Russ Rucinski, FNAL

VLPC Cryocooler cryostat

Status – June 7, 2006

Russ Rucinski, FNAL Jun 7, 2006

VLPC cryocooler cryostat - status

Prototype cryostat is at Fermilab, in the D-Zero assembly building. Commissioned in Spring 2005.

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Prototype worked well. Stable temperatures for weeks Many thermal cycles, no problems Heat loads acceptable

55 W & 4 W Cryocooler at 60% capacity @ 60 Hz, horizontal Cryocooler at 75% capacity @ 50 Hz, horizontal

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Areas for improvement Thermal connection not reliably

duplicated. Used indium wire smashed at interface.

Thermal asymmetry: Tslot1=7.5 K, Tslot2=7.1 K

Lid condensation risk Cassette envelope could

collapse if evacuated with insulating vacuum let up.

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Thermal connection improvement – bolted studs through the envelope is being investigated. – Test this summer.

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

If it works on prototype cryostat (using two spare envelopes), then new production cryostats can be retrofitted.

Practice solder choices & techniques Final choice & technique – leak tight

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Lid condensation risk. A moisture sensor of some type will be added to the alarm

box. Cassette envelope could collapse if evacuated with

insulating vacuum let up. An interlock on the cassette space vacuum pump has

been suggested. Could also possibly solve with a mechanical check valve. Something will be done.

Also want to try a simple improvement – add an invar washer in the bolted thermal connection to the cryocooler sink. Original design loosens when it cools down. An invar washer will make the connection tighter when it cools down since the bolt contracts more than the washer.

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Four additional cryocooler cryostats are being fabricated by Ability Engineering Technology, South Holland, IL, USA.

Design of the four are based on the as-built prototype commissioned last spring.

As I mentioned the improvements can be applied retro-actively.

Expect delivery of parts – End of June ? I still need to order backplane and many other non-

fabrication type parts still. Assemble and commission this fall. By Sept. 2006 ?

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Fabrication at Ability Engineering Technology, Inc...

Russ Rucinski, FNAL

VLPC cryocooler cryostat - status

Fabrication at Ability Engineering Tech....