D. Tommasini

European Organization for Nuclear Research

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

L. Bottura

European Organization for Nuclear Research

E. Todesco

European Organization for Nuclear Research

A. Siemko

Massachusetts Institute of Technology

L. Rossi

Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata

P. Fessia

European Organization for Nuclear Research

Friedrich Lackner

European Organization for Nuclear Research

Daniel Schoerling

European Organization for Nuclear Research

M. Bajko

European Organization for Nuclear Research

F. Savary

European Organization for Nuclear Research

Marco Prioli

Istituto Nazionale di Fisica Nucleare

Cooperative Institutions

European Organization for Nuclear Research

732

Fermi National Accelerator Laboratory

274

Michigan State University

188

Linde (United States)

177

Cryogenic Industries (United States)

167

Cryomagnetics (United States)

149

A. Alikhanyan National Laboratory

129

Centre National de la Recherche Scientifique

107

University of Adelaide

Deutsches Elektronen-Synchrotron DESY

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

The Ultra-Stable Magnet of the Mark II Experiment

IEEE Transactions on Applied Superconductivity (2016)

D. Tommasini H. Baumann A. Eichenberger A. Vorotszhov

A new watt balance experiment is under development at the Federal Institute of Metrology (METAS, Switzerland). Its scope is to link the mass unit to the Plank constant in order to set a new definition of the kilogram, which is no longer based on the international prototype. The experiment is performed in two steps with the same setup and requires that the magnetic field produced in the two steps by the magnet fitted in the setup remains stable within few parts per 10 ⁸ . This paper describes the design, manufacture, and characterization of this magnet, which is performed through a collaboration between METAS and CERN.

Scope (computer science)

10.1109/tasc.2016.2521432

Cite

Citations (9)

Dielectric insulation and high-voltage issues

arXiv (Cornell University) (2011)

D. Tommasini

Electrical faults are in most cases dramatic events for magnets, due to the large stored energy which is potentially available to be dissipated at the fault location. After a reminder of the principles of electrostatics in Section 1, the basic mechanisms of conduction and breakdown in dielectrics are summarized in Section 2. Section 3 introduces the types and function of the electrical insulation in magnets, and Section 4 its relevant failure mechanisms. Section 5 deals with ageing and, finally, Section 6 gives some principles for testing. Though the School specifically dealt with warm magnets, for completeness some principles of dielectric insulation for superconducting accelerator magnets are briefly summarized in a dedicated appendix.

Section (typography)

High Voltage

10.48550/arxiv.1104.0802

Cite

Citations (0)

PERFORMANCE OF LHC MAIN DIPOLES FOR BEAM OPERATION

G. de Rijk M. Bajko L. Bottura Marco Buzio V. Chohan

At present about 90 % of the main dipoles for the LHC have been manufactured and one of the three cold mass assemblers has already completed the production. 85 % of the 1232 dipoles needed for the tunnel have been tested and accepted. In this paper we mainly deal with the performance results: the quench behaviour, the magnetic field quality, the electrical integrity quality and the geometry features will be summarized. PRODUCTION AND QUALITY Production has now reached over 1100 Cold Masses of the 1232 CMs to be installed and is expected to be completed by the end of October 2006 [1]. Cold tests on the remaining ~ 200 CMs are expected to finish by the end of 2006. During CM production the quality at the Cold Mass Assembler factories is assured by an extensive plan, which is an integral part of the technical specification. Early detection of faults during the assembly procedure is provided by a magnetic field measurement at room temperature. A total of 18 cases have been found [2], with 4 faults in the assembly, and 14 non-conform components. Magnetic measurements at room temperature have also been used to locate the position of electrical shorts for 18 cases [3]. Among them, 12 occurred in the inner layer and 4 on the outer one. In all cases the shorts were in the coil heads. After delivery to CERN, tests and measurements in operating (cryogenic) conditions are done to qualify the magnets. These tests are on the geometry, electrical integrity, quench behaviour and magnetic field quality.

Source

Cite

Citations (2)

Design and Use of Capacitive Force Transducers for Superconducting Magnet Models for the LHC

N. Siegel D. Tommasini I. Vanenkov

Capacitive force transducers have been developed and used for monitoring the coil pre-stress during assembly and excitation of several dipole models for LHC. Typically these gauges are strips several tenths of millimeter thick that can be made according to a large variety of geometries. Inserted between two surfaces, they allow to measure the distribution of contact pressures up to 200 MPa from ambient temperature to superfluid helium also in presence of a static magnetic field. The sequence and quality of the manufacturing steps are determining factors in the performance of this kind of gauges. The paper describes the basic principles, possible configuration geometries, fabrication and calibration procedures. Finally the applications of capacitive gauges in the framework of the R&D programme of superconducting short dipole models for LHC are reviewed and discussed.

