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History of the LNCMI in Toulouse

Pulsed magnetic fields were first produced and use at Cambridge, in 1924, with the pioneering work of P.L. Kapitza. In Toulouse, pulsed magnet production started in 1965, at Université Paul Sabatier under the initiative of S. Askénazy in the Laboratoire de Physique des Solides (LPS) with the strong support ofCharles Fert director of the laboratory.

During the first decade, S. Askénazy developed coils producing long duration pulsed magnetic fields up to 40T. Current through the coil was supplied by the discharge of a capacitor bank switched by ignitrons. He then set up a research team to use the field to study semiconductor quantum transport including J. Léotin, J.C. Portal and J.C. Ulmet. The team built up specific instrumentation, electronics, and cryogenics for pulsed magnetic field experiments and was soon successful at measuring quantum magneto-transport and optics in semiconductors, including Shubnikov de Haas, and magnetophonon oscillations, and far-infrared laser based cyclotron resonance. This work was developed in close collaboration with Pr. R.A. Stradling at the Clarendon Laboratory (Oxford), with Pr. P.R. Wallace at McGill University (Montreal) and with the support of J. Bok at Ecole Normale Supérieure. The novel feature of the Toulouse magnets was the long duration of pulses a few hundred milliseconds together with negligible coil vibrations. The power supply was based on 3kV capacitors storing 100kJ.

In 1975, the pulsed magnet set up expanded as a National Facility located on the campus of the Institut National des Sciences Appliquées (INSA) which was supported by CNRS, UPS and INSA and entitled Service National des Champs Magnétiques Pulsés (SNCMP). A new building was constructed to accommodate a set of four experimental set ups having their coils driven by a common power supply based on 1.25MJ (10kV) capacitor bank and a home-made mercury switch. Later, in 1980, the facility was upgraded by a novel switch based on high voltage thyritsors in series and simultaneously triggered by an optical fibre signal. [DOI:10.1117/12.935605]. This home-made technology paved the way for the next generation of pulsed magnet facilities around the world. Another step forward took place with the development of 60T coils made up of copper-wire reinforced with NbTi [DOI:10.1016/0921-4526(94)00934-N] as well as dilution cryogenics down to 100mK. [DOI:10.1016/0921-4526(94)01064-8]. During this second decade new lines of research started on magnetism, superconductivity and organic conductors. As a result, the SNCMP facility has welcomed growing numbers of visitors and established numerous collaborations at both national and international levels, which resulted in large number of publications. 

 

 

In 1990, S. Askénazy introduced the plan to upgrade the SNCMP with a 14 MJ, 24 kV power supply and new coils to produce 1-second pulsed fields up to 60T. The idea behind this was to initiate a European pulsed magnet facility. CNRS, UPS, INSA and Région Midi-Pyrénées endorsed the project and supplied preliminary funds to construct a new building, develop and construct in house the 14 MJ power supply. An extended technical team was then supported to carry out the development and construction of the 14 MJ capacitor based power supply, a world record at this time. In addition a research and technical development activity started to study and produce composite copper wires with high mechanical strength and low resistivity that aimed to reach magnetic fields up to 100T. [DOI:10.1016/0921-4526(94)00934-N]. The SNCMP took an active part in the European consortium « Design studies for 100 T magnet ». [DOI:10.1109/20.305615]. S. Askénazy promotedthe concept of “coilin-coilex” magnets based on two concentric coils energized by two different synchronized capacitors banks [DOI :10.1088/0034-4885/62/6/201, DOI:10.1016/0921-4526(94)00944-Q]. This concept is now widely implemented everywhere in order to produce non-destructive magnetic fields up to 100T. In addition, the SNCMP supported the installation of 30T, 1-second duration pulsed magnets in Porto (Portugal), Saragossa (Spain) as well as Mérida (Venezuela). 

In 2000, the “Laboratoire National de Champs Magnétiques Pulsés” (LNCMP) was created by CNRS, UPS and INSA who appointed then Geert Rikken as the new director. He coordinated an extended research and technical team which rapidly produced outstanding experiments up to 70T. Finally, in 2009, the Toulouse and Grenoble magnet facilities merged in a single laboratory created by CNRS in association with UJF, UPS and INSA, entitled “Laboratoire National des Champs Magnétiques Intenses” (LNCMI).