Papers by Lucio Fiscarelli
The beam commissioning carried out in 2009 has proved that we have a pretty good understanding of... more The beam commissioning carried out in 2009 has proved that we have a pretty good understanding of the behaviour of the relation field-current in the LHC magnets and of its reproducibility. In this paper we summarize the main issues of beam commissioning as far as the magnetic model is concerned. An outline of what can be expected in 2010, when the LHC will be pushed to 3.5 TeV, is also given.
An on-line dynamic magnetic flux analyzer for magnetic measurement is presented. The instrument a... more An on-line dynamic magnetic flux analyzer for magnetic measurement is presented. The instrument achieves on-line harmonic analysis by means of an improved implementation of the sliding DFT algorithm on the basis of the Fast Digital Integrator [1]. In particular, the round-off error, unacceptable in digital integrators, is corrected by employing two buffers alternatively. Details about the structure of the instrument and the algorithm implementation are pointed out, and some experimental results are analyzed in order to validate the proposal.
Magnetic Characterization of Fast-Pulsed Quadrupole Magnets for LINAC4
Review of Scientific Instruments, 2012
The fast digital integrator has been conceived to face most demanding magnet test requirements wi... more The fast digital integrator has been conceived to face most demanding magnet test requirements with a resolution of 10 ppm, a signal-to-noise ratio of 105 dB at 20 kHz, a time resolution of 50 ns, an offset of 10 ppm, and on-line processing. In this paper, the on-field achievements of the fast digital integrator are assessed by a specific measurement campaign at the European Organization for Nuclear Research (CERN). At first, the architecture and the metrological specifications of the instrument are reported. Then, the recent on-field achievements of (i) ±10 ppm of uncertainty in the measurement of the main field for superconducting magnets characterization, (ii) ±0.02% of field uncertainty in quality assessment of small-aperture permanent magnets, and (iii) ±0.15% of drift, in an excitation current measurement of 600 s under cryogenic conditions, are presented and discussed.
Offset Correction in a Digital Integrator for Rotating Coil Measurements
Compensation of Third-Harmonic Field Error in the Main Dipole Magnets
A technique for generating user interfaces in software frameworks for automatic measurement syste... more A technique for generating user interfaces in software frameworks for automatic measurement systems is proposed. The user interface is separated from the application logic with the aim of enhancing flexibility and reusability of the software. A Model-View-Interactor paradigm focuses on the "interaction" between the automatic measurement system, executing test script written by a test engineer, and the application user. This approach has been applied to the flexible software framework for magnetic measurements at the European Organization for Nuclear Research (CERN). Experimental results on the application of the proposed technique to a case study of permeability measurement are reported.
Framework Per Sistemi Flessibili DI Misura
Advanced User Interface Generation in the Software Framework for Magnetic Measurements at Cern
Metrology and Measurement Systems, 2010
... They are the XML-compliant user interface definition languages (XML-UIDL) [22] and their adva... more ... They are the XML-compliant user interface definition languages (XML-UIDL) [22] and their advantage is to be transparent to different interface ... Graphical user interface layouts can be seen as a container subdivided in boxes, where the graphic components (text ...
2010 IEEE Instrumentation & Measurement Technology Conference Proceedings, 2010
Nuclear Research (CERN) is a suitable correction of multipole errors in magnetic field. The feed-... more Nuclear Research (CERN) is a suitable correction of multipole errors in magnetic field. The feed-forward control of the LHC is based on the Field Description for the LHC (FiDel), capable of forecasting the magnet's behavior in order to generate adequate current ramps for main and corrector magnets. Magnetic measurements campaigns aimed at validating the model underlying FiDel highlighted the need for improving the harmonic compensation of the third-harmonic (b3) component of the main LHC dipoles. In this paper, the results of a new measurement campaign for b3 harmonic compensation, carried out through the new Fast Acquisition Measurement Equipment (FAME), are reported. In particular, the mechanism and the measurement procedure of the compensation, as well as the new perspectives opened by preliminary experimental results, are illustrated.
A software framework for developing measurement applications under variable requirements
Review of Scientific Instruments, 2012
A framework for easily developing software for measurement and test applications under highly and... more A framework for easily developing software for measurement and test applications under highly and fast-varying requirements is proposed. The framework allows the software quality, in terms of flexibility, usability, and maintainability, to be maximized. Furthermore, the development effort is reduced and finalized, by relieving the test engineer of development details. The framework can be configured for satisfying a large set of measurement applications in a generic field for an industrial test division, a test laboratory, or a research center. As an experimental case study, the design, the implementation, and the assessment inside the application to a measurement scenario of magnet testing at the European Organization for Nuclear Research is reported.
2009 IEEE Intrumentation and Measurement Technology Conference, 2009
A Measurement-Domain Specific Language (MDSL) for test procedure definition, measurement tasks sy... more A Measurement-Domain Specific Language (MDSL) for test procedure definition, measurement tasks synchronization, and instrument configuration is proposed. MDSL is a formal language specially designed for a specific domain of measurement and test, aimed at specifying complete, easy-to-understand, -reuse, and -maintain applications efficiently and quickly. Owing to MDSL constructs capability of abstracting key concepts of the domain, the test engineer can write more concise and higher level programs in shorter time without being a skilled programmer. The MDSL has been applied to the specifications of superconducting magnet tests of the Large Hadron Collider at CERN.
