MICE Collaboration meeting at CERN March 28 – April 1, 2004

MICE Collaboration meeting at CERN

March 28 – April 1, 2004

MICE Cooling Channel --- AFC Module progress update

Wing Lau – Oxford

A progress update:

Interface scope and responsibility -- defined

Interface control via a global reference system -- set up

Feasibility study of using Cryo-Coolers -- started

Detail design & engineering for module connection -- started

Cost estimate and schedule of work -- prepared

Response to Safety Review committee’s comments -- drafted

Draft Re-baseline document -- prepared

R & D issues

Window measurement and burst testsKEK Absorber cryostat and mechanical seal testsWelded window tests

Detail engineering:

Cold Mass support designCoil support tube design

Supplier Responsible equip. Scope of supply

Oxford / RAL

Focus Coil & Module

magnet coil, cold leads, cold mass supports, cryostat, radiation shields, helium cooling pipe to the coil, warm bore tube, warm vessel, connecting flange for the Large End Plate and the RHS Safety window (both NIU/IIT supply), entrance nozzles for LH2 & GHe feed pipes. Vessel supports

KEK

Absorber body & feed pipes

Absorber body, facing flange for the windows, bolts and mechanical seals for all the window connection, all the LH2 and GHe feed pipes, support connection for the Absorber body, LH2 spillage sump

NIU / IIT

Windows and Large End Plate

The Absorber and Safety windows, The Large End Plate with mechanical seal and fixing bolts, anchoring arrangement for the Large End Plate, any temporary protection to the thin window during assembly.

LBL

Bolting & Sealing of Focus & Coupling Coil

vessels

The design and supply of the flexible flange for sealing between the two vessels. The design & supply of any item that transmit the magnet forces from one vessel to the other.

Interface scope & responsibility

The total supply of the AFC module falls into the following categories:

Oxford / RAL supply


Oxford / RAL

Focus Coil & Module


KEK



NIU / IIT



LBL


vessels




KEK supply


Oxford / RAL

Focus Coil & Module


KEK



NIU / IIT



LBL


vessels




NIU / IIT supply


Oxford / RAL

Focus Coil & Module


KEK



NIU / IIT



LBL


vessels




NIU / IIT supply KEK supply Oxford / RAL supply

Space envelop for the suppliers

Distinguishing between a stand-alone item and an interfacing item through drawing

convention

Stand alone items – in black, blue & red

Interface items – those marked in Pink .

In the MICE project, the Pink parts will have a different drawing convention. Any changes made will be notified to all the related interface suppliers for consent.

Interface control via a global reference system -- introducing the Coat hanger technique

The conventional way of assembling the different parts together is by attaching the adjoining parts to a common interface boundary. Where there are multiple interfaces, or where one part joins onto another part and another part and so forth, it would be difficult to define the order of interface. It would also accumulate errors as parts are assembles related to each other only locally and not globally. This makes the checking of interface compatibility extremely difficult.

The Coat Hanger technique (continue)The conventional way of assembling the different parts together is by attaching the adjoining parts to a common interface boundary. Where there are multiple interfaces, or where one part joins onto another part and another part and so forth, it would be difficult to define the order of interface. It would also accumulate errors as parts are assembles related to each other only locally and not globally. This makes the checking of interface compatibility extremely difficult.

The way to overcome this is to avoid having to assemble parts onto each other. In this new concept, every parts will have a reference centre which coincides with one of the globally registered centres designed to position the magnet modules relatively to the beam line and then to the experimental hall. This reference centre acts like a coat hanger

The Coat Hanger technique (continue)The conventional way of assembling the different parts together is by attaching the adjoining parts to a common interface boundary. Where there are multiple interfaces, or where one part joins onto another part and another part and so forth, it would be difficult to define the order of interface. It would also accumulate errors as parts are assembles related to each other only locally and not globally. This makes the checking of interface compatibility extremely difficult.

The way to overcome this is to avoid having to assemble parts onto each other. In this new concept, every parts will have a reference centre which coincides with one of the globally registered centres designed to position the magnet modules relatively to the beam line and then to the experimental hall. This reference centre acts like a coat hanger

The referencing system works like a global navigation system. Through the reference centres, we can refer the position of each parts to a global coordinate. By hanging the various parts to a globally registered centre, it will automatically assemble the parts to a pre-defined position. Any interface incompatibility will be easily detected as each equipment / parts will have its unique place in the global coordinate system. No two parts should have the same coordinates.

We will insist on this centre being retained on all the stand alone and interface drawings.

This is how it works on MICE:There are different levels of reference centre, designated to have a similar “level” allocation as the WB packages.

