Abstract
| The current LHC external beam dumps (TDE, Target Dump External) are operational
since 2008. The dump cores are 7.6 m long and made up of different grades of
graphite, enclosed in a duplex stainless steel vessel, welded together in
different sections. The core itself is part of a longer assembly immersed in a
nitrogen atmosphere, delimited by a thin stainless steel sheet upstream and a
pure titanium disk downstream. Since end of 2015 a series of leaks of nitrogen
have been observed. Leaks have occurred in all the gaskets upstream of the dumps
(both UD62 and UD68) as well as in the downstream window for one of the two
operational dumps (UD68). This presentation summarises the type of leaks
observed and corrective measures taken during Run 2, together with the vibration
and displacement measurements performed to analyse the behaviour of the device
during beam dumping. Different upgrades are proposed to be implemented during
LS2, aiming at increasing the reliability of the assembly and hence, reducing
corrective interventions or eventual machine downtime. Additionally, numerical
simulations are shown in order to analyse the risk of failure of the upstream
and downstream windows under different beam dumping scenarios, including Run 2,
Run 3 and HiLumi beams, under normal operation or in case of partial dilution
failure. Considerations about the possibility to reach 1.8E11 during Run3 will
be provided, together with upgrade proposals. |