Two types of nested orbit correctors are necessary for LHC upgrade, the so-called MCBXFA and MCBXFB. They share the same cross section, but feature different lengths, 2.5 and 1.5 m, respectively. The power tests performed on two MCBXFB prototypes showed excellent performance when individually powered, but training to reach the nominal torque in combined operation was very long. Moreover, memory was lost after torque direction reversal. A detailed analysis of the power test results concluded that the origin of the problem was insufficient support for the torque at the inner dipole coil ends. A fine tuning of the inner dipole design is proposed to improve the performance of both types of magnets. This paper describes the analytical and numerical models developed to analyze the problem and their results.

A4 Tesla superconducting magnet has been developed by CIEMAT for a compact cyclotron for radioisotope production in the framework of AMIT project (Advanced Molecular Imaging Techniques) in collaboration with other Spanish companies. First power tests were performed using liquid helium transferred from dewars. An autonomous cooling system has been developed in collaboration with CERN, where the system was characterized with a dummy load. Some improvements have been implemented to reduce the cooling time before connecting the cyclotron magnet. A new low-thermal-loss transfer line has been developed to overcome the problems detected in the first cooling tests connecting the magnet.

The second prototype of the MCBXFB nested orbit corrector for the upgrade of the LHC has been manufactured at CIEMAT and assembled at CERN, in the framework of the HL-LHC project. This paper describes the changes introduced with respect to the first prototype in order to test some design improvements intended for the series magnets. The preload of the coils has been carefully studied, aiming to improve the performance in combined operation. A power test campaign has been carried out for this second prototype at CERN. Both dipoles reached ultimate current without any quench when individually powered. However, the results in combined operation did not improve those of the first prototype. Further analysis and studies are ongoing.

The first prototype of the short orbit corrector for the upgrade of the LHC has been fabricated at CIEMAT, in collaboration with CERN, in the framework of the HL-LHC project. It consists of two nested dipoles, with an aperture of 150 mm and physical length of 1.5 m. A first power test was performed without the outer dipole coils, which were replaced by a support structure to align the iron yoke with the collared inner dipole. This test was aimed to validate the coil fabrication techniques, which are innovative for a NbTi Rutherford cable. In the power test of the full assembled magnet, individual training of both dipoles was fine to ultimate current. However, the magnet was not able to reach nominal torque in combined operation. Several power tests and re-assemblies were necessary to be able to power both dipoles till nominal current. This paper describes the test results and analysis of the measurements. The magnet is heavily instrumented with voltage taps, collars with strain gauges and bullet gauges at the axial pushers.