Analytical coupling losses modelling with COLISEUM: generalized approach upgraded to all stages

Predicting analytically the coupling losses generated in a cable for fusion magnets is still a significant challenge. Difficulties are related to the complex geometry of the system: several multi-strand stages embedded in one another with different twist pitches length, difficulty to model multiplets of strands, including compaction to the final shape. A two-stage analytical geometry based model (COLISEUM) has previously been developed at CEA. We try to extend it to any n-stage cables We detail here an iterative enhancement method to an n-stage model. We validated it against experimental data and shown that it is robust enough to fit our measured coupling losses. Finally, this upgraded model can be used to assess coupling losses in fusion n-stage cables in a particularly precise way from only geometrical information and analytical tools.