HL-LHC Inner Triplet Powering and Control Strategy

In order to achieve the target 3000 fb-1 integrated field for the HL-LHC (High Luminosity ' Large Hadron Collider) at ATLAS and CMS, new large aperture quadrupoles are required for the final focusing triplet magnets before the interaction points. These low-' magnets, based on the Nb$_{3}$Sn technology, deliver a peak field of 11.4 T. They consist of two outer quadrupoles, Q1 and Q3 and a central one divided into two identical magnets, Q2a and Q2b. To optimize the powering and the beam dynamics of these triplets, the quadrupoles will be powered in series by a single high-current two quadrants (2-Q) converter [18 kA, ±10 V]. Three 4-Q trim power converters are added over Q1 [±2 kA, ±10 V], Q2a [±0.12 kA, ±10 V] and Q3 [±2 kA, ±10 V] to account for possible transfer function difference between the quadrupoles. This paper presents the powering scheme of the four mentioned coupled circuits. A digital control strategy, using four standard LHC digital controllers, to decouple the four systems and to achieve a high precision control is proposed and discussed.