietcc.csic.es; Llorente, Irene; Andrade, Carmen; Turrillas, Xavier; Alonso, Cruz; Campo, Javier

    2006-05-15

    Even though the electroosmotic flux through hardened cementitious materials during laboratory realkalisation trials had been previously noticed, it has never been in-situ monitored, analysing at the same time the establishment of the electroosmotic flux and the microstructure changes in the surroundings of the rebar. In this paper, two series of cement pastes, cast with CEM I and CEM I substituted in a 35% by fly ash, previously carbonated at 100% CO{sub 2}, were submitted to realkalisation treatments followed on line by simultaneous acquisition of neutron diffraction data. As a result, it has been possible to confirm the electroosmosis as the driving force of carbonates towards the rebar and to determine the range of pH in the anolyte in which most of the relevant electroosmotic phenomena takes place. On the other hand, the behaviour of the main crystalline phases involved in the process has been monitored during the treatment, with the precipitation of portlandite as main result.

  1. In-situ surface contamination removal and cool-down process of the DEAP-3600 experiment

    NASA Astrophysics Data System (ADS)

    Giampa, Pietro; DEAP Collaboration

    2016-05-01

    The DEAP-3600 experiment is a single-phase detector that uses 3600 Kg of liquid argon to search for Dark Matter at SNOLAB, Sudbury, Canada, 6800 ft. underground. The projected sensitivity to the spin-independent WIMP-nucleon cross-section is 10-46 cm2 for a WIMP mass of 100 GeV. A key experimental requirement is the reduction of any possible source of background that would mimic a Dark Matter signal This document will review how radiogenic surface backgrounds were reduced in-situ by removing 500 microns of acrylic from the innermost part of the detector with a resurfacing robot. Furthermore it will review the transient cool-down process of the experiment, necessary to reach cryogenic operating temperature.

  2. In situ observation of deformation processes in nanocrystalline face-centered cubic metals

    PubMed Central

    Kobler, Aaron; Brandl, Christian; Hahn, Horst

    2016-01-01

    Summary The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline PdxAu1− x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin–twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains. PMID:27335747

  3. Carbon isotope analysis; A new tool for monitoring and interpreting the in-situ combustion process

    SciTech Connect

    Hallam, R.J. ); Moore, R.G.; Krouse, H.R. ); Bennion, D.W. )

    1990-11-01

    This paper investigates the use of carbon isotope analysis for monitoring and interpreting responses from the in-situ combustion process. The major finding was that the type of reaction occurring at the combusting front can be distinguished by carbon isotope analyses. These reactions include the classic burning profile at the leading edge; super-wet or low-temperature combustion; a wide combustion zone with a secondary front, which is indicative of oxygen channeling; and carbonate decomposition in carbonate core material. This tool is valuable because, at times, making these interpretations without temperature data or from gas analyses alone is not possible. The study also demonstrated the feasibility of using carbon isotope data to track communication among injection and production wells.

  4. [In situ Raman spectroscopic observation of micro-processes of methane hydrate formation and dissociation].

    PubMed

    Liu, Chang-Ling; Ye, Yu-Guang; Meng, Qing-Guo; Lü, Wan-Jun; Wang, Fei-Fei

    2011-06-01

    Micro laser Raman spectroscopic technique was used for in situ observation of the micro-processes of methane hydrate formed and decomposed in a high pressure transparent capillary. The changes in clathrate structure of methane hydrate were investigated during these processes. The results show that, during hydrate formation, the Raman peak (2 917 cm(-1)) of methane gas gradually splits into two peaks (2 905 and 2 915 cm(-1)) representing large and small cages, respectively, suggesting that the dissolved methane molecules go into two different chemical environments. In the meantime, the hydrogen bonds interaction is strengthened because water is changing from liquid to solid state gradually. As a result, the O-H stretching vibrations of water shift to lower wavenumber. During the decomposition process of methane hydrates, the Raman peaks of the methane molecules both in the large and small cages gradually clear up, and finally turn into a single peak of methane gas. The experimental results show that laser Raman spectroscopy can accurately demonstrate some relevant information of hydrate crystal structure changes during the formation and dissociation processes of methane hydrate.

  5. Sustained release of risperidone from biodegradable microspheres prepared by in-situ suspension-evaporation process.

    PubMed

    An, Taekun; Choi, Juhyuen; Kim, Aram; Lee, Jin Ho; Nam, Yoonjin; Park, Junsung; Sun, Bo kyung; Suh, Hearan; Kim, Cherng-ju; Hwang, Sung-Joo

    2016-04-30

    Risperidone-loaded poly (D,L-lactide-co-glycolide) (PLGA) microspheres were prepared with a suspension-evaporation process with an aqueous suspension containing an in situ-formed aluminum hydroxide inorganic gel (SEP-AL process) and evaluated for encapsulation efficiency, particle size, surface morphology, glass transition temperature, in vitro drug release profile, and in vivo behavior. The SEP-AL microspheres were compared with conventional oil-in-water (O/W) emulsion solvent evaporation method using polyvinylalcohol (PVA) as an emulsifier (CP-PVA process). The microspheres were spherical in shape. DSC measurements showed that risperidone crystallinity was greatly reduced due to the homogeneous distribution of risperidone in PLGA microspheres. In vitro drug release profile from the microspheres showed a sigmoidal pattern of negligible initial burst up to 24h and minimal release (time-lag) for 7 days. After the lag phase, slow release took a place up to 25 days and then rapid release occurred sharply for 1 week. In vivo rat pharmacokinetic profile from the microspheres showed very low blood concentration level at the initial phase (up to 24h) followed by the latent phase up to 21 days. At the 3rd week, main phase started and the blood concentration of the drug increased up to the 5th week, and then gradually decreased. The risperidone-loaded PLGA microspheres produced by SEP-AL process showed excellent controlled release characteristics for the effective treatment of schizophrenia patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. In situ treatment of mixed contaminants in groundwater: Review of candidate processes

    SciTech Connect

    Korte, N.E.; Siegrist, R.L.; Ally, M.

    1994-10-01

    This document describes the screening and preliminary evaluation of candidate treatment for use in treating mixed contaminants volatile organic compounds (VOCs) and radionuclides in groundwater. Treating mixed contaminants presents unusual difficulties. Typically, VOCs are the most abundant contaminants, but the presence of radionuclides results in additional health concerns that must be addressed, usually by a treatment approach different from that used for VOCs. Furthermore, the presence of radionuclides may yield mixed solid wastes if the VOCs are treated by conventional means. These issues were specifically addressed in the evaluation of candidate treatment processes for testing in this program. Moreover, because no research or early development of a particular process would be performed, the technology review also focused on technologies that could be readily adapted and integrated for use with mixed contaminants. The objective is to couple emerging or available processes into treatment modules for use in situ. The three year project, to be completed in September 1996, includes a full-scale field demonstration. The findings reported in this document encompass all activities through the treatment process evaluations.

  7. Thermodynamic stability of transition metals on the Mg-terminated MgB2 (0001) surface and their effects on hydrogen dissociation and diffusion

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Michel, Kyle; Zhang, Yongsheng; Wolverton, C.

    2015-04-01

    The hydrogenation of MgB2 is a critical step in the reversibility of several well-known hydrogen storage reactions. Of the many processes that must occur during rehydrogenation, at least two of them take place near the surface: the dissociation of H2 molecules and the subsequent diffusion of atomic hydrogen. Using first-principles calculations, we determine the energetic barriers for these processes on the ideal Mg-terminated MgB2 (0001) surface, as well as on surfaces containing transition metal dopants (Sc-Zn, Y-Cd, Pt, and Au). The calculated dissociation barrier for H2 on the clean surface is 0.89 eV, and the surface diffusion barrier is 0.17 eV. However, we find examples of dopants that significantly decrease the activation barrier for the dissociation of H2 . Our calculations suggest that Ni, Cu, and Pd are good catalytic candidates for the surface processes involved in MgB2 rehydrogenation.

  8. Towards liquid-helium-free, persistent-mode MgB2 MRI magnets: FBML experience

    NASA Astrophysics Data System (ADS)

    Iwasa, Yukikazu

    2017-05-01

    In this article I present our experience at the Magnet Technology Division of the MIT Francis Bitter Magnet Laboratory on liquid-helium (LHe)-free, persistent-mode MgB2 MRI magnets. Before reporting on our MgB2 magnets, I first summarize the basic work that we began in the late 1990s to develop LHe-free, high-temperature superconductor (HTS) magnets cooled in solid cryogen—I begin by discussing the enabling feature, particularly of solid nitrogen (SN2), for adiabatic HTS magnets. The next topic is our first LHe-free, SN2-HTS magnet, for which we chose Bi2223 because in the late 1990s Bi2223 was the only HTS available to build an HTS magnet. I then move on to two MgB2 magnets, I and II, developed after discovery of MgB2 in 2000. The SN2-MgB2 Magnet II—0.5 T/240 mm, SN2-cooled, and operated in persistent mode—was completed in January 2016. The final major topic in this article is a tabletop LHe-free, persistent-mode 1.5 T/70 mm SN2-MgB2 ‘finger’ MRI magnet for osteoporosis screening—we expect to begin this project in 2017. Before concluding this article, I present my current view on challenges and prospects for MgB2 MRI magnets.

  9. Electron probe microanalysis of Mg-B compounds: stoichiometry and heterogeneity of superconductors

    NASA Astrophysics Data System (ADS)

    Wenzel, T.; Nickel, K. G.; Glaser, J.; Meyer, H.-J.; Eyidi, D.; Eibl, O.

    2003-08-01

    Electron probe microanalysis (EPMA) by wavelength-dispersive X-ray spectroscopy (WDX) was applied to determine the chemical composition of oxygen-bearing magnesium boride compounds. Extremely smooth samples, and the area-mode integration of measurement for the boron K peak are necessary to obtain precise results. An uncorrected analytical total near 100 wt% is a good quality control parameter. A careful sample preparation is necessary to avoid an artificial enrichment of oxygen. The analyzed samples were powders, ceramics, sheathed wires and tapes. MgB2, MgB4, MgB7 and MgB12 were identified as the relevant phases, confirming phase diagram studies. No other compounds (boric oxide, ternary Mg-B-oxides) are necessary to explain the data. Deviations from stoichiometry in Mg-B phase analysis are mainly caused by sample heterogeneities on a sub-m scale, the compounds were found to be largely stoichiometric. Bulk samples of superconducting MgB2 tapes and wires are highly heterogeneous and contain much more oxygen than our other samples. Besides MgB2 they consist of other magnesium borides and MgO with grain sizes from the nm-scale to several microns. Modeling the electron microprobe analyses provides evidence for the development of complex microstructures by oxidation reactions in addition to primary inhomogeneities within the starting material.

  10. Multiple Processes and Multiple Parameters: Applications of In Situ UV Spectroscopy for Aquatic Ecosystems

    NASA Astrophysics Data System (ADS)

    Cohen, M. J.; Hensley, R. T.; Reijo, C. J.; Heffernan, J. B.; Thomas, R. G.; Korhnak, L. V.

    2012-12-01

    Modern sensors afford new temporal and spatial scales of environmental measurements, providing novel insights into processes that govern earth surface and ecosystem dynamics. Recent advances from deploying in situ sensors include inference of reach-scale stoichiometric coupling (C:N:P) of whole-ecosystem metabolism, finely detailed resolution of the behavior of multiple solutes during storm events and snow-melt, and spatial and process disaggregation of nitrogen removal in rivers. These particular process inferences are predicated on in situ UV spectrometers that, to date, have been used principally to provide high quality temporally-dense measurements of nitrate. Here we focus on additional inferences, still largely exploratory, of ecosystem processes that are made possible in parallel with these same sensors. We focus on UV sensors capable of measuring absorbance from the entire UV spectrum at relatively high spectral resolution (ca. 1 nm), and we discuss three new applications. First, we explore the use of UV spectra for inferring information about the quality and quantity of dissolved organic matter. Diel and event driven variation in wavelength-specific absorbance and metrics like spectral slope in the 350-400 nm range (an indicator of aromaticity) illustrate that important inferences relevant to riverine organic matter cycling can be obtained during passive deployments. Second, we present preliminary data to support the use of these sensors for injected solute experiments. Since both nitrate and bromide absorb in the deep UV, these sensors can be used to estimate concentrations of both during co-injection dosing. We present protocols and data from two such deployments, one in a lotic system and another in a wetland where we use high-resolution time series of measured concentrations to draw inference about N retention kinetics. Finally, we present new data from two-station deployments to obtain spatially compact reach scale measurements of N retention

  11. Electrical resistivity, Debye temperature, and connectivity in heavily doped bulk MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Susner, M. A.; Bhatia, M.; Sumption, M. D.; Collings, E. W.

    2009-05-01

    The measured transport critical current densities, Jc, of MgB2 superconductors fall short of their intrinsic Jcs on account of the grain boundary blockage, sausaging, and porosity seen in most powder-processed wire samples. Hence, it becomes important to understand and to be able to measure the degree of what can be referred to as "connectivity" in order to be able to assess the highest attainable Jc in a given class of samples. In this paper connectivity is determined with the aid of normal state resistivity in an extension of the model originally proposed by Rowell. The normal-state resistivity temperature dependence is fitted to a standard Bloch-Grüneisen (B-G) equation in the range 50-300 K. Such an approach leads not only to a connectivity parameter but also to other useful data: the actual intragrain residual resistivity (indirectly related to the upper critical field) and a resistively determined Debye temperature, θR. The latter quantity, coupled to the transition temperature, Tc, provides a measure (by way of the McMillan formula) of the electron-phonon coupling constant, usually designated λ. The B-G-based connectivity model was applied to our own experimental data on binary and heavily doped MgB2 samples as well as published resistivity data. To complete the study, low temperature specific heat measurements, performed on binary and doped bulk samples provided calorimetrically determined Debye temperatures, θD, for comparison to the resistively determined values and excellent agreement was found. Calorimetric measurements also probed the homogeneity of the doped samples in terms of the roundness of the electronic specific heat jump near Tc.

  12. Shock wave consolidated MgB 2 bulk samples

    NASA Astrophysics Data System (ADS)

    Matsuzawa, Hidenori; Tamaki, Hideyuki; Ohashi, Wataru; Kakimoto, Etsuji; Dohke, Kiyotaka; Atou, Toshiyuki; Fukuoka, Kiyoto; Kikuchi, Masae; Kawasaki, Masashi; Takano, Yoshihiko

    2004-10-01

    Commercially available MgB 2 powders were consolidated into bulk samples by two different shock wave consolidation methods: underwater shock consolidation method and gun method. Resistance vs. temperature of the samples was measured by the four-terminal method for pulsed currents of up to 3 A in self-field, as well as Vickers hardness, SEM micrographs of fraction surfaces, packing densities, and X-ray diffraction patterns. These results, in comparison with cold isostatic pressed samples, indicated that the underwater shock consolidated sample was superior in grain connectivity to the others. This is probably because the underwater shock consolidation generated most anisotropic and hence high frictional, compressive, intergrain forces.

  13. Andreev reflections on a MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Aswal, D. K.; Sen, Shashwati; Gadkari, S. C.; Singh, Ajay; Gupta, S. K.; Gupta, L. C.; Bajpai, A.; Nigam, A. K.

    2002-07-01

    An Andreev-reflection study of MgB2/Ag planar junctions as a function of temperature and magnetic field is reported. The differential resistance (dV/dI) versus voltage (V) characteristics exhibited a distinct double minimum feature. This, together with a comparison of Blonder-Tinkham-Klapwijk theory of isotropic superconductor, indicates that data are not consistent with the weak-coupling BCS theory. This is further supported by unusual temperature and magnetic-field dependence of the tunneling characteristics. The results are discussed using various existing theories.

  14. A 0.6 T/650 mm RT Bore Solid Nitrogen Cooled MgB2 Demonstration Coil for MRI-a Status Report.

    PubMed

    Bascuñán, Juan; Lee, Haigunan; Bobrov, Emmanuel S; Hahn, Seungyong; Iwasa, Yukikazu; Tomsic, Mike; Rindfleisch, Matt

    2006-06-01

    Aiming to demonstrate feasibility and practicality of a low cost superconducting MRI magnet system targeted for use in small hospitals, rural communities and underdeveloped countries, MIT-Francis Bitter Magnet Laboratory has developed a 0.6 T/650 mm room temperature bore demonstration coil wound with multifilament MgB2 conductor and cooled via an innovative cryogenic design/operation. The coil is to be maintained cold by solid nitrogen kept in the solid state by a cryocooler. In the event of a power failure the cryocooler is automatically thermally decoupled from the system. In this paper we present details of the MgB2 conductor, winding process, and preliminary theoretical analysis of the current-carrying performance of the conductively cooled coils in zero background field and over the 10-30 K temperature range.

  15. A 0.6 T/650 mm RT Bore Solid Nitrogen Cooled MgB2 Demonstration Coil for MRI—a Status Report

    PubMed Central

    Bascuñán, Juan; Lee, Haigunan; Bobrov, Emmanuel S.; Hahn, Seungyong; Iwasa, Yukikazu; Tomsic, Mike; Rindfleisch, Matt

    2014-01-01

    Aiming to demonstrate feasibility and practicality of a low cost superconducting MRI magnet system targeted for use in small hospitals, rural communities and underdeveloped countries, MIT-Francis Bitter Magnet Laboratory has developed a 0.6 T/650 mm room temperature bore demonstration coil wound with multifilament MgB2 conductor and cooled via an innovative cryogenic design/operation. The coil is to be maintained cold by solid nitrogen kept in the solid state by a cryocooler. In the event of a power failure the cryocooler is automatically thermally decoupled from the system. In this paper we present details of the MgB2 conductor, winding process, and preliminary theoretical analysis of the current-carrying performance of the conductively cooled coils in zero background field and over the 10–30 K temperature range. PMID:25580068

  16. Bacterial-fungal interactions enhance power generation in microbial fuel cells and drive dye decolourisation by an ex situ and in situ electro-Fenton process.

    PubMed

    Fernández de Dios, María Ángeles; del Campo, Araceli González; Fernández, Francisco Jesús; Rodrigo, Manuel; Pazos, Marta; Sanromán, María Ángeles

    2013-11-01

    In this work, the potential for sustainable energy production from wastes has been exploited using a combination fungus-bacterium in microbial fuel cell (MFC) and electro-Fenton technology. The fungus Trametes versicolor was grown with Shewanella oneidensis so that the bacterium would use the networks of the fungus to transport the electrons to the anode. This system generated stable electricity that was enhanced when the electro-Fenton reactions occurred in the cathode chamber. This configuration reached a stable voltage of approximately 1000 mV. Thus, the dual benefits of the in situ-designed MFC electro-Fenton, the simultaneous dye decolourisation and the electricity generation, were demonstrated. Moreover, the generated power was effectively used to drive an ex situ electro-Fenton process in batch and continuous mode. This newly developed MFC fungus-bacterium with an in situ electro-Fenton system can ensure a high power output and a continuous degradation of organic pollutants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2005-02-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this fifth quarterly report of our DoE funded research, we continue the discussion of the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. We have now developed an appropriate upscaling technique for our grids, based on the local-global upscaling approach. We show preliminary results on two-dimensional test cases. On the experimental side, we continued experiments to measure the rates and kinetics of combustion in the presence and absence of metallic additives. In this quarter, we developed a better understanding of the cation replacing power of the various additives that affect combustion performance positively, and obtained a preliminary reactivity series. We also resumed our experimental investigation into the cyclic solvent-combustion process using crude oil from the Hamaca Region of Venezuela. Various measurements were made including oxygen consumption as a function of temperature. Preliminary results show that the temperatures for the onset of combustion are a function of the solvent injected.

  18. In-situ measurements of bottom boundary layer processes in the deep South China Sea

    NASA Astrophysics Data System (ADS)

    Xu, J.; Li, J.; Zhang, Y.; Zhao, Y.; Liu, Z.; Ferreira, J. C. T.; Tate, G.

    2014-12-01

    As part of the South China Sea Deep project, we deployed a free-ascending tripod (FAT) on the sea floor of northern South China Sea at a water depth of 1900 m. During the 5-month deployment, the tripod hosted a suite of acoustic and optical oceanographic instruments that simultaneously measured time-series of 3-D velocity structure of the near bottom flows, temperature and salinity, water turbidity (sediment concentration), and particle size variations. A camera system and an acoustic altimeter closely monitored fine scale changes of the sea floor that could have resulted from either physical processes (erosion/deposition) or biological activities. Our goal of the tripod work, first-ever such study in South China Sea, along with several subsurface moorings that were also collecting flow and sedimentological data in the area, was to investigate the bottom boundary layer (BBL) processes and the regional deep current circulation surrounding a large body of sediment deposit whose formation mechanism and origins of sediment are still unclear. In addition, the tripod instruments were set up to capture the in-situ BBL signature of passing "benthic storms" that are believed to be the most important BBL processes in deep ocean. This presentation also includes a brief description of the technological advances implemented in the FAT deep-water tripod.

