Overall cryogenic cooling power, and in particular for beam screen circuits S. Claudet, Daniel Berkowitz & A. Perin (TE-CRG) On behalf of HL-LHC / WP9 / Heat Load Working Group 6th HiLumi annual meeting, Paris 14-16 Nov 2016

Cryogenic cooling capacity, beam screen circuits Content Introduction Methodology for heat load assessment Global heat loads and capacity margins Specific case of LSS 2 & 8 Summary SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

HL-LHC cryogenic upgrade 2 new cryoplants (~18 kW @ 4.5 K incl. ~3 kW @ 1.8 K ) at P1 and P5 for high-luminosity insertions 1 new cryoplant (~4 kW @ 4.5 K) at P4 for SRF cryomodules. (Alternative under study: upgrade of 1 existing LHC cryoplant and distribution) 11T + Q5@P6 SRF test facility with beam at SPS-BA6 primarily for Crab-Cavities SPS-BA6 This talk concerns all but what is above. => Focus on the 8 sectors, and in particular the beam screen circuits SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

LHC Cryo-Configuration (from Run1 to Run5) 4 sectors with less loads (thanks to P1/P5) 4 sectors with more loads (HiLumi beams) SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Cryogenic cooling capacity, beam screen circuits Content Introduction Methodology for heat load assessment Global heat loads and capacity margins Specific case of LSS 2 & 8 Summary SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Methodology for heat load estimations EDMS 1719021 v0.2 Machine Configuration Beam Conditions Most of the dynamic heat loads are induced by the beam. The amount of refrigerated components can change over the time. Luminosity, Bunch number, … EDMS 1610791 v0.3 i.e. number of components on Sector Heat load data Scaling laws (equations) Scaling factors for: Heat-in leaks Resistive heating Synchrotron radiation Image current … Total heat loads are defined by Beam conditions Machine configurations Recollected from official sources: HLWG 2000 LHC Design Report LHC Project Note 140 … Theoretical values! Measured values to be considered at a later stage. Reference heat loads (for „LHC nominal“) Total heat load on Sector scale up sum all „scaled“ heat loads Values w/o contingency SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Reasons to update heat load data EDMS 1610791 v0.3 Identified points to be refined (after discussions with WP2, G.Iadarola et Al.) Design Report (ch.11 cryogenics) vs calculated by WP2 Image Current: 180 vs 115 mW/m/beam (DR includes 30mW/m/beam for BPM bellows) Synchr. Rad.: consistent within 4% (175 vs 173 mW/m/beam) Electron cloud: new WP2 calculations should be used instead. Heat load data Precision of scaling laws Some heat loads are not scalable Recollected from official sources: HLWG 2000 LHC Design Report LHC Project Note 140 … Estimated as main impact: -36% of IC values (-700W/sector@4.5-20K) MQ others scalable Non-scalable SSS SAMs are approximated using MQs. However, SAMs present no synchr. rad. The „drift“ part differs between SAMs Calculation-based values (SR, IC & e-cloud) can be provided by WP2 A tool is available and can generate calculated values for all magnets at any set of beam-parameters. SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Proposed update of WP9 Input Data Heat Load Studies v.2 WP2 Input Heat Load Studies v.3 (concluded) (new version) EDMS 1610791 v0.3 EDMS 1719021 v0.1 EDMS 1610791 v0.4 EDMS 1719021 v0.3 Heat Load Data Preliminary Heat Load Data Beam Parameters / Scaling Laws Beam Parameters / Scaling Laws Recollected from official sources: HLWG 2000 LHC Design Report LHC Project Note 140 Recollected from official sources & WP2 input HLWG 2000 LHC Design Report LHC Project Note 140 Source of input data Source of input data Heat Load Mechanism Scaling Factor Heat-In leaks X Resistive heating Synchr. Rad. Image Current Photo-el. Effect Beam Scattering Sec. particle losses Heat Load Mechanism Scalingg Factor Calc. Heat-In leaks X Resistive heating Synchr. Rad. Image Current Photo-el. Effect Beam Scattering Sec. particle losses Scaling Factors will be provided, but are for information only. From DR for LHCn From DR for LHCn Provided by WP2 tbd (DR for now) SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Cryogenic cooling capacity, beam screen circuits Content Introduction Methodology for heat load assessment Global heat loads and capacity margins Specific case of LSS 2 & 8 Summary SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Equivalent Refrigerator Capacity (LHC) S3-4 & S4-5 incl. 760 W of RF load Subcooler at QUI (high-load sectors only) and RF-loads lead to higher distribution losses due to inefficient mixing. But heat loads will change for HiLumi (study on-going with WP2) SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Equivalent Refrigerator Margins (For existing LHC refrigerators only) Results based on our model v.2 (new exercise with v.3 ongoing) 1. Obviously, there will be less global cooling capacity margin for transients and unkowns for HiLumi w.r.t present LHC LHC (installed) HL-LHC Baseline 2. Sectors 23 & 78 will be the weakest: - Low Luminosity triplet w.r.t 34 & 67 - Lower initial capacity than 12 & 81 Shows the total margin (nett + loss) Note: Here, the term “margin” implies an ideal “capacity transfer” between temperature levels. Although we know that this is only possible to a limited extend! SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Available margin for e-clouds 160W/half cell. Obtained from “capacity transfer” from 1.8 K loop 100W/half cell. i.e. fill 5448 Nb = 2220 Margin for transients, unknown ~ e-cloud SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Available margin for e-clouds 160W/half cell. Obtained from “capacity transfer” from 1.8 K loop The “Limit” would be lower due to higher heat loads on 1.8 K loop 100W/half cell. i.e. fill 5448 Nb = 2220 Margin for transients, unknown Small margin before reaching the installed capacity ~ e-cloud x 2.7 x 1.9 x 1.0 3. Considering well known beam induced heat loads scaling rules, there will be less cooling capacity margin for the beam screen circuit for transients and unkowns for HiLumi w.r.t present LHC SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Cryogenic cooling capacity, beam screen circuits Content Introduction Methodology for heat load assessment Global heat loads and capacity margins Specific case of LSS 2 & 8 Summary SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Limitations – e-cloud – Straight Sections Chamonix2016 - G. Arduini - Performance Limitations in LHC after LIU Upgrade Complexity # 1 2 3 Action None (as it is now) Open valves (fully) Change valve seat Change valve body Remarks         YETS 2015-16 Software could be done right away t.b.c. with valve supplier! requires cutting the pipes! HW - light HW - heavy   Kv vs. Valve Opening Valve seat Valve needle Control Valve Control Valve   ©Velan D. Berkowitz, S. Claudet SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Limitations – e-cloud – Straight Sections Chamonix2016 - G. Arduini - Performance Limitations in LHC after LIU Upgrade Q6LR5 = scaled from measured data for 2748 bunches would give 3.4 W/m/aperture at the end of the 2015 run on 4/11 increase factor Global limit given by installed refrigeration capacity 1.5 W/m/aperture D. Berkowitz, S. Claudet SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

