Search

BILBY is a recently constructed and commissioned time-of-flight small-angle neutron scattering instrument, operated by the Australian Centre for Neutron Scattering at the Australian Nuclear Science and Technology Organisation (ANSTO). BILBY provides a wide accessible q range (q ≃ 1.0 × 10−3 Å−1 to ∼1.8 Å−1) and variable wavelength resolution (Δλ/λ ≃ 3–30%) to complement the other small-angle and ultra-small-angle neutron scattering capabilities available at ANSTO. Since its construction, BILBY has been used to study samples from a wide range of scientific disciplines, including biology, chemistry, physics and materials science. This article describes the BILBY design and components, and shows data collected from a number of reference samples.

TAIPAN is the thermal-neutron instrument located at the reactor face of Australia’s OPAL reactor (ANSTO). TAIPAN hosts two interchangeable secondary spectrometers ; a classic triple-axis spectrometer (TAS) and a beryllium-filter spectrometer, the latter being a high-throughput, low-energy, band-pass filter spectrometer based on the NIST design (Udovic et al., 2008). The TAS option has been operating in the user programme since 2010 whilst the Be-filter is a newer addition, which began operating at the end of 2015. TAIPAN is renowned for its versatility and high neutron flux which has allowed the TAS to measure successfully a broad range of samples including single crystals , powders, thin films, and co-aligned multi-crystal arrays (Danilkin and Yethiraj, 2009; Danilkin et al., 2012, 2007). While the TAS option is used mostly to study structural and magnetic excitations in materials, the Be-filter option is used to measure vibrational density of states from mainly powder samples (Stampfl et al., 2016). TAIPAN has recently undergone some significant upgrades to improve the accessible momentum and energy range of both the TAS and the Be-filter spectrometers. Four key features have been modified to improve performance: the accessible momentum transfer has been increased by re-designing the enclosure and expanding the available instrument range of motion (section A); a new sapphire-filter translation-stage mechanism (Section B) has been installed to allow epithermal neutrons to pass to the two monochromators ; a new Cu-200 double-focussing monochromator has been installed to allow monochromatic selection of neutrons up to 180 meV (Section C); and finally a new tertiary shutter and snout (Section D) have been designed to improve the signal-to-noise ratio and reduced background outside the instrument enclosure. Extensive testing and alignment of all new motion stages were undertaken with reproducibility within ± 0.05 degrees or ± 0.25 mm obtained for both the monochromator rotation angle & sapphire-filter translation.

QUOKKA is a 40 m pinhole small-angle neutron scattering instrument in routine user operation at the OPAL research reactor at the Australian Nuclear Science and Technology Organisation. Operating with a neutron velocity selector enabling variable wavelength, QUOKKA has an adjustable collimation system providing source–sample distances of up to 20 m. Following the large-area sample position, a two-dimensional 1 m2 position-sensitive detector measures neutrons scattered from the sample over a secondary flight path of up to 20 m. Also offering incident beam polarization and analysis capability as well as lens focusing optics, QUOKKA has been designed as a general purpose SANS instrument to conduct research across a broad range of scientific disciplines, from structural biology to magnetism. As it has recently generated its first 100 publications through serving the needs of the domestic and international user communities, it is timely to detail a description of its as-built design, performance and operation as well as its scientific highlights. Scientific examples presented here reflect the Australian context, as do the industrial applications, many combined with innovative and unique sample environments.

The double-crystal ultra-small-angle neutron scattering (USANS) diffractometer KOOKABURRA at ANSTO was made available for user experiments in 2014. KOOKABURRA allows the characterization of microstructures covering length scales in the range of 0.1–10 µm. Use of the first- and second-order reflections coming off a doubly curved highly oriented mosaic pyrolytic graphite premonochromator at a fixed Bragg angle, in conjunction with two interchangeable pairs of Si(111) and Si(311) quintuple-reflection channel-cut crystals, permits operation of the instrument at two individual wavelengths, 4.74 and 2.37 Å. This unique feature among reactor-based USANS instruments allows optimal accommodation of a broad range of samples, both weakly and strongly scattering, in one sample setup. The versatility and capabilities of KOOKABURRA have already resulted in a number of research papers, clearly demonstrating that this instrument has a major impact in the field of large-scale structure determination.

