sub-system for QUBIC

Heat switches, 1 K and 300 mK sub-system for QUBIC

For Technological Demonstrator (T.D.)

And

For Final Instrument (F.I.)

G. Coppi, A. May, M. McCulloch, S. Melhuish, L. Piccirillo (U. Manchester)

QUBIC Collaboration Meeting, January 18/19, Milano 1

2

Sub-systems

QUBIC Collaboration Meeting, January 18/19, Milano

3

Sub-systems


4QUBIC Collaboration Meeting, January 18/19, Milano

Thermal map

5

1 K fridge



Film breaker redesign


At the last meeting, it was reported that the hold time requirement* was not being met, due to superfluid film flow transporting helium out of evaporator pot

=> new method for breaking film required

*24 hour hold time @ 2 mW load @ 1 K

Film breaker redesign


New approach to film breaker design and fabrication has been used (capillary flow constriction rather than film breaking knife edge)

=> resulting in hold time improvement at 2 mW from 4.5 to 18 hours!

(for same charge)

New insert to pumping tube (see last meeting)

Exceptionally clean mechanical finish using new fabrication method

Hold time


18 hours hold time @ 2 mW

w/ 1.75 mol 4He, 3.2 K condenser temp

NB: now that film breaker problem is solved, the charge can be optimised when we know the exact load requirements (from CF conductivity measurements) and condenser temperature from PTC

Condensation efficiency


Amount of liquid condensed (nl) is strongly a function of temperature

=> need to know 4 K stage temp in order to find required 4He charge @ room temp

Quick calculation* gives:

~80% condensation efficiency @ 3 K



*note that condensation efficiency is itself also a function of initial charge

Load curve


922 mK @ 2 mW

(Not as good as 810 mK with old film breaker, but still well within requirement)

Isolation switch


Agreed at last meeting that isolation switch will be needed to break thermal connection during recycling - would otherwise constitute a substantial thermal load on 1 K box

Switch will be convective - same design and hole pattern as precooling switches (see later), although will use 3He to avoid issues w/ superfluid film flow

What next?


• Hold time test done with 1.75 mol 4He, equivalent to 78 bar charge @ RT => depending on final charge requirement, possible that small expansion volume may be required, although this may be contained within the cold stage and is therefore trivial

• Electrical connector tbd (wiring fixed).

• Mechanical interface already frozen + sent to Claude

• Thermal model being developed w/ Jean-Pierre to find 1 K box temperature rise - this will set upper limit on isolation switch off conductance and recycling time

• Need to know condensation temperature

What next?


• Recycling to be optimised based on PTC limitations; currently using XML script w/ PID loop (to thermostat)

• Need to know max power allowable to dump into 4 K stage

• When CF tube conductivity measurements finished @ APC, we can optimise charge

Status of the sub-system : blocking points and schedule

• What is the status of the sub-system ? • Design/manufacturing (home made/industry)/assembly/tests ? Fridge built, tested. Film beaker working. Need specs to optimise charge, then may

be commissioned on cryostat• When is this phase supposed to be finished ? 03/17

• If you are still designing the sub-system:• Which inputs / specifications / requirements, needed to finish the detailed design of your sub-systems, are not yet delivered ?

• For D.T.Load requirement, PTC temp• For F.I.

• Which other working group should deliver these inputs (see annex 1 for list of main WP) ?• For D.T.APC, Roma• For F.I.

• What time is still needed in order to (for D.T.) – assuming that the above inputs are provided if needed - :• Finish the whole detailed design of D.T. ? 2 months (approx)• Manufacture the sub-system ?• Test the sub-system in your premises before delivery to APC / ROMA ?

• Idem for F.I.

• Do you think you can comply to the target schedule (see annex 2) ?QUBIC Collaboration Meeting, January 18/19, Milano 15

Interfaces with other sub-systems

• List and describe needed interfaces with other systems. Mechanical• Electrical / Signal Thermometry/heaters• Vacuum• Thermal Condenser mating. Grease used to maximise k• Etc…

• Are these interfaces currently frozen ? Yes


Test, Delivery, Assembly, Calibration Operations

• Tests of the sub-system in your premises before delivery at APC or ROMA:• What is the rationale for testing the sub-systems ? 24 hour hold time @ load @ 1 K• Which specifications will be tested ? • What are the criterion for fail / pass ?