IT LowL (45 m) - Influence of BS temperature Example: IT LowL     zoom   SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Elementary budget considerations Operating costs Electrical efficiency For 500W, 7’500h, 10 years 50-75K => 20 W/W 5-20K => 100 W/W 4.5K => 250 W/W 1.9K => 950 W/W (indicative values) Welec per W@Temperature => 45 kCHF => 225 kCHF => 560 kCHF => 2’140 kCHF 60 CHF/MW.h For this order of magnitude (beam screen circuit), it would be more a question of available capacity than optimisation of operation costs ! SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Summary With HiLumi conditions, there will be less global cooling capacity margin for transients and unkowns on the 8 sectors w.r.t present LHC Sectors 23 & 78 will be the weakest (Low Lumi triplets) For IT’s and ARC’s: not much could be done: x1.5 to x1.9 for IT’s, only locally for the ARC’s as global limit would be reached This could in fact only be a temporary solution before LS3 or a way to treat a singularity Reducing the heat loads on LSS R2 and L8 (treatment AC or LESS) would tend to re-align sectors 23 & 78 on the next lowest (12 & 81), but would need significant work by others (WP12, …) Work progress … , thank you for your attention! SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Cryogenic cooling capacity, beam screen circuits Spare slides but with heat load studies V2 (V3 on-going) will be as well shown in absolute capacity SC - 15Nov16 Cryogenic cooling capacity, beam screen circuits

Inputs for the heat load estimations of Sector 2-3 Cryo-Configuration S2-3 (present no changes)   Heat Loads S2-3 (for „LHC nominal“, compilated by HLWG 2015) Refr.2-3 LHC 4 TeV 6.5 TeV Ultimate HL-LHC Nominal IT ARC+DS MS Very high ph-e effect!! Approach for next slides: Factor kept as nominal (fph-e = 1). „Scrubbing campaign“ will depend on the available margin. * w.r.t. 12.5 kW for „LHC nominal sector“ Configuration does not change for S2-3