The BILBY Time-of-Flight (ToF) Small Angle Neutron Scattering (SANS) instrument at the Bragg Institute at ANSTO is among a number of recent additions to the current suite of operating instruments. ...

A high-throughput low-energy band-pass filter spectrometer is a recent addition to the thermal triple-axis spectrometer, TAIPAN [1] at ANSTO. The so-called Be-filter spectrometer option is a near-f...

Inductive fault current limiters (FCLs) have several advantages, such as significant current limitation, immediate triggering and relatively low losses. Despite these advantages, saturated core FCLs have not been commercialized due to its large size and associated high costs. A major remaining challenge is to reduce the footprint of the device. In this paper, a solution to reduce the overall footprint is proposed and discussed. In arrangements of windings on a core in reactors such as FCLs, the core is conventionally grounded. The electrical insulation distance between high voltage winding and core can be reduced if the core is left at floating potential. This paper shows the results of the investigation carried out on the insulation of such a coil-core assembly. Two experiments were conducted. In the first, the behavior of the apparatus under high voltage conditions was assessed by performing power frequency and lightning impulse tests. In the second experiment, a low voltage test was conducted during which voltages of different frequencies and pulses with varying rise times were applied. A finite element simulation was also carried out for comparison and further investigation.

A dimensional analysis for the design of a 100 kVA, 3 phase, iron core, 6.6 kV/240 V, Wye–Wye connected transformer employing Ag sheathed Bi-2223 high-temperature superconducting (HTSC) multi-filament tapes has been carried out. The mass, volume and tape length requirements were calculated over a range of core cross-sectional areas. The objective of this exercise was to minimise the overall transformer volume. A range of suitable designs was then selected. Finite element methods software was used to map the magnetic fields throughout the winding volume of each design, and to estimate the hysteretic loss at full load. The analysis of mass and volume with core area variation showed the presence of distinct points, which would minimise these quantities. However, it was found that these designs were impractical in reality due to the significant length and cost of tape that they would entail. It was also shown that the coil electrical losses in these designs were too high due to the length of tape required and from the higher hysteretic loss. By considering the factors of mass, volume, hysteretic loss, and tape length and cost, a suitable design was found which was a compromise between all the factors involved. Assuming HTSC tape available with a modest Je of 5000 A/cm 2 , it was found that the mass and volume of the transformer could be reduced significantly compared to that of a conventional transformer. The volume decreased from 206 to 129 dm 3 and the dry mass decreased from 400 to 214 kg. The overall hysterises loss at full load was calculated to be 1290 W and the total length of tape required per phase is 1500 m. The minimum possible volume of the transformer for the given rating and engineering current density was found to be 83.8 dm 3 requiring 3508 m of HTSC tape.