The level 1 reference centre is the centre of the experimental hall;

The level 2 reference centres are those along the beam line centre for the positioning of each of the modules;

The level 3 reference centres are the centres of the individual modules

As an example:-

The Focus Coil module will have a level 3 reference centre. All the parts associated with the windows and the absorber will be referenced to this level 3 reference centre.

The Focus Coil modules, the Coupling Coil, the detector modules and any equipment that are aligned to the beam centre line will be referenced to the level 2 reference centre.

The beam line centres will be referenced to the level 1 reference centre etc.

These parts will have level 3 reference centre attached The level 3

reference centre on the FC module

All the AFC parts will then be hung to the level 3 reference centre at the Focus Coil

The hanging of the AFC and Coupling modules

Level 2 reference centres

Level 3 reference centres

Interface compatibility check at a glance

Feasibility study of using Cryo-Coolers on the AFC module

The kind of a cooler that can be used to cool MICE magnets and absorbers

• From a practical standpoint the Sumitomo SDRK-415-D GM cooler (1.5 W at 4.2 K) is our the main choice to cool the MICE magnets. A pulse tube cooler from Cryomech is a distant second choice.

• A two-stage cooler is needed to cool superconducting magnets. A first stage at 40 to 70 K cools the magnet shield, the cold mass support intercepts and the upper leads. The second stage (at 4 K) cools the coils and removes the heat coming down the HTS leads from the first stage.

• A closed cycle cooler can not be a source of helium gas that can be used to cool gas cooled leads. Both the HTS leads and upper current leads must be conduction cooled.

300 K Attachment Ring

Cryocooler First StageT = 25 K to T = 80 K

Cryocooler Second StageT = 2.5 K to T = 20 K

The Sumitomo SDRK 415-D GM Cooler

Cooling the Focusing magnet with a coolers

One Cooler Two Coolers

First Stage of Cooler

MLI Radiation Heat Leak per Cooler (W) 4.8 2.4

Cold Mass Support Heat Leak per Cooler (W) 3.0 1.5

Plumbing Heat Leak per Cooler (W) 1.0 0.5

Instrumentation Heat Leak per Cooler (W) 0.6 0.3

Current Lead Heat Load per Cooler (W) 42.0 21.0

Total Heat Load to 1st Stage per Cooler (W) 51.4 25.7

First Stage Temperature (K) ~63 ~40

Second Stage of Cooler

MLI Radiation Heat Leak per Cooler (W) 0.45 0.18

Cold Mass Support Heat Leak per Cooler (W) 0.15 0.06

Plumbing Heat Leak per Cooler (W) 0.25 0.1

Instrumentation Heat Leak per Cooler (W) 0.12 0.05

Current Lead Heat Load per Cooler (W) ~0.9 ~0.3

Total Heat Load to 2nd Stage per Cooler (W) ~1.87 ~0.69

2nd Stage Temperature (K) > 4.6 > 3.5

Cooler Connection through a Flexible Strap

The temperature drop from the load to the cold head is proportional to the strap length and inversely proportional to the strap area and the strap thermalconductivity.

T L

kATc

Tc = contact resistance

Tc is usually small.

P

Q

T3T2

T1

T0

Cryocooler Cold Head

Cryostat Boundary

Cooling Cryogen

Cooled Load

Liquid Fill Valve (if needed)

Relief Valve

Flexible Cu Strap

T = T3 - T0

Straight Conduction cooling arrangement of the cryocooler

Cooler Connection through a Heat Pipe

The temperature drop from the load to the cold head is independent of the distance between the load and the cooler cold head.

T Tb Tf TcP

Q

T3T2

T1

T0H

h = head for circulating the liquid cryogen

Cryocooler Cold Head

Condensation Plate

Cryostat Boundary

Liquid Tube (any length)

Gas Tube (any length)

Cooling Cryogen

Cooled Load

Gas Charge Valve (if needed)

Relief ValveTb = Boiling T DropTf = Condensing T DropTc = Contact Resistance

These can be made small.

T = T3 - T0

Adapting a “heat pipe” arrangement for the CryoCooler in the AFC magnet cooling

Design & engineering of module connection

Several connection schemes have been looked at to simplify the way the outer vessels of each modules are connected. The original thinking was to provide each connection with two “independent” joints; a flexible joint to ensure leak tightness, and a rigid connection to transmit the magnet forces from one to the other.

Here are the different schemes being looked at:

Design options in the vessel connection

Option 1


Bellow type joint

Option 2


Concertina type joint

Option 3

Likely changes in the vessel connection design

The original thinking on connecting the vessels was to provide each connection with two “independent” joints; a flexible joint to ensure leak tightness, and a rigid connection to transmit the magnet forces from one to the other.