Evolution for S2-3 Scaling factors Heat loads (grouped by heat load mechanism) Evolution for S2-3 Scaling factors Heat loads Run 1 Run 5 ……. Run 1 Run 5 ……. Run 1 Run 5 ……. Heat-In leaks Resistive heating Synchr. radiation Image current Ph-elec. effect Beam gas scattering Sec. part. losses Heat-In leaks Resistive heating Synchr. radiation Image current Ph-elec. effect Beam gas scattering Sec. part. losses Image current & ph.el. effect are dominant. (Although, ph.el. effect was kept constant!) Kept as nominal Kept as nominal Scaling Factor Equivalent Capacity @ 4.5 K [kW]

Equivalent Capacity @ 4.5 K [kW] (grouped by temp. level) Evolution for S2-3 Heat loads Installed capacity 50-75 K Thermal shield 4.5-20 K Deficit for 4.5-20K in Run4 & 5 Beam Screen 4.5 K Cold mass (SAM, DFB) 1.8 K Margin for 1.8 K Cold mass (IT, MQ, MB) 3-4 K Pumping line 20-290 K Current leads Equivalent Capacity @ 4.5 K [kW]

Eq. Cap. @4.5 K inside Sector [kW] (grouped by Run) Evolution for S2-3 Eq. Cap. @4.5 K inside Sector [kW] Distribution of heat mechanism Dynamic / Static ratio Beam Induced 0.70 Static vs. Dynamic 0.87 Installed capacity 1.17 Dynamic ratio doubles w.r.t. Run1 Available capacity for 1.8 K “Capacity transfer” only possible to a limited extend! 1.46 Deficit for 4.5-20K 1.50

Evolution of S2-3 Cryo-Configuration S2-3 (present no changes) (grouped by heat load mechanism) Evolution of S2-3 Cryo-Configuration S2-3 (present no changes) Scaling factors per run Heat loads per run Run 1 Run 5 ……. Run 1 Run 5 ……. Refr.2-3 Heat-In leaks Resistive heating Synchr. radiation Image current Ph-elec. effect Beam gas scattering Sec. part. losses Heat-In leaks Resistive heating Synchr. radiation Image current Ph-elec. effect Beam gas scattering Sec. part. losses IT ARC+DS MS Scal. Factor =1 (LHC nominal) Kept as nominal Configuration does not change for S2-3 Scaling Factor Equivalent Capacity @ 4.5 K [kW]

Heat load margin* Heat Loads on Refr. S2-3 Eq. Cap. @4.5 K LSS R LSS L ARC+DS Heat Loads on Refr. S2-3 Heat load margin* * w.r.t. 12.5 kW for „LHC nominal sector“ Eq. Cap. @4.5 K [W] Heat Load [W] Eq. Cap. @4.5 K [W] Heat Load [W] Heat Load [W] Eq. Cap. @4.5 K [W] Eq. Cap. @4.5 K [W] Heat Load [W] Eq. Cap. @4.5 K [W] Heat Load [W] 4.5K 1.8K 3-4K 20-290K [g/s] 4.5K 1.8K 3-4K 50-75K 4.5-20K 50-75K 4.5-20K 20-290K Margin

Heat load margin* Heat Loads on Refr. S2-3 LSS R LSS L ARC+DS Heat Loads on Refr. S2-3 Heat load margin* * w.r.t. 12.5 kW for „LHC nominal sector“ Eq. Cap. @4.5 K [W] Heat Load [W] The heat loads increase from Run2 to Run5. Especially the ARC heat loads at 4.5-20 K and 1.8 K. Eq. Cap. @4.5 K [W] Heat Load [W] Heat Load [W] strong heat laod increase Eq. Cap. @4.5 K [W] strong margin decrease Eq. Cap. @4.5 K [W] Heat Load [W] Global margin decreased by 70% but it is still OK. However, deficit of 611 W at 4.5-20 K w.r.t. the “LHC nominal sector”. Eq. Cap. @4.5 K [W] Heat Load [W] 4.5K 1.8K 3-4K 20-290K [g/s] 4.5K 1.8K 3-4K 50-75K 4.5-20K 50-75K 4.5-20K 20-290K Margin