Operational Experience of a Prototype LHC Injection Kicker Magnet with a low SEY coating and Redistributed Power Deposition

W Weterings,T Kramer,G Bregliozzi,B Goddard,M J Barnes,G Iadarola,V Vlachodimitropoulos,A Chmielinska,L Vega Cid,L Ducimetière,C Bracco

doi:10.1088/1742-6596/1350/1/012145

Abstract

In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit operation for a few hundred hours due to dynamic vacuum. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of Unidentified Falling Objects, and which is compatible with the high voltage environment, was included in an upgraded MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a damping element: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of the damping element. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.

Highlights

The Large Hadron Collider (LHC) is equipped with two injection kicker (MKI) systems, MKI2 and MKI8, for deflecting incoming particle beams onto the LHC’s equilibrium orbits [1]
electron cloud (ECloud) in the alumina tube of MKI8D resulted in a dynamic pressure rise, measured in the Q5-MKI8D interconnect i.e. at the capacitively coupled end of the MKI8D where HV is induced on the screen conductors, being a factor of up to ∼1000 [9]
To ensure reliable future HL-LHC operation, an upgraded beam screen, relocating beam induced power deposition from the yoke to the upstream ferrite rings, was designed and incorporated in the MKI8D installed in the LHC during the YETS 2017-18 [16]

Summary

Introduction

The Large Hadron Collider (LHC) is equipped with two injection kicker (MKI) systems, MKI2 and MKI8, for deflecting incoming particle beams onto the LHC’s equilibrium orbits [1]. The high SEY of the virgin alumina tube resulted in high dynamic pressure both in the upgraded MKI8D tank and interconnects to both MKI8C and Q5. ECloud in the alumina tube of MKI8D resulted in a dynamic pressure rise, measured in the Q5-MKI8D interconnect i.e. at the capacitively coupled end of the MKI8D where HV is induced on the screen conductors, being a factor of up to ∼1000 [9].

Results

Conclusion