Edward W. Collings

The Ohio State University | OSU · Department of Materials Science and Engineering

Rare earth barium copper oxide (REBCO) coated conductor tapes and cables are promising material candidates for constructing high field magnets. In both the magnet constructing stage and operation stage, transverse pressure is exerted on the tapes/cables. Therefore, understanding the mechanical behavior of tapes/cable under transverse pressure and f...

Multifilamentary MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> strands (filament numbers 36 to 114) prepared by the in-situ power-in-tube (PIT) route with carbon doping contents of 0, 2, and 3.2% were wound on barrels for transport J_c and n -value measurement at 4.2 K in fi...

Current sharing is an important self-protection mechanism in rare earth barium copper oxide (REBCO) coated conductor (CC) tapes and cables that are intended for the construction of high field magnets. Because of the slower quench propagation rate of such cables, we expect that cooling is also required to facilitate the current sharing. We explored...

A series of monofilamentary powder-in-tube MgB 2 wires were fabricated with 2 mol. % C doping and co-additions of 0–3 wt. % Dy 2 O 3 . Irreversibility fields ( μ 0 H irr ), upper critical fields ( μ 0 H c 2 ), and transport critical currents were measured, and from these quantities, anisotropies [Formula: see text] and electronic diffusivities [For...

This paper presents the results of FEM analysis of the effect of REBCO CORC cable magnetization on the field quality of a canted cosine theta (CCT) dipole magnet. The magnetic properties of the CORC cable were the results of our measurements of its M ( H ) curves at 4.2 K and magnetic fields up to 8 T. This magnetization data was used to calcula...

Purpose/Objective(s) Using Monte-Carlo simulation to study the dosimetry of proton therapy under the environment of magnetic field. The results of this study will provide knowledge for us to design and build the MRI system that is integrated to proton therapy to form an MRI-guided proton therapy system using our new developed medium temperature sup...

High field superconducting magnets require a high number of ampere-turns in their windings. To avoid large self-inductances in such magnets they must be wound using high current superconducting cables. Unlike other presently available HTS cables REBCO Roebel and CORC cables have their strands transposed or twisted to reduce both AC loss and magneti...

Quench and protection in magnets wound with coated conductors is of great interest for many applications, including high energy particle accelerators. The relatively large slow normal zone propagation and large MQE of coated conductors and the potential of burn out in well insulated coils has led to an interest in non-insulation coils. A stability...

This paper presents the results of a magnetic design study for 7 T, whole body, actively shielded MRI magnet using Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor. Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn was us...

The aim is to investigate the dose contribution from the secondary particles generated in the interaction of proton beam particles with a phantom patient during the proton therapy under the environment of magnetic fields.

We present magnetic, mechanical and thermal modeling results for a 3 Tesla actively shielded whole body MRI (Magnetic Resonance Imaging) magnet consisting of coils with a square cross section of their windings. The magnet design was a segmented coil type optimized to minimize conductor length while hitting the standard field quality and DSV (Diamet...

Bi-2212 superconducting cables are being considered for use in the high field magnets needed for the next generation of particle accelerators. Magnetization in these cables and the decay of that magnetization lead to field error and field-error drift, respectively, which need to be compensated. To study this, a segment of the winding pack was extra...

Introduction: Proton therapy uses the feature of Bragg peak to target the tumor with a sharp radiation dose fall-off distribution and minimize the dose to the normal tissue. Image-guided is crucial to the success of proton therapy. Magnetic resonance imaging (MRI) has the superiority to identify a tumor from soft tissues. Using MRI to guide proton...

Purpose/Objective(s) To explore the potential application of medium temperature superconductors (MTS) and high temperature superconductors (HTS) to the development of background magnets for MRI systems for use in combination with particle beam therapy (PBT) and the concept design for MRI-guided PBT. Materials/Methods In proton/heavy ion therapy, b...

High temperature superconductors, including Bi:2212, are being considered for high magnetic field magnets to be used in particle accelerators. A knowledge of HTS magnetization properties are needed for calculating field errors in such accelerator magnets. Here we present magnetic measurements of a 17 strand Bi:2212 Rutherford cable. The Bi:2212 str...

