1. 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 Nov 2016

2. 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

3. HL-LHC cryogenic upgrade
2 new cryoplants (~ K incl. ~3 1.8 K ) at P1 and P5 for high-luminosity insertions
1 new cryoplant (~4 4.5 K) at P4 for SRF cryomodules (Alternative under study: upgrade of 1 existing LHC cryoplant and distribution)
11T +
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
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Cryogenic cooling capacity, beam screen circuits

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

5. 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

6. Methodology for heat load estimations
EDMS 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 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
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Cryogenic cooling capacity, beam screen circuits

7. Reasons to update heat load data
EDMS 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 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.
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Cryogenic cooling capacity, beam screen circuits

8. Proposed update of WP9 Input Data
Heat Load Studies v.2
WP2 Input
Heat Load Studies v.3
(concluded)
(new version)
EDMS v0.3
EDMS v0.1
EDMS v0.4
EDMS 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)
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Cryogenic cooling capacity, beam screen circuits

9. 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

10. 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)
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Cryogenic cooling capacity, beam screen circuits

11. 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!
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Cryogenic cooling capacity, beam screen circuits

12. 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
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Cryogenic cooling capacity, beam screen circuits

13. 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

14. 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

15. Limitations – e-cloud – Straight Sections
Chamonix 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
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
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Cryogenic cooling capacity, beam screen circuits

16. Limitations – e-cloud – Straight Sections
Chamonix 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
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Cryogenic cooling capacity, beam screen circuits

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

18. 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
=> 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 !
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Cryogenic cooling capacity, beam screen circuits

19. 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!
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Cryogenic cooling capacity, beam screen circuits

20. 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
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Cryogenic cooling capacity, beam screen circuits

21. 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 kW for „LHC nominal sector“
Configuration does not change for S2-3

22. 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 4.5 K [kW]

23. Equivalent Capacity @ 4.5 K [kW]
(grouped by temp. level)
Evolution for S2-3
Heat loads
Installed capacity
50-75 K
Thermal shield K
Deficit for K 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 K
Current leads
Equivalent 4.5 K [kW]

24. Eq. Cap. @4.5 K inside Sector [kW]
(grouped by Run)
Evolution for S2-3
Eq. 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 K
1.50

25. 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 4.5 K [kW]

26. 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 kW for „LHC nominal sector“
Eq. K
[W]
Heat Load [W]
Eq. K
[W]
Heat Load [W]
Heat Load [W]
Eq. K
[W]
Eq. K
[W]
Heat Load [W]
Eq. 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

27. 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 kW for „LHC nominal sector“
Eq. K
[W]
Heat Load [W]
The heat loads increase from Run2 to Run5. Especially the ARC heat loads at K and 1.8 K.
Eq. K
[W]
Heat Load [W]
Heat Load [W]
strong heat laod
increase
Eq. K
[W]
strong margin
decrease
Eq. K
[W]
Heat Load [W]
Global margin decreased by 70% but it is still OK. However, deficit of 611 W at K w.r.t. the “LHC nominal sector”.
Eq. 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