MICE Collaboration Meeting

Harbin, China 13 – 17 January 2009

Progress on AFC since the PRR

By

Wing Lau, Oxford University

A re-cap of where we are on the AFC module supply contract.

Contract was for the design and supply of 2-off FC modules with the option to purchase the third one at a later stage;

Contract to Tesla was signed in June 2008;

First hiccup was the conductor size and the availability of a continuous conductor length. At the end, we agreed to go for the Type F 174 wire:

Conductor type: F174 (Final purchase F 180 – number of filaments)Dimension bare 1.52 x 0.95 mm²Formvar insulated 1.57 x 1.00 mm²Consisting of 174 NbTi filaments (final purchase – consists of 180 filaments)In a Cu-matrixRatio Cu : NbTi abt. 4.0 : 1Core conductor with Nb-barrierCore Alpha abt. 0.45 Corner radius > 0.20Filament diameter abt. 48 µm (final purchase is now 46 µm )

Ic at 4.2 K; 0.1 µV/cm, 5 T – 686 ARRR > 80

Purchase order for the conductor was released at the end of July to allow for a delivery in late March 2009. This is one of the critical long lead items.

The preliminary design review was held on the 12th of August. It did not go as well as expected with a number of technical issues (Thermal modelling, Quench protection design and cold mass forging) not finalised.

A subsequent meeting on the 24th of September cleared some of these outstanding items. Tesla had done a lot of work since the initial preliminary design review, though the bobbin design was still not satisfactorily completed.

The review paved the way for further detail design work in rediness for the PRR (Production Readiness Review)

A Production Readiness Review was held on the 6th - 7th of November (originally scheduled for the 9th of October)

A list of items which require re-work / design modifications were identified and agreed on. These are listed in the following table with af=greed actions.

Items for re-work Agreed actions Progress to date

1. Thermal model:

Current lead uses a high RRR value (50 c.f 10 or less)

Tesla to re-run thermal model with lower RRR value

completed

Coil assumes an isotropic block of copper

Tesla to remodel copper block using different and realistic conductivities in the three directions, as they did in their quench analysis

Done

Contact resistance on cryocooler 1st stage looks too optimistic

Tesla to confirm values used, including values in contact area.

Conical surface area increased from 5800mm2 to 8000mm2. Issues with trap volumes spotted. May have to make hard physically connection internally via access port.

Further to the review, Tesla has now completed the thermal modelling on the new bobbin configuration with external cooling

Summary

a. The maximum coil temperature calculated is 4.51K which is still lower than thecriterion(4.8K) but leaving only 0.3K margin.

b. Calculation results satisfied all design criteria.

Input data -- Dimension & material data of the turret system including current load

Thermal conductivity of each interface after the iterative calculation

CryoMech cooler PT415 cooling capacity map

Items for re-work Agreed actions Progress to date

1. Thermal model:

Current lead uses a high RRR value (50 c.f 10 or less)

Tesla to re-run thermal model with lower RRR value

completed

Coil assumes an isotropic block of copper

Tesla to remodel copper block using different and realistic conductivities in the three directions, as they did in their quench analysis

Done

Contact resistance on cryocooler 1st stage looks too optimistic

Tesla to confirm values used, including values in contact area.

Conical surface area increased from 5800mm2 to 8000mm2. Issues with trap volumes spotted. May have to make hard physically connection internally via access port.

2 Conductor splicing Tesla to demonstrate satisfactory technique

Tesla will do the first run in the new test facility on another conductor.

3 Bobbin issues:

Consider indirect cooling to allow higher stress allowable

MICE to agree to increase coil ID to 268mm and end plate thickness to 35mm.

Modelling now completes. Looks OK. Stress report available.

Load cases, including transport load, identified

Tesla to ensure all case loads are analysed

Winding load disappear on Cool-down. Reason for active quench.

4 No. of redundancy in their active quench protection

Tesla to consider this in their design

Work has now finished. Tesla proposes to use active quench detection and quenchback.

5 Size of vent line and its effect on heat load at critical areas

Tesla to review this Being incorporated as part of the turret design.

