LHCb upgrade LS 4 cryo design and capacity

LHCb upgrade (LS 4) – cryo design and capacity discussion K. Brodzinski

Outlook • ITs design and capacity limitations • distribution – service module • capacity limitation on the IT bayonet HX • Available capacities for s 7 -8 and 8 -1 cooling regarding BS dynamic heat load • Runs 2, 3, 4 main line of changes and consequences • Perspectives – raw analysis K. Brodzinski_2020. 11. 06

LHC IT 1. 9 K cooling scheme supply – line C (3. 6 bar) HX Return/pumping – line B (16 mbar) Design: 500 W J-T Design before modification: 500 W Modification: Due to global stability issues and related mechanical problems, the bayonet heat exchanger diameter was modified in 2007 reducing thermal performance of the system. Locally installed new HX should compensate for 320 W of total heat load (see next slide). Nota for P 2 and P 8: the bayonet HXs are the same for all Its but Service modules are different. K. Brodzinski_Chamonix_2017. 01. 23

Maximum cooling capacity ITR 1 New: EYETS 12 th April 2017 EH raw heating was 350 W while keeping the process stable. The real maximum cold mass heat load compensated by the cryogenic system was 350*0. 87=305 W (without any contingency). Considering that the test was done on one representative IT and process instabilities might happen, the maximum allowable value for the dynamic heat load compensation is lowered by 10 % and is equal to 270 W. ate d p u Scaling Lpeak for 270 W we get: Lpeak=2. 2 e 34 Hz/cm 2 for 6. 5 Te. V and Lpeak=2. 05 e 34 Hz/cm 2 for 7 Te. V. Remarks: the above estimation of luminosity limit is given only as indication, the cryogenic group considers heat load expressed in Watts as valid communication unit. K. Brodzinski_LMC_2017. 06. 21

Service module design Nota for P 2 and P 8: the bayonet HXs are the same for all ITs. However DATE HX is smaller, estimated at ~140 W (tbc) i. e. in case of higher heat load related service module is to be upgraded! K. Brodzinski_2020. 11. 06

Summary for EC compensation • All sectors were measured to confirm available cooling power for BS cooling (reference fill 5979 selected) • Operation scenario from 2017/2018 will be applied for operation during Run 3 • In case of P 1 and P 5 IT loaded at maximum value at 1. 8 K (~ 270 W what corresponds to L=~2 1034 Hz/cm 2), the available power for BS cooling in s 12, s 81, s 45 and s 56 will decrease by ~5 W/hc) • The above capacity values are valid for Run 3, depending on beam operation scenario and applied Hi. Lumi upgrade/modifications, the above values will have to be reviewed for Run 4 and later. 6 LMC_K. Brodzinski_2019. 04. 10

Perspectives – raw analysis Run 2 and 3 Sector 7 -8 Run 4 (HL) Sector 7 -8 IT IT P 8 IT Sector 8 -1 IT Remark: In run 4 (Hi. Lumi) we will spare capacity previously spent for IT at P 1. If used for BS non – isothermal load 300 W at 1. 9 K -> 1500 W for BS -> 1500/53=~28 W/hc (arc considered as main contributor for EC). Run 5 (HL+new. LHCb) Sector 7 -8 IT P 8 IT Sector 8 -1 IT Remark: In run 5 both cryoplants at P 8 will have to compensate for higher heat load on ITs at P 8 (if the upgrade applied). As P 8 spared P 1 capacity with HL upgrade, this savings could be used for P 8 ITR. However, LHCA will have less capacity for e. g. EC or will has to be upgraded. … options to be presented. K. Brodzinski_2020. 11. 06
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