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ENEA - Fusion division
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NbTi Material
Contact: Luigi Muzzi
e-mail: muzzi@frascati.enea.it
tel.: +39 06 9400 5391
fax.: +39 06 9400 539
Our laboratory is currently involved in studies related to the optimisation of the NbTi strands which will be used in magnets for tokamak fusion reactors.
In fact, NbTi strands available on the market, have performances optimized to operate at low temperatures (T ≤ 4.2K) and magnetic fields below ˜6T, but their performances degrade with increasing operating temperature and field, in some cases reaching critical current values inferior to those which can be extrapolated by measurements at lower temperatures. This is valid mostly for strands characterized by a high Cu:non Cu ratio (≥2).
In the case of ITER, for example, the actual design of the poloidal magnets foresees the use of strands which present the following features:
| magnetic field copper:non copper current density |
PF2,PF3,PF4 | PF5 | PF1,PF6 |
|---|---|---|---|
| B(T) | 4 | 5 | 6 |
| Cu:nonCu | 6.9 | 4.4 | 1.6 |
| Jc(A/mm2) at 6.5K | 994 | 559 | 196 |
Also in the case of the JT-60SA project, involving us in the design and manufacture of all toroidal field magnets, it is foreseen the use of NbTi in ranges of fields and temperatures such as the strands currently available are not able to guarantee a sufficient temperature margin.
For this purpose, in parallel to an extensive characterization campaign of the commercially available strands at the temperatures and field of interest, we are carrying out a NbTi optimization process, together with the Italian LUVATA, to reach the performance required for these applications
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