Mechanical Analysis and Measurements of a Multicomponent NbTi/Cu Superconducting Magnets Structure for the Fully Superconducting Electron Cyclotron Resonance Ion Source*Supported by the National Natural Science Foundation of China under Grant No 11302225, and the China Postdoctoral Science Foundation under Grant Nos 2014M560820 and 2015T81071. (May 2016)