Rapid deformation assessment and uncertainty quantification for operating accelerator magnets based on measured temperature boundaries

Abstract This paper presents a rapid, weakly coupled electro–thermal–structural modelling and uncertainty-propagation approach for quantifying the deformation of accelerator magnets under operating conditions. This approach uses the established coupled analysis workflow to rapidly evaluate magnet deformation by directly mapping measured steady-state coil temperatures as boundary conditions, thus shortening the computational turnaround time compared to full simulations. Probability distributions are assigned to key input quantities, including temperature, current, and material parameters, and Latin hypercube–Monte Carlo sampling is used to obtain the predicted displacement distributions and the associated expanded uncertainties. The model is validated by laser tracker measurements of the steady-state coordinates of the magnet target holder at two operating currents, 95 A and 129 A. In the plane transverse to the accelerator beam axis (global x – y plane), the predicted horizontal x and vertical y displacements agree with the measurements within ±2 standard deviations, while the measured y displacements show larger scatter due to the angular uncertainty of the laser tracker. Model-based analysis further indicates an approximately linear correlation between the target-holder displacement and the measured steady-state outer-wall temperature. When the wall temperature reaches about 37.96 °C, the resultant displacement magnitude in x and y exceeds the 10 µm alignment threshold. The proposed approach enables efficient prediction of in-operation magnet deformation together with a consistent synthesis of boundary-condition uncertainties, providing a quantitative basis for accelerator alignment and magnet-support decisions.