An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility

Abstract

SummaryPredicting the consequences of highly energetic particle beams impacting protection devices as collimators or high power target stations is a fundamental issue in the design of state-ofthe-art facilities for high-energy particle physics. These complex dynamic phenomena, which may induce material phase transitions, extended density changes, shock waves generation, explosions, material fragment projections etc., have been successfully simulated resorting to highly non-linear numerical tools (Hydrocodes). In order to produce accurate results, however, these codes require reliable material constitutive models that, at the extreme conditions induced by a destructive beam impact, are scarce and often inaccurate. In order to derive or validate such models (Equations of State, Strength Models, Failure Models), a comprehensive, first-of-its-kind experiment has been recently carried out at CERN HiRadMat facility: performed tests entailed the controlled impact of intense and energetic proton pulses on a number of specimens made of six different materials. Experimental data were acquired, mostly in real time, relying on extensive embedded instrumentation (strain gauges, temperature and vacuum sensors) and on remote acquisition devices (laser Doppler vibrometer and high-speed camera). The dynamic ranges of the digital acquisition system were sufficient to acquire the very fast and intense shock waves generated by the impact. The high speed video camera allowed capturing a number of frames during the time of flight of the material fragments projected away from impacted specimens. This information is then benchmarked against advanced numerical simulations. Preliminary results of the tests are discussed. In depth post-irradiation analyses are foreseen once the specimens have reached a sufficiently low level of activation. The experimental method presented in this paper may find applications to test materials under very high strain rates and temperatures in domains well beyond particle physics (severe accidents in fusion and fission nuclear facilities, space debris impacts, fast and intense loadings on materials and structures etc.).-2 -

The “Multimat” experiment at CERN HiRadMat facility: advanced testing of novel materials and instrumentation for HL-LHC collimators

“…In parallel with the tests on full-scale collimator components, an experiment, known as HRMT14, was performed in 2012 [8] on specimens of simple geometry, fully instrumented, to benchmark the numerical results obtained with codes such as ANSYS [9]0, Autodyn [10] and LS-Dyna [11]. The test confirmed the precision of the numerical results, when the material models, for the extreme conditions produced by the particle beam impact, are well mastered [12], [13].…”

Cleaning Insertions and Collimation Challenges

“…A complex and comprehensive experiment was carried out at CERN HiRadMat facility [29,30] to assess the consequences of highly energetic particle pulses impacting on sample collimator materials. Tests were also performed on a fully functional LHC collimator with Inermet180 jaws [31].…”

Investigation and Mechanical Modelling of Pure Molybdenum at High Strain-Rate and Temperature

“…In particular, molybdenumbased materials have special importance in a variety of high temperature industrial and nuclear applications [1] thanks to their good combination of properties. As a matter of fact, molybdenum exhibits high strength which is maintained at high temperatures, high Young's modulus (greater than common steel), excellent thermal and electrical conductivities, high melting temperature (2620°C) good resistance to thermal shock and low coefficient of thermal expansion.…”

“…Moreover, it is under study as material for Beam Intercepting Devices (BID) which have to satisfy a lot of requirements due to shock loading conditions induced by direct beam interaction [1,2].…”