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Dive into the research topics where François Debray is active.

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Featured researches published by François Debray.


IEEE Transactions on Applied Superconductivity | 2012

HTS Insert Magnet Design Study

M. Devaux; François Debray; J. Fleiter; P. Fazilleau; T. Lecrevisse; C. Pes; Jean-Michel Rey; J. M. Rifflet; M. Sorbi; Antti Stenvall; Pascal Tixador; G. Volpini

Future accelerator magnets will need to reach higher field in the range of 20 T. This field level is very difficult to reach using only Low Temperature Superconductor materials whereas High Temperature Superconductors (HTS) provide interesting opportunities. High current densities and stress levels are needed to design such magnets. YBCO superconductor indeed carries large current densities under high magnetic field and provides good mechanical properties especially when produced using the IBAD approach. The HFM EUCARD program studies the design and the realization of an HTS insert of 6 T inside a dipole of 13 T at 4.2 K. In the HTS insert, engineering current densities higher than 250 under 19 T are required to fulfill the specifications. The stress level is also very severe. YBCO IBAD tapes theoretically meet these challenges from presented measurements. The insert protection is also a critical because HTS materials show low quench propagation velocities and the coupling with the magnet makes the problem even more challenging. The magnetic and mechanical designs of the HTS insert as well as some protection investigation ways will be presented.


IEEE Transactions on Applied Superconductivity | 2002

Magnet calculations at the Grenoble High Magnetic Field Laboratory

Christophe Trophime; Konstantin Egorov; François Debray; Walter Joss; Guy Aubert

An axisymmetrical constrained semi-analytic optimization process is our basic tool for designing magnets. Developments of 3-D numerical models are undertaken to complement this approach. Such models are needed to investigate the overall behavior of our magnets. They are likely to provide suitable insights to solve the design problems arising from the demand for high magnetic field with both great spatial homogeneity and temporal stability.


IEEE Transactions on Applied Superconductivity | 2012

SMES Optimization for High Energy Densities

Pascal Tixador; N. T. Nguyen; Jean-Michel Rey; T. Lecrevisse; V. Reinbold; Christophe Trophime; X. Chaud; François Debray; S. Semperger; M. Devaux; C. Pes

High critical temperature superconductors (HTS) bring a lot of opportunities for SMES (Superconducting Magnetic Energy Storage). The large current densities under very high fields and the mechanical strength of IBAD route ReBaCuO coated conductors are very favorable characteristics. Electricity storage still is an issue in general and SMES bring a very interesting solution for pulse current supplies especially if its energy density increases. The record for SC magnet is 13.4 kJ/kg today. We study how to enhance this value. One of the main limitations for the SMES energy density is the mechanical stress as shown i.a. by the viriel theorem, which links simply stress and energy. The current density is another limitation not only the critical characteristic. Indeed protection also plays an important part and often is the real limitation for LTS magnets. We optimized solenoids with mechanical stress and current density constraints. 20 kJ/kg requires current densities of the order of 400 and stresses of about 400 MPa. These values are compatible with YBCO data but pose protection difficulties, which should be perhaps rethought. The design and these protection issues are discussed.


Review of Scientific Instruments | 2010

SEISM: a 60 GHz cusp electron cyclotron resonance ion source.

L. Latrasse; M. Marie-Jeanne; T. Lamy; T. Thuillier; J. Giraud; C. Fourel; Christophe Trophime; François Debray; P. Sala; J. Dumas

LPSC has been involved for several years in a challenging research and development program on the production of pulsed ions beams with high ionization efficiency primarily dedicated to radioactive ion beams. The generation of the high magnetic field requires the use of helix techniques developed at Laboratoire National des Champs Magnétiques Intenses. As a first approach, a cusp structure has been chosen. 3D simulations were used to define the geometry of the helices. The computer aided design of the mechanical parts of the magnetic structure has been performed at LPSC and was optimized to decrease the total volume of the source. The first 60 GHz magnetic structure (helices coils in their tanks, electrical, and water cooling environment) should be available before the end of 2009.


IEEE Transactions on Applied Superconductivity | 2013

HTS Dipole Insert Developments

Jean-Michel Rey; M. Devaux; F. Bertinelli; X. Chaud; François Debray; M. Durante; G. Favre; P. Fazilleau; T. Lecrevisse; C. Mayri; C. Pes; F. Pottier; M. Sorbi; Antti Stenvall; Pascal Tixador; Jean-Marc Tudela; T. Tardy; G. Volpini

Future accelerator magnets will need to reach a magnetic field in the 20 T range. Reaching such a magnetic field is a challenge only reachable using high temperature superconductor (HTS) material. The high current densities and stress levels needed to satisfy the design criterion of such magnets make YBaCuO superconductor the most appropriate candidate especially when produced using the IBAD route. The HFM EUCARD program is aimed at designing and manufacturing a dipole insert made of HTS material generating 6 T inside a Nb3Sn dipole of 13 T at 4.2 K. In the HTS insert, engineering current densities higher than 250 MA/m2 under 19 T are required to reach the performances. The stress level is consequently very high. The insert protection is also a critical issue as HTS shows low quench propagation velocity. The coupling with the Nb3Sn dipole makes the problem even more difficult. The magnetic and mechanical designs of the HTS insert will be presented as well as the technological developments underway to realize this compact dipole insert.