• Delivery to APC or ROMA:• Special care needed for the transportation and handling of the goods ? Yes if shipped pressurized - however Manchester

have experience with this. Alternatively may be charged and sealed in Roma?

• Assembly Operations in APC or/and ROMA:• Same questions as first point above. As above• + which other sub-systems should be integrated before yours? After yours ? Assembled after 1 K box, mount to 4 K• + Is there any specific material needed for assembly ? (see annex 3 for help) Leak checker• What are the test sequences needed to be performed during/after integration Cycle• + How many FTE will you send people at APC / ROMA for help during assembly ? 1-2

• Calibration Operations at APC:• Same questions as for Assembly operations. As above


18

Heat switches

Summary

• HSs required for precooling 4 K and 1 K stages, as well as operating 1 K fridge (Chase fridge switches are self contained)

• Convective HS design selected over minimal gap design (see last meeting) for all switches

• All switches to use same hole pattern and construction - only difference is length of steel tubes and helium isotope used

• Requirement of convective switches that cold end is at the top w.r.t. gravity, although tilted operation ok



Summary


Description Quantity Connecting? Type

Name in 'TD

thermometers

and heaters list'

spreadsheet

Total height (mm) for

switch + support piece

Isolation

switch 1-2

1 K box - 1 K

fridge

Convective

3He Isolation switch 370mm (max)

Precooling

switch 2

1 K box - 4 K

stage

Convective

4He

Switch3 and

Switch4 340mm(max)

Precooling

switch 2

4 K stage - 40

K stage

Convective

4He

Switch1 and

Switch2 159mm (max)

Cryopump

switch 1

1 K fridge

cryopump - 4

K stage

Convective

4He

He4 pump

switch

199.20 (like now in 3D

CAD)

Development

• For each switch we have the length requirements from cryostat (Giuseppe) (previous slide)

• On/off conductance requirements from thermal modelling (Jean-Pierre) (see presentation at this meeting)

• Length can be taken up either entirely by switch (determined by length of steel tubed) or by a shorter switch (with higher on conductivity) and a copper support (see photo), which will also increase the off conductivity


Development

• Switch on conductance increases with helium charge (last meeting)

• Off conductance is constant with increasing charge until saturation of cryopump, at which point residual gas increases off conductance

• Workshop in Manchester currently modifying switch for new style, larger pump

• Will then investigate limit of cryopump/charge, giving maximum on conductance

• Can then find, from limits given by thermal model, requirements of copper support and switch lengths for each


Schedule

• Cryopump testing beginning of next month

• Copper supports very quick to manufacture

• Modification of length of steel tubes in switch also very quick (workshop simply desolder, cut tubes, resolder)

• Inferred from another experiment before Christmas that switch conductance at higher temperatures does not change significantly - further tests required to confirm and to measure more accurately



• What is the status of the sub-system ? • Design/manufacturing (home made/industry)/assembly/tests ? Modifications happening at present - next set of tests in Feb• When is this phase supposed to be finished ? 03/17


• For D.T. After tests finished, will need to validate against thermal model • For F.I.

• Which other working group should deliver these inputs (see annex 1 for list of main WP) ?• For D.T.APC• For F.I.

• What time is still needed in order to (for D.T.) – assuming that the above inputs are provided if needed - :• Finish the whole detailed design of D.T. ?• Manufacture the sub-system ?• Test the sub-system in your premises before delivery to APC / ROMA ?

• Idem for F.I.

• Do you think you can comply to the target schedule (see annex 2) ?



• List and describe needed interfaces with other systems. Mechanical• Electrical / Signal Thermometry, heaters• Vacuum• Thermal Will be mounted to Cu straps (Giuseppe). Vac grease to increase

thermal contact

• Etc…

• Are these interfaces currently frozen ? Yes



• Tests of the sub-system in your premises before delivery at APC or ROMA:• What is the rationale for testing the sub-systems ? Validate conductance• Which specifications will be tested ? Conductance• What are the criterion for fail / pass ?