The Field Description of the Large Hadron Collider (FiDeL) model is a set of semi-empirical equat... more The Field Description of the Large Hadron Collider (FiDeL) model is a set of semi-empirical equations linking the magnets behaviours established from magnetic measurements to the magnetic properties of the machine observed through beam measurements. The FiDeL model includes the parameterization of static and dynamic (time dependant) components. In the present paper, we outline the relationship between the beam observables (orbit, tune, chromaticity) and the model components during the commissioning to higher beam intensities in 2010-2011, with energy of 3.5 TeV per beam. The main relevant issues are (i) the operation at 10 A/s ramp rate and their influence on chromatic correction, (ii) the beta beating and its relation to the quadrupoles transfer functions and (iii) the origin of the observed tune decay at injection.
The magnetic model of the LHC is based on a fit of the magnetic measurements through equations th... more The magnetic model of the LHC is based on a fit of the magnetic measurements through equations that model the field components (geometric, saturation, persistent) at different currents. In this paper we will review the main results related to the magnetic model during the run of the LHC in 2010-2011: with a top energy of 3.5 TeV, all components of the model but the saturation are visible. We first review the main results relative to the decay at injection plateau, dependence on powering history, and snapback at the beginning of the ramp for both tune and chromaticity. We discuss the precision obtained in tracking the magnets during the ramp, where the persistent current components gradually disappear. We conclude by presenting the behaviour of the quadrupoles model during the squeeze.
IPAC
One of the main requirements for the magnet operation of the Large Hadron Collider at CERN is the... more One of the main requirements for the magnet operation of the Large Hadron Collider at CERN is the correction of the dynamic multipole errors produced. In particular, integrated sextupole errors in the main dipoles must be kept well below 0.1 units to ensure acceptable chromaticity. The feed-forward control of the LHC magnets is based on the Field Description for the LHC (FiDeL), a semi-empirical mathematical model capable of forecasting the magnet's behaviours in order to suitably power the corrector scheme. Measurement campaign were recently undertaken to validate the model making use of a novel Fast rotating-coil Magnetic Measurement Equipment (FAME), able to detect superconductor decay and snapback transient with unprecedented accuracy and temporal resolution. We discuss in this paper the test setup and some measurement results confirming the FiDeL model.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011
A system for the active compensation of magnetic field errors within ±2 ppm relative to the main ... more A system for the active compensation of magnetic field errors within ±2 ppm relative to the main field in superconducting magnets is proposed. A high-performance rotating coils system is exploited in order to combine high time resolution and integral field measurements. The compensation is based on an enhanced characterization of the corrector magnets and the measured field: this allows the system to be used as off-line reference in accelerator facilities. As an experimental case study, the measurement system and the procedure for compensating field errors of dipole magnets of the Large Hadron Collider at the European Organization for Nuclear Research (CERN) are illustrated.
The magnetic model of the LHC is based on a fit of the magnetic measurements through equations th... more The magnetic model of the LHC is based on a fit of the magnetic measurements through equations that model the field components (geometric, saturation, persistent) at different currents. In this paper we will review the main results related to the magnetic model during the run of the LHC in 2010-2011: with a top energy of 3.5 TeV, all components of the model but the saturation are visible. We first review the main results relative to the decay at injection plateau, dependence on powering history, and snapback at the beginning of the ramp for both tune and chromaticity. We discuss the precision obtained in tracking the magnets during the ramp, where the persistent current components gradually disappear. We conclude by presenting the behaviour of the quadrupoles model during the squeeze.
IEEE Transactions on Instrumentation and Measurement, 2000
A measurement-domain-specific language, which is based on a model-driven paradigm for measurement... more A measurement-domain-specific language, which is based on a model-driven paradigm for measurement-testprocedure definition, instrument configurations, and task synchronization, is proposed. This formal language, which is particular for a specific measurement field, aims at specifying complete, easyto-understand, easy-to-reuse, and easy-to-maintain applications efficiently and quickly by means of a script. The script is checked and integrated into the existing software framework automatically by a specific parser-builder chain, in order to produce the measurement application. Constructs for abstracting key concepts of the domain allow the test engineer to write more concise and higher level programs by natural language-like sentences in a shorter time without being a skilled programmer. As an experimental case study, the proposed language has been applied to the flexible framework for magnetic measurements at the European Organization for Nuclear Research (CERN).
IEEE Transactions on Instrumentation and Measurement, 2000
A Petri net (PN)-based approach to software synchronization in automatic measurement systems is p... more A Petri net (PN)-based approach to software synchronization in automatic measurement systems is proposed. Tasks are synchronized by means of a PN modeling an execution graph, where nodes represent tasks and arrows among nodes point out time succession among the corresponding tasks. This allows software synchronization to be abstracted above the code level by leaving the test engineer to work at a more intuitive level. As an experimental case study, the design, the implementation, and the application to a measurement scenario of the PN-based synchronizer inside the software framework for testing magnets at the European Organization for Nuclear Research (CERN) are illustrated.
Fast Cycled Magnet Demonstrator Program at CERN: Instrumentation and Measurement Campaign
IEEE Transactions on Applied Superconductivity, 2000
ABSTRACT In an effort to develop economical magnets for an upgrade of the LHC injector complex, C... more ABSTRACT In an effort to develop economical magnets for an upgrade of the LHC injector complex, CERN started an R&D program on superconducting Fast Cycled Magnets (FCM) in 2009. One of the challenges in this program was to develop a test station, which started working in summer 2012 when the FCM dipole demonstrator was tested. The magnet contains several important features, like forced-flow cooling of supercritical He and it has a protection scheme based direct voltage measurement with co-wound voltage tap wires. In this paper we report on the cryogenic and powering requirements and operation, the quench protection system, the temperature and mechanical measurements. The functioning of the test station and instrumentation are evaluated and we will discuss the measurements on a detailed level.
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Papers by Lucio Fiscarelli