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Nr 15: Margin in field angle dependent HTS superconductors

Goal

Calculate peak fields in strands, position on the load line, temperature margins accounting for the field angle dependence on the critical current density of REBCO conductors.

Description

  • Cable definition: see attached pdf.

  • 2D options:

    • Fields & forces = TRUE makes ROXIE calculate the magnetic field and Lorentz forces in the position of every line current in the model. The conductor is discretized by a number of line currents defined by N1 and N2.

    • Margin to Jc-fit = TRUE triggers the calculation of the position of each block on the load line. For low temperature superconductors, this is the position of the strand in the block that is exposed to the highest field. In the case of superconductors where the critical current depends on the field direction, this is the position of the strand in the block that is closer to the critical surface. The margins are calculated by bisection w.r.t. the Jc-fit function that is specified in the .cadata file. The parametrization of the critical surface is described in [1]. The operational temperature is defined in the cadata file.

    • Margin to linear Jc-approx. = FALSE. This option would calculate the margin w.r.t. to a linear approximation of the Jc-fit.

    • Enthalpy margins: = FALSE. This option triggers the calculation of enthalpy margins to quench, that is to say, we determine how much energy can be deposited in the coils to raise the temperature above the critical level. The material properties of the conductor ar specified in the .cadata file but they are only available NbTi and Nb3Sn superconductors.

    • Block Restriction: This field is a list of those blocks, in which we want to calculate the fields, forces, and margins. No entry is equivalent to selecting all blocks. option is meant to be a time saver in optimizations.

  • Plotting 2D:

    • We visualize the field and all of the above margins in the cross-section. In addition to thes plots, the following automatic plots are provided:

    • Force on each conductor of the block (automatic when Fields & forces = TRUE)

    • Margin to Jc-fit of each block on the load line

References

  1. J. Fleiter and A. Ballarino. Parameterization of the critical surface of REBCO conductors from Fujikura. EDMS Nr: 1426239

Files

use_case_15.zip