12 T VE dipole program
The preliminary design of the 12 T VE has been concluded. A preliminary design review was carried out last July 7th and the reviewers acknowledged the work done by the team and suggested some improvements now under implementation. The first winding tests to assess the end spacer shape and in general the cable behaviour during coil manufacturing were accomplished. Further extensive tests with end spacer variations are planned in the next weeks.
A 12 T cross section with collared coils and one with bladders and keys have been designed, optimized and the components for the mock-ups to validate the computations are under production. To obtain measurements as soon as possible in the mock ups we will use pieces of discarded HL-LHC 11 T coils and shrinking cylinders. The mock up cross section accommodates these 11 T components into a 12 T cross section. This is considered in the FEM simulations, so the feedback from the measurements can be directly used for the 12 T VE program.
Figure 1 Separate inner and outer layer coils and collars for the mock-ups.
Both cross sections were defined to minimize the compression of the brittle Nb3Sn coils during the complete magnet lifecycle. The influence of construction tolerances and tool misalignment has been considered as well. It must be mentioned that a bladder and keys, double-aperture, cos(theta) coil dipole structure, was never designed before.
The tests to optimize an internal splice and allow less redundant coil boundaries are underway.
The mirror coil test facility has been designed to accommodate single coils of different size (including old 11 T coils and FalconD INFN coils) and pair of coils to create a single aperture dipole. It is a very flexible tools that will be precious to quickly test the first coils that will be produced in 2024. Tests of new coil protection systems can be possible as well. Most of the mirror parts are designed and some already under manufacturing.
A successful design review of the mirror was carried out last December 14th. The reviewers congratulated the team and acknowledged the potential of the new features introduced in the structure both for this project and for future ones.
Figure 2 The austenitic stainless-steel shell of the mirror.
SMC and 14+T program
The SMT program foresees the construction of several flat coils to test and validate in a simple configuration possible solution to be then introduced in more complex magnets. Several SMT variants with coils impregnated with different resins were tested in the last months.
The coils showed unexpected performance degradation during test as shown in figure 3. The causes of this behaviour and possible mitigation measures are under analysis.
Figure 3 Training performances of the SMC 2G_104 with a progressive degradation from quench 17.
The work on the 14+T dipole cross section continued with the analysis of the different cable and cross section parameters both for a single and a double aperture. Important to mention that a double aperture block coil dipole has never been built before, so its design is a real challenge.
INFN FalconD
The design of the FalcobD dipole is well advanced and INFN team is starting the engineering and manufacturing phase.
It is interesting to remark that starting from different viewpoints and with different teams at work, the proposed structures of the FalconD and of the 12 T VE are different. But they present a convergence of some basic principles like the coils stress levels and the closure of the gaps to use the iron yoke stiffness to contain deformations and related stresses.
Figure 4 FalconD cross section
CEA Collaboration
The copper R2D2 prototype coil was produced and is now under investigation. Winding of Nb3Sn coils is expected during the year 2024.
Figure 5 The prototype copper coil at CEA.
CIEMAT Collaboration
The commissioning of the prototype magnet laboratory is proceeding.
A parametric study, both magnetic and mechanical, of a common coil dipole is progressing.
Figure 6 A view of the new laboratory.
PSI Collaboration
The design of a Stress-Managed Asymmetric Common-Coils (SMAAC) dipole is progressing.
Figure 7 The SMAAC dipole cross section
The construction of a Subscale Stress-Managed Common-Coils prototype is advancing.
Figure 8 Parts for the coils of the subscale prototype.
Author: D. Perini