Speaker
Description
This contribution presents the development of a 750 MHz IH DTL cold model, a prototype of the second accelerating structure of the LINAC7 proton linac. The compact geometry required at this frequency imposes micron level tolerances, making mechanical alignment especially challenging. This constraint motivated the implementation of a virtual assembly workflow to control GD&T from the early design phase.
The mechanical design is based on CST electromagnetic simulations and particle-tracking studies, which define the Drift Tubes (DT) positioning tolerances. Drift Tubes are individually manufactured, aligned in two stacks using precision pins (±5 µm transverse, 0.01 mm axial), and integrated into a conical 1.4° cavity structure. All components were defined through MBD, and a digital twin was created using 3DCS to evaluate tolerance chains and optimize GD&T. After fabrication, CMM measurements feed a second virtual assembly using SpatialAnalyzer, allowing verification of real geometries, detection of real alignment features, and minimization of rework before physical assembly.
This methodology has enabled GD&T optimization through statistical simulations, prediction of alignment behaviour prior to fabrication, and early mitigation of assembly risks. The cold model is now being assembled, and forthcoming low-power RF tests will validate the electromagnetic performance and support the final IH DTL design.