IEEE Transactions on Applied Superconductivity | 2000

The 20 MW-50 mm bore diameter magnet of the Grenoble High Magnetic Field Laboratory

G. Aubert; François Debray; Walter Joss; H. Jongbloets; M. Ohl

A 30 Tesla-20 MW magnet with a 50 mm bore was set into operation at the Grenoble High Magnetic Field Laboratory (GHMFL) in April 1998. It is made of two 10 MW magnets. The inner magnet is composed of a series of 10 helices, electrically in parallel with two thin Bitter coils connected in series. We give the specifications of this magnet and present the design of the 14 helix insert which is now under construction for a 34 mm bore magnet.


IEEE Transactions on Applied Superconductivity | 2013

HTS Coil Test Facility in a Large Bore 20 T Resistive Magnet at LNCMI

Y. Miyoshi; X. Chaud; François Debray; Benjamin Vincent; Pascal Tixador; Thibaud Lecrevisse; Jean-Michel Rey; Hideyuki Oguro; Satoshi Awaji; K. Watanabe; Gen Nishijima; Hitoshi Kitaguchi

The high temperature superconductor (HTS) coil development, especially in the interest of high field insert coil, requires characterizations of a prototype coil in high magnetic field. Our test probe fits into the bore of Ø 170 mm 20 T dc magnet, and the sample space Ø 130 mm allows test coils with ~Ø 110 mm and 140 mm height. A fast data acquisition method at sampling period of 0.1 ms was developed for coil quench test program, and a working principle of the method is demonstrated for a small test coil. To accommodate high current required in tests such as Ic and hoop stress tests, the new current leads were manufactured with an optimal current measured in the range of 600 ~ 700 A, which was sufficient for the envisaged coil tests. For short duration, the current lead could carry more than 1000 A without any influence of overheating in short sample Ic test. A demonstration of short sample Ic test is also presented.


IEEE Transactions on Applied Superconductivity | 2012

Final Design of the New Grenoble Hybrid Magnet

P. Fazilleau; C. Berriaud; R. Berthier; François Debray; B. Hervieu; W. Joss; F. P. Juster; M. Massinger; C. Mayri; Yannick Queinec; C. Pes; Rolf Pfister; P. Pugnat; L. Ronayette; Christophe Trophime

A CEA-CNRS French collaboration is currently developing a new hybrid magnet; this magnet combines a resistive insert composed of Bitter and polyhelix coils and a new large bore superconductor outsert to create an overall continuous magnetic field of 42+ T in a 34 mm warm aperture. The design of the superconducting coil outsert has been completed after thorough studies and successful experimental validation phases. Based on the novel development of a Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by the mean of a bath of superfluid helium at atmospheric pressure, the superconducting coil aims to produce a continuous magnetic field of 8.5 T in a 1.1 m cold bore diameter. The main results of the final design studies of the superconducting coil are presented including the 2D and 3D mechanical stress analysis, the conductor and coil specifications, the coil protection system as well as the required cryogenics infrastructure. The final design of the resistive insert coils is also described.


IEEE Transactions on Applied Superconductivity | 2010

A New Design for the Superconducting Outsert of the GHMFL 42+ T Hybrid Magnet Project

A. Bourquard; D. Bresson; A. Daël; François Debray; P. Fazilleau; B. Hervieu; W. Joss; F. P. Juster; C. Mayri; P. Pugnat; J. M. Rifflet; L. Ronayette; Christophe Trophime

A new superconducting coil outsert has been designed to be integrated within the existing infrastructure of the GHMFL hybrid project. Based on the novel development of a Nb-Ti Rutherford Cable On Conduit Conductor (RCOCC) cooled at 1.8 K by a bath of superfluid helium at atmospheric pressure, the superconducting coil aims to produce a continuous magnetic field of 8.5 T in a 1.1 m bore diameter. Combined with resistive insert coils, an overall continuous magnetic field of 42+ T will be produced in a 34 mm warm aperture. The main results of the conceptual study are reported including the conductor and coil specifications, the mechanical stress analysis, the coil protection scheme as well as the required cryogenics infrastructure. First developments and tests regarding the RCOCC are also presented.


Superconductor Science and Technology | 2014

Homogeneous performance and strain tolerance of long Bi-2223 HTS conductors under hoop stress

Y Miyoshi; Hitoshi Kitaguchi; X. Chaud; François Debray; Gen Nishijima; Yoshinori Tsuchiya

Two types of high-strength industrial Bi-2223 conductor, one laminated by copper alloy and the other laminated by stainless steel, have been tested to examine the effect of hoop stress on the transport property. The specimens (~2 m long) were prepared by winding one layer around a GFRP mandrel and the measurements were made in a liquid helium bath with the hoop stress calculated from the BJR product applied by external magnetic field. A careful measurement wire configuration was necessary to cancel the noise pick-up from the environment for more accurate determination of Ic and n-value. We show for the first time that both conductors showed homogeneous voltage–current characteristics over a long length and degradations with hoop stress occurred uniformly, which is crucial information for the development of HTS magnet technology. The onset of degradation occurred at 200 MPa and 220 MPa, with additional bending stress present from the winding diameter of 108 mm, for copper alloy laminated and stainless steel laminated conductors, respectively. After considering the effect of bending strain, our result agrees well with the previously measured data.

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Christophe Trophime

Centre national de la recherche scientifique

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X. Chaud

Centre national de la recherche scientifique

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J. Dumas

Centre national de la recherche scientifique

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Jean-Pierre Franc

Centre national de la recherche scientifique

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Pascal Tixador

Centre national de la recherche scientifique

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Rolf Pfister

Centre national de la recherche scientifique

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Nadine Vidal

Centre national de la recherche scientifique

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