  19. Significant enhancement of the in-field critical current density of the MgB2 superconductor through codoping of nano-TiC with nano-SiC

    NASA Astrophysics Data System (ADS)

    Vinod, K.; Varghese, Neson; Roy, S. B.; Syamaprasad, U.

    2009-05-01

    Nanoparticles of two carbides, SiC and TiC, having different reactivities with the Mg/B are doped into the MgB2 system. These carbides are added in mono-and codoping conditions through the in situ solid state reaction, and the structural and superconducting properties are studied. The results show distinct modifications in the structural and superconducting properties by the two dopants. SiC causes considerable C substitution at the B site and the formation of intragrain inclusions, whereas TiC remains unreacted and does not cause any substitution. The codoped samples show significantly enhanced JC(H) performance compared to the undoped and monodoped samples. Compared to the undoped sample, the enhancement of JC is more than two orders of magnitude at 15 K for fields >7 T for the best sample. The results of JC(H) performance of the samples are discussed.

  20. The role of thermal analysis techniques in the in-situ combustion process

    SciTech Connect

    Jka, K.N.; Verkoczy, B.

    1984-04-01

    Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies were conducted on two Lloydminster heavy oil cores, extracted oil and mineral matter. The order of reaction was adjusted to best fit the data in nonisothermal kinetic analysis. The values of the order of reaction used and estimated activation energies, preexponential factors and rate constants for overall reactions occurring in appropriate temperature regimes are listed. A general schematic of the thermal processes, such as evaporation, distillation, thermolysis, low temperature oxidation, thermal cracking, combustion, coking, polymerization and thermal alteration of mineral matter, is depicted. The fuel contents in the core samples were determined from the TGA weight loss curves. The data generated by DSC and TGA experiments were used to calculate enthalpy values and ignition temperatures. Data suggests that heat generated by LTO reactions is significant during in situ combustion. Thermal alteration of the mineral matter at 600/sup 0/ and 900/sup 0/C was significant. The percentage of fine particles, <2..mu.., doubled at 600/sup 0/ and 900/sup 0/C compared to the mineral extracted at 100/sup 0/C. Although kaolinite constituted 65% of the fine particles in the extracted sand, it was not detected when the sand was heated at 600/sup 0/ or 900/sup 0/C. These results indicate potential production problems resulting from the migration of fine particles. The data obtained from the two reservoirs studied suggest that swelling of clays during wet combustion may not be sufficient to have a deleterious effect on air/water injectivity. It is apparent that the results generated by TGA/DSC experiments are complementary to those obtained by combustion tube tests and provide the kinetic, thermal and mineralogical data required for numerical simulation, planning and design of an in situ combustion project.

  1. Low-temperature Mechanical Properties of Bulk MgB2 Fabricated by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Murakami, A.; Teshima, H.; Naito, T.; Fujishiro, H.; Kudo, T.; Iwamoto, A.

    Mechanical properties ina MgB2superconducting bulk sample,whose packing ratio is 92%,fabricated by hot isostatic pressing (HIP)areevaluated at 77 K through bending tests.The fracture strength at 77 K is higher than at room temperature. From the bending test result at 77 K, the fracture strength of ideal bulk MgB2,whose packing ratio is 100%,is estimated. The fracture strength at very low temperature of the HIP bulk MgB2is also estimated from the bending test results at 77 K and room temperature.

  2. Preparation of variable-thickness MgB 2 thin film bridges by AFM nanolithography

    NASA Astrophysics Data System (ADS)

    Gregor, M.; Plecenik, A.; Plecenik, T.; Tomasek, M.; Kus, P.; Micunek, R.; Stefecka, M.; Zahoran, M.; Grancic, B.; Kubinec, M.; Gasparik, V.

    2006-03-01

    In this paper we focus our attention on preparation of superconducting MgB2 thin films and variable-thickness MgB2 thin film bridges using the Atomic Force Microscope nanolithographic technique. Microstructures and their following variable-thickness bridges were prepared on nonsuperconducting MgB thin films. Final structures were annealed in argon atmosphere at temperature 680 °C and exhibit transition to the superconducting state Tcon = 33 K and zero critical temperature Tc0 = 30.5 K. Critical current density jc (4.2 K) measured on the bridge was higher than 106 A/cm2.

  3. Phase transitions in a MgB2 granular BCS superconductor in weak magnetic fields

    NASA Astrophysics Data System (ADS)

    Derevyanko, V. V.; Sungurov, M. S.; Sukhareva, T. V.; Finkel', V. A.; Shakhov, Yu. N.

    2017-02-01

    The character of temperature dependences of the electric conductivity of MgB2 granular BCS superconductors at temperatures of 35-45 K in external magnetic fields H ext of up to 2 kOe is studied. An increase in the superconducting transition width Δ T c with an increase in Hext is found. The presence of a system of weak links in MgB2-based granular superconductors is established. On the basis of experimental data, MgB2 granular superconductor is assigned to two-level superconducting systems and the H-T phase diagram is constructed.

  4. Study of Sn removal processes for in-situ collector cleaning

    NASA Astrophysics Data System (ADS)

    Elg, Daniel T.; Panici, Gianluca A.; Srivastava, Shailendra N.; Ruzic, D. N.

    2016-03-01

    An in-situ hydrogen plasma cleaning technique to clean Sn off of EUV collector optics is studied in detail. The cleaning process uses hydrogen radicals (formed in the hydrogen plasma) to interact with Sn-coated surfaces, forming SnH4 and being pumped away. This technique has been used to clean a 300mm-diameter stainless steel dummy collector optic, and EUV reflectivity of multilayer mirror samples was restored after cleaning Sn from them, validating the potential of this technology. This method has the potential to significantly reduce downtime and increase source availability. However, net Sn removal is limited by decomposition of the SnH4 molecule upon impact with the collector and the resulting redeposition of Sn. This is true in all cleaning systems that make use of hydrogen radicals. Thus, to guide the design of effective cleaning systems, the transport of Sn in the chamber, and the fundamental processes affecting it, must be understood. Accordingly, an investigation into these processes Sn removal is being performed. These processes include the advection of gas through the chamber, the creation of hydrogen radicals, the etching of Sn by radicals, and the surface decomposition of SnH4. In this paper, experiments to determine the radical density are presented, along with a theoretical plasma chemistry model that explains the processes behind radical creation and validates the radical density measurements. Additionally, experiments are shown that provide an insight into the etching of Sn by hydrogen radicals, yielding calculations of etching probability as well as showing that Sn etching is very sensitive to oxygen contamination and surface morphology.

  5. In-situ monitoring of plasma ion assisted deposition (PIAD) processes

    NASA Astrophysics Data System (ADS)

    Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef

    2015-09-01

    Present photonics applications depend on accurate production techniques. Plasma based processes might be termed the backbone of multilayer optical coatings which are the key components of dielectric mirrors, filters or antireflectives. However, the sector strongly relies on process recipies based on empirical optimization of thin film properties. Limitations in quality, repeatability and yield are faced. In this contribution results of efforts on plasma characterization of a beam source employed for PIAD are presented. Data on electron and ion kinetics as well as optical emission facilitated a comprehensive understanding of underlying physics of ion beam generation and propagation in an industrial type batch coater. In order to promote the development of next generation production plants, concepts for in-situ diagnostics are investigated. Results from monitoring of optical radiance of the plasma plume near the source and electron density near the substrates are discussed. The novel concept of the multipole resonance probe is applied during deposition in order to trace variations not only in magnitude of plasma density, but also its spatial distribution. Coating materials comprise TiO2, Ta2O5, Al2O3 and SiO2. Funded by the German Federal Ministry of Education and Research (BMBF) under Grant 13N13213).

  6. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    NASA Astrophysics Data System (ADS)

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Strittmatter, André; Rodt, Sven; Reitzenstein, Stephan

    2015-07-01

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  7. Aquifer restoration at in-situ leach uranium mines: evidence for natural restoration processes

    SciTech Connect

    Deutsch, W.J.; Serne, R.J.; Bell, N.E.; Martin, W.J.

    1983-04-01

    Pacific Northwest Laboratory conducted experiments with aquifer sediments and leaching solution (lixiviant) from an in-situ leach uranium mine. The data from these laboratory experiments and information on the normal distribution of elements associated with roll-front uranium deposits provide evidence that natural processes can enhance restoration of aquifers affected by leach mining. Our experiments show that the concentration of uranium (U) in solution can decrease at least an order of magnitude (from 50 to less than 5 ppM U) due to reactions between the lixiviant and sediment, and that a uranium solid, possibly amorphous uranium dioxide, (UO/sub 2/), can limit the concentration of uranium in a solution in contact with reduced sediment. The concentrations of As, Se, and Mo in an oxidizing lixiviant should also decrease as a result of redox and precipitation reactions between the solution and sediment. The lixiviant concentrations of major anions (chloride and sulfate) other than carbonate were not affected by short-term (less than one week) contact with the aquifer sediments. This is also true of the total dissolved solids level of the solution. Consequently, we recommend that these solution parameters be used as indicators of an excursion of leaching solution from the leach field. Our experiments have shown that natural aquifer processes can affect the solution concentration of certain constituents. This effect should be considered when guidelines for aquifer restoration are established.

  8. In situ quantitative analysis of etching process of human teeth by atomic force microscopy.

    PubMed

    Watari, Fumio

    2005-06-01

    Etching is one of the most fundamental steps in the restoration of teeth by adhesion of composite resin in dental clinics. Atomic force microscope (AFM) was used for the in situ observation of the etching process of human enamel, dentin and synthetic hydroxyapatite in the three different acid agents, 2% phosphoric acid, 10% citric acid and 10% polyacrylic acid. To measure the absolute depth from the initial level before etching and to correlate the surface height between the changing AFM images obtained, the depth profiles were recorded with etching time by carrying out the line scan consecutively at the representative place of the observed area. These chronological series of depth profiles enabled us to perform quantitative analysis of etched amount in addition to the surface roughness obtained from relative depth profile within one image. The course of etching process from the dissolution of smear layer, appearance of enamel prizms or dentinal tubules to progress of demineralization could clearly be observed. The depth profile, surface roughness, etching amount, etching rate and smear layer thickness could then be evaluated. The different etching characteristics of three acid agents and the effect of surface roughness produced by different mechanical prepolish were compared and discussed.

  9. Subglacial processes recorded by in situ wireless probes: stick-slip motion and till deposition

    NASA Astrophysics Data System (ADS)

    Hart, J. K.; Martinez, K.

    2016-12-01

    We investigate the subglacial behaviour of a glacier resting on a deformable bed with a `fast' transfer rate through the ice, using the unique Glacsweb wireless in situ probes, embedded in both the ice and till. This glacier responds immediately to changes in surface meltwater inputs, with a secondary slower englacial pathway with a five lag. In summer the subglacial hydrology is in semi-equilibrium and most meltwater fluctuations are absorbed by the system. However, whenever meltwater inputs exceed the subglacial hydrological systems ability to cope (a few days in summer, but all the time in winter) a distinct pattern of stick-slip motion occurs. Melt events cause basal sliding, leading to antithetic (backwards) tilt, water pressure decreases and dilatant strengthening, followed by a slow water pressure rise and strain softening, until the next cycle begins. We show the bed is a patchwork of different strengths, indicate their scale and describe any temporal changes. We reveal the behaviour of the till, showing that deformation occurs all year, with a combination of lodging and till flowing around obstacles, stable `islands' of high pressures with constant depositional processes, and variable water pressures leading to a more complex sedimentary patterns. These processes combine together to produce a deformation till.

  10. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    SciTech Connect

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Rodt, Sven Reitzenstein, Stephan; Strittmatter, André

    2015-07-15

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  11. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    PubMed

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil.

  12. Investigation of the Geokinetics horizontal in situ oil shale retorting process. Seventh annual report, 1983

    SciTech Connect

    Henderson, K.B.

    1984-08-01

    In the Geokinetics process, a pattern of blast holes is drilled from the surface, through the overburden, and into the oil shale bed. The holes are loaded with explosives and fired using a carefully planned blast system. The blast produces a fragmented mass of oil shale with high permeability. The fragmented zone constitutes an in situ retort. The project site is in the Mahogany Zone oil shale in Utah. During 1983 significant milestones were achieved. The burn of Retort No. 26 was completed on February 22, 1983, having produced 22,889 barrels of oil. By the end of July, 1983, all preparations were complete for the ignition of Retort No. 27. However, ignition was delayed until August 11, 1983, pending completion of the retort off gas processing facility. By early October, final preparations for the ignition of Retort No. 28 were completed and the retort was ignited on October 18, 1983. A facility to remove ammonia and hydrogen sulfide contaminants from Retorts No. 27 and No. 28 off gas was constructed at the site. Numerous environmental tests and experiments were conducted, primarily to gather data for permitting purposes. A pond to hold water produced by Retorts No. 27 and No. 28 was completed during August, 1983. The pond was put into service at the same time as the ignition of Retort No. 27.

  13. A new application of passive samplers as indicators of in-situ biodegradation processes.

    PubMed

    Belles, Angel; Alary, Claire; Criquet, Justine; Billon, Gabriel

    2016-12-01

    In this paper, a method for evaluating the in-situ degradation of nitro polycyclic aromatic hydrocarbons (nitro-PAH) in sediments is presented. The methodology is adapted from the passive sampler technique, which commonly uses the dissipation rate of labeled compounds loaded in passive sampler devices to sense the environmental conditions of exposure. In the present study, polymeric passive samplers (made of polyethylene strips) loaded with a set of labeled polycyclic aromatic hydrocarbons (PAH) and nitro-PAH were immersed in sediments (in field and laboratory conditions) to track the degradation processes. This approach is theoretically based on the fact that a degradation process induces a steeper concentration gradient of the labeled compounds in the surrounding sediment, thereby increasing their compound dissipation rates compared with their dissipation in abiotic conditions. Postulating that the degradation magnitude is the same for the labeled compounds loaded in polyethylene strips and for their native homologs that are potentially present in the sediment, the field degradation of 3 nitro-PAH (2-nitro-fluorene, 1-nitro-pyrene, 6-nitro-chrysene) was semi-quantitatively analyzed using the developed method.

  14. Characterization of MgB2 Superconducting Hot Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Cunnane, D.; Kawamura, J. H.; Wolak, M. A.; Acharya, N.; Tan, T.; Xi, X. X.; Karasik, B. S.

    2014-01-01

    Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at the Terahertz frequencies. However, the current state of the art NbN mixers suffer from a small intermediate frequency (IF) bandwidth as well as a low operating temperature. MgB2 is a promising material for HEB mixer technology in view of its high critical temperature and fast thermal relaxation allowing for a large IF bandwidth. In this work, we have fabricated and characterized thin-film (approximately 15 nanometers) MgB2-based spiral antenna-coupled HEB mixers on SiC substrate. We achieved the IF bandwidth greater than 8 gigahertz at 25 degrees Kelvin and the device noise temperature less than 4000 degrees Kelvin at 9 degrees Kelvin using a 600 gigahertz source. Using temperature dependencies of the radiation power dissipated in the device we have identified the optical loss in the integrated microantenna responsible as a cause of the limited sensitivity of the current mixer devices. From the analysis of the current-voltage (IV) characteristics, we have derived the effective thermal conductance of the mixer device and estimated the required local oscillator power in an optimized device to be approximately 1 microwatts.

  15. Low-noise THz MgB2 Josephson mixer

    NASA Astrophysics Data System (ADS)

    Cunnane, Daniel; Kawamura, Jonathan H.; Acharya, Narendra; Wolak, Matthäus A.; Xi, X. X.; Karasik, Boris S.

    2016-09-01

    The potential applications for high frequency operation of the Josephson effect in MgB2 include THz mixers, direct detectors, and digital circuits. Here we report on MgB2 weak links which exhibit the Josephson behavior up to almost 2 THz and using them for low-noise heterodyne detection of THz radiation. The devices are made from epitaxial film grown in the c-axis direction by the hybrid physical-chemical vapor deposition method. The current in the junctions travels parallel to the surface of the film, thus making possible a large contribution of the quasi-two-dimensional σ-gap in transport across the weak link. These devices are connected to a planar spiral antenna with a dielectric substrate lens to facilitate coupling to free-space radiation for use as a detector. The IcRn product of the junction is 5.25 mV, giving confirmation of a large gap parameter. The sensitivity of the mixer was measured from 0.6 THz to 1.9 THz. At a bath temperature of over 20 K, a mixer noise temperature less than 2000 K (DSB) was measured near 0.6 THz.

  16. Compressibility of the MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Prassides, K.; Iwasa, Y.; Ito, T.; Chi, Dam H.; Uehara, K.; Nishibori, E.; Takata, M.; Sakata, M.; Ohishi, Y.; Shimomura, O.; Muranaka, T.; Akimitsu, J.

    2001-07-01

    Considerable excitement has been caused recently by the discovery that the binary-boride system with stoichiometry MgB2 is superconducting at the remarkably high temperature of 39 K [J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, and J. Akimitsu, Nature 410, 63 (2001)]. This potentially opens the way to even higher-Tc values in a new family of superconductors with unexpectedly simple composition and structure. The simplicity in the electronic and crystal structures could allow the understanding of the physics of high-Tc superconductivity without the presence of the multitude of complicated features, associated with the cuprates. Synchrotron x-ray diffraction was used to measure the isothermal compressibility of MgB2, revealing a stiff tightly packed incompressible solid with only moderate bonding anisotropy between intralayer and interlayer directions. These results, combined with the pressure evolution of the superconducting transition temperature, Tc, establish its relation to the B and Mg bonding distances over a broad range of values.

  17. Characterization of MgB2 Superconducting Hot Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Cunnane, D.; Kawamura, J. H.; Wolak, M. A.; Acharya, N.; Tan, T.; Xi, X. X.; Karasik, B. S.

    2014-01-01

    Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at the Terahertz frequencies. However, the current state of the art NbN mixers suffer from a small intermediate frequency (IF) bandwidth as well as a low operating temperature. MgB2 is a promising material for HEB mixer technology in view of its high critical temperature and fast thermal relaxation allowing for a large IF bandwidth. In this work, we have fabricated and characterized thin-film (approximately 15 nanometers) MgB2-based spiral antenna-coupled HEB mixers on SiC substrate. We achieved the IF bandwidth greater than 8 gigahertz at 25 degrees Kelvin and the device noise temperature less than 4000 degrees Kelvin at 9 degrees Kelvin using a 600 gigahertz source. Using temperature dependencies of the radiation power dissipated in the device we have identified the optical loss in the integrated microantenna responsible as a cause of the limited sensitivity of the current mixer devices. From the analysis of the current-voltage (IV) characteristics, we have derived the effective thermal conductance of the mixer device and estimated the required local oscillator power in an optimized device to be approximately 1 microwatts.

  18. Production and Characterization of Bulk MgB2 Material made by the Combination of Crystalline and Carbon Coated Amorphous Boron Powders

    NASA Astrophysics Data System (ADS)

    Hiroki, K.; Muralidhar, M.; Koblischka, M. R.; Murakami, M.

    2017-07-01

    The object of this investigation is to reduce the cost of bulk production and in the same time to increase the critical current performance of bulk MgB2 material. High-purity commercial powders of Mg metal (99.9% purity) and two types of crystalline (99% purity) and 16.5 wt% carbon-coated, nanometer-sized amorphous boron powders (98.5% purity) were mixed in a nominal composition of MgB2 to reduce the boron cost and to see the effect on the superconducting and magnetic properties. Several samples were produced mixing the crystalline boron and carbon-coated, nanometer-sized amorphous boron powders in varying ratios (50:50, 60:40, 70:30, 80:20, 90:10) and synthesized using a single-step process using the solid state reaction around 800 °C for 3 h in pure argon atmosphere. The magnetization measurements exhibited a sharp superconducting transition temperature with T c, onset around 38.6 K to 37.2 K for the bulk samples prepared utilizing the mixture of crystalline boron and 16.5% carbon-coated amorphous boron. The critical current density at higher magnetic field was improved with addition of carbon-coated boron to crystalline boron in a ratio of 80:20. The highest self-field Jc around 215,000 A/cm2 and 37,000 A/cm2 were recorded at 20 K, self-field and 2 T for the sample with a ratio of 80:10. The present results clearly demonstrate that the bulk MgB2 performance can be improved by adding carbon-coated nano boron to crystalline boron, which will be attractive to reduce the cost of bulk MgB2 material for several industrial applications.

  19. Critical current densities and n-values of MgB2 strands over a wide range of temperatures and fields

    NASA Astrophysics Data System (ADS)

    Li, G. Z.; Yang, Y.; Susner, M. A.; Sumption, M. D.; Collings, E. W.

