First Prototype of the Long Orbit Nested Corrector for HL-LHC

2.5-m-long nested orbit correctors (so-called MCBXFA) are necessary for the upgrade of LHC, in the framework of HL-LHC project. These magnets provide 2.1 T in vertical and horizontal direction and they share the same cross-section of their shorter version MCBXFB, for which two prototypes and the first two series magnets have been manufactured and tested. In this paper we first present the specific aspects of MCBXFA magnet design: (i) field quality in the different powering scenarios, and (ii) mechanical analysis, with special attention to torque under combined operation. We then overview the manufacturing techniques, which are very similar to those used for MCBXFB, pointing out some difficulties that have arisen during the coil vacuum impregnation. The components of the prototype magnet are being produced by CIEMAT and the magnet will be assembled at CERN facilities.