ANL, Lemont, Illinois, USA
RadiaBeam, Santa Monica, California, USA
Fabrication of the corrugated structure that generates a field gradient 100 m-1 at 180 GHz is challenging and required an unconventional method of production. The corrugated waveguide with 2 mm inner diameter will be produced by electroplating copper on the aluminum mandrel as proposed in the reference*. A thin seed layer is usually applied to achieve uniform wetting to plate copper on the aluminum mandrel. The copper waveguide is retrieved by removing aluminum and the seed layer. Therefore, uniform copper plating and etching of the seed layer and the Aluminum mandrel is a crucial step to keep the surface free of impurities that are especially necessary for the RF application. Previous studies suggest that electroplated copper has variations in both electrical and mechanical properties compared with those of bulk copper from the batches of production. In this paper, we discuss the copper microstructure produced by the electroforming method and literature study on the variations, which can be attributed to the disparity of the crystallinity of grains structure in plated material.
*A. Zholentset al., "A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi-User X-ray Free-Electron Laser Facility, "in Proc. IPAC 18, 2018, pp. 1266-1268.
ANL, Lemont, Illinois, USA
The Advanced Photon Source Upgrade project has employed the use of high heat load dual mirror systems in the new feature beamlines being built. Due to the shallow operating angles of the mirrors at a particular beamline, XPCS, the two mirrors needed to be approximately 2.5 m apart to create a distinct offset. Two separate mirror tanks are used for this system. However, it is unclear if the vibrational performance of these tanks would be better if they were both mounted on one large plinth or each mounted on a small plinth. Using accelerometers at the installation location, the floor vibrations were measured. The resulting frequency response function was then imported into a Finite Element Analysis software to generate a harmonic response analysis. The two different plinth schemes were modeled and the floor vibration was introduced as an excitation to the analysis. The relative pitch angle (THETA Y) between the mirrors was evaluated as well as the relative gap between the mirrors (XMAG). Results showed that a single plinth reduces the relative XMAG (RMS) compared to two plinths by approximately 25%. However, the relative THETA Y (RMS), which is arguably more critical, is significantly lower by approximately 99.7% in two plinths when compared to a single plinth. Therefore, it is more effective to use two separate plinths over a longer distance as opposed to a single longer granite plinth.
TUPC05
UW-Madison, Madison, Wisconsin, USA
ANL, Lemont, Illinois, USA
Beam driven wakefield accelerators offer great potential for the realization of compact, low-cost x-ray free electron laser (XFEL) sources. Achieving high accelerating gradients in these devices requires the use of mm-wave RF structures which present a range of fabrication challenges due to their small size and tight dimensional tolerances. One promising technique for manufacturing these structures involves electroplating a mandrel with copper and subsequently dissolving the mandrel to leave behind the desired metal cavity. Because the resulting copper shell is electroplated, its purity, grain structure, and surface finish will be different from that of conventionally machined copper. Understanding the electrical and thermal performance of the electroformed components requires experimental measurement of the plated copper material properties. In this paper, an experiment for measuring the conductivity of electroplated copper at 170 GHz-200 GHz using a WR-5 waveguide meander is presented and the results are applied to the design of a corrugated waveguide wakefield accelerator.
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
ANL, Lemont, Illinois, USA
The world of beamline science is often fast-paced and dynamic. One of the major challenges in this environment is to be able to design, manufacture and then implement new items for use on the beamlines in a fast and accurate manner. Many times, this involves iterating the design to address unknown or new variables which were not present at the beginning of the project planning task. Through the use of additive manufacturing, I have been able to support the user programs of various (APS) Advanced Photon Source beamlines* across multiple scientific disciplines. I will provide a few detailed examples of Items that were created for specific beamline applications and discuss what benefits they provided to the pertinent project. I will also talk about why choosing consumer-level printer options to produce the parts has been the direction I went and the pros and cons of this decision. Primarily, this choice allowed for quicker turnaround times and the ability to make more frequent changes in an efficient manner. Currently, we are utilizing only the fused deposition modeling (FDM) type printers but I am exploring the addition of UV-activated resin printing, exotic materials that can be utilized using the current toolset, and the possibility of commercial metal printing systems. This technology has been a game-changer for the implementation of new support items and instrumentation over the last couple of years for the different disciplines I am supporting. I will discuss how the roadmap ahead and what the evolving technologies could potentially allow us to do.
