scholarly journals Brazing of Mo to Glidcop Dispersion Strengthened Copper for Accelerating Structures

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1658 ◽  
Author(s):  
Valentina Casalegno ◽  
Sergio Perero ◽  
Monica Ferraris ◽  
Mauro Taborelli ◽  
Gonzalo Arnau Izquierdo ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Mechanical Performance ◽  
High Vacuum ◽  
Rf Sputtering ◽  
High Heat ◽  
Ultra High Vacuum ◽  
Light Sources ◽  
Interfacial Chemistry ◽  
Ofe Copper

Alumina dispersion-strengthened copper, Glidcop, is used widely in high-heat-load ultra-high-vacuum components for synchrotron light sources (absorbers), accelerator components (beam intercepting devices), and in nuclear power plants. Glidcop has similar thermal and electrical properties to oxygen free electrical (OFE) copper, but has superior mechanical properties, thus making it a feasible structural material; its yield and ultimate tensile strength are equivalent to those of mild-carbon steel. The purpose of this work has been to develop a brazing technique to join Glidcop to Mo, using a commercial Cu-based alloy. The effects of the excessive diffusion of the braze along the grain boundaries on the interfacial chemistry and joint microstructure, as well as on the mechanical performance of the brazed joints, has been investigated. In order to prevent the diffusion of the braze into the Glidcop alloy, a copper barrier layer has been deposited on Glidcop by means of RF-sputtering.

scholarly journals Brazing of Mo to Glidcop Dispersion Strengthened Copper for Accelerating Structures

2018 ◽  
Author(s):  
Valentina Casalegno ◽  
Sergio Perero ◽  
Monica Ferraris ◽  
Mauro Taborelli ◽  
Gonzalo Arnau Izquierdo ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Mechanical Performance ◽  
High Vacuum ◽  
Rf Sputtering ◽  
High Heat ◽  
Ultra High Vacuum ◽  
Light Sources ◽  
Interfacial Chemistry ◽  
Brazed Joints

Alumina dispersion-strengthened copper, Glidcop, is used widely in high-heat-load ultra-high-vacuum components for synchrotron light sources (absorbers), accelerator components (beam intercepting devices) and in nuclear power plants. Glidcop has similar thermal and electrical properties to OFE (oxygen free electrical) copper, but has superior mechanical properties, thus making it a feasible structural material; its yield and ultimate strength are equivalent to those of mild-carbon steel. The purpose of this work has been to develop a brazing technique to join Glidcop to Mo, using a commercial Cu-based alloy. The effects of the excessive diffusion of the braze along the grain boundaries on the interfacial chemistry and joint microstructure, as well as on the mechanical performance of the brazed joints, has been investigated. In order to prevent the diffusion of the braze into the Glidcop alloy, a copper barrier layer has been deposited on Glidcop by means of RF-sputtering.

Manufacturing Technologies for Ultra-High-Vacuum–Compatible 10 MW/M2 High Heat Flux Components for Application in Fusion Devices

2021 ◽  
pp. 1-12
Author(s):  
Hitesh Patel ◽  
Nirmal Panda ◽  
Nitin Kanoongo ◽  
K. Balasubramanian ◽  
M. J. Singh ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Vacuum ◽  
High Heat ◽  
Ultra High Vacuum ◽  
High Heat Flux ◽  
Manufacturing Technologies

HREM Observations of Mg2Si-Based Multilayers for Soft X-Ray Optics

1991 ◽  
Vol 49 ◽  
pp. 906-907
Author(s):  
A. R. Modak ◽  
David J. Smith ◽  
Z. G. Li ◽  
P. Boher ◽  
Ph. Houdy
Keyword(s):  
High Vacuum ◽  
Rf Sputtering ◽  
Ultra High Vacuum ◽  
Silicon Substrates ◽  
Ray Optics ◽  
X Ray ◽  
Long Period ◽  
The Past ◽  
X Ray Scattering ◽  
Short Period

Multilayers fabricated with alternating materials having significant differences in X-ray scattering powers are being investigated for applications in soft X-ray optics. Multilayers consisting of combinations of W, Rh, Fe, Si3N4, SiO2 and Si, C, B4C have been studied in the past. Mg2Si based multilayer structures are theoretically efficient reflectors of wavelengths above the Mg-Kα line (9.89 Å) and the Mg-Lα line (251.5 Å) because of their low absorption in the respective wavelength regimes due to the presence of magnesium. In the present study, Mg2Si based multilayers fabricated on silicon substrates by ultra high vacuum rf sputtering have been characterized by HREM. W, Si, and Mg2Si targets in conjunction with the introduction of nitrogen were employed to deposit alternate Mg2Si and W or Si3N4 layers. We report here our preliminary observations of a characteristic short period W/Mg2Si layered structure used above the Mg-Kα line and two long period multilayers based on W/Mg2Si and Si3N4/Mg2Si used above the Mg-Lα line.