Research into in-situ MgB2 strand has been focused on improvements in J C through reduction of porosity. Both of cold-high-pressure-densification (CHPD) and advanced-internal-magnesium-infiltration (AIMI) techniques can effectively remove the voids in in-situ MgB2 strands. This study shows the nature of the reduced porosity for in-situ MgB2 strands...

We measured stability and quench in a YBCO pan-cake coil in liquid nitrogen bath (77.3 K) and in liquid helium bath (4.2 K) in externally applied magnetic fields up to 10 T. The pancake coil was instrumented with voltage taps and thermocouples in the winding for measurements of radial and azimuthal quench propagations. A heater was placed on the in...

We present measurements on high-temperature superconducting (HTS) superconducting cables using a NbTi-wound, 3-T dipole ac magnetometer. Our goal is to measure the magnetization properties of the cables for use in accelerator magnet field error calculations. YBCO-wound CORC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www...

High-temperature-superconducting (HTS) cables are being considered for use in particle accelerator beam steering magnets. Knowledge of the magnetic properties of these HTS cables is needed for accelerator magnet design. Here, we present the results from a Hall probe magnetometer made for measuring the M-μ <sub xmlns:mml="http://www.w3.org/1998/Math...

A 9-tape, 14 mm wide ReBCO Roebel cable was soldered onto a U-shaped holder. The critical current, Ic, was measured at 77 K and self-field. The cryostability of the cable was studied in response to the application of local pulses of 1–14 W at several values of i = I/Ic. A detailed analysis of the cable's cryostability was presented. With a Stekly p...

A react-and-wind MgB2 coil segment for a conduction-cooled magnetic resonance imaging (MRI) machine has been fabricated and tested. The coil was developed as part of a collaborative effort on a conduction-cooled, MgB2-based, whole-body MRI image guided radiation therapy device. This study focuses on the fabrication, winding, instrumentation, coolin...

In this work we studied the influence of SnO2 doping on the critical fields and temperatures of MgB2 bulk samples. Bulk samples were made by mixing ex-situ MgB2 powder with 5 wt% SnO2 powder and then pressing the mixed powders into pellets using a pressure of 2000 psi. The bulk pellets were sintered at 900°C in a furnace under flowing Ar. The sampl...

There are a few key conductor-specific factors which influence the power loss of superconductors; these include critical current, geometry, and normal metal resistivity. This paper focuses on the influence of sample geometry on the power loss of superconducting strips and the effect of filamentation and sample length as a function of the field pene...

The magnetizations of eight high-gradient quadrupole cables designated HQ and QXF and a pair of strands, identical in architecture but with different effective strand diameters extracted from an HQ and a related QXF cable, were measured. In the service of field quality assessment, the cable magnetizations and losses were measured by pickup coil mag...

The 4.2 K non-barrier transport Jc values of the powder-in-tube (PIT) in-situ MgB2 wires have been enhanced by cold high pressure densification (CHPD). With respect to the control wire, the 1.5 GPa pressure induced the J c improvement of the wire at 4.2 K and 10 T by 25 %. The Jc enhancement induced by the CHPD may result from two aspects. First, t...

(Ba,Sr)1-xKxFe2As2 superconductor is of great interest as a wire for practical applications. In this paper, Ba0.6K0.4Fe2As2 precursor powder was prepared by high-energy ball-milling aided sintering (12h/750°C). The prepared precursor was drawn to powder-in-tube round wire. Partial as-drawn wires were subjected to biaxial cold pressure densification...

A new facility for the measurement of AC loss in superconductors at high dB/dt has been developed. The test device has a spinning rotor consisting of permanent magnets arranged in a Halbach array; the sample, positioned outside of this, is exposed to a time varying AC field with a peak radial field of 0.566 T. At a rotor speed of 3600 RPM the frequ...