*Thanks to the members of the DYS, MM, and TRR groups for their collaboration.
ANL, Lemont, Illinois, USA
MSB, Naperville, Illinois, USA
NVHS, Naperville, Illinois, USA
ANL, Lemont, Illinois, USA
As part of the Advanced Photon Source Upgrade (APS-U) project, the Coherent Surface Scattering Imaging (CSSI) [1] instrument is currently being developed. One of the most important components of the CSSI instrument at the 9-ID beamline of the APS-U, the Kirkpatrick-Baez (K-B) mirror system, will focus hard X-rays to a diffrac-tion-limited size of 500 nanometers at a working distance of 550 mm. High angular stability (19 nrad for the hori-zontal mirror and 14 nrad for the vertical mirror) is speci-fied no just for the focused beamsize but, more important-ly, to ensure the beam stability at the detector position that is up to 24 m from the K-B mirrors. A large sample-to-detector distance (up to 23 m), one of the beamline’s unique features for achieving a sufficient coherent-imaging spatial oversampling, requires sample angular stability of 50 nrad. In CSSI scattering geometry, the vertically placed sample reflects X-rays in the horizontal direction at an extremely shallow angle. The design in-cludes two high-precision rotary stages for sample pitch (vertical axis) and yaw (horizontal axis). The current design of instrument’s nano-positioning stages [2] and metrology required to satisfy the stability and positioning requirements are discussed in this paper.
*T. Sun et al., Nat. Photonics 6, 586 (2012).
**D. Shu et al., this conference.
ANL, Lemont, Illinois, USA
Kirkpatrick and Baez (K-B) mirror-based nanofocusing optics* will be applied to many beamlines endstation instruments for the APS-Upgrade (APS-U) project. Precision nanopositioning stages with nanometer-scale linear positioning resolution and nanoradian-scale angular stability are needed as alignment apparatus for the K-B mirror hard X-ray nanofocusing optics. For instance, at the APS-U 19-ID In Situ Nanoprobe beamline endstation**, to maintain stability of a 20-nm focal spot on the sample, nanofocusing K-B mirror system with 5-nrad angular stability is required. Similar angular resolution and stability are also required for APS-U 9-ID CSSI***, APS-U 34-ID ATOMIC**** and other beamline endstation instruments. Modular nanopositioning flexure stages have been developed for the K-B mirror nanofocusing optics, which includes: linear vertical and horizontal flexure stages, tip-tilting flexure stages, and flexure mirror benders for bendable nanofocusing K-B mirrors, to overcome the performance limitations of precision ball-bearing-based or roller-bearing-based stage systems. The mechanical design and preliminary test results are described in this paper.
* Kirkpartrick and Baez, JOSA. 1948; 38(9): 766-773.
** S. Kearney et al., this conference.
*** J. Anton et al., this conference.
**** C. Preissner et al., this conference.
LNLS, Campinas, Brazil
After successfully designing, installing, and commissioning two units of the High-Dynamic Double-Crystal Monochromator (HD-DCM) at the Brazilian Synchrotron Light Laboratory (LNLS) - Sirius, two more units are now required. Since they demand only a smaller energy range (5 to 35 keV), the total gap stroke of the new instruments can be significantly reduced, creating an opportunity to adapt the existing design towards the so-called HD-DCM-Lite. Removing the large gap adjustment mechanism allows a reduction of the main inertia by a factor of 5, enabling the HD-DCM-Lite to deliver energy flyscans of hundreds of eV reaching 20 cycles per second while keeping fixed exit and the pitch stability in the range of 10 nrad RMS (1 Hz - 2.5 kHz). Hence, an unparallel bridge between slow step-scan DCMs and fast channel-cut monochromators is created. This work presents the in-house development of the HD-DCM-Lite, focusing on its mechanical design, discussions on the ultimate scanning constraints (rotary stage torque, voice-coil forces, interferometers and encoders readout speed limits and subdivisional errors), and thermal management.
