AbstractAt the Max-Planck-Institut für Plasmaphsik (IPP), Garching, the Wendelstein 7-X stellarator (W 7-X) is in the stage of the beginning R&D phase. The experiment will be a large modular machine with nonplanar coils, following the Garching development line. It fits into the range of next step devices [G. Beidler et al., Fusion Technol. 17 (1990) 148–168]. The main technical parameters are: major radius: R0 = 5.5 m, magnetic induction: B0 = 3 T, stored magnetic energy: Wm = 600 MJ, average plasma radius: r0 = 0.53 m. The expected plasma parameters are: central temperatures: Ti(0), Te(0)=2–5keV central electron density: ne(0) = 0.1−2 × 1020 m−3, energy confinement time: τE = 0.1−0.5 s, average beta value: 〈β〉 ⩽ 0.05. The design has to allow steady-state plasma operation. Consequently the coil system is superconducting. An internally cooled cable-in-conduit conductor with copper stabilized NbTi strands will be used at 4 K (LHe). The paper presents an overview of the design features of the machine and describes in particular the conductor design, the coil arrangement with electrical, hydraulic and mechanical parameters as well as the sequence of prototype steps which are foreseen for establishing a well-developed series production of the magnet.