Dynamic Response of Advanced Materials Impacted by Particle Beams: The MultiMat Experiment

Abstract

The introduction at CERN of new extremely energetic particle accelerators, such as the high-luminosity large hadron collider (HL-LHC) or the proposed future circular collider (FCC), will increase the energy stored in the circulating particle beams by almost a factor of two (from 360 to 680 MJ) and of more than 20 (up to 8500 MJ), respectively. In this scenario, it is paramount to assess the dynamic thermomechanical response of materials presently used, or being developed for future use, in beam intercepting devices (such as collimators, targets, dumps, absorbers, spoilers, windows, etc.) exposed to potentially destructive events caused by the impact of energetic particle beams. For this reason, a new HiRadMat experiment, named "MultiMat", was carried out in October 2017, with the goal of assessing the behaviour of samples exposed to high-intensity, high-energy proton pulses, made of a broad range of materials relevant for collimators and beam intercepting devices, thinfilm coatings and advanced equipment. This paper describes the experiment and its main results, collected online thanks to an extensive acquisition system and after the irradiation by non-destructive examination, as well as the numerical simulations performed to benchmark experimental data and extend materials constitutive models. Keywords Dynamic material behaviour • Thermomechanical stresses • Carbon-based and copper composites • Molybdenum and tungsten alloys • Particle beam impacts • Quasi-instantaneous heat deposition * M.

Thermomechanical Characterisation of Copper Diamond and Benchmarking with the MultiMat Experiment

“…e material is assumed to be isotropic in nature, based on previous study of the material [6], and is assumed to behave in an elasto-plastic manner based on the fourpoint bending test presented in this study. Similar analyses have been performed on other materials tested in the MultiMat experiment, and information on the thermomechanical modelling aspects in such scenarios is detailed in previous studies [13,15]. Similarly, analytical solutions for the dynamic response of slender beams subjected to thermal shock have also been studied extensively [34][35][36][37][38][39].…”

“…Tested specimens were equipped with thermal probes and strain gauges and placed on graphitic supports. Other materials tested in the MultiMat experiment included heavy alloys such as titanium zirconium molybdenum, Inermet180 and tantalum tungsten, carbide-graphite composites, silicon carbide, and carbon foams [13][14][15][16].…”

“…For f f � 1.016 kHz and f t � 6.794 kHz, Young's modulus is computed at 193.7 GPa, with Poisson's ratio of 0.248, while for f f � 1.016 kHz and f t � 7.238 kHz, Young's modulus is calculated at 193.6 GPa, with Poisson's ratio of 0.104. Considering previous data on similar CuCD grades, the value of ] � 0.248 was deemed to be the physically valid one and retained for the material model, along with a rounded Young's modulus value of 194 GPa [13]. e final values for Young's modulus and Poisson's ratio are shown in Table 3.…”

Targetry Challenges & HiRadMat

“…The facility originated from the LHC Collimation Project [4] where there was a need to test accelerator equipment under beam shock impacts using equivalent LHC type beam conditions. Hi-RadMat was designed for these R&D purposes and has successfully completed several experiments in this category [5][6][7][8][9]. However, the facility has also developed into a world renowned high energy testing facility with users from many global institutes performing experiments outside its design remit including tests on superconducting magnetic components [10], developments of beam monitoring equipment [11,12] and validation of numerical simulations hypothesising the effects of high energy beam pulses [13].…”

Resistivity Characterization of Molybdenum-Coated Graphite-Based Substrates for High-Luminosity LHC Collimators

“…Apart from low resistivity, the coating material must show good adhesion to the bulk substrate and have a large melting point to prevent damage against beam losses. In order to verify the coating robustness, different graphitic materials coated with metallic thin films have been tested in the CERN HiRadMat facility [20] with proton beams. Among the proposed metallic thin films, the molybdenum coating shows the least extended beam damage, mainly due to its higher melting temperature.…”