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

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

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

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

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

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

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

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

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

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

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

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

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

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

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