Design concept for a modular in-vacuum Hall probe mapper for in-vacuum undulators and cryogenic permanent magnet undulators of varying magnetic length

2011 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
J. Rank ◽  
D. Harder ◽  
G. Rakowsky ◽  
T. Tanabe
Keyword(s):  
Permanent Magnet ◽  
Modular Design ◽  
Magnetic Measurement ◽  
High Vacuum ◽  
Design Concept ◽  
Ultra High Vacuum ◽  
Light Sources ◽  
Hall Probe ◽  
Wide Range ◽  
Magnetic Length

Both in-vacuum undulators (IVUs) and cryogenic permanent magnet undulators (CPMUs), each important to third-generation light sources, are best characterized in their operating environment. To create a precision Hall probe map of an IVU/CPMU (IVU hereafter), an in-vacuum magnetic measurement (IVMM) system is proposed. Point-by-point measurement of field and trajectory error informs corrective tuning.A novel design concept for a universal IVMM System has been developed and explored. The IVMM seals to the rectangular Ultra High Vacuum (UHV) flange of the IVU and shares its common vacuum space. Moreover, a modular design permits a wide range of IVUs of varying magnetic length to be mapped with a single IVMM, and is thus cost effective when multiple IVUs of varying configurations are planned. Here we review aspects of the modular IVMM design concept.

scholarly journals Significantly Reduced Secondary-Electron-Yield of Aluminum Sheet with Fluorocarbon Coating

Coatings ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 249 ◽  
Author(s):  
Feipeng Wang ◽  
Qi Zhao ◽  
Jian Li ◽  
Kaizheng Wang ◽  
Zhengyong Huang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Coating Thickness ◽  
Secondary Electron ◽  
High Vacuum ◽  
Rf Sputtering ◽  
Ultra High Vacuum ◽  
Water Contact ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
The Cost

In this work, the surface of Al sheet was coated with a fluorocarbon (FC) thin film by radio frequency (RF) sputtering of polytetrafluoroethylene (PTFE) to investigate the influence of dielectric coatings on the secondary electron yield (SEY) behavior of Al sheets. Atomic-force microscopy (AFM) and energy-dispersive spectroscopy (EDS) were employed to identify the surface topographies and elemental contents of the samples with FC coatings. Water contact angle (WCA) measurements were performed to characterize the surface tension as well as the polar and dispersion components of the samples’ surface. The secondary electron- mission (SEE) behavior of the samples was determined by measuring the SEY coefficients in an ultra-high vacuum chamber with three electron guns. The experimental results indicated that the longer sputtering time effectively led to the increase in coating thickness and a higher ratio of F/C, as well as the continued decrease of surface tension. A quite thin FC coating of about 11.3 nm on Al sheet resulted in the value of maximum SEY (δmax) dropping from 3.02 to 1.85. The further increase in coating thickness beneficially decreased δmax down to 1.60, however, at the cost of a ten-fold thicker coating (ca. 113 nm). It is found that increasing the coating thickness contributes to reducing SEY coefficients as well as suppressing SEE. The results are expected to guide the design of dielectric-coating for SEY reduction as well as multipactor suppression on Al.

Effect of gap design pressure on the LWR fuel rods lifetime

Kerntechnik ◽  
2021 ◽  
Vol 86 (3) ◽  
pp. 202-209
Author(s):  
M. Ghasabian ◽  
F. Mofidnakhaei ◽  
S. Talebi
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Mechanical Performance ◽  
Fission Products ◽  
Fuel Temperature ◽  
Fuel Rods ◽  
Fuel Rod ◽  
Fuel Burn ◽  
Water Reactors ◽  
Centerline Temperature

Abstract The fuel burn-up rate has been raised in recent years to improve the efficiency of nuclear LWRs (light water reactors). Therefore, surveying and estimating changes in fuel properties and structural materials during radiation exposure is of paramount importance. In the present study, the researchers focused on analyzing the role of LWR fuel rod initial gap pressure (initial gas pressure when a fuel rod is fabricated) on the rod’s thermal and mechanical performance. FRAPCON-4.0 steady-state fuel performance code was used to simulate the effect of initial gap pressure on the behavior of a specific BWR-type fuel rod that was irradiated under the HALDEN research program. This fuel rod is similar to commercial BWR fuel rods in all respects, except that the research reactors have a height limit. The important fuel design criteria, such as the centerline temperature, effective stresses, total released fission gas to the fuel rod’s void volumes, and the cladding strains, were included in the analysis. According to the present study, a potential initial gap pressure range could be suggested to increase fuel rods’ lifetime by improving the safety criteria margins, especially fuel centerline temperature and the released amount of gaseous fission products. As we know, lower fuel temperature leads to having a reactor with a higher power density and, consequently, a maximum fuel burn-up rate, which can affect the economy and safety of nuclear power plants.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

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