Two things happened since, and they might have a significant effect on the vessel connection design.




The ability to adjust the coil position to fiducially out on the vessel via the new Cold Mass support design means there are now less misalignments for the flexible joint to take up.

General Arrangement of the cold mass support system

This means the coils can be aligned independently of the vessel position

Integrated Tensioning Device/ Anchor on warm vessel

End Cap welded to form a vacuum tight joint.




The ability to adjust the coil position to fiducially out on the vessel via the new Cold Mass support design means there are now less misalignments for the flexible joint to take up.

The possible reduction in the magnet forces – due to the re-arrangement of the coil positions, Mike Green now believes that the magnet out-of-balance force have been reduced dramatically. It is now feasible to pass these magnet forces to floor via the supports, instead of from module to module. This would mean the elimination of the rigid connection between each module, leaving just a flexible joint for leak tightness.

Center Focus Coil Coupling Coil End Focus Coil #1 End Focus Coil #2 Matching Coil #1 Matching Coil #2 Detector End Coil #1 Detector Center Coil Detector End Coil #2

Longitudinal Magnetic Force

at 200 MeV/c (kN)

1550.1

85.7 -1554.1 2161.9 -137.1 554.6 152.8 31.9

-1357.2

0.0

85.7 kN = 8.8 tons

607.8 kN = 62.0 tons

-755.0 kN = -77 tons

Net Cold to Warm Force

* Note: the forces on the other half of the channel have the same magnitude but the opposite sign.

Center Focus Coil Coupling Coil End Focus Coil #1 End Focus Coil #2 Matching Coil #1 Matching Coil #2 Detector End Coil #1 Detector Center Coil Detector End Coil #2

Longitudinal Magnetic Force

at 200 MeV/c (kN)

2350 133

-2260 2205 220 63

1050 -21

-1430

0.0

133 kN = 13.6 tons

-55 kN = 5.6 tons

-118 kN = - 12.0 tons

Net Cold to Warm Force

* Note: the forces on the other half of the channel have the same magnitude but the opposite sign.

Magnet force in the previous coil arrangement mainly caused by a separation between focus coil and 1st matching coil of 200 mm

Magnet force in the revised coil arrangement

mainly caused by a separation between

focus coil and 1st matching coil of 600 mm

Imbalanced magnet forces

Passing the load to the floor

Cost estimate & schedule of work – with in-house built

Cost estimate & schedule of work – without in-house built

Response to Safety Review committee’s comments

There are two areas which need further information:-

Once these are received, the report will be by the group before it is released for issue.

Response to the Safety Review

comments

~ draft copy ~

A draft report on our point by point response to the questions raised by the Safety Review Committee has been prepared

Clarification + diagram

on Hydrogen Safety system

Detail descriptions

of the Control system

Re-baseline documentThe re-baseline document is 90% complete. The following information is still outstanding:

Detail description of the C&I design

and arrangement

Product details /

category of the control

instruments applicable in

the AFC module

Work schedule of the Window

test and supply

Work schedule of the Absorber

body, mechanical

seal and other relevant

equipment

The re-formatting of

the Word document as it

is nor readable by some Word browsers

Re-baseline document on the AFC

Module

R & D issuesWindow measurement and burst tests

KEK Absorber cryostat and mechanical seal tests

Both talks will be covered by Ed Black later

Welded Window test

Status of test vessels:

1st vessel is waiting to have the threaded bayonet milling.

2nd vessel is having the vacuum and pressure port machined, then milling of the threaded bayonets will be done -- next week.

Welding test samples are machined & ready

Thermocouple

Detail engineering:

Cold Mass support designThe design is in an advanced stage and details of it will be covered in Rohan’s talk

Coil support tube design

Both the thermal and stress analyses have now completed. This will be

explained in Stephanie’s talk

SummaryThe basic project infrastructure of the work packages within the AFC module is now in an advance stage.

We still need further effort in the C&I area which has not been receiving the level of support that we expected

The use of Cryo-Cooler is looking promising and further effort is needed to make sure that Safety of the system is not compromised.

Following the reduction in the imbalance magnet force, as a result of repositioning the detector coils, it is now feasible to “pass” the magnet forces to the individual module support legs. If proven, this will simplify our module to module connection greatly. Work will continue to ensure that there is no other show

The R&D work is progressing, albeit a little slower than planned.

Interface with the detector module supplier is progressing and further effort is needed to bring this to a reasonable stage where detail engineering work can start.

Documents

MICE Collaboration meeting at CERN March 28 – April 1, 2004