Electromagnetic behaviors of superconducting Nb3Sn wire under a time-dependent current injection

Abstract

We build a 3D model to analyze the electromagnetic behaviors of Nb3Sn filamentary strand exposed to a time-varying current injection, under the consideration of n value and strain effect. Electromagnetic behaviors, performance degradation and AC loss are investigated. Results show that the filament bundles prevent a further field penetration from the outer shell into the interior matrix. Different current/field profiles occur in the strand and outside. Compared to the critical current, the average transport current keeps a high value with little change over a broader strain range, and has a larger magnitude by several orders of magnitude. Increasing the strain results in a suppression of the current transport capacity, and part of the current is expelled into the metal matrix causing larger AC loss. The larger twist pitch implies a longer current circuit and more magnetic flux enclosed, thus increasing the loss. More details are presented in the paper.

3D simulation of AC loss in a twisted multi-filamentary superconducting wire

“…In fact, larger pitch length provides longer circuit that the current has to pass through, so the resistive loss is enlarged. A similar behavior is evident in [41]. Fig.…”

“…They analyze the effect of barrier and twist pitch on AC loss. Ta [41] et al build a 3D model to analyze the electromagnetic behaviors of Nb 3 Sn filamentary strand exposed to a timevarying current injection. In these approaches, the superconductor is homogenized, and as far as we know, they cannot simulate the varying local current density in the superconductor along the twist filament without consideration of the anisotropic conductivity in filament.…”

Физические Принципы Создания Магнитолевитационных Систем На Основе Высокотемпературных Сверхпроводящих Композитов Второго Поколения (Обзор)

“…Эти пакеты по большей части используют метод конечных элементов или метод конечных разностей для решения дифференциальных уравнений в частных производных. В настоящее время используются четыре наиболее распространенных подхода описания поведения сверхпроводников методом FEM: H-формализм [101][102][103][104][105][106], (A−V)формализм [107,108], (T− )-формализм [109,110], (A−T)-формализм [111,112]. Слово " формализм" -общепринятое сокращение, которое по сути указывает на параметр, выступающий в качестве зависимой переменной модели при решении материальных уравнений, в данном случае уравнений Максвелла.…”

A 3D Model on the Electromechanical Behavior of a Multifilament Twisted Nb3Sn Superconducting Strand

“…The mechanical and electromagnetic analyses are always carried out separately. Recently, several models are proposed to consider the impact of strain on the electromagnetic behavior of Nb 3 Sn strand [19,25]. In these works, the strain is always assumed to uniformly distribute on the strand cross section.…”

“…In recent years, attempts are made to study the mechanical and electromagnetic behaviors of superconductors in different geometries by numerical simulations [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The extreme complexity of hierarchical geometry and structure of a Nb 3 Sn strand and CICC requires a special concern for the modeling of the strand entity.…”