View
213
Download
0
Tags:
Embed Size (px)
Citation preview
Briefs submitted for the TB to approve Tesla’s long lead items:
1) Cold Mass Forging
2) Super conductor wire
Dimensions and material of the Cold Mass
Dimension of the Cold Mass as specified in the AFC Technical Spec.
Coil size:-
Latest agreement on the conductor size with Tesla is:-
Formvar insulated:- 1.57 x 1.00mm
With a 0.1mm thick interlayer insulation, this makes the coil size:-
~ 210 x 84mm
As long as the forging provides a generous machining allowance, there shall be no risk in this respect.
Material:-
We specified Aluminium T6061
Tesla propose the same material.
Material fully compliant!
Cold mass profile as per AFC Technical Spec
Profile of the Tesla Bobbin forging
Average machining allowance is 9 – 10mm on both surfaces. This is acceptable!
Details of Tesla’s procurement related QA / QC documents are in Attachment 1 and are summarised in the table below
Item Drawing no. Material Specification
Lead Time
Preferred Vendor
Location Fall Back
Vendor
Acceptance Criteria
Super-conducting Wire
Tesla Part no,156-A3000P01
See below 7 months European Advanced Superconductors GmbH
Germany none CoC, chemical analysis and suppliers inspection report to Tesla purchase spec
Bobbin Forging
Tesla Drg no. 156-D2203
6061-T6 12 weeks Anvil Alloys Ltd U.K
UK none CoC, mill report analysis and suppliers inspection report to Tesla purchase spec
Cryocooler Tesla Part no,156-A3300P03
PT415 (Cryomech Part No.)
18 weeks Cryomech Inc USA none CoC
Super-conductor wire
What was in the AFC Module Conductor Spec
Conductor size: 1.65x1.05 over insulation
Coil width 210mm
Thickness 84mm
Turns/layer 127
Layers 76
Helium volume 9.5 litres/coil
Inter-layer insulation 0.1mm
Ic=760A(5T,4.2K)
What Tesla offers and requires our approval:-
Conductor size: 1.52 x 0.95mmFormvar insulated:- 1.57 x 1.00mmwith 0.1mm interlayer insulation
Coil width ~ 210mmCoil thickness ~84mm
Turns / layer:- 132No. of layer:- 76
Helium volume 9.5 litre / coil
Ic=686A(5T,4.5K)
Obviously Tesla’s proposal is different to that specified in our AFC technical specification
Material composition and details of the proposed super-conductor wire
Type F 174
Dimension bare 1.52 x 0.95 mm²Formvar insulated 1.57 x 1.00 mm²Consisting of 174 NbTi filamentsIn a Cu-matrixRatio Cu : NbTi abt. 4.0 : 1Core conductor with Nb-barrierCore Alpha abt. 0.45 Corner radius > 0.20Filament diameter abt. 48 µmIc at 4.2 K; 0.1 µV/cm, 5 T – 686 ARRR > 80
A meeting was held on the25th of July and following Elwyn Baynham’s assessment of the proposed wire size (see Appendix 2), we have recommended the acceptance of the type F174 wire;
Tesla confirmed that the above change does not have any implication on cost or delivery schedule;
Attachment 1
The following documents are submitted with this review brief:-
Word document:- “Final Customer Approval” by Tesla
PDF document:- “Purchasing Plan” by Tesla
PDF document:- “General Purchasing Specification” by Tesla
Attachment 2
Elwyn Baynham’s preliminary assessment of the MICE specified super-conductor wire with that proposed by Tesla
AFC Module Conductor Spec
Spec
Conductor 1.65x1.05 over insulation Ic=760A(5T,4.2K)
Coil width 210mm
Thickness 84mm
Turns/layer 127
Layers 76
Helium volume 9.5 litres/coil
Inter-layer insulation 0.1mm
Attachment 2 P1 of 4
AFC Module Conductor Spec
Conductor Options
Stay with Original Specification 1.65x1.05 with 0.1mm inter-layer insulation
Tesla tolerance specification =/- 0.01mm
Turns/layer – 127 turns/layer should be maintained as specified
At nominal conductor size the coil width will be 209.55mm
This is an allowance of 3.5 microns /turn for conductor spacing
Tesla should confirm that in their experience this is sufficient margin to wind 127 turns in each layer
At conductor max size 1.65+0.01mm it is not possible to fit 127 turns in the layer
Tesla should indicate what they propose to do in this case to meet the specification
Increase the coil channel width – what would be required?
Contd on next slide
Attachment 2 P 2 of 4
AFC Module Conductor Spec
Conductor Options - contd
Stay with Original Specification 1.65x1.05 with 0.1mm inter-layer insulation
Tesla tolerance specification =/- 0.01mm
Coil thickness
76 layers at 1.05+0.1mm interlayer insulation thickness ( we believe the interlayer insulation requirement was accepted by Tesla)
Spec was 76 layers at 84mm thickness
For this conductor option at nominal size 76 layers x 1.15 =87.4mm
For this conductor at max size 76 layers at 1.16 = 88.2mm
Consequences/impact
The increased thickness will move the coil centre radially outwards and this would require an increase in the operating current of ~ 1Amp ( no real effect)
The increased radial thickness would reduce the Helium volume in a single coil by 20% at the max size – this we are concerned about relaxing at this stage because we do not have yet the detailed design calculations from Tesla to confirm heat loads, coil losses during ramping etc
Both of these issues were discussed at the meeting in September 07 and communicated to Tesla in a memo at the beginning of May 2008
At both instances we requested that Tesla should give their assessment of the coil thickness build up and possible variations
Attachment 2 P 3 of 4
AFC Module Conductor Spec
Conductor Options 2
Change the conductor size to1.57x1.00 with 0.1mm inter-layer insulation
Tesla tolerance specification =/- 0.01mm
Ic=686A(5T,4.5K)
Turns/layer – 132 turns/layer should be considered as new spec
At nominal conductor size the coil width will be 207.24mm
This is an allowance of 20 microns /turn for conductor spacing
At max conductor size the coil width will be 208.56mm
This is an allowance of 10 microns /turn for conductor spacing which seems realistic – Tesla should comment
Coil thickness
Coil thickness is maintained to specification
Margins spreadsheet shows that the operating point is 75% along the load line with temperature margin ~ 1.5K
Operating current would be 200.3 A for 200Mev/c
Attachment 2 P 4 of 4