Investigating of EBW Process Weldment Connections Stresses in ILSF 100 MHz Cavity by Simufact. Welding Software
239
V. Moradi
ILSF, Tehran, Iran
A. Adamian, N.B. Arab
PPRC, Tehran, Iran
The cavity is one of the main components of all accelerators, which is used to increase the energy level of charged particles (electrons, protons, etc.). The cavities increase the energy level of the charged particle by providing a suitable electric field to accelerate the charged particle. Here, information about electron beam welding analysis in 100 MHz cavities of ILSF design will be explained. According to studies performed in most accelerators in the world, connections in cavities are made by various methods such as explosive welding, brazing, electron beam welding, etc. Many articles on large cavities state that the connection of the side doors must be done by the electron beam welding process. However, in the present paper, the three-dimensional model of the cavity is imported into Simufact. Welding software after simplification and mesh process was done, and then the heat source of electron beam welding and other welding factors such as beam power, Gaussian distribution, etc. are applied in the software. The purpose of this study is the number of residual stresses during the EBW process in the 100 MHz cavity of ILSF.
CFD Predictions of Water Flow Through Impellers of the ALBA Centrifugal Pumps and Their Aspiration Zone. An Investigation of Fluid Dynamics Effects on Cavitation Problems
299
A. González Romero
ESEIAAT, Terrassa, Spain
J.J. Casas, C. Colldelram, M. Quispe
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
Currently, the ALBA refrigeration system pumps present cavitation when operating at their nominal regime. To alleviate this phenomenon temporarily until a definitive solution was found, the water flow was reduced to 67% of its nominal value. As this flow exchanges heat with the cooling water produced in an external cogeneration plant, modifying the working point of the pumps resulted in a reduction of the Accelerator cooling capacity. However, even at such low flow conditions, the flow has an anomalous oscillatory behaviour in the distributor of the aspiration zone, implying that the cause may be in a bad dimensioning of the manifold. This paper presents a study of Computational Fluid Dynamics (CFD) applied to the aspiration zones of the pumps, to investigate the effects of fluid dynamics on cavitation problems and understand what may be happening in the system. The need for such research arises from the urge to recover the accelerator cooling capacity and the constant pursuit for the improvement of the system. The geometries for this study include the general manifold in the aspiration zone and a simplified model of the pump impeller. The simulations have been carried out with the ANSYS-FLUENT software. Studies performed include considering the total water flow in nominal and under current operating conditions. In addition, the cases in which the flow is distributed through the manifold tubes in uniform and non-uniform ways have been treated separately. Pressure and velocity fields are analysed for various turbulence models. Finally, conclusions and recommendations to the problem are presented.
A Fast Simulation Tool to Calculate Spectral Power Density Emitted by Wigglers and Short Insertion Devices
303
J. Reyes-Herrera, M. Sanchez del Rio
ESRF, Grenoble, France
The analysis of thermal stress of beamline components requires a comprehensive determination of the absorbed power profile. Consequently, accurate calculations of beam power density and its dependency on the photon energy are required. There exist precise tools to perform these calculations for undulator sources, like several methods available in the OASYS toolbox* considering, for example, the contribution of the different harmonics of the undulator radiation or using ray-tracing algorithms**. This is not the case for wiggler sources, in particular for short insertion devices that are used as source for the bending magnet beamlines in some upgraded storage rings like the ESRF-EBS. Wiggler radiation is incoherent and although it is possible the use of undulator methods for calculating it, this is very inefficient. In this work, we describe a tool that performs fast calculations of spectral power density from a wiggler source. The emission is calculated starting from a tabulated magnetic field and computes the power spatial and spectral density. It uses concepts inspired from Tanaka’s work***. It is implemented in a user-friendly widget in OASYS and can be connected to widgets to calculate absorbed and transmitted power density along the beamline components. The accuracy of the method is verified by calculating three examples and comparing the results with ray-tracing. The three insertion devices simulated are: the EBS-ESRF-3PW, the ESRF W150 (a high power wiggler) and the 3PW for the BEATS project at the SESAME synchrotron source. *L. Rebuffi, M. Sanchez del Rio, Proc. SPIE 10388: 130080S (2017). **L. Rebuffi et al., J Synchrotron Rad, 27, 1108-1120 (2020). ***T. Tanaka, H. Kitamura, AIP Conference Proceedings 705, 41 (2004).
Notch Geometry Optimization of APS Upgrade High Heat Load Mirror Systems
J.J. Knopp
ANL, Lemont, Illinois, USA
Funding:Work supported by the U.S. Department of Energy, Office of Science, under Control DE-AC02-06CH11357. Thermal deformation of x-ray optics can have a profound impact on beamline performance. The thermal deformation of these x-ray optics due to heat loads of the x-ray beam has been previously shown to be able to be partially mitigated by adding a groove or notch on the side of the optic and below the optical surface. This notch acts as a thermal break which allows for anti-clastic bending and the notch geometry can be optimized for various heat loads. By optimizing the notch height, depth, and distance from the optical surface the thermal deformation on the optic can be minimized. The High Heat Load Mirror systems of the Advance Photon Source (APS) feature beamlines rely on this notch geometry to be able to take full advantage of the new source of the APS Upgrade.
