# Presentation: 219026

## Summary of Magnet Discussions

- P. Wanderer
- LARP CM9
- October 19, 2007

- We magnet folk would like to thank our SLAC hosts, particularly Tom and Naomi.
- We would also like to thank our colleagues from CERN for their comments and (**bold**) proposal.

## Key questions & answers

- Where are we?
- 		We discussed data from *several* 1m quad and 	other recent Nb3Sn dipoles
- Where do we want to go?
- 200 T/m, 4 m quad by 12/31/09
- more understanding of materials & magnets
- c) Carefully evaluate proposed “Phase I” goal
- When do we get there?
- 	a) Three “long, strong” quads by 12/31/09
- 	b) Initial evaluation Dec. 1; report/revu June08

## Where are we?

- We can make Nb3Sn magnets that
- reach ~ 90% of conductor limit (4.5K)
- with predictable harmonics
- Examples:
- 1 m cos2θ models (several)
- 1 m and 2 m cosθ mirror dipoles
- Mirror = one coil + iron in place of 2nd coil
- 4 m racetrack coils
- But ... we don’t understand everything yet

- Materials – the “fundamental building blocks” of our magnets

## Increase Subelement Number 

**RRP Strand Development with OST (Barzi)**

**114/127 restack with spaced SE’s**
**Jcmax~3000 A/mm****2**** **

**108/127 restack**
**Jcmax~2400 A/mm****2**** **

**54/61 restack**
**Jcmax~3000 A/mm****2**** ****  **

**60/61 restack with spaced SE’s**
**Jcmax********3000 A/mm****2**** **

**Increase Subelement Number**** **

**Increase Subelement Spacing**** **

**RRP1**

**RRP0**

## TQ Data: BNL-FNAL-LBNL

- 1.9 K calc

- Ic calc +/- 0.1% strain

## Strand Production

## RRP-8648, 0.7 mm RRR ~ 3102.09 K 

- TQ - 1 m quadrupoles – quench 					performance at 4.5 K, 1.9 K
- 			TQS – shell support
- 			TQC – collar support

## TQS01  (technology quad – shell support structure)

## Summary (Caspi)

- 4 TQS tests:
- Maximum gradients at       4.4K  -  178-222 T/m
- Plateau reached after 4-20 quenches with 80-90% of short-sample
- Maximum gradients at 1.9-3.2K  -  192-225 T/m
- Plateau reached after 20    quenches with 80-84% of short-sample
- Bronze/Titanium  islands under axial tension/compression
- TQS01 quenches in inner layer straight section (near island gaps)
- TQS02a dominated by outer layer quenches
- At 12 kA layer 2 (outer) field is 1.2 T less than layer 1 (inner)

## Summary – issues (Caspi)

- 	PW: discussion  outer layer quenches very likely originate in turn with maximum preload (> 150 MPa?)
- A monotonic increase in training current between 4.4K and 1.9K (no jump)
- No gain in current returning from 1.9K to 4.4K
- Epoxy “bubbles” at 1.9 K on the inner layer free surface
- High MIITS (7+) degrade the plateau and impacts coil stress
- But heating can improve performance (reduces strain ?)

## TQS01 & TQS02 Plateau QuenchesLietzke & Lizarazo

- Three TQS-magnets performed below “short-sample” projections:
- TQS01a (coils 5, 6, 7, 8)
- TQS01b (coils 7, 8, 14, 15)
- TQS02a (coils 20, 21, 22, 23)  coils into “TQE02”
- Quench onset and propagation examined:
- Short-sample error?
- Mechanical motion?
- Flux-jumps?
**Local conductor degradation? – PW: most likely cause ... but source degradation unknown**

## TQE02 (likely to be renamed TQC02)uses coils from TQS02 (Bossert/Ambrosio)

- Magnet data  *cable testing* as a function of the usual variables (temperature, background field) + strain is important  discuss collaboration with CERN