Zenergy Power has successfully designed, built, tested, and installed in the US electrical grid a saturable reactor Fault Current Limiter. Beginning in 2007, first as SC Power Systems and from 2008 as Zenergy Power, Inc., ZP used DOE matching grant and ARRA funds to help refine the design of the saturated reactor fault current limiter. ZP ultimately perfected the design of the saturated reactor FCL to the point that ZP could reliably design a suitable FCL for most utility applications. Beginning with a very basic FCL design using 1G HTS for a coil housed in a LN2 cryostat for the DC bias magnet, the technology progressed to a commercial system that was offered for sale internationally. Substantial progress was made in two areas. First, the cryogenics cooling system progressed from a sub-cooled liquid nitrogen container housing the HTS coils to cryostats utilizing dry conduction cooling and reaching temperatures down to less than 20 degrees K. Large, round cryostats with “warm bore” diameters of 1.7 meters enabled the design of large tanks to hold the AC components. Second, the design of the AC part of the FCL was refined from a six legged “spider” design to a more compact and lighter design with better fault current limiting capability. Further refinement of the flux path and core shape led to an efficient saturated reactor design requiring less Ampere-turns to saturate the core. In conclusion, the development of the saturable reactor FCL led to a more efficient design not requiring HTS magnets and their associated peripheral equipment, which yielded a more economical product in line with the electric utility industry expectations. The original goal for the DOE funding of the ZP project “Design, Test and Demonstration of Saturable Reactor High-Temperature Superconductor Fault Current Limiters” was to stimulate the HTS wire industry with, first 1G, then 2G, HTS wire applications. Over the approximately 5 years of ZP’s product development program, the amount of HTS wire employed per FCL and its cost as a percentage of the total FCL product content had not dropped substantially from an unsustainable level of more than 50% of the total cost of the FCL, nor had the availability increased (today the availability of 2G wire for commercial applications outside of specific partnerships with the leading 2G wire manufacturers is extremely limited). ZP had projected a very significant commercial potential for FCLs with higher performance and lower costs compared to the initial models built with 1G wire, which would come about from the widespread availability of low-cost, high-performance 2G HTS wire. The potential for 2G wires at greatly reduced performance-based prices compared to 1G HTS conductor held out the potential for the commercial production of FCLs at price and performance levels attractive to the utility industry. However, the price of HTS wire did not drop as expected and today the available quantities of 2G wire are limited, and the price is higher than the currently available supplies of 1G wire. The commercial option for ZP to provide a reliable and reasonably priced FCL to the utility industry is to employ conventional resistive conductor DC electromagnets to bias the FCL. Since the premise of the original funding was to stimulate the HTS wire industry and ZP concluded that copper-based magnets were more economical for the foreseeable future, DOE and ZP decided to mutually terminate the project.

In order to obtain a more compact Superconducting Fault Current limiter (SFCL), a special geometry of core and AC coil is required. This results in a unique magnetic flux pattern which differs from those associated with conventional round core arrangements. In this paper the magnetic flux density within a Fault Current Limiter (FCL) is described. Both experimental and analytical approaches are considered. A small scale prototype of an FCL was constructed in order to conduct the experiments. This prototype comprises a single phase. The analysis covers both the steady state and the short-circuit condition. Simulation results were obtained using commercial software based on the Finite Element Method (FEM). The magnetic flux saturating the cores, leakage magnetic flux giving rise to electromagnetic forces and leakage magnetic flux flowing in the enclosing tank are computed.

Series reactors are used in distribution grids to reduce the short-circuit fault level. Some of the disadvantages of the application of these devices are the voltage drop produced across the reactor and the steep front rise of the transient recovery voltage (TRV), which generally exceeds the rating of the associated circuit breaker. Simulations were performed to compare the characteristics of a saturated core High-Temperature Superconducting Fault Current Limiter (HTS FCL) and a series reactor. The design of the HTS FCL was optimized using the evolutionary algorithm. The resulting Pareto frontier curve of optimum solution is presented in this paper. The results show that the steady-state impedance of an HTS FCL is significantly lower than that of a series reactor for the same level of fault current limiting. Tests performed on a prototype 11 kV HTS FCL confirm the theoretical results. The respective transient recovery voltages (TRV) of the HTS FCL and an air core reactor of comparable fault current limiting capability are also determined. The results show that the saturated core HTS FCL has a significantly lower effect on the rate of rise of the circuit breaker TRV as compared to the air core reactor. The simulations results are validated with short-circuit test results. (6 pages)

This paper presents a three-dimensional numerical analysis of the electromagnetic forces within a high voltage superconducting Fault Current Limiter (FCL) with a saturated core under short-circuit conditions. The effects of electrodynamics forces in power transformer coils under short-circuit conditions have been reported widely. However, the coil arrangement in an FCL with saturated core differs significantly from existing reactive devices. The boundary element method is employed to perform an electromagnetic force analysis on an FCL. The analysis focuses on axial and radial forces of the AC coil. The results are compared to those of a power transformer and important design considerations are highlighted.