Zhibi Wang

Low-cycle-fatigue behavior of copper materials and their use in synchrotron beamline components

Abstract Analyses and evaluation of the life cycle number and crack propagation rate were performed on oxygen-free high-conductivity copper X-ray beamline components based on data available in the literature. Recommendations are made with respect to the safe use of materials in high-heat-load beamline component design. The available literature is critically reviewed for low-cycle fatigue properties at the elevated temperatures typically found in synchrotron operations.

Thermal and deformation analyses of a cryogenically cooled silicon monochromator for high‐heat‐flux synchrotron sources

The analytical results and design considerations for a cryogenically cooled advanced photon source (APS) silicon monochromator are presented. The high conductivity and low thermal expansion coefficient of silicon at cryogenic temperatures are advantages that are used to solve the high‐heat‐flux problem from undulator radiation. The APS monochromator features a machined slot with variable thicknesses below the surface. This configuration is designed to reduce absorption by the crystal and decrease the maximum temperature of the crystal. The transmitted power through the crystal is absorbed by a second element that can be cooled by standard cooling techniques. Different parameters and configurations are analyzed to maximize the performance of the monochromator and minimize the total absorbed power by the crystal.

Modular filter design for the white‐beam undulator/wiggler beamlines at the Advanced Photon Source

A new filter has been designed at Argonne National Laboratory that is intended for the use in undulator/wiggler beamlines at the Advanced Photon Source. The water‐cooled frame allows up to four individual filter foil banks simultaneously in the beam path. Additionally, the bottom of each frame holds two thin (20 μm) uncooled carbon filters in tandem for low‐energy filtering. Therefore a maximum of 625 filter selection combinations is theoretically possible. The design is compact and modular, with great flexibility for the users. To prevent accidental movement of the filter, effort has been taken to provide a mechanically locked, fail‐safe actuator system. Programming aspects are under development as part of the general personnel and equipment protection system to provide an intelligent control system. Aspects of the design and operational principles of the filter are presented in this paper.

Postbuckling behavior of windows subjected to synchrotron radiation X-rays

Abstract To fully understand the behavior of windows after buckling so as to precisely predict failure, this paper first reviews test data and then examines the postbuckling behavior of thin-shell structures under thermal or mechanical load. The paper presents postbuckling analyses of beryllium windows subjected to X-ray thermal loads and investigates the possibility of incorporating elastic buckling into window designs.

Vibration analysis of the photon shutter designed for the Advanced Photon Source.

Abstract The photon shutter is a critical component of the beamline front end for the 7 GeV Advanced Photon Source (APS) project, now under construction at Argonne National Laboratory (ANL). The shutter is designed to close in tens of milliseconds to absorb up to 10 kW heat load (with high heat flux). Our shutter design uses innovative enhanced heat transfer tubes to withstand the high heat load. Although designed to be lightweight and compact, the very fast movement of the shutter gives rise to concern regarding vibration and dynamic sensitivity. To guarantee long-term functionality and reliability of the shutter, the dynamic behavior should be fully studied. In this paper, the natural frequency and transient dynamic analysis for the shutter during operation are presented. Through analysis of the vibration characteristics, as well as stress and deformation, several options in design were developed and compared, including selection of materials for the shutter and structural details.

Performance analysis of a novel monochromator design for the APS SRI‐CAT beamline 2‐ID‐E

Third‐generation synchrotron x‐ray facilities, such as the Advanced Photon Source, produce x‐ray beams that generate a very high heat flux in a very small area. In order to preserve the brilliance of the source, optical components have to be designed to undergo very small thermal deformation (or a change of slope of a flat surface). When an optical component is subjected to a heat load, there will be thermal deformation caused by a temperature increase from the initial state. For a plate‐like structure, the temperature difference over the thickness causes bending, and the average temperature increment causes axial deformation. For an optical element, the slope change due to bending is the main reason for the degradation of the performance of the optical component. The change of slope should be limited to a few microradians. There are many ways to control the thermal deformation, such as cryogenic cooling, inclined geometry, liquid‐metal cooling, pin‐posts or microchannels, using a high‐heat‐conductivity m...

A high‐precision self‐adapted optical structure

Third‐generation synchrotron x‐ray facilities, such as the Advanced Photon Source, generate a very high heat flux in a very small area. When an optical component is subjected to a heat load, there will be thermal deformation caused by a temperature increase. For a plate‐like structure, the temperature difference over the thickness causes bending, and the average temperature increment causes axial deformation. For an optical element, the slope change due to bending is the main reason for the degradation of functionality in the optical component. In order to preserve photons, optical components have to be designed to have very small thermal deformation or small change of slope in the surface. Typically the change of slope is limited to a few microradians. The structure proposed here offers advantages in terms of cost, complexity, and operations.

Using metallic filters in APS undulator beamlines

Metallic filters are needed by APS users in their beamlines. Two general areas of use for the white‐beam metallic filters are: (1) to attenuate the x‐ray beam to reduce the thermal load during routine operations and (2) to attenuate the x‐ray beam during alignment and for special testing of optics at low power. Metallic filters are important for users who will be working primarily in the high energy x‐ray range because unwanted lower energy photons are absorbed through the metallic filters. Notwithstanding their high thermal conductivity, the metals, in general, absorb x‐rays significantly near surface layers and hence can attain very large temperatures causing structural deformations and/or damage. Thermomechanical behavior and failure prediction need to be done carefully. In this paper, particulars of metallic filters are discussed and generalized analytical solutions are offered to help users of metallic filters determine their applicability for x‐ray beamlines

Performance analysis of the commissioning filter and window assembly for insertion device beamlines at the Advanced Photon Source

Although the Advanced Photon Source (APS) undulator beamlines are designed for windowless operation, a special window assembly will be used during the commissioning phase of the beamlines until sufficient operational experience is gained with the powerful undulator A photon beam. This assembly is called a ‘‘commissioning window.’’ The commissioning window assembly as designed consists of a 300‐μm‐thick filter (made of graphite), a fixed mask (made of Glidcop), a multipurpose transmitting filter/BPM disk (made of 127‐μm‐thick CVD diamond), and set of a double windows (made of 250‐μm‐thick beryllium). Due to the high total power and power density, the filter/window assembly must be carefully designed to guarantee longevity and satisfactory performance throughout its service. Hence extensive analytical work has been conducted on various thermal and structural aspects of the commissioning window assembly. This paper summarizes the analytical results and presents the expected performance characteristics of the...

On filter design and critical thickness of synchrotron x‐ray filters

A ‘‘critical thickness’’ for a synchrotron radiation x‐ray filter exists. Because x‐ray absorption in media is an exponential function of depth and because radiation and conduction both play a role in the cooling of the filter assembly, the heat transfer mechanism changes from radiation dominant to conduction dominant as the thickness increases. For a thin filter, radiative heat transfer is the main mechanism. The maximum temperature in the filter increases as the thickness increases due to the fact that the total heat load increases while the total area for radiative heat transfer remains the same. For a thick filter, conductiveheat transfer is the main cooling mechanism. When the filter thickness increases, the heat absorption per unit thickness decreases and so does the maximum temperature. At a certain thickness, the temperature in the filter is the maximum. This is the critical thickness. For third‐generation synchrotron radiation facilities, the maximum temperature and thermal stresses in a filter are the main factors considered in a filter assembly design. It is very important to avoid designing a filter inside the critical thickness range.