In the framework of a design study for a post-LHC 100 TeV circular hadron collider, namely FCC-hh, high-gradient Nb3Sn lattice quadrupoles were investigated, following closely the specifications from the optic layout of that machine. After several iterations, a baseline design of the main quadrupole was selected and, then, included in the FCC-hh Conceptual Design Report. The article deals with the preliminary results of the 3-D electromagnetic and mechanical conceptual design. The 3-D design of Nb3Sn coil ends is known to be a critical phase, especially for small apertures. To tackle the potential issues, 3-D electromagnetic design was first carried out, taking into account the field quality constraints, the field margins in critical areas, and the windability of the coil ends. Then, winding trials with actual cables were performed, to help selecting designs and identifying critical geometrical parameters.

中文翻译：

---

主四极杆的 FCC-hh 概念设计和可卷绕性

在 LHC 后 100 TeV 圆形强子对撞机（即 FCC-hh）的设计研究框架中，研究了高梯度 Nb3Sn 晶格四极杆，并严格遵循该机器光学布局的规格。经过多次迭代，选择了主四极杆的基线设计，然后将其包含在 FCC-hh 概念设计报告中。本文介绍了 3-D 电磁和机械概念设计的初步结果。众所周知，Nb3Sn 线圈末端的 3D 设计是一个关键阶段，尤其是对于小孔径。为了解决潜在问题，首先进行了 3-D 电磁设计，同时考虑了场质量限制、关键区域的场余量以及线圈末端的可缠绕性。然后，进行了实际电缆的缠绕试验，