1. Preparation for the 3He Injection Test
05/2008 Duke
D. Dutta*, H. Gao, M. Busch, Q. Ye, X. Qian, W. Zheng, X. Zhu (Duke University)
ASU, BU, Caltech, LANL, MIT, MSU, NCSU, SFU
And others in nEDM collaboration
*Mississippi State University.

2. Outline
Introduction
Safety
Magnets
Glassware
Cryogenics
pNMR
Summary

3. Helium gas
Filling pipe To
ABS
Helium bath vessel
50K 4k
Heat exchanger
1.3k
0.7k
0.24k
Film burner
Pyrex cell
Dilution
refrigerator
tricoil

4. Update Problem with jacket pyrex cell
Seal <1K and safety when boil off
Cool the cell with OFHC copper foil
To ABS
DR 1K pot
Cs ring
Filling pipe
for L-He
Copper foil to cool the cell
Measurement
DR MX at 0.24K

5. Safety I: Boil off of LHe within pyrex cell
23.58 cc LHe within pyrex cell
boil off rate: ~1 mol/s
Heat rate: W/m2, in worst case
Effuse through ABS beamline, pressure difference ~25.2 Pa
Gas density at 273 K and 1 atm
Id: 0.04 m, L=1.0 m
Flow velocity: 17.8 m/s
Reynold constant: Re =
Resistance coefficient, K=0.9
From T. Ito and Applied Fluid Dynamics Handbook
Effect of thermal baffles not included

6. Protection for ABS vacuum system
A pneumatic valve to protect ABS beamline
A rupture disc for pressure relief 2”
ABS
If P>10-5 torr
Activate the
Pneumatic valve 5” 2”
Gate
valve
Vacuum
Gauge and
pump 5”
Rupture disk/
Pressure relief
ABS low Beam line
Non-magnetic
Pneumatic
valve
Catastrophic
Boil off

7. Safety II: boil off of LHe within Tricoil can
Siphon pipe to fill LHe into tricoil can
Pipe for safety venting
Heat rate: 2 kW/m2
Pressure drop: 5.5 psi
Gas
By J. Long
Venting velocity: 97m/s
1.375” ID, 45” length
Reynold number: 5.7x105
resistant coefficient: 0.49
Rupture
Avoiding Taconis resonance
Siphon pipe
Vacuum
vent pipe

8. Safety III: No problem with superconductor quench
Energy within tri-coil: J
Energy within transport solenoid coil: 6.3mJ, negligible
Quench will evaporate 2.84 liter of He gas at 4K
Amount to 8.67 mol He
The volume of tri-coil container: ~17 liter
Bottom :14 lit, top: 3 lit.
The pressure will increase by <50%
Assume space of coil : 7 lit
Acceptible to tricoil vessel
FEA analysis done by E. Iholff
Pressure
<2atm

9. Tricoil Magnet system Tricoil current lead
300K to 50K: copper wire, #11 AWG
50K to 4K: silver wire with filaments of HTS ceramic (BiPbSrCaCuO)
Low thermal conductivity
From American Superconductor
Solder with eutectic InAg with no flux

10. Cryogenics Cs ring Made by dry ice Epoxy 2850GT Kapton gasket
Heat load to DR mix:~ 5mW
~2.5mW from superfluid film burner
By G. Seidel
0.5mW for pNMR and support
1.1mW for gas introduction tube
13.8mW cooling
Cs ring to slow down superfluid flow rate
Torch to chase Cs vapor
Dry ice to condense Cs effectively
Sealing test undergoing
Pyrex to copper adapter
After fail and try, kapton gasket seals well with copper flange
Cs ring
Made by dry ice
Epoxy
2850GT
Kapton gasket

11. pNMR system Faraday cage Semi-rigid coax Weakly magnetized SS
Two tunable capacitor
Resonant coil
Copper
Semi-rigid coax
Center: Ag coated BeCu
Dielectric: teflon
Sheath: BeCu
From D. G. Crabb, UVA
Weakly magnetized SS
Tosca simulation by Tim, ASU
Faraday cage

12. Wire connection for temperature sensors
Thermometer leads: twisted pair , Phosphor bronze
Suggested by S. Williamson
Noninductive winding scheme
Minimizing induced voltage due magnetic flux change
Voltage wires and current wires thermal anchor separately
Wire lengths for thermal anchoring (300K to 4K)
1.1cm for #32 AWG
3.8cm for #24 AWG
Heat
sink
post

13. Summary
Design work is almost done, ready for fabrication and assembling. Injection test will be ready in the end of July

14. Thanks!