6 Tolerance on vessel flange – implication on overall module alignment

MICE to confirm beam height, and Tesla to advise on achievable tolerance

Awaiting Andy Nichol’s confirmation

7 Cryocooler and HTS Leads

Implication from indirect cooling; size of condensing lines; sensitivity to impurities at cryostat bottom were raised

Tesla to address these issues

Model set up and is being worked on.

Flexibility on HTS leads to cater for thermal contractions; provision of thermal clamping; positioning of Leads and motor to suit magnetic field etc

Tesla to address these issues

Change in the turret design made that improves the tolerance to stresses induced by thermal contraction. Fiducial mark on lead to allow ribbon 90o to field direction. Shield around motor reduce field to 20 Gauss around cryocooler.

8 Consider AL 1100 (instead of 6063) for radiation shield

Tesla to consider Thermal model showd good results with 6063. To be decided at the time

9 Confirm UTS value of S-glass straps

Tesla to confirm Test results suggest UTS of 1.6 GPa (Futura report available now.)

10 Supports for current leads RAL to advise on routing and support locations

Andy Nichol to advise

11 Instrumentation & Services Tesla to provide inventory

Inventory is being compiled. Expect to complete soon.

12 Hydrogen system

Move the inter-connectors further up into the turret

Tesla agreed New turret design reflects this change.

Cryocooler 1st stage may need heat exchanger

MICE (TB) to advise Heat exchanges are being incorporated to the cooler 1st stage, but Tesla is having difficulty incorporating the length of heat exchange. I may still be possible.

OK to route Instrumentation cables through vacuum port

Tesla to confirm Requires an inventory of instrumentation. This is in hand

Confirm that the two vacuum systems can withstand atmospheric / vacuum combination

ANSYS model confirmed this is OK. Report has been circulated for comments.

Dummy Safety window needed to gauge warm bore

MICE to provide dummy window

Wing Lau to provide this – this is in hand.

13 Other items

Fault cases need to be looked at by Tesla

Such as over-current, wrong polarity in AFC and other modules

Work already started.

Weld qualification Tesla to add In hand

Disassembly Tesla to ensure that critical items can be removed and replaced etc

Access port added on the OVC for access to HTS leads which have been moved to the outside of assembly. Crycooler can be removed from top plate. Access to wire looms is via side access port etc.

Summary of the AFC status:

Bobbin Issues Following Document was submitted to MICE team on5th January:-

MICE AFC Bobbin linearization report – this analysis proves 6061-t6 Bobbin with the increased sizes detailed therein will meet the stress seen during operation. Document is on Web page for comment by MICE team.

Vacuum VesselFollowing Document was submitted to MICE team on5th January:-

MICE AFC Vacuum Vessel – analysis of the vacuum vessel integrity under differing vacuum/pressure combinations.

Document is on Web page for comment by MICE team.

Suspension SystemS-Glass Testing results submitted. Document is on Web page for comment by MICE team. Further stress modelling of the suspension system is continuing.

MICE Quench ProtectionThe final design report is now available. It concluded that an active Quench detection and protection system is needed.

Indirect Cooling Thermal ModelThermal model set up and ran, A

simplified excel model has already been run and a report has been submitted on 6th January.

Turret RedesignThe turret redesign incorporating the changes for the Vent line, HTS lead

configuration, Hydrogen system interconnects, Hydrogen system heat exchanger and accessibility issues are nearing completion and will be available early next week.

Instrument ServicesListing has commenced

Fault CasesThis has commenced

Critical Items – Vessel FlangesMethod of manufacture will be detailed to ensure tolerances can be achieved.

Superconductor SplicingFurther work on this will be undertaken at Tesla prior to receipt of Superconductor which is still on schedule for delivery end March09.

Project PlanThis has been updated to show current status. It shows a delay of 39 days. Delivery

of the 1st module is now the beginning of January 2010

Documents relating to the AFC

All the technical reports from Tesla are now kept in the STFC web page:-

www. eng-external.rl.ac.uk/miceafc

This webpage is managed by Tom Bradshaw and is password protected. Please email me or Tom for detail.