• Delivery to APC or ROMA:• Special care needed for the transportation and handling of the goods ? As for fridge

• Assembly Operations in APC or/and ROMA:• Same questions as first point above. As above• + which other sub-systems should be integrated before yours? After yours ? After 1 K box, mounted on 4 K• + Is there any specific material needed for assembly ? (see annex 3 for help) Leak checker • What are the test sequences needed to be performed during/after integration Leak test• + How many FTE will you send people at APC / ROMA for help during assembly ? 1-2



28

300 mK fridge


Summary

• Due to illness and workshop issues, the EPR experiment in Manchester that is using the 300 mK Chase fridge is currently behind schedule

• We have an agreement that wherever they get to by Feb we will get the fridge back

• However, as fridge has been functioning perfectly well in experiment, we will have only redressing, minimal testing and varnishing electrical connections to do before fridge is ready

• In meantime, the EPR cryostat is warm for the next few days so I’ll get the hole pattern measured and sent to Claude before end of the week QUBIC Collaboration Meeting, January 18/19, Milano 30


• What is the status of the sub-system ? • Design/manufacturing (home made/industry)/assembly/tests ? Final testing to start – load curve, hold time, temp stability.• When is this phase supposed to be finished ? 03/17


• For D.T. Condenser temp, PTC? Is precooling of focal plane to 320 mK required? Warm up during recycling?• For F.I.

• Which other working group should deliver these inputs (see annex 1 for list of main WP) ?• For D.T.Roma? APC?• For F.I.

• What time is still needed in order to (for D.T.) – assuming that the above inputs are provided if needed - :• Finish the whole detailed design of D.T. ?• Manufacture the sub-system ?• Test the sub-system in your premises before delivery to APC / ROMA ? ~3 months

• Idem for F.I.

• Do you think you can comply to the target schedule (see annex 2) ?



• List and describe needed interfaces with other systems. Mechanical• Electrical / Signal Thermometry and heaters• Vacuum• Thermal Condenser mating. Should use vacuum grease to maximise thermal

contact

• Etc…

• Are these interfaces currently frozen ? Mech: yes. Connector tbd



• Tests of the sub-system in your premises before delivery at APC or ROMA:• What is the rationale for testing the sub-systems ? Validate cooling to 320 mK, temperature stability• Which specifications will be tested ? Heat lift, temp, hold time• What are the criterion for fail / pass ? 20 uW @ 320 mK, hold time > 24 hours

• Delivery to APC or ROMA:• Special care needed for the transportation and handling of the goods ? As for 1 K fridge

• Assembly Operations in APC or/and ROMA:• Same questions as first point above. As above• + which other sub-systems should be integrated before yours? After yours ? Assembled after 1 K box, mount to 4 K• + Is there any specific material needed for assembly ? (see annex 3 for help) Leak checker, thermometry/heater readout• What are the test sequences needed to be performed during/after integration Leak test, check thermometry/heaters• + How many FTE will you send people at APC / ROMA for help during assembly ? 1-2



34

Management

Budget (excluding salaries)for T.D. + F.I.

Spendings (type and amount)

Funding (source and amount)

Status of funding (granted / under examination)

2017

2018


Covered by departmental grant

Manpower

Name and responsibility % FTE 2017 % FTE 2018

COPPI 20 20

MAY 20 20

PICCIRILLO 5 5

TOTAL FTE 45 45


Risks analysis

• Primary concern will be delays with manufacturing/testing switches. Have advised workshop of schedule.


Summary/final thoughts

• 1 K fridge needs final load requirement and 4 K stage temperature to determine optimal charge and cycling. However, critical technical issues have now been solved

• Switch operation has been demonstrated, need another battery of tests (Feb) with new cryopumps to confirm on/off conductances and validate w/ Jean-Pierre’s thermal model

• Chase fridge will be tested in Feb, minimal work required


39

Backup slides

Annex 1: list of main-sub-system and WP leaders


Annex 2 : Target schedule


Annex 3: examples of possibly needed major tools or utilities

• High voltage (380 V) power

• Cold water

• Liquid or gaseous N2 / He

• Compressed air

• Clean air laminar flow / clean room / conditioned air

• Assembly Hall

• Mechanical workshop

• IT network or Wifi

• Chemicals


• ESD equipments

• Crane or heavy handling systems

• Metrology systems (Faro, MMT, Laser…)

• VNA

• Calibration source

• Mount (or fake)

• Vacuum systems (including degassing)

• Acquisition systems

• Computers / data acq. systems

• Electrical test with probe station

Documents

sub-system for QUBIC