    2012-02-01

    Transport measurements of critical current density, Jct, in monocore powder-in-tube MgB2 strands have been carried out at temperatures, T, of from 4.2 to 40 K, and in transverse fields, B, of up to 14 T. Processing methods used were conventional continuous tube forming/filling (CTFF) and internal magnesium diffusion (IMD). Strands with several powder compositions were measured, including binary (undoped) MgB2, 2% carbon doped MgB2, and 3% carbon doped MgB2. Magnetization loops (M-B) were also measured, and magnetic critical current density, Jcm, values extracted from them. The transport, Jct(B) and magnetic, Jcm(B), critical current densities were compared. Also studied was the influence of doping on the resistively measured irreversibility field, Birr, and upper critical field, Bc2. Critical current densities, Jct, and n-values were extracted from transport measurements and were found to be universally related (for all B and T) according to n\\propto {J}_{{ct}}^{m} in which m = 0.52 ± 0.11. Likewise n was found to be related to B according to n ∝ B-p with a T-dependent p in the range of about 0.08-0.21. Further analysis of the field (B) and temperature (T) dependences of n-value resulted in an expression that enabled n(B,T), for all B and T, to be estimated for a given strand based on the results of transport Jct(B) measurements made at one arbitrarily chosen temperature.

  20. Cyanobacteria to Link Closed Ecological Systems and In-Situ Resources Utilization Processes

    NASA Astrophysics Data System (ADS)

    Brown, Igor

    Introduction: A major goal for the Vision of Space Exploration is to extend human presence across the solar sys-tem. With current technology, however, all required consumables for these missions (propellant, air, food, water) as well as habitable volume and shielding to support human explorers will need to be brought from Earth. In-situ pro-duction of consumables (In-Situ Resource Utilization-ISRU) will significantly facilitate current plans for human ex-ploration and colonization of the solar system, especially by reducing the logistical overhead such as recurring launch mass. The production of oxygen from lunar materials is generally recognized as the highest priority process for lunar ISRU, for both human metabolic and fuel oxidation needs. The most challenging technology developments for future lunar settlements may lie in the extraction of elements (O, Fe, Mn, Ti, Si, etc) from local rocks and soils for life support, industrial feedstock and the production of propellants. With few exceptions (e.g., Johannson, 1992), nearly all technology development to date has employed an ap-proach based on inorganic chemistry (e.g. Allen et al., 1996). None of these technologies include concepts for inte-grating the ISRU system with a bioregenerative life support system and a food production systems. Bioregenerative life support efforts have recently been added to the Constellation ISRU development program (Sanders et al, 2007). Methods and Concerns: The European Micro-Ecological Life Support System Alternative (MELiSSA) is an ad-vanced concept for organizing a bioregenerative system for long term space flights and extraterrestrial settlements (Hendrickx, De Wever et al., 2005). However the MELiSSA system is a net consumer of ISRU products without a net return to in-situ technologies, e.g.. to extract elements as a result of complete closure of MELiSSA. On the other hand, the physical-chemical processes for ISRU are typically massive (relative to the rate of oxygen

  1. Sensor-model prediction, monitoring and in-situ control of liquid RTM advanced fiber architecture composite processing

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D.; Kingsley, P.; Hart, S.; Loos, A.; Hasko, G.; Dexter, B.

    1992-01-01

    In-situ frequency dependent electromagnetic sensors (FDEMS) and the Loos resin transfer model have been used to select and control the processing properties of an epoxy resin during liquid pressure RTM impregnation and cure. Once correlated with viscosity and degree of cure the FDEMS sensor monitors and the RTM processing model predicts the reaction advancement of the resin, viscosity and the impregnation of the fabric. This provides a direct means for predicting, monitoring, and controlling the liquid RTM process in-situ in the mold throughout the fabrication process and the effects of time, temperature, vacuum and pressure. Most importantly, the FDEMS-sensor model system has been developed to make intelligent decisions, thereby automating the liquid RTM process and removing the need for operator direction.

  2. Magnetic field dependent stability and quench behavior and degradation limits in conduction-cooled MgB2 wires and coils

    NASA Astrophysics Data System (ADS)

    Ye, Liyang; Cruciani, Davide; Xu, Minfeng; Mine, Susumu; Amm, Kathleen; Schwartz, Justin

    2015-03-01

    Long lengths of metal/MgB2 composite conductors with high critical current density (Jc), fabricated by the powder-in-tube process, have recently become commercially available. Owing to its electromagnetic performance in the 20-30 K range and relatively low cost, MgB2 may be attractive for a variety of applications. One of the key issues for magnet design is stability and quench protection, so the behavior of MgB2 wires and magnets must be understood before large systems can emerge. In this work, the stability and quench behavior of several conduction-cooled MgB2 wires are studied. Measurements of the minimum quench energy and normal zone propagation velocity are performed on short samples in a background magnetic field up to 3 T and on coils in self-field and the results are explained in terms of variations in the conductor architecture, electrical transport behavior, operating conditions (transport current and background magnetic field) and experimental setup (short sample versus small coil). Furthermore, one coil is quenched repeatedly with increasing hotspot temperature until Jc is decreased. It is found that degradation during quenching correlates directly with temperature and not with peak voltage; a safe operating temperature limit of 260 K at the surface is identified.

  3. Magnetic field dependent stability and quench behavior and degradation limits in conduction-cooled MgB2 wires and coils.

    PubMed

    Ye, Liyang; Cruciani, Davide; Xu, Minfeng; Mine, Susumu; Amm, Kathleen; Schwartz, Justin

    2015-03-01

    Long lengths of metal/MgB2 composite conductors with high critical current density (Jc), fabricated by the power-in-tube (PIT) process, have recently become commercially available. Owing to its electromagnetic performance in the 20 K - 30 K range and relatively low cost, MgB2 may be attractive for a variety of applications. One of the key issues for magnet design is stability and quench protection, so the behavior of MgB2 wires and magnets must be understood before large systems can emerge. In this work, the stability and quench behavior of several conduction-cooled MgB2 wires are studied. Measurements of the minimum quench energy and normal zone propagation velocity are performed on short samples in a background magnetic field up to 3 T and on coils in self-field and the results are explained in terms of variations in the conductor architecture, electrical transport behavior, operating conditions (transport current and background magnetic field) and experimental setup (short sample vs small coil). Furthermore, one coil is quenched repeatedly with increasing hot-spot temperature until Jc is decreased. It is found that degradation during quenching correlates directly with temperature and not with peak voltage; a safe operating temperature limit of 260 K at the surface is identified.

  4. Magnetic field dependent stability and quench behavior and degradation limits in conduction-cooled MgB2 wires and coils

    PubMed Central

    Ye, Liyang; Cruciani, Davide; Xu, Minfeng; Mine, Susumu; Amm, Kathleen; Schwartz, Justin

    2015-01-01

    Long lengths of metal/MgB2 composite conductors with high critical current density (Jc), fabricated by the power-in-tube (PIT) process, have recently become commercially available. Owing to its electromagnetic performance in the 20 K – 30 K range and relatively low cost, MgB2 may be attractive for a variety of applications. One of the key issues for magnet design is stability and quench protection, so the behavior of MgB2 wires and magnets must be understood before large systems can emerge. In this work, the stability and quench behavior of several conduction-cooled MgB2 wires are studied. Measurements of the minimum quench energy and normal zone propagation velocity are performed on short samples in a background magnetic field up to 3 T and on coils in self-field and the results are explained in terms of variations in the conductor architecture, electrical transport behavior, operating conditions (transport current and background magnetic field) and experimental setup (short sample vs small coil). Furthermore, one coil is quenched repeatedly with increasing hot-spot temperature until Jc is decreased. It is found that degradation during quenching correlates directly with temperature and not with peak voltage; a safe operating temperature limit of 260 K at the surface is identified. PMID:25883414

  5. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD.

  6. Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

    DOEpatents

    Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

    2016-03-01

    A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

  7. Superior homogeneity of trapped magnetic field in superconducting MgB2 bulk magnets

    NASA Astrophysics Data System (ADS)

    Ishihara, A.; Akasaka, T.; Tomita, M.; Kishio, K.

    2017-03-01

    Homogeneity of trapped magnetic field in radial and circumferential directions of high temperature superconducting bulk magnets, MgB2 (T c ˜38.3 K) and YBa2Cu3O y (T c ˜91.5 K), have been measured. In polycrystalline MgB2 bulks, the circularity of trapped magnetic field in a cylindrical disk is over 97% at 20-32.5 K, while that of YBa2Cu3O y was ˜87% at 77 K. Magnetic field distribution of MgB2 bulk was satisfactorily homogeneous and these measurements suggest MgB2 bulks with highly efficient cryocoolers should be very useful for novel high field permanent magnet applications.

  8. Properties of MgB2 wires made by internal magnesium diffusion into different boron powders

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Rosova, A.; Kulich, M.; Melišek, T.; Kopera, L.; Brunner, B.

    2015-09-01

    Different boron powders were used for MgB2 wires manufactured by internal magnesium diffusion. The structure of the MgB2 core, critical temperature and critical currents of Cu/Ti sheathed wires differing only in boron powder were analyzed and compared. It was found that the particle size and purity of boron powders influence the creation of the MgB2 phase and, consequently, also considerably influence its superconducting properties. The highest critical current density in the low external field was measured for wire with a boron purity of 98.5% produced by Pavezyum. It was used also for stabilized multi-core MgB2 wire with high engineering current densities in low magnetic fields at 20 K, which may be attractive for some low field applications, e.g. high-power wind generators.

  9. Characterization of phase evolution in YBCO coated conductors produced by the ex situ BaF{sub 2} process.

    SciTech Connect

    Feenstra, R.; List, F. A.; Zhang, Y.; Christen, D. K.; Maroni, V. A.; Miller, D. J.; Feldmann, D. M.; ORNL; Univ. of Wisconsin

    2007-06-01

    Raman microprobe spectroscopy and scanning electron microscopy were used to study the initial nucleation and growth of YBCO in thick precursors by the BaF2 ex situ process. For quenched films of 2 mum thickness, the data indicate a low density of c-axis nuclei near the substrate, apparently due to a reduced oxygen concentration deep inside the precursor layer. Significant non c-axis growth was also observed; the majority of this material nucleates away from the substrate. Measurement of the conversion rate by in situ XRD for films in the range 0.2-2 mum suggest a weak thickness dependence.

  10. Detection of circulating tumor cells in breast cancer patients using multiplex reverse transcription-polymerase chain reaction and specific primers for MGB, PTHRP and KRT19 correlation with clinicopathological features.

    PubMed

    Skondra, Maria; Gkioka, Eliona; Kostakis, Ioannis D; Pissimissis, Nikolaos; Lembessis, Panagiotis; Pectasides, Dimitrios; Koutsilieris, Michael

    2014-11-01

    The aim of this study was to correlate the clinicopathological features of breast cancer patients with the positive detection of parathyroid hormone-related protein (PTHRP), cytokeratin protein 19 (KRT19) and mammaglobin (MGB) using a multiplex reverse transcription polymerase chain reaction (RT-PCR) assay developed to detect circulating tumor cells (CTCs) in peripheral blood of patients with breast cancer. Peripheral blood samples were collected from 54 breast cancer patients and 20 healthy blood donors. Subsequently, the samples were processed for RNA extraction and analyzed for the expression of PTHRP, KRT19 and MGB using specific primers and multiplex RT-PCR. The positive detection rates in breast cancer patients for PTHRP, KRT19 and MGB were 68.5%, 63% and 22.2% and for healthy donors 10%, 0% and 10%, respectively. The statistical analysis revealed that PTHRP- and KRT19-positive detections correlated with the diagnosis of breast cancer while the combined positive detections of PTHRP-plus-KRT19 correlated with the presence of distant metastasis, especially with bone metastasis. Moreover, positive detections of KRT19 correlated with high proliferation rate of breast cancer tumors. MGB-positive detections did not add any diagnostic advantage in such analysis. Multiplex-PCR based detection of CTCs using PTHRP and KRT19 primers can provide useful information for the disease. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  11. Quantifying bulk and surface recombination processes in nanostructured water splitting photocatalysts via in situ ultrafast spectroscopy.

    PubMed

    Appavoo, Kannatassen; Liu, Mingzhao; Black, Charles T; Sfeir, Matthew Y

    2015-02-11

    A quantitative description of recombination processes in nanostructured semiconductor photocatalysts-one that distinguishes between bulk (charge transport) and surface (chemical reaction) losses-is critical for advancing solar-to-fuel technologies. Here we present an in situ experimental framework that determines the bias-dependent quantum yield for ultrafast carrier transport to the reactive interface. This is achieved by simultaneously measuring the electrical characteristics and the subpicosecond charge dynamics of a heterostructured photoanode in a working photoelectrochemical cell. Together with direct measurements of the overall incident-photon-to-current efficiency, we illustrate how subtle structural modifications that are not perceivable by conventional X-ray diffraction can drastically affect the overall photocatalytic quantum yield. We reveal how charge carrier recombination losses occurring on ultrafast time scales can limit the overall efficiency even in nanostructures with dimensions smaller than the minority carrier diffusion length. This is particularly true for materials with high carrier concentration, where losses as high as 37% are observed. Our methodology provides a means of evaluating the efficacy of multifunctional designs where high overall efficiency is achieved by maximizing surface transport yield to near unity and utilizing surface layers with enhanced activity.

  12. In situ process diagnostics of silane plasma for device-quality a-Si:H deposition

    NASA Astrophysics Data System (ADS)

    Shing, Y. H.; Perry, J. W.; Hermann, A. M.

    Coherent anti-Stokes Raman spectroscopy (CARS) and mass spectrometry (MS) have been applied to in situ process diagnostics of a silane plasma for device-quality a-Si:H film deposition. Silane depletion was directly measured by CARS and is linearly dependent on RF power in the region of 4-12 W with a slope of 0.5 percent/mW-sq cm. The depletion is also dependent on SiH4 flow rate starting with a 50 percent depletion at a low flow rate of 5.6 sccm and asymptotically approaching an 8 percent depletion at a flow rate of 80 sccm. The mass spectral line signal intensity of disilane increases with RF power and shows an apparent transition at 6 W. Disilane formation in silane plasma, film deposition rate, and silane depletion ratio as a function of the RF power indicate that the film growth mechanism in the low-power region of 3.5-6.5 W is substantially different from that in the high-power region of 6.5-12 W.

  13. System for producing a uniform rubble bed for in situ processes

    DOEpatents

    Galloway, Terry R.

    1983-01-01

    A method and a cutter for producing a large cavity filled with a uniform bed of rubblized oil shale or other material, for in situ processing. A raise drill head (72) has a hollow body (76) with a generally circular base and sloping upper surface. A hollow shaft (74) extends from the hollow body (76). Cutter teeth (78) are mounted on the upper surface of the body (76) and relatively small holes (77) are formed in the body (76) between the cutter teeth (78). Relatively large peripheral flutes (80) around the body (76) allow material to drop below the drill head (72). A pilot hole is drilled into the oil shale deposit. The pilot hole is reamed into a large diameter hole by means of a large diameter raise drill head or cutter to produce a cavity filled with rubble. A flushing fluid, such as air, is circulated through the pilot hole during the reaming operation to remove fines through the raise drill, thereby removing sufficient material to create sufficient void space, and allowing the larger particles to fill the cavity and provide a uniform bed of rubblized oil shale.

  14. Energy from true in-situ processing of Antrim shale: methane burner ignition system

    SciTech Connect

    VanDerPloeg, M.L.; Pihlaja, R.K.

    1980-08-01

    A rugged yet simple burner that can be easily ignited and reignited is a necessity if in situ thermal methods of energy extraction are to be feasible. During extraction trials at the Dow Chemical Company's oil shale site at Peck, Michigan such a burner was utilized. The performance of the TOR Development burner and ignitor system proved to be reliable and practical under field conditions. However, some recently discovered measures are crucial in protecting the burner and associated downhole hardware. With such precautions burner life was extended by a factor of 15. In the first trial burner life was two days and in the second trial the burner remained intact at least thirty days. Also described is a system which monitored burner performance by continuously analyzing burner exhaust gases. A slip stream sampling technique utilized the high well pressure to transport, at nearly Mach I, a sample of burner exhaust gas to the analytical trailer. There the sample was analyzed for CO, CO/sub 2/, unburned hydrocarbons, and O/sub 2/ by a bank of high speed process gas analyzers. Burner flameouts could be detected in less than 2 minutes. Also the system allowed burner (air/fuel) ratios to be determined on a real time basis. These ratios were used for (1) setting the proper air-fuel mixtures for ignition and steady state operation, (2) leak detection, (3) estimation of burner deterioration after extended use, and (4) study of the burner's steady state and transient response characteristics.

  15. In situ gasification process for producing product gas enriched in carbon monoxide and hydrogen

    DOEpatents

    Capp, John P.; Bissett, Larry A.

    1978-01-01

    The present invention is directed to an in situ coal gasification process wherein the combustion zone within the underground coal bed is fed with air at increasing pressure to increase pressure and temperature in the combustion zone for forcing product gases and water naturally present in the coal bed into the coal bed surrounding the combustion zone. No outflow of combustion products occurs during the build-up of pressure and temperature in the combustion zone. After the coal bed reaches a temperature of about 2000.degree. F and a pressure in the range of about 100-200 psi above pore pressure the airflow is terminated and the outflow of the combustion products from the combustion zone is initiated. The CO.sub.2 containing gaseous products and the water bleed back into the combustion zone to react endothermically with the hot carbon of the combustion zone to produce a burnable gas with a relatively high hydrogen and carbon monoxide content. About 11 to 29 percent of the gas recovered from the combustion zone is carbon monoxide which is considerably better than the 4 to 10 percent carbon monoxide obtained by employing previously known coal gasification techniques.

  16. Process improvements for the supercritical in situ transesterification of carbonized algal biomass.

    PubMed

    Levine, Robert B; Bollas, Alexandra; Savage, Phillip E

    2013-05-01

    This work focuses on the production of biodiesel from wet, lipid-rich algal biomass using a two-step process involving hydrothermal carbonization (HTC) and supercritical in situ transesterification (SC-IST). Algal hydrochars produced by HTC were reacted in supercritical ethanol to determine the effects of reaction temperature, time, ethanol loading, water content, and pressure on the yield of fatty acid ethyl esters (FAEE). Reaction temperatures above 275 °C resulted in substantial thermal decomposition of unsaturated FAEE, thereby reducing yields. At 275 °C, time and ethanol loading had a positive impact on FAEE yield while increasing reaction water content and pressure reduced yields. FAEE yields as high as 79% with a 5:1 ethanol:fatty acid (EtOH:FA) molar ratio (150 min) and 89% with a 20:1 EtOH:FA molar ratio (180 min) were achieved. This work demonstrates that nearly all lipids within algal hydrochars can be converted into biodiesel through SC-IST with only a small excess of alcohol.

  17. In situ monitoring of the hydration process of K-PS geopolymer cement with ESEM

    SciTech Connect

    Sun Wei; Zhang Yunsheng; Lin Wei; Liu Zhiyong

    2004-06-01

    Environmental scanning electron microscope (ESEM) was used to in situ quantitatively study the hydration process of K-PS geopolymer cement under an 80% RH environment. An energy dispersion X-ray analysis (EDXA) was also employed to distinguish the chemical composition of hydration product. The ESEM micrographs showed that metakaolin particles pack loosely at 10 min after mixing, resulting in the existence of many large voids. As hydration proceeds, a lot of gels were seen and gradually precipitated on the surfaces of these particles. At later stage, these particles were wrapped by thick gel layers and their interspaces were almost completely filled. The corresponding EDXA results illustrated that the molar ratios of K/Al increase while Si/Al decrease with the development of hydration. As a result, the molar ratios of K/Al and Si/Al of hydration products at an age of 4 h amounted to 0.99 and 1.49, respectively, which were close to the theoretical values (K/Al=1.0, Si/Al=1.0 for K-PS geopolymer cement paste). In addition, well-developed crystals could not been found at any ages; instead, spongelike amorphous gels were always been observed.

  18. System for producing a uniform rubble bed for in situ processes

    DOEpatents

    Galloway, T.R.

    1983-07-05

    A method and a cutter are disclosed for producing a large cavity filled with a uniform bed of rubblized oil shale or other material, for in situ processing. A raise drill head has a hollow body with a generally circular base and sloping upper surface. A hollow shaft extends from the hollow body. Cutter teeth are mounted on the upper surface of the body and relatively small holes are formed in the body between the cutter teeth. Relatively large peripheral flutes around the body allow material to drop below the drill head. A pilot hole is drilled into the oil shale deposit. The pilot hole is reamed into a large diameter hole by means of a large diameter raise drill head or cutter to produce a cavity filled with rubble. A flushing fluid, such as air, is circulated through the pilot hole during the reaming operation to remove fines through the raise drill, thereby removing sufficient material to create sufficient void space, and allowing the larger particles to fill the cavity and provide a uniform bed of rubblized oil shale. 4 figs.

