**Magnet Cryostat Tasks**

The following magnet cryostat tasks have been identified as relevant to
the successful, safe, and/or efficient testing of LBQ and D20 magnets at
1.8K, and are listed in rough order of immediate concern. Among various
options that have been examined, the option which currently seems the
wisest is listed, along with the reason for the task. Each task has been
assigned a rough priority (P) for implementation. The priority groups
have the following meaning:

1.  Essential for safe, reliable, successful operation of LBQ at 1.8K.

2.  Presently deferrable, but essential for safe, reliable operation of
    D20 at 1.8K.

3.  Sanity/time/cost saving, and quality enhancements.

4.  Disaster insurance.

5.  Non-essential simplifications.

The initials of the primary coordinator (Co) for each task is listed (PB
= Paul Bish, JC = Julian Cortella, DS = Dick Schafer, AL = Al Lietzke,
HO = Hans Van Oort).

+-------------------+----------------------+---------------------+---+---+
| **Item**          | **Task**             | **Reason**          | * | * |
|                   |                      |                     | * | * |
|                   |                      |                     | P | C |
|                   |                      |                     | * | o |
|                   |                      |                     | * | * |
|                   |                      |                     |   | * |
+-------------------+----------------------+---------------------+---+---+
| 1.  Power-lead    | Surround leads with  | Safer electrical    | 1 | P |
|     insulation:   | loose Kapton sheet   | operation.          |   | B |
|                   | on ground side.      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 2.  Cold R-V      | Reverse plate to     | Copper gasket       | 1 | P |
|     sealing       | provide a 3/4" thick | causes 30W          |   | B |
|     surface:      | SS sealing surface.  | conduction load to  |   |   |
|                   |                      | 1.8K.               |   |   |
+-------------------+----------------------+---------------------+---+---+
| 3.  Fiber-optic   | Beveled Teflon seal  | The 3/4" Teflon     | 1 | P |
|     tubing        | onto 3/4" OD tube    | seal is already     |   | B |
|     feed-thru     | (or plug).           | finished and        |   |   |
|     pipe, lower   |                      | waiting.            |   |   |
|     seal:         |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 4.  19-wire V-tap | Provide 2" long      | \>10W conduction to | 1 | P |
|     wire copper   | silicone-rubber      | 1.8K.               |   | B |
|     tubing:       | sealed Teflon or     |                     |   |   |
|                   | Nema plug.           |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 5.  Power-lead    | Provide 3" of        | \>4.8W/lead         | 1 | P |
|     feed-thru     | silicone-rubber      | conduction load to  |   | B |
|     from 4.3K:    | sealed, clamped Nema | 1.8K (RRR = 40).    |   |   |
|                   | tube (\>1/8" wall)   |                     |   |   |
|                   | attached to the      |                     |   |   |
|                   | present Teflon seal. |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 6.  R-V riser     | Install 4-5          | 2W radiation & 2W   | 1 | D |
|                   | "Schafer" butterfly  | thermal acoustic    |   | S |
|  thermal-acoustic | baffles with         | load to 1.8K.       |   |   |
|     & radiation   | irregular spacing.   |                     |   |   |
|     baffles:      |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 7.  Holes in LN   | Plug with Al tape or | 3-4W radiation load | 1 | P |
|     shields:      | foil.                | to 1.8K blankets.   |   | B |
+-------------------+----------------------+---------------------+---+---+
| 8.  Cryostat      | Install diagnostics. | Diagnostic          | 1 | P |
|     diagnostics:  |                      | capability.         |   | B |
+-------------------+----------------------+---------------------+---+---+
| 9.  Liquid helium | Provide ball-valve   | Safer, easier       | 1 | P |
|     removal warm  | with upper tapered   | insertion & removal |   | B |
|     valve:        | Teflon seal at least | of stinger or plug. |   |   |
|                   | 2" above valve.      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 10. South-end     | Chase, and lubricate | Reduce threat of    | 1 | P |
|     cold R-V      | threads on cold R-V  | seizure.            |   | B |
|     actuator rod  | actuator rod.        |                     |   |   |
|     threads:      |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 11. All R-V's:    | Provide H~2~O        | Safer, more         | 1 | P |
