A two-layer subscale canted-cosine-theta 4.5 T has been built and successfully tested. The design of the magnet is based on Nb 3 Sn cable wound into aluminum bronze mandrels, and an external aluminum ...shell. The magnet was conceived as an agile platform for the development of canted-cosine-theta magnets and general magnet technology. The main fabrication, assembly and analysis processes developed for this magnet are discussed in detail. The training behavior and mechanical response of magnet's structure in relation to previous canted-cosine-theta magnets are also discussed.
This article reports a physicochemical comparison of synthetic and biological Hydroxyapatite (HAp). Eight samples were separated into two groups: bio and commercial hydroxyapatite (bio-HAp and ...commercial-HAp). The bio-HAp group containing defat, alkaline, and calcined samples taken from bovine bone were obtained by using three different treatments, in order to establish their effect on the final product quality. The commercial-HAp group, from different sources: NIST, sigma, apafill G, coralina, and biograft, were analyzed and compared with the bio-HAp results. Thermogravimetric analysis (TG) was used in order to establish thermal degradation of the samples; structural behavior was then analyzed by X-Ray Diffraction (XRD) to found the crystalline phases, as well as the crystalline quality. Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to identify the corresponding HAp functional groups within the samples. The surface morphology was analyzed by Scanning Electron Microscopy (SEM) and the elemental composition was established by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). It was found that the calcination process obtains HAp with comparable quality to the commercial samples. A crystallinity greater than 62% after the alkaline process was found. Additionally, the surface of the alkaline sample presents a transition behavior between dense and porous morphology.
•HAp with alkaline and calcination processes meet crystallinity for applications.•Biograft commercial sample and defat sample present organic compounds.•Calcined sample presents typical interconnecting porous network.•Alkaline and Calcination processes are good methods to obtain HAp with good quality.•HAp with adequate properties for medical applications to low cost of production.
High-temperature superconducting <inline-formula><tex-math notation="LaTeX">\rm{REBa}_{2} Cu_{3} O_{7-x}</tex-math></inline-formula> ( REBCO ) conductors have the potential to generate a high ...magnetic field over a broad temperature range. The corresponding accelerator magnet technology, still in its infancy, can be attractive for future energy-frontier particle colliders such as a multi-TeV muon collider. To help develop the technology, we explore the requirements and potential characteristics of a REBCO magnet, operating at 4.2 or 20 K, with a dipole field of 8 - 10 T in a clear aperture of 150 mm. We use the canted <inline-formula><tex-math notation="LaTeX">\cos \theta</tex-math></inline-formula> magnet configuration to reduce the electromagnetic stresses on the conductors. We present the resulting dipole fields, field gradients for combined-function cases, conductor stresses, magnet dimensions and conductor lengths. We also discuss the conductor performance that is required to achieve the target dipole field at 4.2 and 20 K. The information can provide useful input to the development of REBCO magnet and conductor technology for collider-ring magnets in a muon collider.
Crystalline fcc Al0.7Cr0.3OxN(1-x) oxynitride-based dense coatings were deposited in a semi-industrial coater using the arc-PVD technique. The microstructural analysis of the as-coated oxynitrides ...showed the increased formation of defects such as porosity, droplets, and pinholes upon the O-raise during deposition, while the columnar-like features oriented in the (200) direction were maintained. Meanwhile, the c-Al0.7Cr0.3N reference nitride coating presented a similar microstructure but was mostly texturized in the (111) direction, maintaining the fcc crystal structure. These microstructural characteristics correlated well with the mechanical response of both nitrides. In the c-Al0.7Cr0.3N, significant plastic deformation was registered compared to the c-Al0.7Cr0.3OxN(1-x) coating. However, the interface mismatch did not affect the adhesion strength of the oxynitride. Upon treatment at 950 °C, the c-Al0.7Cr0.3N nitride displayed increased average roughness due to the oxidation and formation of plate-like oxides, probably an α-(CrAl)2O3 phase, while tiny oxide whiskers grow on the c-Al0.7Cr0.3OxN(1-x) coating. The presence of other oxide phases upon thermal treatment was identified. Only slight changes in the nano-hardness & elastic modulus are registered on the thermally treated coatings at 950 °C, which is confirmed by the/E (elastic strain to failure) parameter analysis, indicating that the thermal treatment for the c-AlCrN and the c-AlCrON coatings did not affect their cracking behavior. However, in the as-coated state, the c-AlCrON shows less tendency to form cracking than the c-AlCrN. This cracking behavior agrees with what was found in the scratch testing, supporting the idea that O increases the cracking resistance in the c-AlCrON and results in mixed cohesive + adhesive failure modes in this oxynitride.
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•Hard c-AlCrON oxynitride coatings were deposited applying the arc-PVD method in a semi-industrial coater.•Macro-defects (pores, voids, & droplets) are induced upon the increased O-content during c-AlCrON deposition.•Better cohesive resistance and adhesive strength were measured on the c-AlCrON coating than on the c-AlCrN.•The hardness of c-AlCrN increases while the elastic modulus decreases upon the adding O.•The O-addition into the nitride to form the c-AlCrON increased the cracking resistance of the oxynitride coating.
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•The dependence between the BC-surface condition and the α-Al2O3 phase formation.•Low-temperature α-Al2O3 formation in the pre-oxidation treatments.•Influence of the grit-blasting on ...the oxidation kinetics of β-(Ni, Pt)Al System.•In the grit-blasted samples, oxidation stable-state is reached less than 2 h.•Stifle the growth of metastable θ-Al2O3 and accelerate θ- to α-Al2O3 at > 1000 °C.
