Development of an Assembly Procedure to Reduce the Uncertainty Propagation by Geometric Tolerance Stackup Analysis of a Complex Ion Source for Nuclear Physics Applications

At Legnaro National Laboratories of the Italian National Institute for Nuclear Physics, Design for Assembly principles were applied to ease and improve the assembly procedure of the Forced Electron Beam Induced Arc Discharge ion source for the SPES Isotope Separation On-Line facility. Such device is a key component for the whole system, as its correct functioning is fundamental to provide the radioactive ion beam to the experimental users; furthermore, its reliability and performance stability are directly affected by the construction and placement accuracy of the parts that compose the assembly. A deep critical analysis of the current assembly procedure was performed to identify the main issues that affect the mounting accuracy of the ion source components. Consequently, a new assembly procedure was developed to fix the identified issues without applying relevant modification to the ion source parts; specifically, a custom assembly tool was designed not only for an easier coupling of the components, but also to improve the accuracy of the functional surfaces positioning to increase the device performance stability during operation. To achieve this, a custom assembly tool was designed to reduce the number of the elements of the tolerance stackup and, therefore, the uncertainty propagation. The proposed assembly procedure results significatively less time consuming than the current one, moreover it improves the accuracy of the FEBIAD ion source components position once assembled, as confirmed by Coordinate Measuring Machine measures