  19. Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

    SciTech Connect

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H. F.

    2015-11-24

    A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

  20. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes

    PubMed Central

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-01-01

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data. PMID:27782200

  1. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes.

    PubMed

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-10-26

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data.

  2. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-10-01

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data.

  3. In Situ Reduction of Hexavalent Chromium in Alkaline Soils Enriched with Chromite Ore Processing Residue.

    PubMed

    Higgins, Thomas E; Halloran, Amy R; Dobbins, Maribeth E; Pittignano, Alex J

    1998-11-01

    In investigating chromium sites in New Jersey, it has been observed that an organic-rich 0.5- to 4-foot-thick layer of decayed vegetation (locally known as "meadowmat") underlying the chromium-containing material acts as a natural barrier to the migration of Cr(VI). The groundwater in a sand layer directly beneath the meadowmat has been shown to contain low or nondetectable levels of chromium. The meadowmat is under highly reduced conditions due to bacterial activity associated with the organic material. Based on the observed ability of the meadowmat to reduce Cr(VI) to Cr(III), the feasibility of in situ reduction of Cr(VI) to Cr(III) at chromite ore processing residue (COPR) sites was investigated in biologically-active, laboratory-scale test columns. COPR typically has a high pH (in excess of 12) and may contain total chromium concentrations as high as 70,000 mg/kg. Experimental results demonstrated that the addition of a mineral acid (to lower the pH to between 7.0 and 9.5) and a bacteria-rich organic substrate (fresh manure) resulted in the reduction of Cr(VI) to the less toxic and less mobile trivalent form. Pore water Cr(VI) was reduced from approximately 800 mg/L to less than 0.05 mg/L over a period of eight months. This is less than the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for chromium in drinking water of 0.1 mg/L. Solid phase Cr(VI) concentrations decreased from approximately 2,000 mg/kg to less than 10 mg/kg in the columns over a period of 11 months while the total chromium concentrations remained unchanged. Toxicity Characteristic Leaching Procedure (TCLP) extract from the treated columns met the regulatory limit of 5 mg/L of Cr, whereas the untreated samples had TCLP extract concentrations greater than 40 mg/L. This study demonstrated the potential applicability of in situ reduction to soils contaminated with Cr(VI) by adjusting the pH to between 7.0 and 9.5 and mixing in a bacteria-rich organic substrate.

  4. In situ reduction of hexavalent chromium in alkaline soils enriched with chromite ore processing residue

    PubMed

    Higgins; Halloran; Dobbins; Pittignano

    1998-11-01

    In investigating chromium sites in New Jersey, it has been observed that an organic-rich 0.5- to 4-foot-thick layer of decayed vegetation (locally known as "meadowmat") underlying the chromium-containing material acts as a natural barrier to the migration of Cr(VI). The groundwater in a sand layer directly beneath the meadowmat has been shown to contain low or nondetectable levels of chromium. The meadowmat is under highly reduced conditions due to bacterial activity associated with the organic material. Based on the observed ability of the meadowmat to reduce Cr(VI) to Cr(III), the feasibility of in situ reduction of Cr(VI) to Cr(III) at chromite ore processing residue (COPR) sites was investigated in biologically-active, laboratory-scale test columns. COPR typically has a high pH (in excess of 12) and may contain total chromium concentrations as high as 70,000 mg/kg. Experimental results demonstrated that the addition of a mineral acid (to lower the pH to between 7.0 and 9.5) and a bacteria-rich organic substrate (fresh manure) resulted in the reduction of Cr(VI) to the less toxic and less mobile trivalent form. Pore water Cr(VI) was reduced from approximately 800 mg/L to less than 0.05 mg/L over a period of eight months. This is less than the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for chromium in drinking water of 0.1 mg/L. Solid phase Cr(VI) concentrations decreased from approximately 2,000 mg/kg to less than 10 mg/kg in the columns over a period of 11 months while the total chromium concentrations remained unchanged. Toxicity Characteristic Leaching Procedure (TCLP) extract from the treated columns met the regulatory limit of 5 mg/L of Cr, whereas the untreated samples had TCLP extract concentrations greater than 40 mg/L. This study demonstrated the potential applicability of in situ reduction to soils contaminated with Cr(VI) by adjusting the pH to between 7.0 and 9.5 and mixing in a bacteria-rich organic substrate.

  5. In Situ Mass Spectrometric Monitoring of the Dynamic Electrochemical Process at the Electrode-Electrolyte Interface: a SIMS Approach.

    PubMed

    Wang, Zhaoying; Zhang, Yanyan; Liu, Bingwen; Wu, Kui; Thevuthasan, Suntharampillai; Baer, Donald R; Zhu, Zihua; Yu, Xiao-Ying; Wang, Fuyi

    2017-01-03

    The in situ molecular characterization of reaction intermediates and products at electrode-electrolyte interfaces is central to mechanistic studies of complex electrochemical processes, yet a great challenge. The coupling of electrochemistry (EC) and mass spectrometry (MS) has seen rapid development and found broad applicability in tackling challenges in analytical and bioanalytical chemistry. However, few truly in situ and real-time EC-MS studies have been reported at electrode-electrolyte interfaces. An innovative EC-MS coupling method named in situ liquid secondary ion mass spectrometry (SIMS) was recently developed by combining SIMS with a vacuum compatible microfluidic electrochemical device. Using this novel capability, we report the first in situ elucidation of the electro-oxidation mechanism of a biologically significant organic compound, ascorbic acid (AA), at the electrode-electrolyte interface. The short-lived radical intermediate was successfully captured, which had not been detected directly before. Moreover, we demonstrated the power of this new technique in real-time monitoring of the formation and dynamic evolution of electrical double layers at the electrode-electrolyte interface. This work suggests further promising applications of in situ liquid SIMS in studying more complex chemical and biological events at the electrode-electrolyte interface.

  6. Real-time in-situ chemical sensing, sensor-based film thickness metrology, and process control in W-CVD process

    NASA Astrophysics Data System (ADS)

    Xu, Yiheng

    2000-10-01

    A real-time in-situ sampling system has been implemented for chemical sensing in tungsten chemical vapor deposition process (W-CVD) using mass spectrometry. Sensor integration was realized to allow synchronous capture of equipment state signals and process signals (chemical information from mass spectrometry). Wafer state metrology from integrated mass spectrometry signals of different gaseous chemical species in the reaction was established with an uncertainty of 2--7% depending on the conversion rate of the process, which is determined by the process chemistry and processing conditions. The mass spectrometry-based wafer state metrology obtained was applied to implement fault detection and W film thickness process control: run-to-run control in H2 reduction W-CVD and real time end point control in SiH4 reduction process. The results demonstrate the benefit of combining real-time mass spectrometry sensor data with equipment state information for process control. The important generic issues regarding real-time in-situ chemical sensing using mass spectrometry in the context of a multi-component chemical reaction system like W-CVD have also been discussed. The accomplishments of this research demonstrate the value of in-situ chemical sensing in complex manufacturing process systems and provide clear pathways toward advanced process control methodology.

  7. High critical currents in iron-clad superconducting MgB2 wires.

    PubMed

    Jin, S; Mavoori, H; Bower, C; van Dover, R B

    2001-05-31

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  8. High critical currents in iron-clad superconducting MgB2 wires

    NASA Astrophysics Data System (ADS)

    Jin, S.; Mavoori, H.; Bower, C.; van Dover, R. B.

    2001-05-01

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000Acm-2 at 4.2K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the `weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  9. A flow cell for in situ synchrotron x-ray diffraction studies of scale formation under Bayer processing conditions

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Madsen, Ian C.; Loan, Melissa J.; Scarlett, Nicola V. Y.; Wallwork, Kia S.

    2009-08-01

    The design, construction, and commissioning of a stainless steel flow cell for in situ synchrotron x-ray diffraction studies of scale formation under Bayer processing conditions is described. The use of the cell is demonstrated by a study of Al(OH)3 scale formation on a mild steel substrate from synthetic Bayer liquor at 70 °C. The cell design allows for interchangeable parts and substrates and would be suitable for the study of scale formation in other industrial processes.

  10. In-Situ Statistical Analysis of Autotune Simulation Data using Graphical Processing Units

    SciTech Connect

    Ranjan, Niloo; Sanyal, Jibonananda; New, Joshua Ryan

    2013-08-01

    Developing accurate building energy simulation models to assist energy efficiency at speed and scale is one of the research goals of the Whole-Building and Community Integration group, which is a part of Building Technologies Research and Integration Center (BTRIC) at Oak Ridge National Laboratory (ORNL). The aim of the Autotune project is to speed up the automated calibration of building energy models to match measured utility or sensor data. The workflow of this project takes input parameters and runs EnergyPlus simulations on Oak Ridge Leadership Computing Facility s (OLCF) computing resources such as Titan, the world s second fastest supercomputer. Multiple simulations run in parallel on nodes having 16 processors each and a Graphics Processing Unit (GPU). Each node produces a 5.7 GB output file comprising 256 files from 64 simulations. Four types of output data covering monthly, daily, hourly, and 15-minute time steps for each annual simulation is produced. A total of 270TB+ of data has been produced. In this project, the simulation data is statistically analyzed in-situ using GPUs while annual simulations are being computed on the traditional processors. Titan, with its recent addition of 18,688 Compute Unified Device Architecture (CUDA) capable NVIDIA GPUs, has greatly extended its capability for massively parallel data processing. CUDA is used along with C/MPI to calculate statistical metrics such as sum, mean, variance, and standard deviation leveraging GPU acceleration. The workflow developed in this project produces statistical summaries of the data which reduces by multiple orders of magnitude the time and amount of data that needs to be stored. These statistical capabilities are anticipated to be useful for sensitivity analysis of EnergyPlus simulations.

  11. In situ evolution of trivalent chromium process passive film on Al in a corrosive aqueous environment.

    PubMed

    Dong, Xuecheng; Argekar, Sandip; Wang, Peng; Schaefer, Dale W

    2011-11-01

    In situ neutron reflectivity (NR) is used to observe the structure and evolution of a Trivalent Chromium Process (TCP) passive film on Al in a NaCl-D(2)O solution. Using a split liquid reflectivity cell we mimicked the corrosion process on the anodic sites in alloy AA 2024-T3 in a pitting scenario. The split cell separates the anodic and cathodic reactions, allowing NR observation of the corroding anodic surface under potential control. We observed the evolution of the TCP film on the Al anode and compared the degradation of the Al with and without TCP protection. When held at 100 mV above the open-circuit potential (OCP), unprotected aluminum dissolves at a rate of 120 Å/h. By contrast, TCP-coated Al is stable up to the pitting potential (200 mV above OCP). In the passive state D(2)O molecules penetrate the bulk TCP film by partially replacing the hydrate water. In spite of exchange of hydration water, the TCP film is stable and the underlying aluminum is fully protected. The passive character of the TCP film is due to a dense layer at the metal-TCP interface and/or to suppression of ion transport in the bulk film. As the pitting potential is approached the film swells and NaCl-D(2)O solution penetrates the TCP film. At this point, 50 vol % of the TCP film is occupied by bulk NaCl-D(2)O solution. Failure occurs by aluminum dissolution under the swollen TCP film as the imbibed solution contacts the Al metal. Further increase in potential leads to complete stripping of the TCP film.

  12. Image processing for identification and quantification of filamentous bacteria in in situ acquired images.

    PubMed

    Dias, Philipe A; Dunkel, Thiemo; Fajado, Diego A S; Gallegos, Erika de León; Denecke, Martin; Wiedemann, Philipp; Schneider, Fabio K; Suhr, Hajo

    2016-06-11

    In the activated sludge process, problems of filamentous bulking and foaming can occur due to overgrowth of certain filamentous bacteria. Nowadays, these microorganisms are typically monitored by means of light microscopy, commonly combined with staining techniques. As drawbacks, these methods are susceptible to human errors, subjectivity and limited by the use of discontinuous microscopy. The in situ microscope appears as a suitable tool for continuous monitoring of filamentous bacteria, providing real-time examination, automated analysis and eliminating sampling, preparation and transport of samples. In this context, a proper image processing algorithm is proposed for automated recognition and measurement of filamentous objects. This work introduces a method for real-time evaluation of images without any staining, phase-contrast or dilution techniques, differently from studies present in the literature. Moreover, we introduce an algorithm which estimates the total extended filament length based on geodesic distance calculation. For a period of twelve months, samples from an industrial activated sludge plant were weekly collected and imaged without any prior conditioning, replicating real environment conditions. Trends of filament growth rate-the most important parameter for decision making-are correctly identified. For reference images whose filaments were marked by specialists, the algorithm correctly recognized 72 % of the filaments pixels, with a false positive rate of at most 14 %. An average execution time of 0.7 s per image was achieved. Experiments have shown that the designed algorithm provided a suitable quantification of filaments when compared with human perception and standard methods. The algorithm's average execution time proved its suitability for being optimally mapped into a computational architecture to provide real-time monitoring.

  13. Nucleation and aggregative growth process of platinum nanoparticles studied by in situ quick XAFS spectroscopy.

    PubMed

    Harada, Masafumi; Kamigaito, Yoshiko

    2012-02-07

    The early stage in the nucleation and subsequent aggregative particle growth of the colloidal platinum (Pt) dispersions produced by photoreduction in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) was quantitatively investigated by means of in situ quick XAFS (QXAFS) measurements. The stages of the reduction-nucleation and the association process (aggregative particle growth and Ostwald ripening) of Pt atoms to produce Pt nanoparticles was successfully discriminated in course of the photoreduction time. The present QXAFS analysis indicated that Pt nuclei (i.e., (Pt(0))(m) nucleates approximately m = 4) were continuously produced in the reduction-nucleation process at the early time, followed by the aggregative particle growth with the autocatalytic reduction of Pt ionic species on the surface of Pt nuclei to produce Pt nanoparticles. Subsequently the particle growth proceeded via Ostwald ripening, resulting in the production of larger Pt nanoparticles at a later time. It was also found that the aggregative particle growth follows a sigmoidal profile well described either by the solid-state kinetic model or by the chemical-mechanism-based kinetic model, specifically the Avrami-Erofe'ev or Finke-Watzky models. The difference in terms of the formation mechanism was observed between the reduction of Pt(IV)Cl(6)(2-) and Pt(II)Cl(4)(2-) as a source material. Also presented is that the addition of the photoactivator such as benzoin, benzophenone, and acetophenone in the system is very effective to enhance the rate for the formation of Pt nanoparticles.

  14. A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

    PubMed Central

    González Lazo, Marina A.; Katrantzis, Ioannis; Dalle Vacche, Sara; Karasu, Feyza; Leterrier, Yves

    2016-01-01

    A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA) within a low-shrinkage acrylated hyperbranched polymer (HBP) and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA) of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS) negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125°) and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10°) and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5°) and also featured self-cleaning properties. PMID:28773860

  15. Remediation of TCE contaminated soils by in situ EK-Fenton process.

    PubMed

    Yang, G C; Liu, C Y

    2001-08-17

    The treatment performance and cost analysis of in situ electrokinetic (EK)-Fenton process for oxidation of trichloroethylene (TCE) in soils were evaluated in this work. In all experiments, an electric gradient of 1V/cm, de-ionized water as the cathode reservoir fluid and a treatment time of 10 days were employed. Treatment efficiencies of TCE were evaluated in terms of the electrode material, soil type, catalyst type, and catalyst dosage and granular size if applicable. Test results show that graphite electrodes are superior to stainless steel electrodes. It was found that the soil with a higher content of organic matter would result in a lower treatment efficiency (e.g. a sandy loam is less efficient than a loamy sand). Experimental results show that the type of catalyst and its dosage would markedly affect the reaction mechanisms (i.e. "destruction" and "removal") and the treatment efficiency. Aside from FeSO4, scrap iron powder (SIP) in the form of a permeable reactive wall was also found to be an effective catalyst for Fenton reaction to oxidize TCE. In general, the smaller the granular size of SIP, the lower the overall treatment efficiency and the greater the destruction efficiency. When a greater quantity of SIP was used, a decrease of the overall treatment efficiency and an increase of percent destruction of TCE were found. Experimental results have shown that the quantity of electro-osmotic (EO) flow decreased as the quantity of SIP increased. It has been verified that the treatment performances are closely related to the corresponding EO permeability. Results of the cost analysis have indicated that the EK-Fenton process employed in this work is very cost-effective with respect to TCE destruction.

  16. Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

    SciTech Connect

    Huang, Chin-Pao

    2001-05-31

    This project will study electrochemical processes for the in situ treatment of soils contaminated by mixed wastes, i.e., organic and inorganic. Soil samples collected form selected DOE waste sites will be characterized for specific organic and metal contaminants and hydraulic permeability. The soil samples are then subject to desorption experiments under various physical-chemical conditions such as pH and the presence of surfactants. Batch electro-osmosis experiments will be conducted to study the transport of contaminants in the soil-water systems. Organic contaminants that are released from the soil substrate will be treated by an advanced oxidation process, i.e., electron-Fantan. Finally, laboratory reactor integrating the elector-osmosis and elector-Fantan processes will be used to study the treatment of contaminated soil in situ.

  17. Chemical and physical interactions of an in situ oil-shale process water with a surface soil

    SciTech Connect

    Leenheer, J.A.; Stuber, H.A.; Noyes, T.I.

    1981-01-01

    Chemical and physical interactions of an in situ oil-shale process (retort) water with a surface soil were investigated by soil and effluent analyses of three soil-column experiments whereby soil was leached with: (1) Distilled water, (2) a synthetic retort water containing only inorganic solutes, and (3) an actual retort water produced by in situ processing of oil shale. Major findings of this study include an ion exchange-precipitation reaction, in which exchangeable calcium in the soil is displaced by ammonium from retort water and precipitated as carbonate by inorganic carbon in retort water. This precipitation process affects soil permeability. Ammonium was strongly adsorbed from retort water by the soil, and was not removed by subsequent distilled-water leaching and drying. 26 refs.

  18. Magnetic flux noise in MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Khare, Neeraj; Singh, D. P.; Gupta, Ajai K.

    2008-05-01

    Magnetic flux noise in MgB2 polycrystalline sample is measured using a high-TC rf-superconducting quantum interference device in the temperature range of 6-40K. A small magnetic field (˜200mG ) was applied while cooling the sample. The flux noise exhibits 1/fα type of behavior with α ˜1.0-1.3 and shows enhanced noise around 24 and 37K. The flux noise seems to originate from thermally activated vortex hopping. The large magnetic noise at 24K indicates the presence of larger density of pinning sites with energies ˜0.061eV leading to enhanced magnetic fluctuations at temperatures much below TC.

  19. Superconductivity of MgB2: covalent bonds driven metallic.

    PubMed

    An, J M; Pickett, W E

    2001-05-07

    A series of calculations on MgB2 and related isoelectronic systems indicates that the layer of Mg2+ ions lowers the nonbonding B pi ( p(z)) bands relative to the bonding sigma ( sp(x)p(y)) bands compared to graphite, causing sigma-->pi charge transfer and sigma band doping of 0.13 holes/cell. Because of their two dimensionality the sigma bands contribute strongly to the Fermi level density of states. Calculated deformation potentials of gamma point phonons identify the B bond stretching modes as dominating the electron-phonon coupling. Superconductivity driven by sigma band holes is consistent with the report of destruction of superconductivity by doping with Al.

  20. Constraining processes of landscape change with combined in situ cosmogenic 14C-10Be analysis

    NASA Astrophysics Data System (ADS)

    Hippe, Kristina

    2017-10-01

    Reconstructing Quaternary landscape evolution today frequently builds upon cosmogenic-nuclide surface exposure dating. However, the study of complex surface exposure chronologies on the 102-104 years' timescale remains challenging with the commonly used long-lived radionuclides (10Be, 26Al, 36Cl). In glacial settings, key points are the inheritance of nuclides accumulated in a rock surface during a previous exposure episode and (partial) shielding of a rock surface after the main deglaciation event, e.g. during phases of glacier readvance. Combining the short-lived in situ cosmogenic 14C isotope with 10Be dating provides a valuable approach to resolve and quantify complex exposure histories and burial episodes within Lateglacial and Holocene timescales. The first studies applying the in situ14C-10Be pair have demonstrated the great benefit from in situ14C analysis for unravelling complex glacier chronologies in various glacial environments worldwide. Moreover, emerging research on in situ14C in sedimentary systems highlights the capacity of combined in situ14C-10Be analysis to quantify sediment transfer times in fluvial catchments or to constrain changes in surface erosion rates. Nevertheless, further methodological advances are needed to obtain truly routine and widely available in situ14C analysis. Future development in analytical techniques has to focus on improving the analytical reproducibility, reducing the background level and determining more accurate muonic production rates. These improvements should allow extending the field of applications for combined in situ14C-10Be analysis in Earth surface sciences and open up a number of promising applications for dating young sedimentary deposits and the quantification of recent changes in surface erosion dynamics.

