C. Charrondière

European Organization for Nuclear Research

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A. Rijllart

European Organization for Nuclear Research

Michael Guinchard

European Organization for Nuclear Research

H. Reymond

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

K. Kubo

Nagoya Institute of Technology

T. Tauchi

High Energy Accelerator Research Organization

Juergen Pfingstner

European Organization for Nuclear Research

Rogelio Tomás

European Organization for Nuclear Research

Federico Carra

European Organization for Nuclear Research

Marcin Patecki

Warsaw University of Technology

S. Kuroda

The Graduate University for Advanced Studies, SOKENDAI

Cooperative Institutions

European Organization for Nuclear Research

Fermi National Accelerator Laboratory

Linac Coherent Light Source

Menlo School

Centre National de la Recherche Scientifique

University of Naples Federico II

High Energy Accelerator Research Organization

The Graduate University for Advanced Studies, SOKENDAI

University of Geneva

Instituto de Física Corpuscular

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Design and Construction of an Instrumentation System to Capture the Response of Advanced Materials Impacted by Intense Proton Pulses

Shock and Vibration (2021)

Federico Carra C. Charrondière Michael Guinchard Óscar Sacristán De Frutos

In recent years, significant efforts were taken at CERN and other high‐energy physics laboratories to study and predict the consequences of particle beam impacts on devices such as collimators, targets, and dumps. The quasi‐instantaneous beam impact raises complex dynamic phenomena which may be simulated resorting to implicit codes, for what concerns the elastic or elastoplastic solid regime. However, when the velocity of the produced stress waves surpasses the speed of sound and we enter into the shock regime, highly nonlinear numerical tools, called Hydrocodes, are usually necessary. Such codes, adopting very extensive equations of state, are also able to well reproduce events such as changes of phase, spallation, and explosion of the target. In order to derive or validate constitutive numerical models, experiments were performed in the past years at CERN HiRadMat facility. This work describes the acquisition system appositely developed for such experiments, whose main goal is to verify, mostly in real time, the response of matter when impacted by highly energetic proton beams. Specific focus is given to one of the most comprehensive testing campaigns, named “HRMT‐14.” In this experiment, energy densities with peaks up to 20 kJ/cm 3 were achieved on targets of different materials (metallic alloys, graphite, and diamond composites), by means of power pulses with a population up to 3 × 1013 p at 450 GeV. The acquisition relied on embarked instrumentation (strain gauges, temperature probes, and vacuum sensors) and on remote acquisition devices (laser Doppler vibrometer and high‐speed camera). Several studies have been performed to verify the dynamic behaviour of the standard strain gauges and the related cabling in the chosen range of acquisition frequency (few MHz). The strain gauge measurements were complemented by velocity measurements performed using a customised long‐range laser Doppler vibrometer (LDV) operating in the amplitude range of 24 m/s; the LDV, together with the high‐speed video camera (HSVC), has been placed at a distance of 40 m from the target to minimize radiation damage. In addition, due to the large number of measuring points, a radiation‐hard multiplexer switch has been used during the experiment: this system was designed to fulfil the multiple requirements in terms of bandwidth, contact resistances, high channel reduction, and radiation resistance. Shockwave measurements and intense proton pulse effects on the instrumentation are described, and a brief overlook of the comparison of the results of the acquisition devices with simulations, performed with the finite element tool Autodyn, is given. Generally, the main goal of such experiments is to benchmark and improve material models adopted on the tested materials in explicit simulations of particle beam impact, a design scenario in particle accelerators, performed by means of Autodyn. Simulations based on simplified strain‐dependent models, such as Johnson–Cook, are run prior to the experiment. The model parameters are then updated in order to fit the experimental response, under a number of load cases to ensure repeatability of the model. This paper, on the other hand, mostly focuses on the development of the DAQ for HiRadMat experiments, and in particular for HRMT‐14. Such development, together with the test design and run, as well as postmortem examination, spanned over two years, and its fundamental results, mostly in terms of dedicated instrumentation, have been used in all successive HiRadMat experiments as of 2014. This experimental method can also find applications for materials undergoing similarly high strain rates and temperature changes (up to 106 s‐1 and 10.000 K, respectively), for example, in the case of experiments involving fast and intense loadings on materials and structures.

Instrumentation

10.1155/2021/8855582

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JACoW : Ground vibration monitoring at CERN as part of the international seismic network

16th Int. Conf. on Accelerator and Large Experimental Control Systems (ICALEPCS'17), Barcelona, Spain, 8-13 October 2017 (2018)

C. Charrondière Kevin Develle Michael Guinchard Morgane Cabon

Ground vibrations

10.18429/jacow-icalepcs2017-thpha134

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Experimental Verification Towards Feed-Forward Ground Motion Mitigation at ATF2

Juergen Pfingstner Kurt Artoos C. Charrondière Stef Janssens Marcin Patecki

Without counter measures, ground motion effects would deteriorate the performance of future linear colliders to an unacceptable level. An envisioned new ground motion mitigation method (based on feed-forward control) has the potential to improve the performance and to reduce the system cost compared to other proposed methods. For the experimental verification of this feed-forward scheme, a dedicated measurement setup has been installed at ATF2 at KEK. In this paper, the progress on this experimental verification is described. An important part of the feed-forward scheme could be already demonstrated, namely the prediction of the orbit jitter due to ground motion measurements.

