During the last year, several advancements have been made in the Warm Powering; among them some important steps towards implementing expanded modularity and guaranteeing unprecedented precision.
In the LHC, to date, only 1-Q (1-Quadrant) power converters (LHC main and individually powered quadrupole circuits, ATLAS toroid) have been conceived with modularity and feature N+1 redundancy whereas the 2-Q (LHC dipole circuits) and the 4-Q power converters (LHC correctors circuits) are all monolithically built. In HL-LHC, modularity will be extended to all power converters.
During LS2, two new types of 4-Q power converters are being installed: the R2ELHC600A-10V (to replace the LHC600A-10V in radiation exposed areas) and the first power converters designed and developed entirely within the HL-LHC, the R2E-HL-LHC600A-10V which will trim the current in the 11 T magnets. Both power converters are made of two modules of 400A each; for the 11 T circuits (where maximum current is 250 A) this represents full redundancy: if one of the two modules fails, the other suffices to guarantee the required trimming (to compensate the transfer function mismatch with the LHC dipoles).
In addition to this first delivery, the prototype of the HL-LHC2kA-10V (that will power both the IT trims, Q1 and Q3, and the IT correctors) has been validated. This converter is made of 5+1 400A-modules whose concept is similar to the ones of the R2E-HL-LHC600A-10V but with less stringent requirements in terms of radiation tolerance and common mode voltage withstanding. The design challenge was to have six of them working seamlessly in parallel over the four quadrants in the I-V plane. This objective was fully achieved!
Besides the progress on the powering itself, an important step was made towards achieving the most demanding precision performance for the power converters belonging to accuracy Class 0: the HL-LHC18kA-10V and the HL-LHC14kA-08V (powering the IT main and the D1/D2 circuits respectively). The prototype of a key component of the Class 0 high-precision measurement chain, the ADC HPM7177, has been successfully validated. This is a fundamental achievement, as the precision performance of the power converter cannot be better than the one of its measurement chain. The HPM7177 ADC was shown to offer unprecedented DC/Low Frequency performance in power converter application for particle accelerators, featuring better than 0.05 parts-per-million (rms) stability over 20 minutes: a step forward with respect to the LHC main dipole and quadrupole circuits.