  1. In Situ Data Processing With Workflow-based Embedded Cyberinfrastructure (emCI)

    NASA Astrophysics Data System (ADS)

    Mehta, G.; Silva, F.; Graham, E. A.; Vahi, K.; Deelman, E.; Rundel, P.

    2011-12-01

    The decreasing cost of sensors and sensor networks has led to the wide scale adoption of this technology by large numbers of scientists for the collection of data in the field. At the same time, advances in both hardware and software have resulted in increased processing power at the sensor, enabling sensors in the field to do more than just data collection. With an increase in the number of sensors and deployments, scientists need tools for the configuration, operation, and debugging problems on their sensor networks. Furthermore, as the amount of data increases, scientists need a way to quickly and easily tag, process, archive, and share their datasets. Without proper tools, it is common for data processing to happen weeks or sometimes months after it is collected. This leads to important events being missed and makes real-time data analysis impossible. Additionally, because data is often manually processed through a series of repetitive steps, the analysis is susceptible to errors that are hard to track after data is combined and shared among researchers. Our emCI (embedded cyberinfrastructure) toolkit enables researchers to easily collect, analyze, and share their data. emCI provides a web-portal with upload/download capabilities that accept data in a number of different formats and ultimately can be used to archive data and share datasets among scientists. emCI uses an embedded general-purpose computer in the field for interfacing with sensors, coordinating data collection, and providing reliable data transfer to the emCI web portal. emCI relies on workflow technologies to automate data processing pipelines and to provide provenance information. In particular, emCI uses the Pegasus Workflow Management System as a core component, adapting it to the embedded computation environment. emCI allows scientists to distribute tasks among sensors in field and servers in the lab. In-situ processing using embedded workflows enable data reduction and validation in the

  2. Effect of deformation with Bridgman anvils on the structure, hardness, and critical current of a massive MgB2-based sample

    NASA Astrophysics Data System (ADS)

    Akshentsev, Yu. N.; Degtyarev, M. V.; Pilyugin, V. P.; Krinitsina, T. P.; Kuznetsova, E. I.; Blinova, Yu. V.; Sudareva, S. V.; Romanov, E. P.

    2015-05-01

    The structure and properties of synthesized massive MgB2-based samples subjected to deformation with Bridgman anvils have been studied. Deformation results in the formation of fine-grained structure of the MgB2 phase, enhancement of interconnection of grains, complete disappearance of friable MgB2-phase areas, and abrupt increase in the microhardness.

  3. Friction Stir Processing of Al-TiB2 In Situ Composite: Effect on Particle Distribution, Microstructure and Properties

    NASA Astrophysics Data System (ADS)

    Yadav, Devinder; Bauri, Ranjit

    2015-03-01

    Aluminum-based in situ composites suffer from the age-old issue of particle segregation along the grain boundaries after casting. In the present study, friction stir processing (FSP) was employed as a secondary process to improve the distribution of in situ formed TiB2 particles in Al-based composite. All the agglomerates of TiB2 were broken, and uniform distribution of particles was achieved after double-pass FSP. Also, FSP removed the casting defects and caused significant grain refinement of the Al matrix. The microstructure was characterized by equiaxed fine grains with average size of 3 µm and narrow grain size distribution. The microstructural refinements and homogenization after FSP not only enhanced the strength but also improved the ductility of the as-cast composite.

  4. A new scaling relation for n-AlN doped superconducting MgB2

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Dey, T. K.

    2013-09-01

    The scaling behavior of nano-aluminum nitride added polycrystalline MgB2 superconductor is discussed. A series of polycrystalline MgB2 samples with different amounts of nanosized AlN addition are synthesized by solid reaction. All the synthesized pellets are subjected to x-ray diffraction, field emission gun scanning electron microscopy (FEG-SEM), and transmission electron microscopy (TEM) to examine their micro-structural features. A marginal decrease in lattice parameters of pure MgB2 with AlN nanoparticles addition is observed. Surface morphology reveals randomly oriented hexagonal MgB2 grains decorated with AlN nanoparticles between the grain boundaries and also scattered on the grain surface. For higher concentration, n-AlN agglomerates are visible. Resistivity data confirm a decrease in superconducting transition temperature (Tc) from 38.5 to 37 K and increase in transition width (ΔTc) with increased loading of n-AlN in MgB2. The critical current density (Jc) of the pellets at 4, 10, 20, and 30 K is evaluated from the magnetization data between ±6 T and is explained well in the framework of collective pinning model. The normalized pinning force density of n-AlN doped MgB2 at various temperatures indicates an excellent scaling with respect to Hn (the field corresponding to which Fp drops to half of its maximum value) as the scaling field. A new scaling expression derived, using the expression of field dependence of Jc proposed by "collective pinning model" in small bundle regime, demonstrates an excellent agreement with the measured normalized pinning force density (viz., Fp/Fpmax vs. hn) of the AlN nanoparticles doped MgB2 superconductors.

  5. Fourier-transform spectral interferometry for in situ group delay dispersion monitoring of thin film coating processes.

    PubMed

    Schlichting, Sebastian; Willemsen, Thomas; Ehlers, Henrik; Morgner, Uwe; Ristau, Detlev

    2016-10-03

    A fast Fourier-based measurement system to determine phase, group delay, and group delay dispersion during optical coating processes is proposed. The in situ method is based on a Michelson interferometer with a broad band light source and a very fast spectrometer. To our knowledge, group delay dispersion measurements directly on the moving substrates during a deposition process for complex interference coatings have been demonstrated for the first time. Especially for the very precise production of chirped mirrors it is advantageous to get information about the phase properties of the grown layer stack to react on errors and retrieve more information about the coating process.

  6. Application of superconducting magnesium diboride (MGB2) in superconducting radio frequency cavities

    NASA Astrophysics Data System (ADS)

    Tan, Teng

    The superconductivity in magnesium diboride (MgB2) was discovered in 2001. As a BCS superconductor, MgB2 has a record-high Tc of 39 K, high Jc of > 107 A/cm2 and no weak link behavior across the grain boundary. All these superior properties endorsed that MgB2 would have great potential in both power applications and electronic devices. In the past 15 years, MgB2 based power cables, microwave devices, and commercial MRI machines emerged and the next frontier are superconducting radio frequency (SRF) cavities. SRF cavities are one of the leading accelerator technologies. In SRF cavities, applied microwave power generates electrical fields that accelerate particle beams. Compared with other accelerator techniques, SRF cavity accelerators feature low loss, high acceleration gradients and the ability to accelerate continuous particle beams. However, current SRF cavities are made from high-purity bulk niobium and work at 2 K in superfluid helium. The construction and operational cost of SRF cavity accelerators are very expensive. The demand for SRF cavity accelerators has been growing rapidly in the past decade. Therefore, a lot of effort has been devoted to the enhancement of the performance and the reduction of cost of SRF cavities. In 2010, an acceleration gradient of over 50 MV/m has been reported for a Nb-based SRF cavity. The magnetic field at the inner surface of such a cavity is ~ 1700 Oe, which is close to the thermodynamic critical field of Nb. Therefore, new materials and technologies are required to raise the acceleration gradient of future SRF cavity accelerators. Among all the proposed approaches, using MgB2 thin films to coat the inner surface of SRF cavities is one of the promising tactics with the potential to raise both the acceleration gradient and the operation temperature of SRF cavity accelerators. In this work, I present my study on MgB2 thin films for their application in SRF cavities. C-epitaxial MgB2 thin films grown on SiC(0001) substrates

  7. Biodiesel production from rice bran by a two-step in-situ process.

    PubMed

    Shiu, Pei-Jing; Gunawan, Setiyo; Hsieh, Wen-Hao; Kasim, Novy S; Ju, Yi-Hsu

    2010-02-01

    The production of fatty acid methyl esters (FAMEs) by a two-step in-situ transesterification from two kinds of rice bran was investigated in this study. The method included an in-situ acid-catalyzed esterification followed by an in-situ base-catalyzed transesterification. Free fatty acids (FFAs) level was reduced to less than 1% for both rice bran A (initial FFAs content=3%) and rice bran B (initial FFAs content=30%) in the first step under the following conditions: 10 g rice bran, methanol to rice bran ratio 15 mL/g, H(2)SO(4) to rice bran mass ratio 0.18, 60 degrees C reaction temperature, 600 rpm stirring rate, 15 min reaction time. The organic phase of the first step product was collected and subjected to a second step reaction by adding 8 mL of 5N NaOH solution and allowing to react for 60 and 30 min for rice bran A and rice bran B, respectively. FAMEs yields of 96.8% and 97.4% were obtained for rice bran A and rice bran B, respectively, after this two-step in-situ reaction.

  8. In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

    NASA Astrophysics Data System (ADS)

    Albino, J. D.; Nambi, I. M.

    2009-12-01

    Microbial Enhanced Oil Recovery (MEOR) and remediation of aquifers contaminated with hydrophobic contaminants require insitu production of biosurfactants for mobilization of entrapped hydrophobic liquids. Most of the biosurfactant producing microorganisms produce them under aerobic condition and hence surfactant production is limited in subsurface condition due to lack of oxygen. Currently bioremediation involves expensive air sparging or excavation followed by exsitu biodegradation. Use of microorganisms which can produce biosurfactants under anaerobic conditions can cost effectively expedite the process of insitu bioremediation or mobilization. In this work, the feasibility of anaerobic biosurfactant production in three mixed anaerobic cultures prepared from groundwater and soil contaminated with chlorinated compounds and municipal sewage sludge was investigated. The cultures were previously enriched under complete anaerobic conditions in the presence of Tetrachloroethylene (PCE) for more than a year before they were studied for biosurfactant production. Biosurfactant production under anaerobic conditions was simulated using two methods: i) induction of starvation in the microbial cultures and ii) addition of complex fermentable substrates. Positive result for biosurfactant production was not observed when the cultures were induced with starvation by adding PCE as blobs which served as the only terminal electron acceptor. However, slight reduction in interfacial tension was noticed which was caused by the adherence of microbes to water-PCE interface. Biosurfactant production was observed in all the three cultures when they were fed with complex fermentable substrates and surface tension of the liquid medium was lowered below 35 mN/m. Among the fermentable substrates tested, vegetable oil yielded highest amount of biosurfactant in all the cultures. Complete biodegradation of PCE to ethylene at a faster rate was also observed when vegetable oil was amended to the

  9. Closed-looped in situ nano processing on a culturing cell using an inverted electron beam lithography system

    SciTech Connect

    Hoshino, Takayuki; Mabuchi, Kunihiko

    2013-03-08

    Highlights: ► An electron beam lithography (EBL) was used as an in situ nano processing for a living cell. ► A synchronized optics was containing an inverted EBL and an optical microscope. ► This system visualized real-time images of the EB-induced nano processing. ► We demonstrated the nano processing for a culturing cell with 200–300 nm resolution. ► Our system would be able to provide high resolution display of virtual environments. -- Abstract: The beam profile of an electron beam (EB) can be focused onto less than a nanometer spot and scanned over a wide field with extremely high speed sweeping. Thus, EB is employed for nano scale lithography in applied physics research studies and in fabrication of semiconductors. We applied a scanning EB as a control system for a living cell membrane which is representative of large scale complex systems containing nanometer size components. First, we designed the opposed co-axial dual optics containing inverted electron beam lithography (I-EBL) system and a fluorescent optical microscope. This system could provide in situ nano processing for a culturing living cell on a 100-nm-thick SiN nanomembrane, which was placed between the I-EBL and the fluorescent optical microscope. Then we demonstrated the EB-induced chemical direct nano processing for a culturing cell with hundreds of nanometer resolution and visualized real-time images of the scanning spot of the EB-induced luminescent emission and chemical processing using a high sensitive camera mounted on the optical microscope. We concluded that our closed-loop in situ nano processing would be able to provide a nanometer resolution display of virtual molecule environments to study functional changes of bio-molecule systems.

  10. Flux jump behaviors and mechanism of FeTi doped MgB2 at 5 K

    NASA Astrophysics Data System (ADS)

    Lee, H. B.; Kim, G. C.; Kim, Y. C.; Ahmad, D.

    2015-08-01

    This study examined the flux jump behaviors of Fe-doped MgB2 according to content of FeTi particles at 5 K, at which flux jump has been shown to be more frequent. The samples were synthesized in a stainless steel tube with Mg, B and FeTi particles. The motives of flux jump in MgB2 superconductors are over-moving fluxes around the defects and the low heat capacity of MgB2. MgB2 was doped with FeTi particles to overcome these vulnerable points of MgB2. The flux jump of MgB2 decreased with increasing content of doped FeTi particles. On the other hand, excessive doping of FeTi resulted in a decrease of diamagnetic properties and the flux pinning effects together. It is concluded that FeTi particles in MgB2 do not block the flux jump itself, but the propagation of flux jump of MgB2.

  11. Concurrent doping effect of Ti and nano-diamond on flux pinning of MgB 2

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Ke, C.; Cheng, C. H.; Feng, Y.; Yang, Y.; Munroe, P.

    2010-11-01

    Nano-diamond and titanium concurrently doped MgB2 nanocomposites have been prepared by solid state reaction method. The effects of carbon and Ti concurrent doping on Jc-H behavior and pinning force scaling features of MgB2 have been investigated. Although Tc was slightly depressed, Jc of MgB2 have been significantly improved by the nano-diamond doping, especially in the high field region. In the mean time, the Jc value in low field region is sustained though concurrent Ti doping. Microstructure analysis reveals that when nano-diamond was concurrently doped with titanium in MgB2, a unique nanocomposite in which TiB2 forms a thin layer surrounding MgB2 grains whereas nano-diamond particles were wrapped inside the MgB2 grains. Besides, nano-diamond doping results in a high density stress field in the MgB2 samples, which may take responsibility for the Δκ pinning behavior in the carbon-doped MgB2 system.

  12. TOPICAL REVIEW: The widely variable resistivity of MgB2 samples

    NASA Astrophysics Data System (ADS)

    Rowell, John M.

    2003-06-01

    In this brief review, I consider a rather mundane property of MgB2, namely its resistivity as a function of temperature. It turns out that a comparison of resistivity data for a wide variety of samples, from single crystals to films, wires and polycrystalline bulk, is surprisingly informative. The majority of samples of MgB2 exhibit resistivities that are much higher than the low values that are seen in a relatively small number of single crystals, bulk samples and films. In many cases, the resistivity is increased over the single crystal values by orders of magnitude. Even at these high values, there is often still a metallic temperature dependence of the resistivity, and surprisingly, Tc is often at or near the bulk value of 39 K. The resistivity increase has been ascribed to a reduction in the effective current-carrying cross-sectional area of the sample. If this loss of cross-sectional area is the dominant factor contributing to the increase in resistivity of MgB2 samples, then the critical current density must be decreased by the same loss in the effective area. Comparisons of the MgB2 resistivity with the properties of disordered 'cluster compound' superconductors, of HTS materials and of granular Al (heavily contaminated with oxygen), show similarities between the MgB2 behaviour and the results of the HTS and Al studies. I discuss various effects that might contribute to the reduction in effective sample area in MgB2 samples, to the increase in resistivity and to a reduction in Jc. I speculate that a Josephson junction model of the grain boundaries in MgB2 might apply to samples with extremely high resistivities. Alternatively, it has been suggested that the two-band nature of MgB2 can result in an unusual behaviour of its resistivity and Tc as the material changes from the 'clean' to 'dirty' limits. I conclude that measurements of both the resistivity and the transport critical current density in a wide variety of bulk and film samples would be very useful

  13. Thermoluminescent dosimetric comparison for two different MgB4O7:Dy production routes

    NASA Astrophysics Data System (ADS)

    Souza, L. F.; Vidal, R. M.; Souza, S. O.; Souza, D. N.

    2014-11-01

    There are several routes employed for the production of synthetic magnesium tetraborate, for example, sol-gel method, combustion, wet reaction synthesis, solid-state route and precipitation (crystal growth). The most commonly used synthesis methods are the wet reaction (precipitation) and solid-state synthesis; both production routes are efficient, but is very difficult to find a direct comparison for them. The present work proposes a direct comparison of both production routes used for magnesium tetraborate synthesis for thermoluminescent (TL) dosimetry. In this work, MgB4O7:Dy was prepared by both methods, wet reaction or precipitation-route 1, and solid-state synthesis -route 2, with the same amount of dopant (0.1%). In the first part of work, the crystalline phases were confirmed by X-ray diffraction (XRD) and it was observed that MgB4O7:Dy can be obtained satisfactorily through both routes, although a very intense crystalline phase of H3BO3 for the powder produced through route 1 was observed. The dose response curve of MgB4O7 pellets (produced for both routes) presents linear behavior when the materials are irradiated with 60Co in the dose range of 10-100 Gy. The results showed that both methods produce MgB4O7:Dy efficiently; however, solid-state synthesis produces MgB4O7:Dy more sensitive to gamma radiation.

  14. Evaluations of MgB2 Coatings on 2'' Copper Discs for Superconducting Radio Frequency Applications

    NASA Astrophysics Data System (ADS)

    Withanage, Wenura; Tan, Teng; Lee, Namhoon; Banjade, Huta; Eremeev, Grigory; Welander, Paul; Valente-Feliciano, Anne-Marie; Kustom, Robert; Wolak, Matthäus; Nassiri, Alireza; Xi, Xiaoxing

    We propose that coating the inner walls of copper RF cavities with superconducting MgB2 (Tc = 39 K) can result in a viable alternative to the already established niobium-based SRF technology. This approach improves the thermal conductivity, allows for operation at higher temperatures, and reduces the need for large helium refrigeration, thereby resulting in lower operational costs. For our studies, we grew MgB2 films via hybrid physical chemical vapor deposition (HPCVD) on 2'' Cu substrates. Since Mg and Cu readily form an alloy at higher temperatures, the HPCVD setup was modified in order to achieve lower deposition temperatures, minimize alloy formation, and provide high quality MgB2 films. This method yielded MgB2 coatings on 2'' Cu discs with transition temperatures around 38 K. The samples were characterized with regards to their RF attributes and showed similar performance in comparison to Nb reference samples. The presented results show that MgB2 coated copper can be a suitable alternative for use in SRF cavities.

  15. Thermographic in-situ process monitoring of the electron-beam melting technology used in additive manufacturing

    NASA Astrophysics Data System (ADS)

    Dinwiddie, Ralph B.; Dehoff, Ryan R.; Lloyd, Peter D.; Lowe, Larry E.; Ulrich, Joe B.

    2013-05-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  16. In situ dynamic tracking of heterogeneous nanocatalytic processes by shell-isolated nanoparticle-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Hua; Wang, Chen; Sun, Han-Lei; Fu, Gang; Chen, Shu; Zhang, Yue-Jiao; Chen, Bing-Hui; Anema, Jason R.; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

    2017-05-01

    Surface molecular information acquired in situ from a catalytic process can greatly promote the rational design of highly efficient catalysts by revealing structure-activity relationships and reaction mechanisms. Raman spectroscopy can provide this rich structural information, but normal Raman is not sensitive enough to detect trace active species adsorbed on the surface of catalysts. Here we develop a general method for in situ monitoring of heterogeneous catalytic processes through shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) satellite nanocomposites (Au-core silica-shell nanocatalyst-satellite structures), which are stable and have extremely high surface Raman sensitivity. By combining operando SHINERS with density functional theory calculations, we identify the working mechanisms for CO oxidation over PtFe and Pd nanocatalysts, which are typical low- and high-temperature catalysts, respectively. Active species, such as surface oxides, superoxide/peroxide species and Pd-C/Pt-C bonds are directly observed during the reactions. We demonstrate that in situ SHINERS can provide a deep understanding of the fundamental concepts of catalysis.

  17. In situ dynamic tracking of heterogeneous nanocatalytic processes by shell-isolated nanoparticle-enhanced Raman spectroscopy

    PubMed Central

    Zhang, Hua; Wang, Chen; Sun, Han-Lei; Fu, Gang; Chen, Shu; Zhang, Yue-Jiao; Chen, Bing-Hui; Anema, Jason R.; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

    2017-01-01

    Surface molecular information acquired in situ from a catalytic process can greatly promote the rational design of highly efficient catalysts by revealing structure-activity relationships and reaction mechanisms. Raman spectroscopy can provide this rich structural information, but normal Raman is not sensitive enough to detect trace active species adsorbed on the surface of catalysts. Here we develop a general method for in situ monitoring of heterogeneous catalytic processes through shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) satellite nanocomposites (Au-core silica-shell nanocatalyst-satellite structures), which are stable and have extremely high surface Raman sensitivity. By combining operando SHINERS with density functional theory calculations, we identify the working mechanisms for CO oxidation over PtFe and Pd nanocatalysts, which are typical low- and high-temperature catalysts, respectively. Active species, such as surface oxides, superoxide/peroxide species and Pd–C/Pt–C bonds are directly observed during the reactions. We demonstrate that in situ SHINERS can provide a deep understanding of the fundamental concepts of catalysis. PMID:28537269

  18. Determining the locus of a processing zone in an in situ oil shale retort by sound monitoring

    DOEpatents

    Elkington, W. Brice

    1978-01-01

    The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale is determined by monitoring for sound produced in the retort, preferably by monitoring for sound at at least two locations in a plane substantially normal to the direction of advancement of the processing zone. Monitoring can be effected by placing a sound transducer in a well extending through the formation adjacent the retort and/or in the fragmented mass such as in a well extending into the fragmented mass.