A rig was fabricated to test single-strand excitation and current sharing in Nb3 Sn Rutherford Cables. Measurements were performed on 400 mm lengths of a 27-strand, cored cable. In preparation for measurement, the cable was mounted onto a U-shaped holder, reacted for 72-48-50 h at 210-400-665 °C under 20 MPa. Current was injected into a single stra...

This paper describes a detailed design of a 6-T Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting racetrack coil designed for conduction cooling. We then describe a bench test pursued as a proof of concept for one winding of an actively shielded air-core electric machine wit...

Calorimetric measurement of coupling loss versus frequency has been measured on two sets of cored and uncored LARP high gradient quadrupole Nb3Sn Rutherford cables. Studied are the responses of the resulting interstrand contact resistances (ICR) to variation of stainless-steel (SS) core width and position and to variation of reaction-heat-treatment...

Standard in situ type MgB <sub xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> strands manufactured by Hyper Tech, Inc., have 19-36 subelements, a Monel outer sheath, and a Cu interfilamentary matrix. Typical transport J <sub xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> s of the strands are 2 × 10 <sup xmlns:xlink="http://www.w3.org/1999/x...

The internal oxidation technique can generate ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nano particles in Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands, which markedly refine the Nb <sub xmlns:mml="http://www.w3.or...

Conventional methods of Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> As <s...

This work focuses on finite element modeling of the hydroforming process for niobium tubes intended for use in superconducting radio frequency (SRF) cavities. The hydroforming of tubular samples into SRF-relevant shapes involves the complex geometries and loading conditions which develop during the deformation, as well as anisotropic materials prop...

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....

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...

In this work, a two layer conductor on round core cable was tested for stability and normal zone propagation at 77 K in a liquid nitrogen bath. The cable was instrumented with voltage taps and wires on each strand over the cable's central portion (i.e. excluding the end connections of the cable with the outside world). A heater was placed in the ce...

The heat treatment, tensile testing, and bulge testing of Cu and Nb tubes has been carried out to gain experience for the subsequent hydroforming of Nb tube into seamless superconducting radio frequency (SRF) cavities for high energy particle acceleration. In the experimental part of the study samples removed from representative tubes were prepared...

Significantly enhanced critical current density (J c) for MgB 2 superconducting wires can be obtained following the advanced internal Mg infiltration (AIMI) route. But unless suitable precautions are taken, the AIMI-processed MgB 2 wires will exhibit incomplete MgB 2 layer formation, i.e. reduced superconduc-tor core size and hence suppressed curre...

The coupling magnetization of a Rutherford cable is inversely proportional to an effective interstrand contact resistance Reff, a function of the crossing-strand resistance Rc, and the adjacent strand resistance Ra. In cored cables, Reff continuously varies with W, the core width expressed as percent interstrand cover. For a series of un-heat-treat...

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, particularly at low field, where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reprod...

For many accelerator magnets field quality at the bore is a critical requirement for which reason it is necessary to fully characterize the persistent-current magnetization of strands of the kind under consideration for these magnets. The magnetization of a strand is generally measured in a magnetometer. However, certain effects can differentiate s...

A Roebel cable, one twist pitch long, was modified from its as-received state by soldering copper strips between the strands to provide inter-strand connections enabling current sharing. Various DC transport currents (representing different percentages of its critical current) were applied to a single strand of such a modified cable at 77 K in a li...

Fault Current Limiters (FCL) provide protection for upstream and/or downstream devices in electric power grids. Conventional FCL require the use of expensive conductors and liquid or gas cryogen handling. Disclosed embodiments describe FCL systems and devices that use lower cost superconductors, require no liquid cryogen, and are fast cycling. Thes...

Described are the results of magnetization loss measurements made at 77 K on several YBCO conductor-on-round-core (CORC) cables in ac magnetic fields of up to 80 mT in amplitude and frequencies of 50 to 200 Hz, applied perpendicular to the cable axis. The cables contained up to 40 tapes that were wound in as many as 13 layers. Measurements on the c...

