Estimation of Screening Current Induced Field on Short Period Planar HTS Undulator

Abstract

One of the possible obstacles for future high temperature superconductor (HTS) undulator is undesirable field distribution changes due to screening current induced field (SCF). In this study, we investigated the effects of SCF of short period planar undulator magnet using a numerical simulation, specifically H-formulation with nonlinear BH curve of iron core considered. First, we used a periodic screening current analysis model to investigate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> -value and spool-by-spool critical current dependent hysteresis behavior of undulator field change due to SCF. The results with selected <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> -value and spool-by-spool critical current values may be used to estimate the possible variations of undulator field due to SCF. After that, the temporal behavior of undulator field with and without the current sweep reversal method is also investigated.