|                   | condensation         | reliable R-V        |   | B |
|                   | protection for all   | operation and       |   |   |
|                   | R-V's having         | resealing.          |   |   |
|                   | frequent usage.      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 12. Glue-joint,   | Provide plastic      | Safer assembly &    | 1 | P |
|     lower bellows | guide-pins, and      | disassembly of      |   | B |
|     seal:         | backing screws.      | blind glue-joints.  |   |   |
+-------------------+----------------------+---------------------+---+---+
| 13. North-end     | Provide 10 psi       | Safer automatic     | 1 | J |
|     cold R-V      | capability.          | operation.          |   | C |
|     spring:       |                      |                     |   |   |
|                   |                      | Easier manual       |   |   |
|                   |                      | operation.          |   |   |
+-------------------+----------------------+---------------------+---+---+
| 14. South-end     | Provide 10 psi       | Safer automatic     | 2 | J |
|     cold R-V      | capability.          | operation.          |   | C |
|     spring:       |                      |                     |   |   |
|                   |                      | Easier manual       |   |   |
|                   |                      | operation.          |   |   |
+-------------------+----------------------+---------------------+---+---+
| 15. Fiber-optic   | Replace 1-long       | Easier and safer    | 2 | H |
|     feed-thru     | epoxy-filled pipe    | magnet insertion    |   | O |
|     sealing pipe: | with 2 short pipes.  | and removal.        |   |   |
+-------------------+----------------------+---------------------+---+---+
| 16. Fiber-optic   | Provide super-fluid  | 0.086W/tube-in.     | 2 | H |
|     tube          | seals between        | conduction load on  |   | O |
|     super-fluid   | well-spaced          | exposed 1/8"        |   |   |
|     seals:        | 1.8K-2.2K contours.  | tubing.             |   |   |
+-------------------+----------------------+---------------------+---+---+
| 17. Fiber-optic   | Provide warm helium  | Reduce helium loss  | 2 | H |
|     tube warm     | seals on all         | thru tubing.        |   | O |
|     seals:        | feed-thrus.          |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 18. Cryostat      | Warm-check           | Catch errors before | 2 | A |
|     diagnostics:  | data-acquisition     | cool-down.          |   | L |
|                   | capability           |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 19. Liquid helium | Provide safe, low    | Reduce cool-down    | 3 | J |
|     displacer:    | enthalpy, low helium | and LHe             |   | C |
|                   | absorption           | accumulation time.  |   |   |
|                   | displacer.           |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 20. Manually      | Provide a 2"         | Safer operation &   | 3 | P |
|     operated,     | Teflon-sealed        | more reliable       |   | B |
|     warm R-V:     | ball-valve that can  | sealing of          |   |   |
|                   | be operated quickly. | automatic R-V's.    |   |   |
+-------------------+----------------------+---------------------+---+---+
| 21. Cold R-V      | Provide for          | Easier modification | 3 | D |
|     manual        | external, threaded   | and/or repair.      |   | S |
|     actuation     | insertion.           |                     |   |   |
|     rod:          |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 22. South-end     | Split brass spacer   | Easier super-fluid  | 3 | P |
|     cold R-V      | tube.                | sealing.            |   | B |
|     shim:         |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 23. Glue-joint    | Provide guide-pins   | Safer assembly &    | 3 | P |
|     (LL1 - LL2):  | and backing screws.  | disassembly of glue |   | B |
|                   |                      | joints.             |   |   |
+-------------------+----------------------+---------------------+---+---+
| 24. V-tap wires:  | Route away from      | Reduce inductive    | 3 | A |
|                   | power leads.         | pick-up on V-tap    |   | L |
|                   |                      | wires.              |   |   |
+-------------------+----------------------+---------------------+---+---+
| 25. LN blanket,   | Cut ID smaller to    | Reduce LL1 load;    | 3 | P |
|     top ring:     | help old shield.     | keep O-ring warm.   |   | B |
+-------------------+----------------------+---------------------+---+---+
| 26. Local         | Add gauges to read   | Better-informed     | 3 | P |
