rossana bonomi [email protected] ess cryomodule status meeting, 9/1/2013
TRANSCRIPT
SPL RF power couplerthermal performance
Rossana Bonomi [email protected]
ESS Cryomodule Status Meeting, 9/1/2013
Short Cryomodule
ESS Cryomodule Status Meeting, 9/1/2013
Simulation tool• Mathcad semi-
analytical model *• One dimensional• Mesh with 22 nodes
• 3 series of nodes (inner wall, outer wall, gas)
* Based on O. Capatina ‘s presentation: http://indico.cern.ch/getFile.py/access?contribId=3&resId=1&materialId=slides&confId=86123
ESS Cryomodule Status Meeting, 9/1/2013
Geometry • DWT length = 300 mm• Inner wall diameter = 100 mm• Cu sputter thickness = 4 um• Inner wall thickness = 1.5 mm• Outer wall thickness = 2 mm• Wall cross section = 1152 mm2
• Antenna diameter = 44 mm
ESS Cryomodule Status Meeting, 9/1/2013
ESS Cryomodule Status Meeting, 9/1/2013
Boundary conditions• Cold flange temperature = 2 K• Warm flange temperature = 300 K• Antenna temperature = 330 K• Inlet gas temperature = 4.5 K (1 bar)• Inlet gas mass flow = 40 mg/s• Convection coefficient = 40
W/m2/K
Material properties• Th-mech properties function of temperature
• Solids: Cryocomp• Fluid (helium): Hepak
ESS Cryomodule Status Meeting, 9/1/2013
Outer wall
Inner wall
Copper RRR=30
Material properties• Radiative properties function of temperature
• Copper on wall
ESS Cryomodule Status Meeting, 9/1/2013
Cuivre poli mequanique from “Cryogenie” 1995 – Blue book
Temperature profiles• Results are comparable
with FE 2D simulations (Comsol)• Heat load at bath:
< 0.5 W• RF power: around 10 W• Antenna radiation load:
around 1 W
Inner wall
No COOL
40 mg/s He
Outer wall
Inner wall
Gas
RF power distribution• RF currents node position is
critical ..• 704 MHz, 50 ohm• Power: 1 MWp
• Duty cycle: 10%• Current: = 200 Ap
RF currents
ESS Cryomodule Status Meeting, 9/1/2013
RF power distribution
RF currents
ESS Cryomodule Status Meeting, 9/1/2013
• RF currents node position is critical ..
currents
power
Sensitivity analysis: RF node• No cooling
ESS Cryomodule Status Meeting, 9/1/2013
Shift [mm]
P rf [W]
Q rad [W]
Q bath [W]
0 23.688 0.753 24.381
10 24.863 0.767 24.799
20 25.940 0.785 25.110
50 27.738 0.840 25.159
100 24.682 0.823 23.034
CF
CF
Sensitivity analysis: RF node• Gas cooling with 40 mg/s
ESS Cryomodule Status Meeting, 9/1/2013
Shift [mm]
P rf[W]
Q rad [W]
Q bath [W]
0 10.208 1.346 0.104
10 11.425 1.354 0.121
20 12.660 1.360 0.155
50 15.531 1.369 0.338
100 14.136 1.349 0.538
CF
Sensitivity analysis: Mass flow
ESS Cryomodule Status Meeting, 9/1/2013
Mass flow(mg/s)
Qheater(W)
Prf(W)
Qrad(W)
Qbath (W)
0 0 23.688 0.753 24.381
30 32.722 12.542 1.461 0.151
40 49.669 10.208 1.346 0.104
50 63.629 9.667 1.284 0.103
• RF node @ cold flange (shift = 0)
Conclusions
ESS Cryomodule Status Meeting, 9/1/2013
• Mathematical tool can be tuned to simulate different geometries and cryo fluids
• Looking forward to the mock-up test for confirmation of this model
• ..and to suggestions !
• THANK YOU !
Operating condition Value
Beam current/pulse lenght 40 mA/0.4 ms beam pulse
20 mA/0.8 ms beam pulse
cryo duty cycle 4.11% 8.22%
quality factor 10 x 109 5 x 109
accelerating field 25 MV/m 25 MV/m
Source of Heat Load Heat Load @ 2K
Beam current/pulse lenght 40 mA/0.4 ms beam pulse 20 mA/0.8 ms beam pulse
dynamic heat load per cavity 5.1 W 20.4 W
static losses <1 W (tbc) <1 W (tbc)
power coupler loss at 2 K <0.2 W <0.2 W
HOM loss in cavity at 2 K <1 <3 W
HOM coupler loss at 2 K (per coupl.)
<0.2 W <0.2 W
beam loss 1 W
Total @ 2 K 8.5 W 25.8 W
SPL operational conditions
(Figure from: « An Introduction to Cryogenics », Ph.Lebrun, CERN/AT 2007-1)
He refrigeration He Liquefaction
Thermodynamic efficiency of gas cooling
• Electrical power for liquefaction of 1 g/s helium: 6200 Wel
• Carnot COP @ 4.5 K: 66 Wel/Wth
• 1 g/s liquid helium is equivalent to 100 Wth @ 4.5 K *
* U. Wagner s presentation: http://cdsweb.cern.ch/record/808372/files/p295.pdf
ESS Cryomodule Status Meeting, 9/1/2013
Thermodynamic efficiency of gas cooling
• Comparison with other ways of cooling (heat intercepts, self-sustained cooling)
• 990 @ 2 K, 220 @ 9 or 4.5 K, 16 @ 80 KCase Q @ 2K
[W]P [Wel]
Q @ 9K [W]
P [Wel]
Q @ 80K[W]
P [Wel]
vapours rate[g/s]
Q equiv. @ 4.5K
[W] (1g/s=100W)
P [Wel]
Total power[Wel]
A) No intercept 12.6 12,375 - - - - - 12,375B) 1 optimised intercept @ 80K 2.2 2,178 - - 44.6 714 - - - 2,892
C) 2 optimised intercepts @ 80K & 9K 0.18 178 3.2 704 30.6 490 - - - 1,372
D) 4.5K self-sustained vapour cooling 0.03 30 - - - - 0.020 2 440 470
E) He vapour cooling (4.5K-300K) 0.10 99 - - - - 0.04 4 880 979
F) He vapour cooling (4.5K-300K),RF power on
0.50 495 - - - - 0.04 4 880 1,375
G) No He vapour cooling,RF power on 22 21,780 - - - - 0 0 0 21,780
ESS Cryomodule Status Meeting, 9/1/2013
(B) 1 Heat intercept
Q @ 2K
300K
x1
L
Q @ 80K
(C) 2 Heat intercepts
Q @ 2K
300K
Q @ 8K
Q @ 80K
L
x 1
x 2
(D) He vapour cooling
300K
4.5K
Q in g/s
L
attenuation factor
Geometry
Geometry
Mesh
CF WF