Quench Simulation of Superconducting Magnet

Thermal stability and quench propagation have long been a major concern of the superconducting magnet technology. Everything can be simulated if there are enough memory and cpu power in a computer. But magnet quench was thought to require too much computer resources. But the time has come. The computer situation as of today is very much different from that of a few years ago. It is possible to do the complete FEM analysis of realistic superconducting magnets.
The 3D FEM simulation of accelerator magnet was first done in 2003 ("2-D/3-D Quench Simulation Using ANSYS for Epoxy Impregnated Nb3Sn High Field Magnets", R.Yamada, E.Marscin, A.Lee, M.Wake, J.Rey, IEEE Trans.Appl.Sup.Mag. 13 1696 ) The technique to apply FEM programs to the quench simulation was found in this work. Now the analysis method is more systematic and complete. This example is for a cos theta type magnet.
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This example is for the quench of a Nb3Al common coil magnet made at Fermilab. The design of this magnet is exactly the same as the magnet built at LBNL. All the turns, all the insulators, all the cooling conditions and all the current situations are taken into account in this simulation. The quench starts at the high field region and propagetes only in the high field edge of the cable at the beginning because of the large difference of the magnetic field at both edge of the cable. The turn to turn thermal conductivity enhances the propagation of the quench. The quench velocity is turns out to be as fast as 300m/sec.
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This is a large solenoid magnet "mu2eDS". Dimensions are 2m diameter and 11m length. It has 2T to 1T gradient section of 4m and accurate 1T field of 6m. To have linear gradient, 10 thick spacers are inserted. 2T section and far end of the low field section has thin conductors. Therefore the structure of the magnet is geometrically complicated and traditional QUENCH program is difficult to apply. Cooling tube arrangement at every 45 degree and eddy current effect are also included in the model. Quench back happens in the middle of quench prpoagation. A 1/8 portion of the magnet is shown in this display. The quench data graph is also shown. It looks as vivid as if it is an experimental result, but it is just a simulation result.
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