A series of MgB2 superconducting composite strands co-doped with Dy2O3 and C were prepared via an advanced internal Mg infiltration (AIMI) route. The transport properties and MgB2 layer growth were studied in terms of the Dy2O3 doping level, reaction temperature, and reaction time. Transport studies showed that both critical current densities, Jcs,...

The impacts of heat treatment (HT) temperature and Ti doping on low-field flux jumping and 12 T Jc of high-performance internal-Sn, distributed barrier (Nb-Ta)3Sn strands have been explored. It was found that higher HT temperatures could suppress low-field flux jumps by not only reducing the Jc (B) curve slope, but also increasing the heat capacity...

In an investigation of possible atomic substitution for the Mg site in MgB2, superconducting thin films were deposited by pulsed laser deposition using MgB2 and ZrB2 targets. The resulting c-axis-oriented thin films contained various concentrations of Zr. The structural, chemical, and superconductive properties of these films were investigated. ZrB...

One of the goals of the Large Hadron Collider Accelerator Research Program (LARP) is to demonstrate the feasibility of Nb3Sn technology for a proposed luminosity upgrade based on large aperture high gradient quadrupole (HQ) magnets. For such magnets, field quality at the bore is a critical requirement for which reason the parasitic magnetization of...

In this paper, we report the properties of two tube type Ta doped Nb3Sn strands: one strand was additionally Ti doped by way of a Sn-Ti alloy core, and the other had high Cu/Sn ratio within the filaments. Higher irreversibility field (Birr) was obtained on the quaternary strand with respect to the (Nb-7.5 wt.%Ta)3Sn strand. High Cu/Sn ratio decreas...

A series of high-performing continuous-tube-filling-forming-fabricated (CTFF) powder-in-tube-type (PIT) MgB2 strands have been prepared, with critical current densities, Jcs, higher than 1.30×105 A/cm2 and n-values above 30 at 4.2 K, 5 T. The transport Jcs and corresponding n-values of a selected sample C1 were reported at temperatures, T, of 4.2-3...

A dc transport current was applied to the strands of a Roebel cable at 77 K in liquid nitrogen bath. The inter-strand contact resistance was measured. It was modified either by applying a pressure on the cable at 77 K in liquid nitrogen bath or using different soldering patterns between the strands of the cable. Magnetization ac losses were measure...

We have used high-pressure, high-temperature synthesis at 1500-1700 °C and 10 MPa to create homogeneously C-substituted MgB2 from a B4C + Mg mixture. X-ray diffraction analysis showed large peak-shifts consistent with a decrease in the a lattice parameter for the B4C-derived MgB2 as compared to an undoped sample (0.033-0.037 Å, depending on the sam...

In this letter we demonstrate that if oxygen can be properly supplied to (Nb-Zr)-Sn wires, ZrO2 precipitates will form during the heat treatment, refining the Nb3Sn grain size markedly. Here, a Nb3Sn subelement was fabricated in which Nb-1Zr alloy was used, and oxygen was supplied via SnO2 powder. The results showed that such a design could supply...

We have studied thermodynamic phase stability in the Mg–B system through use of a high-pressure, high-temperature apparatus consisting of a large pressure vessel and an RF induction heater. The incongruent melting temperature for MgB2 was found to be ∼1450 °C at 10 MPa using thermal analysis data applied to both MgB2 powder samples and Mg/B mixture...

Suppression of magnetization and effective filament diameter deff with twisting was investigated for a series of recent Bi2212 strands manufactured by Oxford Superconducting Technologies. We measured magnetization as a function of field (out to 14 T), at 5.1 K, of twisted and nontwisted 37 × 18 double restack design strands. The samples were helica...

In this work, an analytic model for phase formation and volume expansion during heat treatment in tube type Nb3Sn strands is presented. Tube type Nb3Sn conductors consist of Nb or Nb-Ta alloy tube with a simple Cu/Sn binary metal insert to form the basic subelement (filament). A number of these elements, each with an outer Cu jacket, are restacked...

An advanced internal Mg infiltration method (AIMI) in this paper has been shown to be effective in producing superconducting wires containing dense MgB2 layers with high critical current densities. In this study, the in-field critical current densities of a series of AIMI-fabricated MgB2 strands were investigated in terms of C doping levels, heat t...