|     pressure      | local pressure.      | valve operation.    |   | B |
|     gauges:       |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 27. Super-fluid   | Provide small        | Super-seal & heat   | 3 | P |
|     penetrations: | gas-flow ports       | intercept           |   | B |
|                   |                      | diagnostic access.  |   |   |
+-------------------+----------------------+---------------------+---+---+
| 28. Local         | Add leak-rate        | Super-seal & heat   | 3 | P |
|     flow-meters:  | flow-meters.         | intercept           |   | B |
|                   |                      | diagnostic.         |   |   |
+-------------------+----------------------+---------------------+---+---+
| 29. R-V plumbing: | Use threaded pipe,   | Cheaper, easier     | 3 | P |
|                   | where practical.     | mods and repairs.   |   | B |
+-------------------+----------------------+---------------------+---+---+
| 30. Vacuum        | Provide RGA port on  | Permit RGA          | 4 | P |
|     gate-valve:   | pump side of         | observation of pump |   | B |
|                   | gate-valve.          | baseline.           |   |   |
+-------------------+----------------------+---------------------+---+---+
| 31. 19 V-Tap wire | Wrap Al foil and     | Reduce heat load to | 4 | P |
|     tube shield:  | shield copper tube   | 1.8K.               |   | B |
|                   | separately, down to  |                     |   |   |
|                   | start of SS.         |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 32. Vacuum        | Provide back-up      | Cheap insurance     | 4 | P |
|     gate-valve:   | valve.               | against bad vacuum. |   | B |
+-------------------+----------------------+---------------------+---+---+
| 33. Flat-plate    | Provide for a        | Decrease chances of | 4 | P |
|     R-V, O-ring   | d                    | O-ring ejection     |   | B |
|     groove:       | ouble-captured/glued | during R-V          |   |   |
|                   | silicone-rubber      | operation.          |   |   |
|                   | O-ring seal.         |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 34. V-Tap wires:  | Provide with Teflon  | Extra insulation    | 4 | P |
|                   | sheath.              | insurance           |   | B |
+-------------------+----------------------+---------------------+---+---+
| 35. Liquid helium | Provide Aero-seal    | Protect super-fluid | 4 | P |
|     removal       | clamp stop on        | sealing surface.    |   | B |
|     stinger       | stinger.             |                     |   |   |
|                   |                      |                     |   |   |
|   insertion-stop: |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 36. Liquid helium | Provide Teflon or SS | Back-up super-seal  | 4 | P |
|     removal       | super-seal on end of |                     |   | B |
|     superfluid    | a warm-sealed stick. |                     |   |   |
|     seal:         |                      |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 37. Flat plate    | Use copper plate,    | Easier resealing of | 4 | P |
|     R-V plate:    | instead of SS.       | frozen O-ring.      |   | B |
+-------------------+----------------------+---------------------+---+---+
| 38. Fiber-Optic   | Bevel lower end of   | Safer, easier       | 4 | P |
|     feed-thru:    | 1/2" bevel-seal.     | feed-thru           |   | B |
|                   |                      | insertion.          |   |   |
+-------------------+----------------------+---------------------+---+---+
| 39. Cold R-V      | Use a flat SS R-V    | 1.5W conduction     | 5 | P |
|     sealing       | plate (no            | thru sealing rings  |   | B |
|     plate:        | seal-rings).         | to 1.8K.            |   |   |
+-------------------+----------------------+---------------------+---+---+
| 40. All cold      | Disconnect (or       | 200mW (100mW)       | 5 | P |
|     valve-stems:  | provide 80K          | conduction down     |   | B |
|                   | intercept).          | stem to 1.8K.       |   |   |
+-------------------+----------------------+---------------------+---+---+
| 41. LHe           | Cut pipe above the   | 40mW radiation-load | 5 | P |
|     valve-stem    | LN blanket, not      | to 1.8K.            |   | B |
|     pipe:         | below.               |                     |   |   |
+-------------------+----------------------+---------------------+---+---+
| 42. S-I between   | Remove S-I between   | Not needed          | 5 | P |
|     LL1 & LL2:    | cold systems.        |                     |   | B |
+-------------------+----------------------+---------------------+---+---+