  19. Chemically sensitive amorphization process in the nanolaminated Cr2AC (A = Al or Ge) system from TEM in situ irradiation

    NASA Astrophysics Data System (ADS)

    Bugnet, Matthieu; Mauchamp, Vincent; Oliviero, Erwan; Jaouen, Michel; Cabioc'h, Thierry

    2013-10-01

    The effect of 320 keV Xe2+ ion-irradiation in Cr2AlC and Cr2GeC is investigated in situ in the transmission electron microscope. Both compounds amorphize at moderate fluences (1013-1014 Xe cm-2) but exhibit different amorphization mechanisms, bearing witness of the major influence of the chemical composition of the nanolaminated Mn+1AXn phases. It is proposed that amorphization takes place via a direct impact amorphization process in Cr2GeC whereas it is governed by a defect accumulation process in Cr2AlC.

  20. In situ monitoring of plasma etch processes with a quantum cascade laser arrangement in semiconductor industrial environment

    NASA Astrophysics Data System (ADS)

    Lang, N.; Röpcke, J.; Zimmermann, H.; Steinbach, A.; Wege, S.

    2009-03-01

    Concentrations of the etch product SiF4 were measured online and in situ in technological etch plasmas with an especially designed quantum cascade laser arrangement for application in semiconductor industrial environment, the Q-MACS Etch. The combination of quantum cascade lasers and infra red absorption spectroscopy (QCLAS) opens up new attractive possibilities for plasma process monitoring and control. With the realization of a specific interface the Q-MACS Etch system is synchronized to the etch process and allows therefore automated measurements, which is important in a high volume production environment.

  1. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    SciTech Connect

    Klug, Jeffrey A. Emery, Jonathan D.; Martinson, Alex B. F.; Proslier, Thomas; Weimer, Matthew S.; Yanguas-Gil, Angel; Elam, Jeffrey W.; Seifert, Sönke; Schlepütz, Christian M.; Hock, Adam S.

    2015-11-15

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er{sub 2}O{sub 3} ALD on amorphous ALD alumina and single crystalline sapphire.

  2. Sailing into uncharted waters: recent advances in the in situ monitoring of catalytic processes in aqueous environments

    SciTech Connect

    Shi, Hui; Lercher, Johannes A.; Yu, Xiao-Ying

    2015-01-01

    Catalysis in aqueous environments is attracting enormous interest. Many characterization methods are well established at gas-solid interfaces and a majority of the surface-science approaches were historically limited to model surfaces and vacuum conditions. However, practical scenarios with complex catalyst structures, elevated temperatures and pressures, as well as the presence of two or more condensed phases, can pose significant challenges to these techniques, particularly for catalysts at their dynamic working states. In such contexts, this review highlights the advances over the past five years in the in situ and real-time detection of catalytic processes and related phenomena in aqueous media, ideally under realistic conditions. We underline latest technical innovations, describe novel chemistries that are made accessible by recently developed toolboxes, and discuss future directions of in situ and time-resolved analytical approaches applicable to aqueous phase catalysis.

  3. A modular reactor design for in situ synchrotron X-ray investigation of atomic layer deposition processes

    SciTech Connect

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sonke; Schleputz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present \\textit{in situ} results for 1.) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, 2.) grazing-incidence small angle scattering of MnO nucleation on silicon, and 3.) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  4. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges.

    PubMed

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H

    2014-11-04

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp(2) carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations.

  5. Water dissociation in a radio-frequency electromagnetic field with ex situ electrodes—process characterization

    NASA Astrophysics Data System (ADS)

    Schneider, Jens; Holzer, Frank; Kraus, Markus; Kopinke, Frank-Dieter; Roland, Ulf

    2013-02-01

    A new type of water dissociation at ambient pressure initiated by the irradiation of aqueous electrolytes using an electromagnetic field with a frequency of 13.56 MHz is described in this study. A special reactor design allows the use of ex situ electrodes to form in situ electrical discharges in water vapour bubbles. The observed formation of molecular hydrogen (H2) and oxygen (O2) combined with the emission of light (‘burning water’ phenomenon) originates from a non-thermal plasma in water vapour bubbles. The influences of type of electrolyte, its concentration, pH value and external RF voltage on the gas formation rate as well as on the gas composition are presented.

  6. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges

    PubMed Central

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M.; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H.

    2014-01-01

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp2 carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations. PMID:25331874

  7. In situ flash x-ray high-speed computed tomography for the quantitative analysis of highly dynamic processes

    NASA Astrophysics Data System (ADS)

    Moser, Stefan; Nau, Siegfried; Salk, Manfred; Thoma, Klaus

    2014-02-01

    The in situ investigation of dynamic events, ranging from car crash to ballistics, often is key to the understanding of dynamic material behavior. In many cases the important processes and interactions happen on the scale of milli- to microseconds at speeds of 1000 m s-1 or more. Often, 3D information is necessary to fully capture and analyze all relevant effects. High-speed 3D-visualization techniques are thus required for the in situ analysis. 3D-capable optical high-speed methods often are impaired by luminous effects and dust, while flash x-ray based methods usually deliver only 2D data. In this paper, a novel 3D-capable flash x-ray based method, in situ flash x-ray high-speed computed tomography is presented. The method is capable of producing 3D reconstructions of high-speed processes based on an undersampled dataset consisting of only a few (typically 3 to 6) x-ray projections. The major challenges are identified, discussed and the chosen solution outlined. The application is illustrated with an exemplary application of a 1000 m s-1 high-speed impact event on the scale of microseconds. A quantitative analysis of the in situ measurement of the material fragments with a 3D reconstruction with 1 mm voxel size is presented and the results are discussed. The results show that the HSCT method allows gaining valuable visual and quantitative mechanical information for the understanding and interpretation of high-speed events.

  8. Aqueous dissolution of laboratory and field samples from the in-situ vitrification process

    SciTech Connect

    McGrail, B.P. ); Bates, S.O. )

    1991-08-01

    In-situ vitrification (ISV) is being evaluated in several countries as a remediation technology for immobilizing both hazardous and radioactive buried wastes. A combination of laboratory data and modeling results are presented that establishes the scientific basis for predicting the long-term stability of an ISV glass in the environment. Laboratory experiments included tests with ISV samples obtained from pilot- and intermediate-scale field tests, a nuclear waste glass, and a natural obsidian. 8 refs.

  9. In situ monitoring of a flash light sintering process using silver nano-ink for producing flexible electronics

    NASA Astrophysics Data System (ADS)

    Chung, Wan-Ho; Hwang, Hyun-Jun; Lee, Seung-Hyun; Kim, Hak-Sung

    2013-01-01

    In this work, a flash light sintering process using silver nano-inks is investigated. A silver nano-ink pattern was printed on a flexible PET (polyethylene terephthalate) substrate using a gravure-offset printing system. The printed silver nano-ink was sintered at room temperature and under ambient conditions using a flash of light from a xenon lamp using an in-house flash light sintering system. In order to monitor the light sintering process, a Wheatstone bridge electrical circuit was devised and changes in the voltage difference of the silver nano-ink were recorded during the sintering process using an oscilloscope. The sheet resistance changes during the sintering process were monitored using the in situ monitoring system devised, under various light conditions (e.g. light energy, on-time and off-time duration, and pulse numbers). The microstructure of the sintered silver film and the interface between the silver film and the PET substrate were observed using a scanning electron microscope, a focused ion beam and an optical microscope. The electrical sheet resistances of the sintered silver films were measured using a four-point probe method. Using the in situ monitoring system devised, the flash light sintering mechanism was studied for each type of light pulse (e.g. evaporation of organic binder followed by the forming of a neck-like junction and its growth, etc). The optimal flash light sintering condition is suggested on the basis of the in situ monitoring results. The optimized flash light sintering process produces a silver film with a lower sheet resistance (0.95 Ω/sq) compared with that of the thermally sintered silver film (2.03 Ω/sq) without damaging the PET substrate or allowing interfacial delamination between the silver film and the PET substrate.

  10. In situ monitoring of a flash light sintering process using silver nano-ink for producing flexible electronics.

    PubMed

    Chung, Wan-Ho; Hwang, Hyun-Jun; Lee, Seung-Hyun; Kim, Hak-Sung

    2013-01-25

    In this work, a flash light sintering process using silver nano-inks is investigated. A silver nano-ink pattern was printed on a flexible PET (polyethylene terephthalate) substrate using a gravure-offset printing system. The printed silver nano-ink was sintered at room temperature and under ambient conditions using a flash of light from a xenon lamp using an in-house flash light sintering system. In order to monitor the light sintering process, a Wheatstone bridge electrical circuit was devised and changes in the voltage difference of the silver nano-ink were recorded during the sintering process using an oscilloscope. The sheet resistance changes during the sintering process were monitored using the in situ monitoring system devised, under various light conditions (e.g. light energy, on-time and off-time duration, and pulse numbers). The microstructure of the sintered silver film and the interface between the silver film and the PET substrate were observed using a scanning electron microscope, a focused ion beam and an optical microscope. The electrical sheet resistances of the sintered silver films were measured using a four-point probe method. Using the in situ monitoring system devised, the flash light sintering mechanism was studied for each type of light pulse (e.g. evaporation of organic binder followed by the forming of a neck-like junction and its growth, etc).The optimal flash light sintering condition is suggested on the basis of the in situ monitoring results. The optimized flash light sintering process produces a silver film with a lower sheet resistance (0.95 Ω/sq) compared with that of the thermally sintered silver film (2.03 Ω/sq) without damaging the PET substrate or allowing interfacial delamination between the silver film and the PET substrate.

  11. Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

    SciTech Connect

    Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Muller, A. H.; Ramesh, R.

    1999-06-29

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal and retention loss in Pb(Zr{sub x}Ti{sub 1{minus}x})O{sub 3} (PZT)-based capacitors. Another powerful technique suitable for in situ, real-time characterization of film growth processes and ferroelectric film-based device operation is based on synchrotrons X-ray scattering, which is currently being implemented at Argonne National Laboratory.

  12. The impact of pre-analytical processing on staining quality for H&E, dual hapten, dual color in situ hybridization and fluorescent in situ hybridization assays.

    PubMed

    Babic, Andrea; Loftin, Isabell R; Stanislaw, Stacey; Wang, Maria; Miller, Rachel; Warren, Stephanie M; Zhang, Wenjun; Lau, Alexandria; Miller, Melanie; Wu, Ping; Padilla, Mary; Grogan, Thomas M; Pestic-Dragovich, Lidija; McElhinny, Abigail S

    2010-12-01

    With the advent of personalized medicine, anatomic pathology-based molecular assays, including in situ hybridization (ISH) and mRNA detection tests, are performed routinely in many laboratories and have increased in their clinical importance and complexity. These assays require appropriately fixed tissue samples that preserve both nucleic acid targets and histomorphology to ensure reliable test results for determining patient treatment options. However, all aspects of tissue processing, including time until tissue fixation, type of fixative, duration of fixation, post-fixation treatments, and sectioning of the sample, impact the staining results. ASCO/CAP has issued pre-analytical guidelines to standardize tissue processing for HER2 testing in breast carcinoma specimens: 10% neutral-buffered formalin (NBF) with a fixation time from at least 6 to 48h [1]. Often, this recommendation is not followed to the detriment of staining results [2]. In this paper, we used a human breast carcinoma cell line (MCF7) generated as xenograft tumors as a model system to analyze the effects of different pre-analytical conditions on ISH staining. We performed H&E, FISH and dual colorimetric HER2 ISH assays using specimens fixed across a range of times in six different commonly used fixatives. Additionally, we investigated the effects of varying tissue section thickness, which also impacted the quality of ISH staining. Finally, we evaluated the effects of three different decalcifying solutions on human breast specimens, typically a treatment that occurs post-fixation for evaluating metastases to bone. The results indicate that time and type of fixation treatment, as well as appropriate tissue thickness and post-fixation treatment, all contribute to the quality of ISH staining results. Our data support the ASCO/CAP recommendations for standardized tissue processing (at least 6h in formalin-based fixatives and 4μm section thickness) and indicate that certain fixatives and post

  13. Influence of twisting and bending on the Jc and n-value of multifilamentary MgB2 strands

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Li, G.; Susner, M.; Sumption, M. D.; Rindfleisch, M.; Tomsic, M.; Collings, E. W.

    2015-12-01

    The influences of strand twisting and bending (applied at room temperature) on the critical current densities, Jc, and n-values of MgB2 multifilamentary strands were evaluated at 4.2 K as function of applied field strength, B. Three types of MgB2 strand were evaluated: (i) advanced internal magnesium infiltration (AIMI)-processed strands with 18 filaments (AIMI-18), (ii) powder-in-tube (PIT) strands processed using a continuous tube forming and filling (CTFF) technique with 36 filaments (PIT-36) and (iii) CTFF processed PIT strands with 54 filaments (PIT-54). Transport measurements of Jc(B) and n-value at 4.2 K in fields of up to 10 T were made on: (i) PIT-54 after it was twisted (at room temperature) to twist pitch values, Lp, of 10-100 mm. Transport measurements of Jc(B) and n-value were performed at 4.2 K; (ii) PIT-36 and AIMI-18 after applying bending strains up to 0.6% at room temperature. PIT-54 twisted to pitches of 100 mm down to 10 mm exhibited no degradation in Jc(B) and only small changes in n-value. Both the Jc(B) and n-value of PIT-36 were seen to be tolerant to bending strain of up to 0.4%. On the other hand, AIMI-18 showed ±10% changes in Jc(B) and significant scatter in n-value over the bending strain range of 0-0.6%.

  14. Influence of Twisting and Bending on the Jc and n-value of Multifilamentary MgB2 Strands.

    PubMed

    Yang, Y; Li, G; Susner, M; Sumption, M D; Rindfleisch, M; Tomsic, M; Collings, E W

    2015-12-15

    The influences of strand twisting and bending (applied at room temperature) on the critical current densities, Jc , and n-values of MgB2 multifilamentary strands were evaluated at 4.2 K as function of applied field strength, B. Three types of MgB2 strand were evaluated: (i) advanced internal magnesium infiltration (AIMI)-processed strands with 18 filaments (AIMI-18), (ii) powder-in-tube (PIT) strands processed using a continuous tube forming and filling (CTFF) technique with 36 filaments (PIT-36) and (iii) CTFF processed PIT strands with 54 filaments (PIT-54). Transport measurements of Jc(B) and n-value at 4.2 K in fields of up to 10 T were made on: (i) PIT-54 after it was twisted (at room temperature) to twist pitch values, Lp , of 10-100 mm. Transport measurements of Jc(B) and n-value were performed at 4.2 K; (ii) PIT-36 and AIMI-18 after applying bending strains up to 0.6% at room temperature. PIT-54 twisted to pitches of 100 mm down to 10 mm exhibited no degradation in Jc(B) and only small changes in n-value. Both the Jc(B) and n-value of PIT-36 were seen to be tolerant to bending strain of up to 0.4%. On the other hand, AIMI-18 showed ±10% changes in Jc(B) and significant scatter in n-value over the bending strain range of 0-0.6%.

  15. Electric transport measurements on bulk, polycrystalline MgB2 samples prepared at various reaction temperatures

    NASA Astrophysics Data System (ADS)

    Wiederhold, A.; Koblischka, M. R.; Inoue, K.; Muralidhar, M.; Murakami, M.; Hartmann, U.

    2016-03-01

    A series of disk-shaped, bulk MgB2 superconductors (sample diameter up to 4 cm) was prepared in order to improve the performance for superconducting super-magnets. Several samples were fabricated using a solid state reaction in pure Ar atmosphere from 750 to 950oC in order to determine the optimum processing parameters to obtain the highest critical current density as well as large trapped field values. Additional samples were prepared with added silver (up to 10 wt.-%) to the Mg and B powder. Magneto-resistance data and I/V-characteristics were recorded using an Oxford Instruments Teslatron system. From Arrhenius plots, we determine the TAFF pinning potential, U 0. The I/V-characteristics yield detailed information on the current flow through the polycrystalline samples. The current flow is influenced by the presence of pores in the samples. Our analysis of the achieved critical currents together with a thorough microstructure investigation reveals that the samples prepared at temperatures between 775°C and 805°C exhibit the smallest grains and the best connectivity between them, while the samples fabricated at higher reaction temperatures show a reduced connectivity and lower pinning potential. Doping the samples with silver leads to a considerable increase of the pinning potential and hence, the critical current densities.

  16. Selected properties of GlidCop® sheathed MgB2 wires

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Melišek, T.; Kopera, L.; Kováč, J.; Hušek, I.

    2012-09-01

    GlidCop® sheathed MgB2 wires containing 1-30 filaments have been manufactured by a powder-in-tube process. Two materials (Nb or Ti) have been used for barriers protecting the filaments against the diffusion of copper. Different deformations (drawing, rolling, rotary swaging and isostatic pressing) have been applied to the 30-filament wires prior to the final heat treatment. Critical current densities, Jc, were measured at low external magnetic fields including the self-field and at temperatures from 4.2 to 20 K by a short pulse currents. This allows a detailed pinning force analysis to be made, which has not been done up to now from the transport current data. The resistance of 1-30 filament wires against axial tensile stress has also been examined at 4.2 K. It was found that filament density influences not only the transport Jc but also the resistance to tension stress. While an increased filament density improves Jc the opposite effect has been found for resistance to axial tension. AC losses measured by a calibration-free technique of non-twisted wires have shown the dominant effect of the filament architecture and critical current densities.

  17. Preferentially grown nanostructured MgB2C2: A new material for lightening applications

    NASA Astrophysics Data System (ADS)

    Singh, Paviter; Singh, Kulwinder; Kaur, Manpreet; Kaur, Harpreet; Singh, Bikmramjeet; Kaur, Gurpreet; Kaur, Manjot; Kumar, Manjeet; Kaur, Kamalpreet; Bala, Rajni; Kumar, Akshay

    2017-03-01

    Nanostructured MgB2C2 is a promising candidate as functional material. High Temperature synthesis conditions were the limitations for its exploitation in materials research. Present study deals with the synthesis of specifically oriented nanostructured MgB2C2 at relatively low temperature by solvothermal route. The synthesis conditions are modified to grow these nanostructures in least dense plane (002). Optical properties are explored for the first time. XRD analysis confirms the formation of MgB2C2 phase. Morphological analysis (Transmission/Scanning Electron Microscopy) indicated that the synthesized material is in nano range. Photoluminescence study shows that the synthesized material emits light in visible spectrum when excited at 380 nm. The quantum efficiency of synthesized material calculated by De Mello's method is approximately 23% which makes the material efficient enough for lightening applications.

  18. Status of MgB2 wire and cable applications in Europe

    NASA Astrophysics Data System (ADS)

    Ballarino, A.; Flükiger, R.

    2017-07-01

    Since its discovery in 2001, MgB2 has generated interest for practical applications. Its availability in the form of multifilamentary round wire makes it suitable for production of cables. Together with relatively high critical temperature and potential low-cost, this renders it appealing for use in superconducting devices where its limited in-field performance can be tolerated. The state-of-the-art properties of commercially available wire and the potential of MgB2 conductors for use in superconducting systems are discussed. An overview of high-current electrical transmission projects where MgB2 has been proposed as an alternative to conventional Nb-Ti or High Temperature Superconductors is presented.

  19. Three-dimensional MgB2-type superconductivity in hole-doped diamond.

    PubMed

    Boeri, Lilia; Kortus, Jens; Andersen, O K

    2004-12-03

    We substantiate by numerical and analytical calculations that the recently discovered superconductivity below 4 K in 3% boron-doped diamond is caused by electron-phonon coupling of the same type as in MgB2, albeit in three dimensions. Holes at the top of the zone-centered, degenerate sigma-bonding valence-band couple strongly to the optical bond-stretching modes. The increase from two to three dimensions reduces the mode softening crucial for T(c) reaching 40 K in MgB2. Even if diamond had the same bare coupling constant as MgB2, which could be achieved with 10% doping, T(c) would be only 25 K. Superconductivity above 1 K in Si (Ge) requires hole doping beyond 5% (10%).

  20. Surface impedance measurements of single crystal MgB2 films for radiofrequency superconductivity applications

    NASA Astrophysics Data System (ADS)

    Xiao, B. P.; Zhao, X.; Spradlin, J.; Reece, C. E.; Kelley, M. J.; Tan, T.; Xi, X. X.

