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2009 MAGNET DEVELOPMENT AND INSTRUMENTATIONPulsed high-field coilsThe production of user coilsAlso in 2009 the copper-zylon coils remain the workhorseof the laboratory. The production of these coils has nowbecome standard; parts are parameterized and can be producedin 2 weeks on the computerized milling machine,the actual winding takes less than a week and testing a fewdays. Since most of the time parts are in stock and at least4 members of the team have the experience to wind a coil,a standard coil can be produced in 10 days. Moreover, thepolicy is to have at least one standard coil in stock, in orderto avoid as far as possible any delay for users after a(finally unavoidable) coil failure. A first glidcop zylon coilwas tested up to 72 T and is now available for users duringthe time the 1 MJ transportable generator is available.Given the success of this small-volume, short-pulse prototype,we have constructed a longer pulse (t max = 33 ms,t total = 200 ms ) 72 T coil which can be energized by the14 MJ generator. This magnet has been successfully testedand is now available to users on a permanent basis.Figure 168:XXL coilSpecial coilsIn 2009 a special coil for optical experiments (BMV) wasdeveloped and successfully tested in house and to the highestfield at our colleagues in Dresden. This coil (nicknamedXXL - see figure 168) is an up-scaled version of the X-coil. This coil produced 300 T 2 .m and is an improvementof 1100% compared to the former X-coils. The split coil,specially designed for synchrotron X-ray experiments, wasfinally tested inside its cryostat after some problems due tothe complicated integration of the coil-body with the liquidnitrogen cryostat. Last, but not least, a mini-coil madefrom Cu-stainless wire was produced by Jérome Béard andhe was able to break with this coil (used as an insert in astandard 60 T coil) the record field of the Toulouse laboratorythat now stands at 81 T. This test was partly made tovalidate our multi-coil design code that was used to designa large two-coil magnet (ARMS4).Technical developmentsMost of the time in coil winding is spent on applying thezylon reinforcement, therefore we decided to improve thezylon spinhead by making it more reliable (new frictionbrakes) and easier to maintain (the spinhead modules canbe exchanged in 2 minutes, to be cleaned and maintained).Since the main progress in coil performance has to comefrom progress in materials it is of utmost importance tostudy the materials used in coil construction under realisticconditions (cryogenic temperature and high mechanicalloads). To test the efficiency of the fibre reinforcement wedecided to continue the explo-vessel studies (as first developedin at the Universiteit van Amsterdam). Unfortunatelyonce the setup was running (using the high-pressure rig atthe Clarendon Laboratory in Oxford) and 30 pressure vesselshad been produced, it turned out that this installationwas not longer available to us due to changing priorities inOxford. Another high-pressure rig was identified in Franceand we expect to restart the explo-vessel tests before theend of the year. These tests will be used to determine forthe first time the properties of zylon reinforcement underrealistic conditions, study the influence of various impregnatesand impregnation methods, and last but not least toinvestigate other high-strength fibres that could be used as afall back solution in case zylon would not be available anymore.Apart from the mechanical strength of the conductorand the fibre reinforcement the quality of the isolation underhigh mechanical load at cryogenic temperature is of greatimportance to have coils with a long lifetime. In order totest various types of insulations we developed an isolationtest on wires applying realistic loads to the isolation. Thisinstallation has started to work and the first results will beavailable before the end of the year.OutlookThe success of pulsed fields combined with large-scale neutronand X-ray sources has created a demand for more timeat high magnetic fields per 24 hour period. This will be realizedby improving the duty cycle of the coils by increasingthe pulse duration (to prolong lifetime) combined with a reductionof the cool down time. Some test with liquid nitrogenbased on techniques used up to now in dc fields lookedvery promising (cool down times of only a few minutes). Itis likely that by implementing these techniques in our coilswe can gain at least a factor of ten in the duty cycle.J. Béard, J. Billette, P. Frings, F. Giquel , J.-M. Lagarrigue, J. Mauchain119