Numerous classes of dopant have been added to MgB2 in order to raise the upper critical field, Bc2, and hence to increase the field range over which the pinned superconductor has the possibility of supporting supercurrent. Thus dopant additions to grain-boundary-pinned MgB 2, for example, have the effect of raising the high field critical current d...

In this paper, a series of high-performing powder-in-tube MgB2 strands have been prepared. Transport voltage-current measurements were performed to determine the effects of C doping and strand geometry such as filament numbers. The best J(c) for our samples was 1.0 x 10(5) A/cm(2) at 4.2 K, 7 T, for a strand using B powder with 3% C addition. The c...

Coupling- and persistent-current magnetization of Nb3Sn Rutherford cables with cores of stainless steel (SS) and woven glass-fiber tape were measured by pick-up coil magnetometry in transverse magnetic fields of amplitude 400 mT and frequencies of up to 90 mHz applied in the face-on orientation. Analysis of the results yielded the interstrand conta...

We present a design and details of construction of two calorimetric systems that allow us to measure the total loss in high temperature superconducting coils or linear samples carrying alternating current while exposed to a strong alternating magnetic field. This measurement technique is based on the boil-off of liquid nitrogen. The first system is...

Unlike the known isoelectronic undoped intrinsic FeAs compounds, LiFeAs does not show any spin-density wave behavior but exhibits superconductivity at ambient pressures without chemical doping. It has a superconducting transition temperature, T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub>...

In this work, pulse calorimetry was used to measure the specific heats of four superconducting materials at temperatures from 0 to 300 K and in magnetic fields from 0 to 14 T. Specific heat measurements were performed on Bi2212 round wire samples with a two-dimensional random oriented single stack design, made by Supramagnetics Inc., and a conventi...

In this work, the transport and magnetization properties of distributed-barrier Rod-in-Tube (RIT) strands and Tube Type strands are studied. While Tube Type strands had smaller magnetizations and thus better stabilities in the low field region, their 12 T non-Cu Jcs were somewhat smaller than those of the RIT strands. Microstructures were investiga...

The plastic constitutive equation of tubular materials under hydraulic pressure needs to be determined for the successful application of hydroforming technique to the seamless fabrication of multicell superconducting radiofrequency cavities. This paper provides the empirical constitutive properties of tubular material determined by tensile and hydr...

Intra-wire resistance and AC loss of various multi-filamentary MgB2 wires with filaments surrounded by Nb barriers have been measured and analyzed. The intra-wire resistance is measured with a direct four-probe voltage–current method at various temperatures. The AC loss is acquired by both vibrating sample magnetometer (VSM) and magnetization measu...

Cu sheathed polycrystalline Ba0.6K0.4Fe2As2 superconducting wire was prepared by a two-step powder-in-tube method. A pressure of 2 GPa was applied to a short sample before heat treatment. Magnetization and transport measurements were performed to investigate the effects of cold high pressure densification on the microstructure and superconductivity...

A model helical undulator 250 mm in length, designed and fabricated with a period of 14 mm, was tested in a liquid helium bath. The helical coil was wound with a multifilamentary, tube-type Nb3Sn strand with 217 sub-elements. The coil Ic and the magnetic field in the bore were measured at 4.2 K in a liquid helium bath using a Hall probe. Ic was fou...

Recent advances in MgB2 conductors are leading to a new level of performance. Based on the use of proper powders, proper chemistry, and an architecture which incorporates internal Mg diffusion (IMD), a dense MgB2 structure with not only a high critical current density Jc, but also a high engineering critical current density, Je, can be obtained. In...

We present an analysis of stability, heating and quench propagation in a 50 Tesla solenoid immersed in a liquid helium bath at 4.2 K, obtained by numerical Finite Element Method (FEM) modeling. The solenoid was assumed to be wound of a cable made of YBCO coated conductor tapes. Full heat transfer curve in the whole temperature range (from 4.2 K up...