    2012-09-01

    We report microstructure analyses and superconducting radiofrequency (SRF) measurements of macroscopic scale epitaxial MgB2 films. MgB2 films on 5 cm diameter sapphire disks were fabricated by a hybrid physical chemical vapor deposition (HPCVD) technique. The electron-beam backscattering diffraction (EBSD) results suggest that the film is a single crystal complying with a MgB2(0001)∥ Al2O3(0001) epitaxial relationship. The SRF properties of different film thicknesses (200 and 350 nm) were evaluated under different temperatures and applied fields at 7.4 GHz. A surface resistance of 9 ± 2 μΩ has been observed at 2.2 K.

  1. Fabrication of superconducting nanowires from ultrathin MgB2 films via focused ion beam milling

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Wang, Da; Liu, Zheng-Hao; Zhang, Yan; Ma, Ping; Feng, Qing-Rong; Wang, Yue; Gan, Zi-Zhao

    2015-02-01

    High quality superconducting nanowires were fabricated from ultrathin MgB2 films by a focused ion beam milling technique. The precursor MgB2 films in 10 nm thick were grown on MgO substrates by using a hybrid physical-chemical vapor deposition method. The nanowires, in widths of about 300-600 nm and lengths of 1 or 10 μm, showed high superconducting critical temperatures (Tc's) above 34 K and narrow superconducting transition widths (ΔTc's) of 1-3 K. The superconducting critical current density Jc of the nanowires was above 5 × 107 A/cm2 at 20 K. The high Tc, narrow ΔTc, and high Jc of the nanowires offered the possibility of making MgB2-based nano-devices such as hot-electron bolometers and superconducting nanowire single-photon detectors with high operating temperatures at 15-20 K.

  2. Superconductivity of MgB 2 with embedded multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yeoh, W. K.; Xu, X.; Dou, S. X.; Munroe, P.; Rindfleisch, M.; Tomsic, M.

    2006-11-01

    We studied the effects of MgB2 with embedded multiwall carbon nanotubes (MWCNTs) on the crystallinity, lattice parameters, critical current density (Jc), upper critical field (Hc2), irreversibility field (Hirr), and microstructure of MgB2. Fe sheathed un-doped and MWCNT doped MgB2 wires were fabricated by the powder-in-tube (PIT) method and sintered at the high sintering temperatures of 900 °C. We observed that for the MWCNT doped sample high temperature sintering resulted in depressed crystallinity, shrinkage of the a-lattice parameter, higher Jc up to 12 T, and lower critical temperature (Tc) values. Specifically, MWCNT doped samples sintered at 900 °C exhibited excellent Jc, ∼104 A cm-2 up to 9 T at 4.2 K. This can be explained by lattice distortion and poor crystallinity due to carbon (C) substitution from the MWCNT.

  3. Retention of two-band superconductivity in highly carbon-doped MgB2

    NASA Astrophysics Data System (ADS)

    Schmidt, H.; Gray, K. E.; Hinks, D. G.; Zasadzinski, J. F.; Avdeev, M.; Jorgensen, J. D.; Burley, J. C.

    2003-08-01

    Tunneling data on MgB1.8C0.2 show a reduction in the energy gap of the π bands by nearly a factor of 2 from undoped MgB2 that is consistent with the Tc reduction, but inconsistent with the expectations of the dirty limit. Dirty-limit theory for undoped MgB2 predicts a single gap about three times larger than measured and a reduced Tc comparable to that measured. Our heavily doped samples exhibit a uniform dispersion of C suggestive of significantly enhanced scattering, and we conclude that the retention of two-band superconductivity in these samples is caused by a selective suppression of interband scattering.

  4. In situ monitoring and control of moisture content in pharmaceutical powder processes using an open-ended coaxial probe

    NASA Astrophysics Data System (ADS)

    Gradinarsky, Lubomir; Brage, Henric; Lagerholm, Bengt; Niklasson Björn, Ingela; Folestad, Staffan

    2006-07-01

    An analysis of microwave measurements of the complex dielectric constant of different mixtures of pharmaceutical materials using an open-ended coaxial probe is presented. Using the probe in combination with a network analyser, measurements in the frequency range of 1-19 GHz were conducted. Calibration measurements on conditioned samples were first acquired in a controlled laboratory environment, and then in situ measurements, taken in a small-scale high-shear mixer, were also obtained. The dominating material in the investigated mixtures was microcrystalline cellulose. By using the suggested microwave method, a novel possibility for in situ measurements of the initial moisture content of the powder mixture before and at the beginning of the water addition stage is demonstrated. In situ density-independent estimation of the moisture content having a relative error of below 10% for the moisture interval of 2-14% is demonstrated. The possibility of performing an adaptive control of the evolution of the mixing process by utilizing the microwave sensor information is also presented.

  5. Development of 2-D Array of Superconducting Magnesium Diboride (MgB2) for Far-IR Investigations of the Outer Planets and Icy Moons

    NASA Astrophysics Data System (ADS)

    Lakew, Brook

    2009-09-01

    A 2-D array of superconducting Magnesium Diboride(MgB2) far -IR thermal detectors has been fabricated. Such an array is intended to be at the focal plane of future generation thermal imaging far-IR instruments that will investigate the outer planets and their icy moons. Fabrication and processing of the pixels of the array as well as noise characterization of architectured MgB2 thin films will be presented. Challenges and solutions for improving the performance of the array will be discussed.

  6. Development of CFD-Based Simulation Tools for In-Situ Thermal Processing of Oil Shale/Sands

    SciTech Connect

    None, None

    2012-02-01

    In our research, we are taking the novel approach of developing and applying high performance computing, computational fluid dynamics (CFD)-based simulation tools to a modified in-situ process for production of oil from oil shale. The simulation tools being developed capture the relevant physical processes and data from a large-scale system. The modified in-situ application is a pilot-scale heat transfer process inside Red Leaf Resources EcoShale capsule. We demonstrate the need to understand fluid flow behavior in the convective channels of the rubblized shale bed as convective heating greatly decreases the time required to heat the oil shale to the production temperature when compared with conductive heating alone. We have developed and implemented a geometry creation strategy for a representative section of the EcoShale capsule, developed a meshing approach to deal with the complicated geometry and produce a well-behaved mesh, analyzed the effects of boundary conditions on the simulation results, and devised a new operator splitting solution algorithm that reduces computational costs by taking advantage of the differing convective and conductive time scales occurring in the simulation. These simulation tools can be applied to a wide range of processes involving convective fluid flow heating in rubblized beds.

  7. Suppression of superconductivity in epitaxial MgB2 ultrathin films

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Wang, Yue; Wang, Da; Zhang, Yan; Liu, Zheng-Hao; Feng, Qing-Rong; Gan, Zi-Zhao

    2013-07-01

    MgB2 ultrathin films have potential to make sensitive superconducting devices such as superconducting single-photon detectors working at relatively high temperatures. We have grown epitaxial MgB2 films in thicknesses ranging from about 40 nm to 6 nm by using the hybrid physical-chemical vapor deposition method and performed electrical transport measurements to study the thickness dependence of the superconducting critical temperature Tc. With reducing film thickness d, although a weak depression of the Tc has been observed, which could be attributed to an increase of disorder (interband impurity scattering) in the film, the Tc retains close to the bulk value of MgB2 (39 K), being about 35 K in the film of 6 nm thick. We show that this result, beneficial to the application of MgB2 ultrathin films and in accordance with recent theoretical calculations, is in contrast to previous findings in MgB2 films prepared by other methods such as co-evaporation and molecular-beam epitaxy, where a severe Tc suppression has been observed with Tc about one third of the bulk value in films of ˜5 nm thick. We discuss this apparent discrepancy in experiments and suggest that, towards the ultrathin limit, the different degrees of Tc suppression displayed in currently obtained MgB2 films by various techniques may arise from the different levels of disorder present in the film or different extents of proximity effect at the film surface or film-substrate interface.

  8. Lightweight MgB2 superconducting 10 MW wind generator

    NASA Astrophysics Data System (ADS)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  9. Microwave Properties of Superconducting MgB_2

    NASA Astrophysics Data System (ADS)

    Sridhar, S.

    2002-03-01

    The electrodynamic response of MgB2 at microwave (GHz) and radio (MHz) frequencies is important both for fundamental physics and for technological applications. In the Meissner state, precision microwave measurements of the penetration depth and surface resistance on thin films and bulk samples are analyzed. The microwave results thus far are consistent with a gapped superconductor, however the gap value deduced is much smaller than the mean-field BCS value. The relationship of experimental data and current theories of superconductivity in terms of the gap parameter, quasiparticles, and penetration depth in this material will be discussed. In the mixed state induced by a static magnetic field, radiofrequency (MHz) measurements probe fundamental aspects of vortex dynamics. The measurements yield quantitative results for parameters such as pinning force constants, vortex viscosity, and critical fields, and have led to the observation of a field-induced crossover from pinning to flow at a field scale H*(T) close to the irreversibility line. The entire field- and temperature-dependent behavior of the rf penetration depth is well described by a quantitative model of dynamic response of vortex diffusion in the presence of a field-dependent barrier, which softens with increasing magnetic field. The relationship of material microstructure to available microwave data, and the prospects and status of microwave device applications will be discussed. Work supported by the Office of Naval Research.

  10. In situ optical diagnostics of growing surfaces in the process of nanoheterostructure fabrication

    SciTech Connect

    Kazakov, I. P. Glazyrin, E. V.; Savinov, S. A.; Tsekhosh, V. I.; Shmelev, S. S.

    2010-11-15

    It is demonstrated that in situ reflectance and reflectance-anisotropy measurements can be used as efficient real-time monitoring tools for all stages of the growth of heterostructures with ultrathin (few-monolayer) GaAs and AlAs layers. Changes in the layer composition at normal GaAs/AlAs interfaces in the active region of resonant-tunneling diode structures are detected with a thickness resolution on the order of one monolayer. Resonant-tunneling diodes with a peak-to-valley ratio of 3.3 and peak current density of 6.6 x 10{sup 4} A/cm{sup 2} are fabricated.

  11. High-temperature ultrasonic sensor for in-situ monitoring of hot isostatic processing

    NASA Astrophysics Data System (ADS)

    Stubbs, David A.; Dutton, Rollie E.

    1996-11-01

    A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900 degrees C and pressures above 150 MPa. The sensor is based on a unique form of aluminum nitride that retains tits piezoelectric properties at high temperatures. The sensor works with standard ultrasonic pulse-receivers and has demonstrated the capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and coupling of the ultrasound to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs and at elevated temperatures in air are presented.

  12. Low-Temperature Synthesis of Superconducting Nanocrystalline MgB 2

    DOE PAGES

    Lu, Jun; Xiao, Zhili; Lin, Qiyin; ...

    2010-01-01

    Magnesium diboride (MgB 2 ) is considered a promising material for practical application in superconducting devices, with a transition temperature near 40 K. In the present paper, nanocrystalline MgB 2 with an average particle size of approximately 70 nm is synthesized by reacting LiBH 4 with MgH 2 at temperatures as low as 450 ° C. This synthesis approach successfully bypasses the usage of either elemental boron or toxic diborane gas. The superconductivity of the nanostructures is confirmed by magnetization measurements, showing a superconducting critical temperature of 38.7 K.

  13. Transport behavior and critical current densities in MgB2 wires

    NASA Astrophysics Data System (ADS)

    Pradhan, A. K.; Feng, Y.; Zhao, Y.; Koshizuka, N.; Zhou, L.; Zhang, P. X.; Liu, X. H.; Ji, P.; Du, S. J.; Liu, C. F.

    2001-09-01

    We report on the transport and magnetization properties of MgB2 wires fabricated by a powder-in-tube (PIT) technique. Temperature and magnetic-field-dependent resistivity displays a high conductivity and upper critical field Hc2 generally observed in dense samples. The electronic mass anisotropy γ≈1.3±0.15 predicts some texturing in the wire. Our data on transition temperature TC, Hc2, and both magnetic and transport critical current density Jc indicate that MgB2 can be manufactured in a wire form using a PIT technique and required engineering Jc can be achieved on further optimization.

  14. Effect of heat-treatment temperatures on density and porosity in MgB 2 superconductor

    NASA Astrophysics Data System (ADS)

    Liu, C. F.; Yan, G.; Du, S. J.; Xi, W.; Feng, Y.; Zhang, P. X.; Wu, X. Z.; Zhou, L.

    2003-04-01

    The density, porosity, and microstructures of MgB 2 samples are very important factors for transition critical current density. The effect of heat-treatment temperatures on density and porosity in MgB 2 superconductors has been investigated. The open porosity increases with increasing heat-treatment temperatures, but close porosity decreases. The calculated theory densities from the lattice parameters of the measured samples are 2.6-2.63 g/cm 3. The average measured total porosity (including open and close porosity) is about 50%.

  15. Preparation of MgB2 superconducting microbridges by focused ion beam direct milling

    NASA Astrophysics Data System (ADS)

    Zhang, Xuena; Li, Yanli; Xu, Zhuang; Kong, Xiangdong; Han, Li

    2017-01-01

    MgB2 superconducting microbridges were prepared by focused ion beam (FIB) direct milling on MgB2 films. The surface topography of the microbridges were observed using SEM and AFM and the superconductivity was measured in this paper. Lots of cracks and holes were found near the milled area. And the superconducting transition temperature was decreased a lot and the bridges prepared were not superconducting due to ion damage after milled with large dose. Through these works, we explored the effect regular of FIB milling and experimental parameters on the performance of microbridges.

  16. MgB2 ultrathin films fabricated by hybrid physical chemical vapor deposition and ion milling

    NASA Astrophysics Data System (ADS)

    Acharya, Narendra; Wolak, Matthäus A.; Tan, Teng; Lee, Namhoon; Lang, Andrew C.; Taheri, Mitra; Cunnane, Dan; Karasik, Boris. S.; Xi, X. X.

    2016-08-01

    In this letter, we report on the structural and transport measurements of ultrathin MgB2 films grown by hybrid physical-chemical vapor deposition followed by low incident angle Ar ion milling. The ultrathin films as thin as 1.8 nm, or 6 unit cells, exhibit excellent superconducting properties such as high critical temperature (Tc) and high critical current density (Jc). The results show the great potential of these ultrathin films for superconducting devices and present a possibility to explore superconductivity in MgB2 at the 2D limit.

  17. Preparation and properties of amorphous MgB2/MgO superstructures: Model disordered superconductor

    NASA Astrophysics Data System (ADS)

    Siemons, W.; Steiner, M. A.; Koster, G.; Blank, D. H. A.; Beasley, M. R.; Kapitulnik, A.

    2008-05-01

    In this paper, we introduce a unique method for fabricating MgB2/MgO multilayers and demonstrate the potential for using them as a new model for disordered superconductors. In this approach, we control the annealing of the MgB2 to yield an interesting new class of disordered (amorphous) superconductors with relatively high transition temperatures. The multilayers appear to exhibit quasi-two-dimensional superconductivity with controlled anisotropy. We discuss the properties of the multilayers as the thickness of the components of the bilayers vary.

  18. Tunneling spectroscopy and magnetization measurements of the superconducting properties of MgB2

    NASA Astrophysics Data System (ADS)

    Sharoni, Amos; Felner, Israel; Millo, Oded

    2001-06-01

    Cryogenic scanning tunneling microscopy and magnetization measurements were used to study the superconducting properties of MgB2. The magnetization measurements show a sharp superconductor transition at Tc=39 K, in agreement with previous works. The tunneling spectra exhibit BCS-like gap structures, with gap parameters in the range of 5 to 7 meV, yielding a ratio of 2Δ/kBTc~3-4. This suggests that MgB2 is a conventional BCS s-wave superconductor, either in the weak-coupling or in the ``intermediate-coupling'' regime.

  19. In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth.

    PubMed

    Luo, Jun; Martinez-Casado, Francisco Javier; Balmes, Olivier; Yang, Jiaojiao; Persson, Cecilia; Engqvist, Håkan; Xia, Wei

    2017-09-26

    Brushite cements are fast self-setting materials that can be used as bone substitute materials. While tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material's further development and use in the clinics. In this study, the setting rate, phase formation and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy (SEM) was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to micro scale within 1 min and the brushite content increased linearly after the nucleation until all MCPM (monocalcium phosphate monohydrate; Ca(H2PO4)2ˑH2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to β-TCP (β-tricalcium phosphate; β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, while the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

  20. Laser processing of in situ TiN/Ti composite coating on titanium.

    PubMed

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding.

  1. In situ biosynthesis of bacterial nanocellulose-CaCO3 hybrid bionanocomposite: One-step process.

    PubMed

    Mohammadkazemi, Faranak; Faria, Marisa; Cordeiro, Nereida

    2016-08-01

    In this work, a simple and green route to the synthesis of the bacterial nanocellulose-calcium carbonate (BNC/CaCO3) hybrid bionanocomposites using one-step in situ biosynthesis was studied. The CaCO3 was incorporated in the bacterial nanocellulose structure during the cellulose biosynthesis by Gluconacetobacter xylinus PTCC 1734 bacteria. Hestrin-Schramm (HS) and Zhou (Z) culture media were used to the hybrid bionanocomposites production and the effect of ethanol addition was investigated. Attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, inverse gas chromatography and thermogravimetric analysis were used to characterize the samples. The experimental results demonstrated that the ethanol and culture medium play an important role in the BNC/CaCO3 hybrid bionanocomposites production, structure and properties. The BNC/CaCO3 biosynthesized in Z culture medium revealed higher O/C ratio and amphoteric surface character, which justify the highest CaCO3 content incorporation. The CaCO3 was incorporated into the cellulosic matrix decreasing the bacterial nanocellulose crystallinity. This work reveals the high potential of in situ biosynthesis of BNC/CaCO3 hybrid bionanocomposites and opens a new way to the high value-added applications of bacterial nanocellulose.

  2. Simulations on the gelling process of particle suspension systems for in-situ preparing porous materials in a capillary

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, J. J.; Yang, Y.; Wang, X. J.; Luo, X.; Zhang, L.; Jiang, G.

    2015-10-01

    The gelling process of particle suspension in a capillary which is crucial for in-situ preparing small size foam products has been simulated with an off-lattice diffusion limited cluster aggregation (DLCA) model by the three-dimensional Monte Carlo simulations. The effects of the model parameters, such as the interaction between capillary wall and particles, particle volume fraction, capillary size etc. on the density distribution of the system have been fully explored. And the aggregation kinetics process over a broad range of volume fractions and interactions have also been discussed. The results show that the geometric constraint of capillary can be analogous to a weak repulsive interaction between capillary wall and particles. And we found that as the capillary size or particle volume fraction increase, particle concentration distribution will be more uniform with other parameters constant. Porous network with relatively uniform density distribution can be also obtained through controlling the interaction between capillary wall and particles. In addition, by analyzing the aggregation kinetics process, we found that the attraction of capillary wall dramatically reduces the probability of gelation in the small-scale capillary. The obtained results will be of great importance in controlling the density distribution of porous materials prepared by in-situ methods.

  3. In situ monitoring of the seed stage of a fermentation process using non-invasive NIR spectrometry.

    PubMed

    Nordon, Alison; Littlejohn, David; Dann, Alison S; Jeffkins, Paul A; Richardson, Mark D; Stimpson, Sarah L

    2008-05-01

    Non-invasive NIR spectrometry has been used to monitor in situ the seed stage of a streptomyces fermentation process. The main spectral change occurred at 7263 cm(-1) in the 1st derivative spectrum, and from comparison with off-line NIR spectra acquired of components present in the fermentation broth, can be attributed to biomass. The biomass signal was constant for the first 20 h of the seed stage, after which it decreased before increasing again. The time at which the minimum occurred in the NIR profile was either the same or slightly earlier than that at which a maximum in the carbon dioxide evolution rate (CER) occurred. The changes observed for the biomass signal in the NIR spectra can be attributed to growth and then fragmentation of mycelia, which indicates a change in metabolic activity. Hence, it may be possible to use NIR spectrometry in situ to determine the optimum transfer time for the seed stage of a fermentation process. Spectra were also acquired of the final stage of the same fermentation process. The variation in the biomass signal in the NIR spectra was more complicated in the final stage owing to changes in stir rate, and biomass concentration and morphology.