- HQ – Explore larger aperture, higher gradient

## HQ Magnet (Caspi slide; + Felice)

- 130 mm bore  quadrupole  with a gradient of  ~ 200 T/m ( 2 layers).
- Option to inserts TQ coils ( 2+2=4 layers) ,90 mm bore,  Gradient ~ 300 T/m
- Cross-section
- 2 layers
- Clear bore diameter – 133.6 mm (use with TQ coils)
- Outer coil  diameter – 198.3 mm
- Strand diameter 0.8-1.0 mm (so far: 0.7 mm)
- Cable width 15 mm (28-36 strands) - key-stone
- 1 wedge per layer
- Gradient ( 205 T/m) in 130 mm aperture
- 1 m long Nb3Sn coils
- Azimuthal Stress ~ 150 MPa  Shell support structure specifically designed for HQ (Felice)

## Where do we want to go?

- Long range:  develop Nb3Sn magnet as candidate for Phase II upgrade of LHC IR (2016)
- FY08:  Evaluate opportunity to contribute Nb3Sn quads to Phase I upgrade (2012)  [HQ?]
- FY09: Demonstrate good quench performance of 4 m quads, G >200 T/m
- As resources permit:
- Larger aperture/higher gradient (HQ)
- Improve Nb3Sn strand (60/61114/127)

- LQ: 4 m, G > 200 T/m, 90 mm aperture, Nb3Sn quadrupoles

## LQ features (Ambrosio)

- Change as few things in TQ (1m) series as possible
- Conductor
- Coil
- Major issues due to extra length:
- Stored energy/quench protection
- Bow in reacted coil caused by coil (Fermilab 4m dipole)
- Major choice:
- Support structures:  shell, collar

##                                   .

- LRS01 – long racetrack, shell 4m (4.5 K)

- I (plateau) ~ 91% Iss

- LQ with collar support structure

## LQ Status (Nobrega + Schmalzle)

- Reaction tooling is being fabricated and is a single cavity, laminated fixture that can be used for both reaction and epoxy impregnation.

- Practice

## Assembly – LQ based on TQC (Bossert)

- Coil Midplane “Gap” is equal to coil oversize plus coil midplane shim determined from FEA and previous experience with short models.

**4.  Assembly of coils with mid-plane shims.**

**5.  Collaring in 5-6 passes to achieve target preload.**

- LQ with shell support structure

## 2D magnet design from TQS02 to LQS01 (Ferracin)

- TQS
- Structure designed for a 4-layer coil
- Initial design included ss pads
- Key location determined by bladder width
- LQS
- Stainless steel pads (not brittle at 4.2 K)
- Original TQ magnetic design
- Interference keys moved towards mid-plane
- Optimized coil stress (big benefit)
- 8 bladders (small price)
- 4 auxiliary bladders for yoke pre-assembly
- Aluminum shell from 22 mm to 20 mm thick
- Axial rods closer to coil
- Less deflection of end plate

**TQS02**

**LQS01**

## Assembly process

- Separate assembly of 4 shell-yoke sub-assemblies
- Similar to TQS
- Yoke laminations compressed with 1 m long tie rods
- Shell pre-tensioned with yoke bladders (0.8 m) and gap keys
- Assembly of 4 segments
- Segments connected with pins
- Yoke laminations compressed with 3.3 m long tie rods
- Insertion of coil-pad sub-assembly
- Bladders (1.6 m) to align and pre-load

- .

## Alignment features

- Holes for pins shell - yoke
- Slots for keys yoke – yoke
- Hollow pins between yoke laminations
- Slots for keys pad - yoke
- Interference keys
- Masters to facilitate alignment during assembly
- Alignment options
- No alignment (TQS case)
- Shell-yoke
- Necessary for assembly
- Yoke-yoke and pad yoke
- To be discussed

## How do we get there?

- “Projectize” 4 m quad R&D (LQ)
-  Review R&D plan, two candidate support structures
-  review: last week of November
-  “Prioritize” LQ
- Track progress closely
-  Learn from 1 m R&D (e.g., lots of coils)
-  First test ~ 1 year from now
- Continuing resolution is a handicap

## LQ Schedule & Budget (Ambrosio)

- |         2008               |          2009              |

- FY08 budget (w/o contingency): $3.1M

- Plan: LQ01: shell; LQ02: collar; LQ03: TBD

## Opportunity/challenge

- Make 4/8/16 Nb3Sn quads for replacement of IR quads for Phase I upgrade (2012)
- Quads for Phase I  new funds (inside/outside LARP?)
- LARP, CERN discussions underway
- 	Evaluate cost, staff, schedule
- 	June 08: IRUWG report, DOE revue