Modeling of Gradient-Induced Magnet Heating using Equivalent Current Surface and Multi-Physics Finite-Element Methods

With increasing prevalence of ultra-high field magnets and high-performance gradients, it is important to understand gradient-induced magnet heating, which can yield significant helium boil-off. Here, we propose a method to model this effect requiring no knowledge of gradient coil construction. Using measured gradient stray fields, we construct equivalent current surface models of gradient coils that can be input into finite element model of magnet systems to predict the deposited energy. We validate this equivalent current surface method using a gradient with a known winding pattern and further validate the energy deposition models by measuring power deposition in a 7T magnet.