Source

Cite

Citations (25)

Field quality of the short superconducting dipole models for the LHC

IEEE Transactions on Applied Superconductivity (2002)

W. Venturini Delsolaro Z. Ang L. Bottura S. Sanfilippo A. Siemko

A full characterization of the magnetic field in warm and cold conditions was performed as a part of the standard test on the LHC 1-m long superconducting dipole models. Furthermore, dedicated measurement campaigns addressed the effect of current cycles and quenches on field quality. Powering and quenches were found to generate characteristic instabilities in the geometric harmonics. Detailed results are presented on this phenomenon, as well as correlations between warm and cold measurements and field reconstructions.

10.1109/tasc.2002.1018404

Cite

Citations (0)

Construction of the CERN Fast Cycled Superconducting Dipole Magnet Prototype

IEEE Transactions on Applied Superconductivity (2011)

F. Borgnolutti Bernhard Auchmann L. Bottura Federico Carra G. Foffano

CERN is pursuing a small scale R&D on a fast cycled superconducting dipole magnet (FCM) of interest for the upgrade plan of the LHC accelerator complex. The FCM dipole prototype being built has a number of novel features if compared to other magnets for similar applications. In this paper we describe the magnet design, and its expected performance, focusing especially on the novel features (magnetic circuit, mechanical supports, cooling) and on the details of the manufacturing procedure (coil winding and impregnation, joints, instrumentation and quench protection).

Upgrade

Dipole magnet

Niobium-tin

10.1109/tasc.2011.2176451

Cite

Citations (14)

Training Behavior of the Main Dipoles in the Large Hadron Collider

IEEE Transactions on Applied Superconductivity (2017)

E. Todesco Bernhard Auchmann M. Bajko L. Bottura Oliver Brüning

In 2015, the 1232 Nb-Ti dipole magnets in the Large Hadron Collider (LHC) have been commissioned to 7.8 T operational field, with 172 quenches. More than 80% of these quenches occurred in the magnets of one of the three cold mass assemblers (3000 series), confirming what was already observed in 2008. In this paper, the recent analysis carried out on the quench performance of the Large Hadron Collider dipole magnets is reported, including the individual reception tests and the 2008 and 2015 commissioning campaigns, to better understand the above-mentioned anomaly and give an outlook for future operation and possible increase of the operational field. The lower part of the quench probability spectrum is compatible with Gaussian distributions; therefore, the training curve can be fit through error functions. An essential ingredient in this analysis is the estimate of the error to be associated with the training data due to sampling of rare events, allowing to test different hypothesis. Using this approach, an estimate of the number of quenches required to reach 8.3 T (corresponding to the 7 TeV nominal energy) is given, and we propose to have two LHC sectors trained toward this target before the next warm up of the LHC.

10.1109/tasc.2017.2657504

Cite

Citations (9)

A model for the simulation of relaxation phenomena in dielectrics

IEEE Transactions on Electrical Insulation (1990)

G. Degli Esposti D. Tommasini

A simulation of the behavior of the complex permittivity in a polymeric material as a function of frequency is presented. Starting from experimental data and taking into account the occurrence of a distribution function in the relaxation times, an electrical equivalent circuit for each material can be established. Then, the model is used to analyze some insulating systems. The curves are calculated for a stratified insulation and for a single material subjected to chemical degradation. An experimental study on ad hoc polypropylene films purposely processed with different concentrations of a particular polar additive is presented and discussed on the basis of the model. Several possible applications are considered.< >

Polypropylene

Basis (linear algebra)

Experimental data

10.1109/14.57082

Cite

Citations (11)

LHC Normal Conducting Magnets Toward HL-LHC and Beyond: Life Span Evaluations, Corrective Actions, and Future Upgrades

IEEE Transactions on Applied Superconductivity (2016)

P. Fessia Nicola Mariani F. Cerutti Eugenie Gallay Michael Guinchard

After an overview of the radiation hardness needs for the normal conducting magnets installed in the present Large Hadron Collider (LHC) and for the future high-luminosity LHC (HL-LHC) exploitation, this paper describes the tests and modifications that have been carried out on the presently installed magnet types to evaluate their reliability and enhance their lifespan. In spite of the ongoing optimization, it has become evident that to comply with the HL-LHC requirement, new radiation hard magnets will be necessary for the most exposed locations: The solutions under study and the possible approaches will be discussed.

10.1109/tasc.2016.2536361

Cite

Citations (1)

Magnet acceptance and allocation at the LHC magnet evaluation board

P. Bestmann L. Bottura N. Catalan-Lasheras S. Fartoukh S. Gilardoni

The normal and superconducting magnets for the LHC ring have been carefully examined to insure that each of about 1900 assemblies is suitable for the operation in the accelerator. Hardware experts and accelerator physicists have contributed to this work that consisted in magnet acceptance, and sorting according to geometry, field quality and quench level. This paper gives a description of the magnet approval mechanism that has been running since four years, reporting in a concise summary the main results achieved.

10.1109/pac.2007.4439915

Cite

Citations (6)