1. Design of the Injection Can
L. Bartoszek
BARTOSZEK ENGINEERING
12/15/08

2. Elaborating on Matthew’s talk
Matthew described the glass vessel that the ABS injects the polarized 3He into, and the interface with the ABS.
That vessel is not installed during the assembly of its support can (except as a test fit).
That vessel is installed in the can after the can is installed in the cryostat
This talk describes the module (can) that supports the injection vessel and IV1.

3. Caveats
Matthew, Jan and Larry’s models are all different because of independent development of different features
At some point in the near future we will merge all of our models together
We are working out naming and CAD conventions

4. Main items in the Can The injection vessel
The coaxial “chicken wing” valve
The Intermediate Vessel 1 (IV1)
The IV1 coaxial outlet valve
V14 (old name) valve
The cosine theta magnet
The injection vessel level sensor
The injection vessel level sensor valve
The IV1 pressurizer
The IV1 pressurizer actuator
Links to LN2 and LHe shields
Valve actuators
Vessel support struts

5. Overview of the size and shape of the injection can with a man in for scale
It is assembled from its top flange down on a temporary support structure not shown.
Some features are not shown because they have not been designed yet (like the support of the cosine theta magnet.)

6. Cosine theta magnet made transparent to show the vessels inside it
IV1

7. View showing where the injection can lives in the upper cryostat

8. Overview of the upper cryostat showing 3He services

9. A flange is needed here because the plumbing coming down from the Injection Can as shown interferes with assembly of the central detector.

10. G0 valve actuators

11. A note about Novatech G0 valve actuators
This is an electric motor driven valve actuator
They were specially developed for the G0 spectrometer at JLab because of their slender size that takes up less room on a cryostat flange
They provide well-metered force
We are looking into modifying them to run on either air or hydraulic motors

12. Photo of a Novatech valve actuator

13. View showing where the shield plates in the can need to be connected to the radiation heat shields in the upper cryostat

14. View looking through the hole in the cosine theta magnet showing that the injection vessel fits in the opening

15. Matthew and I came up with different methods of supporting the injection vessel.
What is currently missing is a way to hold up IV1 when the injection vessel is not installed yet.
The G-10 rods in my model may get moved or eliminated.
G-10 rods

16. Cross-section of IV1 showing the inlet and outlet coaxial valves

17. .50” aperture coaxial inlet valve needs to be made thermally isolating

18. This outlet valve is a place-holder
This outlet valve is a place-holder. The load path for the coax valve actuators is under study

19. Injection vessel level sensor

20. Level sensor
.50” right-angle valve

21. The elbow connecting the valve to IV1 uses rotatable kapton gasket flanges.
Note the small aperture hole in IV1 to reduce losses of polarized 3He.

22. Another view of the level sensor port on IV1

23. IV1 Pressurizer and its actuator

24. The rocker arm actuator for re-directing the actuator force vector
These pivots allow for differential thermal contraction between the actuator tube and IV1.
The rocker arm actuator for re-directing the actuator force vector

25. Cross-section of the pressurizer

26. Actuators and thermal intercepts on them

27. Linear motion feed-through into the vacuum vessel
Assembly studies are needed to determine the correct location of this connection.
VCR-style connectors are perfect for this connection. We probably need to customize them.

28. LN2 shield
The inner actuator rods also need to be thermally intercepted.
A copper braid (not shown) bridges between the inner and outer actuator tubes.
LHe shield

29. Thermally isolating “Chicken Wing” valves
Steve showed (or will show) Doug’s calculation of the radial gap required to reduce the conduction of heat across a closed valve.
The idea is to separate the volumes of LHe on opposite sides of the piston so that they cannot thermally communicate
There are tolerancing questions on this design that need to be answered by test
There are also alternative designs being considered

30. Cross-section of a right angle chicken wing valve

31. Conclusion
There are a near infinite number of details in each little mechanism in the injection can.
Many items shown as placeholders need to be iteratively re-designed for manufacturability and to match the design of successful lab prototype valves.
Thermally isolated valves need to be tested.
Thermal interception introduces assembly complexity that must be thought-through.