Self-field effects in NbTi subsize cable-in-conduit conductors

Analyses and implications of V–I characteristic of PF insert conductor sample

“…An effective self-field factor k eff [5] is defined in such a way that I cable c (B eff ) ∼ = NI strand c (B eff ), where B eff = B b + k eff I c (B b background field, N number of strands). The peak field factor resulting from the conductor geometry taking into consideration the magnetic field generated by the return conductor is k p = 0.0166 T/kA.…”

DC and transient current distribution analysis from self-field measurements on ITER PFIS conductor

“…The corresponding overdetermined system of linear equations similar to (1) is solved in the least squares sense by using the same TSVD technique. It should be noted that in reality the current is not necessarily distributed uniformly within a petal [8], and the assumption of the intra-petal uniformity is forced by the limited number of the available input data. Much care must be taken in the assembling of matrix G and vector m, as the ill-posed nature of the problem causes errors on data to heavily impact on the solution.…”

Stability Criteria for Cable-in-Conduit Superconducting Cables for Steady or Slow Pulse Operation

“…This simply relates the quench of the overall conductor to the point at which local steady state heating of strands anywhere in the conductor cross-section (particularly on the highest field part) cannot be removed by heat transfer to the helium, when there are no thermal disturbances. A similar approach based on a steady state heat balance is used in [2]- [4]. Both models are simple developments of the familiar Stekly (or 'well-cooled') criteria [5] which assumes an infinite ' ' value.…”

“…Both models are simple developments of the familiar Stekly (or 'well-cooled') criteria [5] which assumes an infinite ' ' value. It was suggested in [2]- [4] that measurements of the quench voltage on NbTi conductors might allow values of strand-helium heat transfer coefficient h to be derived. This approach is further developed here for use as a design criterion to determine a true 'limiting current' at which the conductor will quench.…”

“…In this paper, sensitivity studies will be performed on the finite heat transfer model to assess the conditions under which representative values can be extracted from experimental data. The quench data from the ITER Toroidal Field and Central Solenoid Model Coils (TFMC and CSMC) is then analyzed to extract values for conductors which can be compared to those for NbTi [3], [4]. The implications of these for and NbTi conductor design are then examined.…”