1. Tom Peterson, Fermilab 6 December 2011
Cryomodule Heat Load Estimates Converted to 4.5 K Equivalent Cooling Power
Tom Peterson, Fermilab
6 December 2011

2. Introduction
This short presentation compares numbers within a few sets of cryomodule heat loads by converting 2 K, 5 K and 70 K heat to an equivalent 4.5 K cooling power
Examples here
ILC RDR
S1-global
Estimates for proposed Cornell ERL
Project X
The goal is to highlight some of the primary sources of cryogenic cooling load
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

3. Cryogenic efficiency assumptions
I then calculate back to 4.5 K assuming a large 4.5 K plant at 25% efficiency.
No extra safety factor or margin is applied, just best estimates scaled to 4.5 K.
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

4. Type 4 cryomodule Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

5. 2 K heat loads and power Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

6. 5 K and 40 K heat and power Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

7. Static Heat Leak Measurements
Temperature
Level
Predicted Heat Leak (W)
Measured Heat Leak (W ) Cryomodule #1 (alone)
Measured Heat Leak (W)
Cryomodule #1 (with #2)
Measured
Heat
Leak (W)
Cryomodule #2
70 K
76.8 90
81.5
77.9
4.5 K
13.9 23
15.9 13
2 K
2.8 6 5 4
(from John Weisend, July 2004)
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

8. 4.5 K equivalent cooling power
ILC RDR revised totals
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

9. 4.5 K equivalent cooling power
ILC RDR revised totals
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

10. 4.5 K equivalent cooling power
ILC RDR revised totals
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

11. S1-Global estimated and measured heat
"S1-G-report(Thermal Test).doc"
by Norihito Ohuchi
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

12. 4.5 K equivalent cooling power
S1-Global estimated static only heat,
which agreed well with measured totals
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

13. 4.5 K equivalent cooling power
Cornell ERL estimated totals
dominated by dynamic RF and
HOM heating
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

14. 4.5 K equivalent cooling power
Project X 650 MHz cryomodule estimates
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing

15. Conclusions Approximate equivalencies
2 K heat load x 3 = 4.5 K equivalent
5 K - 8 K heat load x 0.75 = 4.5 K equivalent
40 K - 80 K heat load / 14 = 4.5 K equivalent
For a pulsed linac where RF cavity dynamic heating at 2 K is not completely dominant, input coupler and/or higher order modes may be significant heat loads even though taken at 5 K and 70 K.
Use of low conductivity cables, where feasible for signal transmission, can be a significant benefit.
End effects at a cryomodule cold-to-warm transition to 2 K and to the other temperature levels are generally small compared to other heat loads.
RF heat to 2 K will be significant in high energy and in high duty factor or CW linacs. As we approach CW levels of operation, cavity Q0 may be the dominant factor for cryogenic power.
Cryogenic Cooling Power, 6 Dec 2011
Tom Peterson, TTC Beijing