Feed forward

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First results of an experiment on advanced collimator materials at CERN hiradmat facility

A. Bertarelli O. Aberle R. Aßmann E Berthomé V. Boccone

Collimator

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Mitigation of ground motion effects in linear accelerators via feed-forward control

Physical Review Special Topics - Accelerators and Beams (2014)

Juergen Pfingstner Kurt Artoos C. Charrondière St. Janssens Marcin Patecki

Ground motion is a severe problem for many particle accelerators, since it excites beam oscillations, which decrease the beam quality and create beam-beam offset (at colliders). Orbit feedback systems can only compensate ground motion effects at frequencies significantly smaller than the beam repetition rate. In linear colliders, where the repetition rate is low, additional counter measures have to be put in place. For this reason, a ground motion mitigation method based on feed-forward control is presented in this paper. It has several advantages compared to other techniques (stabilization systems and intratrain feedback systems) such as cost reduction and potential performance improvement. An analytical model is presented that allows the derivation of hardware specification and performance estimates for a specific accelerator and ground motion model. At the Accelerator Test Facility (ATF2), ground motion sensors have been installed to verify the feasibility of important parts of the mitigation strategy. In experimental studies, it has been shown that beam excitations due to ground motion can be predicted from ground motion measurements on a pulse-to-pulse basis. Correlations of up to 80% between the estimated and measured orbit jitter have been observed. Additionally, an orbit jitter source was identified and has been removed, which halved the orbit jitter power at ATF2 and shows that the feed-forward scheme is also very useful for the detection of installation issues. We believe that the presented mitigation method has the potential to reduce costs and improve the performance of linear colliders and potentially other linear accelerators.8 MoreReceived 24 September 2014DOI:https://doi.org/10.1103/PhysRevSTAB.17.122801This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical Society

Feed forward

Orbit (dynamics)

10.1103/physrevstab.17.122801

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High-Speed Data Acquisition of Sensor Signals for Physical Model Verification at CERN HiRadMat (SHC-DAQ)

C. Charrondière Michael Guinchard S.Marques Dos Santos

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Compensation of orbit distortion due to quadrupole motion using feed-forward control at KEK ATF

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment (2018)

Douglas Bett C. Charrondière Marcin Patecki Juergen Pfingstner Daniel Schulte

The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interaction Point (IP). One potential source of luminosity loss is the motion of the ground itself. The resulting misalignments of the quadrupole magnets cause distortions to the beam orbit and hence an increase in the beam emittance. This paper describes a technique for compensating this orbit distortion by using seismometers to monitor the misalignment of the quadrupole magnets in real-time. The first demonstration of the technique was achieved at the Accelerator Test Facility (ATF) at KEK in Japan. The feed-forward system consisted of a seismometer-based quadrupole motion monitoring system, an FPGA-based feed-forward processor and a stripline kicker plus associated electronics. Through the application of a kick calculated from the position of a single quadruple, the system was able to remove about 80% of the component of the beam jitter that was correlated to the motion of the quadrupole. As a significant fraction of the orbit jitter in the ATF final focus is due to sources other than quadrupole misalignment, this amounted to an approximately 15% reduction in the absolute beam jitter.

Interaction point

Orbit (dynamics)

Distortion (music)

Quadrupole magnet

10.1016/j.nima.2018.03.037

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Investigation and Estimation of the LHC Magnet Vibrations Induced by HL-LHC Civil Engineering Activities

9th Int. Particle Accelerator Conf. (IPAC'18), Vancouver, BC, Canada, 29 April-04 May 2018 (2018)

Michael Guinchard Morgane Cabon C. Charrondière Kevin Develle P. Fessia

10.18429/jacow-ipac2018-wepmf080

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Magnetic axis and geometric measurement for the LHC cryomagnet

C. Charrondière A. Rijllart M. Bajko J. García Pérez

The LHC cryomagnets are made with several types of magnets which all need to be aligned. Both magnetic and geometric axis need to be well known before the installation in the LHC tunnel. These measurements require integrated controls for optical, magnetic and geometric measurements systems. The measurement sequence as well as the analysis should be adapted to each type of magnet. To perform the measurement, a mole, equipped with a reflector, a CCD camera and Hall probe sensors should be moved along the tubes of the 15 metres long dipole magnets and rotated around its axis. The geometrical measurements are made with an industrial Laser Tracker system. Homemade systems have been developed for the image and magnetic measurements. Each part can be driven separately and form the lower layer of the system. The control, as well as the interaction of these systems, has been integrated into a single system using UDP communication. The harmonic analysis allows verification of the quality and the orientation of the magnetic field of the magnet. The geometric measurement program has been designed as a master, thus controlling all subsystems and the quality of the acquired data. In order to operate the magnetic and geometric measurement independently, a remote control application has been made. The structure of these two major parts, geometric and magnetic, has been designed so that new functionality can easily be added.

Laser tracker

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INDUSTRIAL CONTROLS FOR TEST SYSTEMS FROM SUPERCONDUCTING STRANDS TILL MAGNET FIDUCIALISATION IN THE TUNNEL FOR THE LHC PROJECT

A. Rijllart C. Charrondière B.A. Khomenko M. Marchesotti Erodis Pérez Michel

The LHC project requires construction and test of a large number of complex components, such as superconducting strands, cables and magnets, most of them produced in industry . T o qualify these components, dif ferent test systems based on industrial controls were developed and installed at the production site, but also at CERN. This paper describes a test system concept based on NI LabVIEW and alliance-members products that can be adapted to the needs of the component or assembly to test. This concept simplifies design and optimises reusability of LabVIEW modules. It will be further used in systems for commissioning the LHC, before particle beams will circulate in the machine.

Component (thermodynamics)

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