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LNLS, Campinas, Brazil
The low emittance and high photon flux beam present at the 4th-generation Sirius synchrotron light source beamlines result in high energy densities and high heat loads at some specific X-ray optics such as monochromators and white beam mirrors. This challenges the design of such systems since the introduction of thermal stresses may lead to optical surface deformation and beam degradation. Thus, to keep the systems within acceptable deformations some of the optical elements are cryogenically cooled. However, this poses the requirements of decoupling the thermal sinks (cryostats) from the optics and the mechanisms to maintain their desired degrees of freedom for alignment and dynamic operation. In this context we present the development of low-stiffness copper-braid-based heat conductors, summarizing the motivation and main aspects regarding their fabrication and application at the beamlines.
ANL, Lemont, Illinois, USA
A new nano-computed tomography projection microscope (n-CT) is being designed as part the Advanced Photon Source Upgrade (APS-U) beamline enhancement at sector 32-ID. The n-CT will take advantage of the APS-U source and provide new capabilities to the imaging program at 32-ID. A Kirkpatrick and Baez (KB) mirror-based nanofocusing optics [1,2] will be implemented in this design. To meet the n-CT imaging goals, it is the desire to have sub 10 nanometer vibrational and thermal drift stability over 10-minute measurement durations between the optic and the sample. In addition to the stability requirements, it is desired to have a variable length sample projection axis of up to 450 mm. Such stability and motion requirements are challenging to accomplish simultaneously due to performance limitations of traditional motion mechanics and present a significant engineering challenge. To overcome these limitations, the proposed n-CT design incorporates granite air bearing concepts initially used in the Velociprobe [3]. These types of granite stages have been incorporated into many designs at APS [4] and at other synchrotron facilities [5]. Utilizing the granite air bearing concept, in tandem with other design aspects in the instrument, the requirements become reachable. A novel multi-degree of freedom wedge configuration is also incorporated to overcome space limitations. The design of this instrument is described in this paper.
TUPC16
Faraday Technology, Inc., Clayton, Ohio, USA
Northern Illinois University, DeKalb, Illinois, USA
ANL, Lemont, Illinois, USA
Advancements in high energy physics require continuous innovations in hardware to support the generation, amplification, transmission, modulation, and detection of radio frequency (RF) electromagnetic waves. Waveguides have garnered increasing interest due to their integral function in the transmission, amplification, and/or manipulation of electromagnetic waves. Waveguides operating in higher than conventional frequency ranges, e.g., 30 to 300 GHz, are of particular interest given the scaling of gradient and shunt impedance with frequency. These higher frequencies necessitate features, such as corrugations, with significantly smaller dimensions. However, traditional manufacturing approaches are inadequate, in terms of manufacturing precision and cost, to meet these requirements - thus, novel fabrication strategies are required. Herein, an economic fabrication approach for electroforming high-purity 26 GHz cylindrical copper waveguides with internal corrugations is presented. A custom, low-additive electrolyte was employed to mitigate impurity inclusion within the copper electroform, ensuring high-purity copper waveguides. Pulse-modulated waveforms employed during copper electrodeposition selectively controlled ionic transport as well as the subsequent deposit morphology and thus facilitate complete copper filling of the corrugations. Scale-up from ~2- to ~6-inch waveguides were demonstrated and confirm the versatility of the pulse-modulated electroforming strategy. A cold test of the ~2-inch copper waveguide using a vector network analyzer (VNA) was conducted. The results of the S-parameter measurements and the bead-pull test indicate reasonable agreement with the design by CST simulation, which validates the novel pulse-modulated electroforming approach.