  4. In situ study of key material and process reliability issues in the chemical vapor deposition of copper

    NASA Astrophysics Data System (ADS)

    Lou, Ishing

    With the limitations of current aluminum based metallization schemes used in microelectronics, the development of a manufacturable chemical vapor deposition (CVD) process for copper metallization schemes is crucial to meet the stringent requirements of sub-quarter micron device technology and beyond. The work presented herein focused on investigating key material and process reliability issues pertaining to Cu CVD processing. In particular, a unique combination of in-situ gas phase Fourier transform infrared (FTIR) and quadrupole mass spectrometry (QMS) was employed to study the role of hydrogen in thermal CVD of copper using (tmvs)Cusp{I}(hfac). These studies showed that hydrogen provides significant enhancement in the deposition rate of copper interconnects. Based on the QMS and FTIR data, this enhancement could be attributed to the role of hydrogen in assisting in the removal of tmvs from (tmvs)Cusp{I}(hfac), thus enhancing the conversion of Cusp{I}(hfac) intermediates to Cusp{o} and Cusp{II}(hfac)sb2 and providing a wider process window with higher conversion efficiency. In addition, in-situ real time QMS studies were performed of the gas phase evolution and decomposition pathways of (tmvs)Cusp{I}(hfac) during thermal CVD of copper. The QMS investigations focused on determining the ionization efficiency curves and appearance potentials of (tmvs)Cusp{I}(hfac) under real CVD processing conditions. The resulting curves and associated potentials were then employed to identify the most likely precursor decomposition pathways and examine relevant implications for thermal CVD of copper from (tmvs)Cusp{I}(hfac). Finally, a hydrogen-plasma assisted CVD (PACVD) process was developed for the growth of device quality gold for incorporation as dopant in emerging Cu CVD based metallization interconnects. In particular, it was demonstrated that the PACVD gold process window identified can maintain very low gold deposition rates (<30 A/min). As such, PACVD gold is a promising

  5. Estimation of hysteretic losses for MgB2 tapes under the operating conditions of a generator

    NASA Astrophysics Data System (ADS)

    Vargas-Llanos, Carlos Roberto; Zermeño, Víctor M. R.; Sanz, Santiago; Trillaud, Frederic; Grilli, Francesco

    2016-03-01

    Hysteretic losses in the MgB2 wound superconducting coils of a 550 kW synchronous hybrid scaled generator were estimated as part of the European project SUPRAPOWER led by the Spanish Fundación Tecnalia Research & Innovation. Particular interest was given to the losses caused by the magnetic flux ripples in the rotor coils originating from the conventional stator during nominal operation. To compute these losses, a 2D finite element analysis was conducted and Maxwell’s equations written in the H-formulation were solved considering the nonlinear material properties of the conductor materials. The modeled tapes are made of multiple MgB2 filaments embedded in a Ni matrix and soldered to a high purity copper strip and insulated with Dacron braid. Three geometrical models of single tape cross sections of decreasing complexity were studied: (1) the first model reproduced closely the actual cross section obtained from tape micrographs. (2) The second model was obtained from the computed elasto-plastic deformation of a round Ni wire. (3) The third model was based on a simplified cross section with the superconducting filaments bundled in a single elliptical bulky structure. The last geometry allowed the validation of the modeling technique by comparing numerical losses with results from well-established analytical expressions. Additionally, the following cases of filament transpositions of the multi-filamentary tape were studied: no transposition, partial and full transposition; thereby improving understanding of the relevance of the tape fabrication process on the magnitude of the determination of ac losses. Finally, choosing the right level of geometrical detail, the following operational regimes of the machine and its impact on individual superconducting tape losses in the rotor were studied: bias-dc current, ramping current under ramping background field and magnetic flux ripples under dc background current and field.

  6. Assessing microbial processes in deep-sea hydrothermal systems by incubation at in situ temperature and pressure

    NASA Astrophysics Data System (ADS)

    McNichol, Jesse; Sylva, Sean P.; Thomas, François; Taylor, Craig D.; Sievert, Stefan M.; Seewald, Jeffrey S.

    2016-09-01

    At deep-sea hydrothermal vents, a large source of potential chemical energy is created when reducing vent fluid and oxidizing seawater mix. In this environment, chemolithoautotrophic microbes catalyze exergonic redox reactions which in turn provide the energy needed to fuel their growth and the fixation of CO2 into biomass. In addition to producing new organic matter, this process also consumes compounds contained both in vent fluid and entrained seawater (e.g. H2, NO3-). Despite their biogeochemical importance, such reactions have remained difficult to quantify due to methodological limitations. To address this knowledge gap, this study reports a novel application of isobaric gas-tight fluid samplers for conducting incubations of hydrothermal vent fluids at in situ temperature and pressure. Eighteen 24 h incubations were carried out, representing seven distinct conditions that examine amendments consisting of different electron donors and acceptors. Microbial activity was observed in all treatments, and time series chemical measurements showed that activity was limited by electron acceptor supply, confirming predictions based on geochemical data. Also consistent with these predictions, the presence of nitrate increased rates of hydrogen consumption and yielded ammonium as a product of nitrate respiration. The stoichiometry of predicted redox reactions was also determined, revealing that the sulfur and nitrogen cycles are incompletely understood at deep-sea vents, and likely involve unknown intermediate redox species. Finally, the measured rates of redox processes were either equal to or far greater than what has been reported in previous studies where in situ conditions were not maintained. In addition to providing insights into deep-sea hydrothermal vent biogeochemistry, the methods described herein also offer a practical approach for the incubation of any deep-sea pelagic sample under in situ conditions.

  7. SMV1 virus-induced CRISPR spacer acquisition from the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2.

    PubMed

    Erdmann, Susanne; Shah, Shiraz A; Garrett, Roger A

    2013-12-01

    Organisms of the crenarchaeal order Sulfolobales carry complex CRISPR (clustered regularly interspaced short palindromic repeats) adaptive immune systems. These systems are modular and show extensive structural and functional diversity, especially in their interference complexes. The primary targets are an exceptional range of diverse viruses, many of which propagate stably within cells and follow lytic life cycles without producing cell lysis. These properties are consistent with the difficulty of activating CRISPR spacer uptake in the laboratory, but appear to conflict with the high complexity and diversity of the CRISPR immune systems that are found among the Sulfolobales. In the present article, we re-examine the first successful induction of archaeal spacer acquisition in our laboratory that occurred exclusively for the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2 that was co-infected with the virus SMV1 (Sulfolobus monocaudavirus 1). Although we reaffirm that protospacer selection is essentially a random process with respect to the pMGB1 genome, we identified single spacer sequences specific for each of CRISPR loci C, D and E that, exceptionally, occurred in many sequenced clones. Moreover, the same sequence was reproducibly acquired for a given locus in independent experiments, consistent with it being the first protospacer to be selected. There was also a small protospacer bias (1.6:1) to the antisense strand of protein genes. In addition, new experiments demonstrated that spacer acquisition in the previously inactive CRISPR locus A could be induced on freeze-thawing of the infected cells, suggesting that environmental stress can facilitate activation. Coincidentally with spacer acquisition, a mobile OrfB element was deleted from pMGB1, suggesting that interplay can occur between spacer acquisition and transposition.

  8. SMV1 virus-induced CRISPR spacer acquisition from the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2

    PubMed Central

    Erdmann, Susanne; Shah, Shiraz A.; Garrett, Roger A.

    2013-01-01

    Organisms of the crenarchaeal order Sulfolobales carry complex CRISPR (clustered regularly interspaced short palindromic repeats) adaptive immune systems. These systems are modular and show extensive structural and functional diversity, especially in their interference complexes. The primary targets are an exceptional range of diverse viruses, many of which propagate stably within cells and follow lytic life cycles without producing cell lysis. These properties are consistent with the difficulty of activating CRISPR spacer uptake in the laboratory, but appear to conflict with the high complexity and diversity of the CRISPR immune systems that are found among the Sulfolobales. In the present article, we re-examine the first successful induction of archaeal spacer acquisition in our laboratory that occurred exclusively for the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2 that was co-infected with the virus SMV1 (Sulfolobus monocaudavirus 1). Although we reaffirm that protospacer selection is essentially a random process with respect to the pMGB1 genome, we identified single spacer sequences specific for each of CRISPR loci C, D and E that, exceptionally, occurred in many sequenced clones. Moreover, the same sequence was reproducibly acquired for a given locus in independent experiments, consistent with it being the first protospacer to be selected. There was also a small protospacer bias (1.6:1) to the antisense strand of protein genes. In addition, new experiments demonstrated that spacer acquisition in the previously inactive CRISPR locus A could be induced on freeze–thawing of the infected cells, suggesting that environmental stress can facilitate activation. Coincidentally with spacer acquisition, a mobile OrfB element was deleted from pMGB1, suggesting that interplay can occur between spacer acquisition and transposition. PMID:24256236

  9. Impedance matching of a coaxial antenna for microwave in-situ processing of polluted soils.

    PubMed

    Pauli, Mario; Kayser, Thorsten; Wiesbeck, Werner; Komarov, Vyacheslav

    2011-01-01

    The present paper is focused on the minimization of return loss of a slotted coaxial radiator proposed for a decontamination system for soils contaminated by volatile or semi-volatile organic compounds such as oils or fuels. The antenna upgrade is achieved by coating it with a 5 mm thick Teflon layer. The electromagnetic characteristics reflection coefficient and power density distribution around the antenna surrounded by soils with different moisture levels are analyzed numerically. Simplified analytical approaches are employed to accelerate the optimization of the given antenna for microwave heating systems. The improved antenna design shows a good matching of the antenna to the surrounding soil with varying moisture levels. This ensures a high efficiency of the proposed in-situ soil decontamination system.

  10. In situ reflectance and virtual interface analysis for compound semiconductor process control

    SciTech Connect

    Breiland, W.G.; Hou, H.Q.; Hammons, B.E.; Klem, J.F.

    1998-05-01

    The authors review the use of in-situ normal incidence reflectance, combined with a virtual interface model, to monitor and control the growth of complex compound semiconductor devices. The technique is being used routinely on both commercial and research metal-organic chemical vapor deposition (MOCVD) reactors and in molecular beam epitaxy (MBE) to measure growth rates and high temperature optical constants of compound semiconductor alloys. The virtual interface approach allows one to extract the calibration information in an automated way without having to estimate the thickness or optical constants of the alloy, and without having to model underlying thin film layers. The method has been used in a variety of data analysis applications collectively referred to as ADVISOR (Analysis of Deposition using Virtual Interfaces and Spectroscopic Optical Reflectance). This very simple and robust monitor and ADVISOR method provides one with the equivalent of a real-time reflection high energy electron reflectance (RHEED) tool for both MBE and MOCVD applications.

  11. In-situ process and condition monitoring of advanced fibre-reinforced composite materials using optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Doyle, C.; Martin, A.; Liu, T.; Wu, M.; Hayes, S.; Crosby, P. A.; Powell, G. R.; Brooks, D.; Fernando, G. F.

    1998-04-01

    This paper presents a general overview of a number of optical fibre sensor systems which have been developed and used in advanced fibre-reinforced composites for in-situ process and condition monitoring. The in-situ process monitoring techniques were optical-fibre-based evanescent wave spectroscopy, transmission near-infrared spectroscopy and refractive index monitoring. The optical fibre sensors were successful in tracking the cure reaction. The condition monitoring of advanced fibre-reinforced composites was carried out using two intensity-based optical fibre sensor systems: an extrinsic multi-mode Fabry-Pérot sensor and Bragg gratings. In addition to this, the feasibility of using the reinforcing fibre as a light guide was demonstrated. These sensor systems were evaluated under quasi-static, impact and fatigue loading. The test specimens consisted of prepreg-based carbon-fibre-reinforced epoxy and glass-fibre-reinforced epoxy filament-wound tubes. Excellent correlation was obtained between surface-mounted strain gauges and the embedded optical fibre sensors. The feasibility of using these sensor systems for the detection of impact damage and stiffness reduction in the composite due to fatigue damage was successfully demonstrated.

  12. Enhancement of Biodiesel Production from Marine Alga, Scenedesmus sp. through In Situ Transesterification Process Associated with Acidic Catalyst

    PubMed Central

    Kim, Ga Vin; Choi, WoonYong; Kang, DoHyung; Lee, ShinYoung; Lee, HyeonYong

    2014-01-01

    The aim of this study was to increase the yield of biodiesel produced by Scenedesmus sp. through in situ transesterification by optimizing various process parameters. Based on the orthogonal matrix analysis for the acidic catalyst, the effects of the factors decreased in the order of reaction temperature (47.5%) > solvent quantity (26.7%) > reaction time (17.5%) > catalyst amount (8.3%). Based on a Taguchi analysis, the effects of the factors decreased in the order of solvent ratio (34.36%) > catalyst (28.62%) > time (19.72%) > temperature (17.32%). The overall biodiesel production appeared to be better using NaOH as an alkaline catalyst rather than using H2SO4 in an acidic process, at 55.07 ± 2.18% (based on lipid weight) versus 48.41 ± 0.21%. However, in considering the purified biodiesel, it was found that the acidic catalyst was approximately 2.5 times more efficient than the alkaline catalyst under the following optimal conditions: temperature of 70°C (level 2), reaction time of 10 hrs (level 2), catalyst amount of 5% (level 3), and biomass to solvent ratio of 1 : 15 (level 2), respectively. These results clearly demonstrated that the acidic solvent, which combined oil extraction with in situ transesterification, was an effective catalyst for the production of high-quantity, high-quality biodiesel from a Scenedesmus sp. PMID:24689039

  13. In situ observation of dynamic electrodeposition processes by soft x-ray fluorescence microspectroscopy and keyhole coherent diffractive imaging

    NASA Astrophysics Data System (ADS)

    Bozzini, Benedetto; Kourousias, George; Gianoncelli, Alessandra

    2017-03-01

    This paper describes two novel in situ microspectroscopic approaches to the dynamic study of electrodeposition processes: x-ray fluorescence (XRF) mapping with submicrometric space resolution and keyhole coherent diffractive imaging (kCDI) with nanometric lateral resolution. As a case study, we consider the pulse-plating of nanocomposites with polypyrrole matrix and Mn x Co y O z dispersoids, a prospective cathode material for zinc-air batteries. This study is centred on the detailed measurement of the elemental distributions developing in two representative subsequent growth steps, based on the combination of in situ identical-location XRF microspectroscopy—accompanied by soft-x ray absorption microscopy—and kCDI. XRF discloses space and time distributions of the two electrodeposited metals and kCDI on the one hand allows nanometric resolution and on the other hand provides complementary absorption as well as phase contrast modes. The joint information derived from these two microspectroscopies allows measurement of otherwise inaccessible observables that are a prerequisite for electrodeposition modelling and control accounting for dynamic localization processes.

  14. Evaluation of Centrifugal Casting Process Parameters for In Situ Fabricated Functionally Gradient Fe-TiC Composite

    NASA Astrophysics Data System (ADS)

    Rahimipour, Mohammad Reza; Sobhani, Manoochehr

    2013-10-01

    A gradient Fe-TiC composite was successfully produced via combination of in situ reaction with centrifugal casting techniques. Additionally, some of the effective parameters of the centrifugal casting process have been studied. Cast iron and ferrotitanium, which were used as raw materials, were melted using a high-frequency induction furnace coupled with centrifugal equipment. The microstructure and phase characterization of the fabricated composite was studied by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results show that the production of a pearlite matrix composite reinforced by TiC particles is feasible. The distribution of TiC in the pearlitic matrix is completely uneven as a result of density difference between molten medium and TiC in the centrifugal casting process.

  15. Nearly Monodispersion CoSm Alloy Nanoparticles Formed by an In-situ Rapid Cooling and Passivating Microfluidic Process

    NASA Astrophysics Data System (ADS)

    Song, Yujun; Henry, Laurence L.

    2009-10-01

    An in situ rapid cooling and passivating microfluidic process has been developed for the synthesis of nearly monodispersed cobalt samarium nanoparticles (NPs) with tunable crystal structures and surface properties. This process involves promoting the nucleation and growth of NPs at an elevated temperature and rapidly quenching the NP colloids in a solution containing a passivating reagent at a reduced temperature. We have shown that Cobalt samarium NPs having amorphous crystal structures and a thin passivating layer can be synthesized with uniform nonspherical shapes and size of about 4.8 nm. The amorphous CoSm NPs in our study have blocking temperature near 40 K and average coercivity of 225 Oe at 10 K. The NPs also exhibit high anisotropic magnetic properties with a wasp-waist hysteresis loop and a bias shift of coercivity due to the shape anisotropy and the exchange coupling between the core and the thin oxidized surface layer.

  16. Thickness dependence of Jc (0) in MgB2 films

    NASA Astrophysics Data System (ADS)

    Chen, Yiling; Yang, Can; Jia, Chunyan; Feng, Qingrong; Gan, Zizhao

    2016-06-01

    MgB2 superconducting films, whose thicknesses range from 10 nm to 8 μm, have been fabricated on SiC substrates by hybrid physical-chemical vapor deposition (HPCVD) method. It is the first time that the Tc and the Jc of MgB2 films are studied on such a large scale. It is found that with the increasing of thickness, Tc elevates first and then keeps roughly stable except for some slight fluctuations, while Jc (5 K, 0 T) experiences a sharp increase followed by a relatively slow fall. The maximum Jc (5 K, 0 T) = 2.3 × 108 A cm-2 is obtained for 100 nm films, which is the experimental evidence for preparing high-quality MgB2 films by HPCVD method. Thus, this work may provide guidance on choosing the suitable thickness for applications. Meanwhile, the films prepared by us cover ultrathin films, thin films and thick films, so the study on them will bring a comprehensive understanding of MgB2 films.

  17. Rational design of MgB2 conductors toward practical applications

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; Motaman, Ashkan; Barua, Shaon; Shahabuddin, Mohammed; Kim, Jung Ho

    2014-09-01

    We report the research progress that has been made on developing rational MgB2 superconducting conductors toward practical applications. Owing to the poor performance of the critical current density (Jc) of bare MgB2, various techniques have been developed to overcome this obstacle. Among these, chemical doping has proved to be the most effective way to enhance the superconducting properties, such as Jc and the irreversibility field (Birr). More than a hundred different forms of dopants have been investigated over the past 13 years. Among these, the most effective dopants have been identified to be silicon carbide, carbon, and malic acid. The best results, Birr of 22 T and Jc of 40,000 A cm-2 at 4.2 K and 10 T, have been reported for malic acid treated MgB2 conductors, which have matched the benchmark performance of commercial low temperature superconductor wire such as Nb-Ti. This work will review and discuss the progress on MgB2 conductor development over the past few years at the University of Wollongong and Hyper Tech Research, Inc.

  18. A Superconducting Joint Technique for MgB2 Round Wires

    PubMed Central

    Yao, Weijun; Bascuñán, Juan; Hahn, Seungyong; Iwasa, Yukikazu

    2009-01-01

    This paper describes a technique to superconductively splice multifilament MgB2 wires. To date the technique has achieved joints capable of carrying a superconducting current of 200 A at 10 K in self field. Joints details, as well as testing methods and results are presented here. PMID:20671806

  19. The doping effect of multiwall carbon nanotube on MgB2/Fe superconductor wire

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yeoh, W. K.; Qin, M. J.; Xu, X.; Dou, S. X.

    2006-07-01

    We evaluated the doping effect of two types of multiwall carbon nanotubes (CNTs) with different aspect ratios on MgB2/Fe monofilament wires. Relationships between microstructure, magnetic critical current density (Jc), critical temperature (Tc), upper critical field (Hc2), and irreversibility field (Hirr) for pure and CNT doped wires were systematically studied for sintering temperature from 650to1000°C. As the sintering temperature increased, Tc for short CNT doped sample slightly decreased, while Tc for long CNT doped sample increased. This indicates better reactivity between MgB2 and short CNT due to its small aspect ratio, and substitution of carbon (C) from short CNT for boron (B) occurs. In addition, short CNT doped samples sintered at high temperatures of 900 and 1000°C exhibited excellent Jc, and this value was approximately 104A /cm2 in fields up to 8T at 5K. This suggests that short CNT is a promising carbon source for MgB2 superconductor with excellent Jc. In particular, inclusion of nanosized MgO particles and substitution of C into the MgB2 lattice could result in strong flux pinning centers.

  20. Coexistence of covalent and metallic bonding in the boron intercalation superconductor MgB2

    NASA Astrophysics Data System (ADS)

    Belashchenko, K. D.; Schilfgaarde, M. Van; Antropov, V. P.

    2001-09-01

    Chemical bonding and electronic structure of MgB2, a boron-based newly discovered superconductor, is studied using self-consistent band-structure techniques. Analysis of the transformation of the band structure for the hypothetical series of graphite-primitive graphite-primitive graphitelike boron-intercalated boron, shows that the band structure of MgB2 is graphitelike, with π bands falling deeper than in ordinary graphite. These bands possess a typically delocalized and metallic, as opposed to covalent, character. The in-plane σ bands retain their two-dimensional (2D) covalent character, but exhibit a metallic hole-type conductivity. The coexistence of 2D covalent in-plane and three-dimensional (3D) metallic-type interlayer conducting bands is a peculiar feature of MgB2. We analyze the 2D and 3D features of the band structure of MgB2 and related compounds, and their contributions to conductivity.