The effect of surface modification by grit-blasting of β-(Ni,Pt)Al bond coats on the growth of α-Al2O3 is here presented. Thermogravimetry tests at 1000 °C, 1050 °C, 1100 °C, and 1150 °C were performed on as-aluminized and as-grit-blasted specimens under the same oxygen partial pressure (pO2 = 2.1 × 10-1 atm), where the parabolic rate constant (kp) was calculated. The oxide phase fraction was obtained from the fitting of the photo-stimulated luminescence spectroscopy (PSLS) results. A strong dependence between the surface condition of the bond coat and the α-Al2O3 phase formation was observed. The thermally treated grit-blasted samples achieved faster the steady-state (1.6 h) of the thermal growth oxide (TGO), while a treatment 2.7 times longer (4.25 h) was required for the as-aluminized specimens. This result contributes to the general understanding of the effect of the surface condition on the TGO formation during pre-oxidation treatment to promote the growth of the α-Al2O3 phase at low temperature and less time without affecting the lifetime of thermal barrier coating systems.
The pulsed wire technique is an attractive option for the measurement of undulators where the measurement access is restricted due to, for example, narrow undulator gaps or cryogenic environments in ...the case of superconducting undulators. Using the pulsed wire technique, direct measurements of the first and second integrals of the magnetic field can be obtained. However, one of the main limitations of this technique is the error introduced by dispersive wave motion, due to the finite flexural rigidity of the wire. For the measurement of the first integral of the magnetic field, an error is also introduced by the use of a current pulse with finite pulse width. In this paper, a general solution is presented for dispersive wave motion in pulsed wire measurements. A method for the measurement of the dispersive wave speed is presented and demonstrated through experimental examples. An algorithm is derived which corrects the dispersion and finite pulse-width errors in the measurement of first magnetic field integrals and the dispersion error in the measurement of second magnetic field integrals. The effectiveness of the correction algorithms is demonstrated through experimental measurements, and the results are compared with Hall probe measurements on a short undulator.
► We derive the equations that describe dispersive motion in a pulsed wire magnetic measurement. ► We develop algorithms that can be used to correct measurement errors that are due to dispersive and finite pulse width effects. ► Excellent agreement is found between the corrected pulsed wire results and Hall probe measurements on a short undulator.
The development of homogeneous, dense, and smooth hard coatings is a challenging task, and that is why the high power impulse magnetron sputtering (HiPIMS) method has been proposed to tailor and ...control the microstructure through the modification of the duty cycle. HiPIMS offers extensive possibilities to obtain good quality films with fine and dense morphology. In this work, the synthesis of CrxN coatings by HiPIMS with the variation of duty cycle (τ = 2.7% and 12%), substrate bias voltages (Vb = −150 and − 250 V), and gas ratio (fN2/Ar = 0.2 and 0.4) was evaluated. The influence of these processing conditions on the chemical composition, microstructure, and adhesion of HiPIMS CrxN was investigated. A significant increment of the deposition rate and the chromium content in the CrxN coatings is observed at τ = 12%; meanwhile, at τ = 2.7%, films showed high nitrogen content. The crystalline phases like α-Cr + h-Cr2N, h-Cr2N, and h-Cr2N + c-CrN were identified in the as-deposited films. The Cr-rich coatings presented faceted columns with cauliflower-like surface morphology, while the growth of the h-Cr2N phase caused a grain size refinement and a denser microstructure. The surface morphology of the h-Cr2N coatings changed from pyramidal to stacked pyramids with the reduction of the duty cycle. The transformation of the h-Cr2N to c-CrN leads to highly dense columnar microstructures with a fine granular morphology and a smooth surface. The duty cycle strategies can be applied to develop a particular microstructure with specific chemical composition and crystallographic phases, resulting in an alternative method to produce graded or multilayer systems. The duty cycle reduction increases the interfacial adhesion strength of the coatings.
•Duty cycle modifies composition, phases, microstructure, and morphology.•Higher duty cycle enhances target current and coating deposition rates.•Duty cycle strategy is a good option to deposit graded or multilayer systems.
The Canted-Cosine-Theta (CCT) magnet design offers significant reductions in conductor stress by using mandrels to prevent the accumulation of operating Lorentz forces. Each mandrel consists of a ...cylindrical spar with ribs guiding the conductor. These ribs intercept the turn-to-turn accumulation of forces by transferring them to the spar. Design studies of a layered CCT coil pack coupled to a shell-based structure are shown. The use of a 3-D periodic symmetry region to reduce the problem size for finite element modeling is detailed along with a discussion of axial boundary conditions. ANSYS calculation results for a two layer NbTi dipole being constructed at LBNL (CCT1) are presented. ANSYS calculations show the Lorentz force induced stress in CCT1 at the single turn level, demonstrating interception and suggesting investigation of CCT design with minimal structure external to the coil pack.
The NDCX-II engineering design Waldron, W.L.; Abraham, W.J.; Arbelaez, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2014, Letnik:
733
Journal Article
Recenzirano
The Neutralized Drift Compression Experiment (NDCX-II) is a user facility located at Lawrence Berkeley National Laboratory which is uniquely designed for ion-beam-driven high energy density ...laboratory physics and heavy ion fusion research. Construction was completed in March 2012 and the facility is now in the commissioning phase. A significant amount of engineering was carried out in order to meet the performance parameters required for a wide range of target heating experiments while making the most cost-effective use of high-value hardware available from a decommissioned high current electron induction accelerator. The technical challenges and design of this new ion induction accelerator facility are described.
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