Test Coil for the Development of a Compact 3 T ${\rm MgB}_{2}$ Magnet

Abstract

An test coil was manufactured and tested as the first step in the development of a 3 T magnet system. Due to the fact that has a higher critical temperature, replacing conventional NbTi superconductor with , higher temperature operation will be possible. It will make the cryogenic design much simpler and less expensive.Furthermore, operating the magnet at higher temperature results in larger heat capacity of the materials and surrounding structures. Higher heat capacity, therefore, results in increased thermal stability of the magnet against quench initiation.The 3 T magnet design consists of several coils. One of the center coils was manufactured for testing the performance at higher temperatures. The test coil was conduction cooled and the quench performance of the coil was good, which means there were no critical issues during the coil manufacturing process. However, AC loss heating, as well as a small resistance of the coil was found, both of which might result from wire design, manufacture, and quality.

Second Test Coil for the Development of a Compact 3 T $ \hbox{MgB}_{2}$ Magnet

“…4. Though these voltages were lower than Test coil 1's voltage (15 mV at 120 A and 20 K) [6], the voltages were not acceptable for magnet's persistent current operation. Test coil 3's n-value related voltage was quite similar to Test coil 2's.…”

“…Fig. 3 shows Test coil 2's ramping current coil voltage and temperatures at around 21 K. From this chart, n-value was calculated to be around 4 [6].…”

“…One test coil targeting for a 3 T magnet (Test coil 1) had been manufactured, tested, and reported already [6]. Though the manufacturing process and coil ramping performance seemed to have no problems, remnant voltage associated with low n-value was found when it was ramped to the designed current.…”

Control of core structure in MgB2 wire through tailoring boron powder

“…The cost of MgB 2 superconducting wire consisting of light elements is also expected to be nearly the same as or even lower than those for conventional superconductors because of the abundant raw materials. These superior characteristics offer an exciting opportunity for the development of the next generation of superconducting magnets, for example, lightweight, space-saving, and low-cost magnetic resonance imaging (MRI) magnets operated at a higher temperature (>10 K) than for the conventional system [3][4][5][6][7]. What is required for the real application of MgB 2 is, however, further improvement of the critical current density.…”

Solid cryogen: a cooling system for future MgB2 MRI magnet

“…Anticipation of increasing LHe prices and possible shortages in the near future have increased demand for LHe-free MRI magnets 1 3 . To fulfill the above requirements, magnesium diboride (MgB 2 ) has great potential among the conventional commercialized low- and high-temperature superconductors 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 . Importantly, the higher T c (39 K) of MgB 2 offers a larger thermal margin than the 9.8 K of Nb-Ti, even under LHe operation 19 20 21 .…”