Thermal Model Validation for the Cryogenic Mirror Systems for Sirius/LNLS
320
L.M. Volpe, J.C. Corsaletti, B.A. Francisco, R.R. Geraldes, M.S. Silva
LNLS, Campinas, Brazil
Funding:Ministry of Science, Technology and Innovation (MCTI) One of the challenges of fourth-generation synchrotron light sources as Sirius at the Brazilian Synchrotron Light Laboratory (LNLS) is the high power density that may affect the beamline optical elements by causing figure deformations that deteriorate the quality of the beam. Indeed, surface specifications for height errors of X-ray mirrors are often within a few nanometers. To deal with these thermal management challenges, thermo-mechanical designs based on cryogenic silicon have been developed, taking advantage of its high thermal conductance and low thermal expansion in temperatures of about 125 K. A liquid nitrogen (LN2) cryostat connected to the optics by copper braids has been used to handle moderate power loads, reducing costs when compared to closed-circuit LN2 cryocoolers and mechanically decoupling flow-induced vibrations from the optics. To guarantee the functionality of such systems, lumped mass thermal models were implemented together with auxiliary finite elements analyses. With the first systems in operation, it has been possible to compare and validate the developed models, and to carry out optimizations to improve them for future projects, by adjusting parameters such as emissivity, thermal contact resistance, and copper braid conductance. This work presents the updated models for CARNAÚBA and CATERETÊ beamlines as reference cases.
Determination of Maximum Repetition Rate of a Corrugated-Waveguide-Based Wakefield Accelerator
336
K.J. Suthar, S.H. Lee, S. Sorsher, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
ANL, Lemont, Illinois, USA
A.E. Siy
UW-Madison/PD, Madison, Wisconsin, USA
Funding:This work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne, provided by the Director, Office of Science, of the U.S. DOE under contract DE-AC02-06CH11357. Thermal stresses generated due to the electromagnetic (EM) heating is a defining phenomenon in the mechanical design of the miniature copper-based corrugated wakefield accelerator (CWA). We investigate the effect of the EM heating due to the high repetition rate electron bunches traveling through a corrugated tube with 1-mm-inner-radius. The steady-state thermal analysis is coupled with computational fluid dynamics, and structural mechanics to determine the thermal effect on the operating conditions of CWA. It could carry a 10 nC drive bunch through the center of corrugated structure that generates a field gradient 100 Mv/m at 180 GHz, accelerating a trailing 0.3 nC witness bunch to 5 GeV. The wakefield produced by the traveling bunches can deposit about 600 W to 3000 W of energy on the inner wall of the device. Also, the instabilities in e-beam trajectories caused by thermal expansion, and the resulting stresses associated high-frequency repetition rate of 10 kHz to 50 kHz are the main concern for the waveguide. Tensile-yield failure due to moderate heating on the surface of the <200 micrometer wide trough regions of the corrugated tube may lead to arcing and loss of the wakefield.
Thermal Contact Conductance in a Typical Silicon Crystal Assembly Found in Particle Accelerators
353
P. Sanchez Navarro
DLS, Oxfordshire, United Kingdom
Every mirror at Diamond Light Source (the UK’s Particle Accelerator) has been installed with the premise of clamping the cooling copper manifolds as lightly as possible to minimize distortion. The problem with this approach is that the Thermal Contact Conductance (TCC) depends on the applied pressure among other factors*. The assembly is usually a symmetric stack of Copper - Indium Foil - Silicon Crystal - Indium Foil - Copper. Variables that interest the most are those that are easily adjustable in the set-up assembly (number of clamps, pressure applied and cooling water flow rate) PT100 temperature sensors have been used along the surface of the crystal and along the surface of the copper manifolds. Custom PCB units have been created for this project to act as a mean of collecting data and Matlab has been used to plot the temperature measurements vs. time. Another challenge is the creation of an accurate model in Ansys that matches reality up to a good compromise where the data that is being recorded from the sensors matches Ansys results within reason. *Gilmore DG. Spacecraft thermal control handbook. Volume I, Volume I, [Internet]. 2002. Available from: http://app.knovel.com/hotlink/toc/id:kpSTCHVFT2/spacecraft-thermal-control
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Heat Load Simulation of Optic Materials at European XFEL
357
F. Yang, D. La Civita, H. Sinn, M. Vannoni
EuXFEL, Hamburg, Germany
The European XFEL GmbH, located in Hamburg area in Germany, is the X-ray free electron laser light source which has been in the operation since 2017. It is designed to provide users high intensity X-ray beam with 27000 pulses/s repetition rate in the photon energy range from 0.5 to 25 keV*. In the beam transport system, the optic components which have direct contact with the beam, e.g. mirror, absorber and beam shutter, etc., could get up to 10 kW heat load on a sub-mm spot in 0.6 ms. Therefore, the thermo-mechanical performance of these optic components is playing an important role in the safety operation of the facility, restricting the maximum allowed beam power delivered to each experiment station. In this contribution, using finite element simulation tools, a parametric study about coupled thermo-mechanical behavior of some general used materials, e.g. CVD diamond, B4C, silicon, etc. is presented. Based on the design of several devices which are already in operation at European XFEL**, an initial damage threshold for these materials is established, with respect to the corresponding beam parameters. Furthermore, the relevant analytical and numerical solutions are discussed and compared, taking the material and geometrical nonlinearities into account. These simulation results can be referred as design and operation benchmark for the optic elements in the beamlines. *Altarelli, M. et al., The XFEL Technical Design Report, 2006. **Tschentscher, Th. et al., Photon Beam Transport and Scientific Instruments at the European XFEL, Applied Sciences 7(6):592, 2017.
