Void Fraction Influence on CICCs Coupling Losses: Analysis of Experimental Results With MPAS Model

Abstract

Modelling by analytical approach the coupling losses of CICCs used in tokamaks remains a challenge to be reliable. This is usually done using either CPU consuming numerical approaches or heuristic models such as MPAS now used for ITER. Experimental measurements of AC losses are performed at CEA using magnetization method on several JT-60SA TF type samples with various void fractions (25%-36%). Influence of void fraction on coupling losses is hard to heuristically model yet. We choose to develop an experimental protocol in order to measure coupling losses in a range of frequency relevant to fusion operation domain. AC losses model as MPAS is confronted to our JOSEFA experimental data. Conclusion and lessons will be taken into account for future work.

Extensive Analyses of Superconducting Cables 3D Geometry With Advanced Tomographic Examinations

“…The contact widths of section III.B.3), naturally associated in 3D with inter-strand contact surfaces, are linked with CICC inter-strand conductance, major driver of CICC coupling losses. For modelling purpose MAG42-2 and MAG42-3 samples coupling losses test were conducted at CEA in JOSEFA facility (see [14]). The resulting Q(f) curves were found shifted and with same peak intensities.…”

Analytical Coupling Losses Modelling With COLISEUM: Generalized Approach Upgrade to All Stages

“…This reduction has been initiated in [6] with the broad parametric exploration of the two-stage COLISEUM. Table I show the validation of our simplification in an application case using the geometric parameters of the two-first stage of JT-60SA TF cable that can be found in [9]:…”

“…We confront the experimental data measured on MAG42-3 samples under transverse sinusoidal field excitation using JOSEFA (see [9]) to the modelling given by the 𝑛-stage COLISEUM. Giving all geometrical parameters of the cable (𝑅 𝑠𝑡𝑟𝑎𝑛𝑑 , 𝑙 𝑝 sequences, and the cable pattern ex: 3x3x3x3x6) as inputs, it is then possible to construct the 5x5-matrix equation corresponding to the desired five-stage cable.…”

“…The only adjustable parameters of the system are the transverse conductances (at each cable stages). We first chose to model the MAG42-3 cable with only five stages without considering the strand interaction with the surrounding stages in order to confront our model to the advanced MPAS (see [9]) which is a five-stage model. Adjusting the conductances set as follows gives us a fairly good agreement with the data we measured in [9] (see Table II and Table III).…”

“…one couple of magnetic parameter per stage as in the MPAS model [8]. This newly developed 𝑛-stage COLISEUM is confronted to MPAS and assessed against the data measured at CEA Cadarache in the JOSEFA facility from a sample representative of JT-60SA TF [9].…”