# Presentation: 880040

## Technology Quadrupole Series (TQ)

*LARP DOE Review*
*June 12-14, 2006*
- Gian Luca Sabbi

_***BNL - FNAL - LBNL - SLAC***_

## TQ Goals, Implementation & Parameters

***Objective: develop the technology base, in preparation for LQ & HQ:***
-  evaluate conductor and cable performance
-  develop and select coil fabrication procedures
-  compare mechanical design concepts and support structures
-  optimized models: ***achieve 200 T/m after training & thermal cycle***
_***Two series of models, same coil design, different mechanical support***_***:***
-  TQC models: collar & stainless steel shell; low axial pre-load
-  TQS models: aluminum shell over iron yoke; high axial pre-load
***Magnet parameters:***
-  1 m length, 90 mm aperture, 11-13 T coil peak field
-  _Nominal gradient 200 T/m_; maximum gradient 215-265 T/m

## FY06 Tasks and Budget

| FY06 WBS & Budget (k$) |  | FNAL | LBNL | Total |
| --- | --- | --- | --- | --- |
| Model Magnet R&D | Sabbi | 1334 | 1063 | 2397 |
|     2.2.1.1 TQS (Technology Quad Shell) | Caspi | 392 | 784 | 1176 |
|     2.2.1.2 TQC (Technology Quad Collar) | Bossert | 942 | 279 | 1221 |

_*Technology Quad Shell – TQS:*_
-  TQS01 	(TQS baseline)
-  TQS01b	(replace one coil)
-  TQS01c 	(increase pre-load)
-  TQS02		(new coils - RRP)

_*Technology Quad Collar – TQC:*_
-  TQC01 	(TQC baseline)
-  TQC01b 	(change collars)
-  TQC02		(new coils - RRP)

- TQS01, TQC01 and TQS01b/c will be completed in FY06
- TQC01b/c, TQC02 and TQS02 will be completed in FY07

## Coil Design and Fabrication

_**Design features:**_
-  Double-layer, shell-type
-  One wedge/octant (inner layer)
-  TQ01: OST-MJR strand, 0.7 mm
-  TQ02: OST-RRP strand, 0.7 mm
-  27-strand, 10.05 mm width
-  Insulation: S-2 glass sleeve

_**Winding & curing (FNAL - all coils)**_

_**Reaction & potting (LBNL - all coils)**_

## TQC Mechanical Support Concept

**Baseline: tabbed collars in body, round collars in ends **
**Axial force of 14 kN**** applied by bullets and end plates**
**Coil end to bullet plate contact is expected at all times**

-  Support structure is derived from MQXB Quad and FNAL Nb3Sn dipoles
-  Stainless steel collars and shell (12 mm thick) share transverse pre-load
-  End plates and bullets provide rigid boundary for axial Lorentz forces
-  Stress relief slot in the inner layer pole to limit coil stress at cool-down
-  Control spacers for collared coil alignment and yoke motion control

## TQS Mechanical Support Concept

-  Support structure is derived from LBNL SM, RD and HD dipole series
-  Aluminum shell over iron yoke for large pre-stress increase at cool-down
-  Aluminum rods provide large axial pre-load to eliminate end gaps
-  Assembly based on bladders and keys, easy to adjust pre-load conditions
-  Issues: coil alignment/field quality (SQ-TQ), length scale-up (LR)

## TQ Performance References & Range

- Jc = 2 kA/mm2
*(12 T, 4.2 K)*
- MJR strand
- Conservative HT
- “First models”

- Jc = 3 kA/mm2
*(12 T, 4.2 K)*
- RRP strand
- Aggressive HT
- “Final models”

| Magnet | Top [K] | Gss [T/m] | Bss(body) [T] | Iss [kA] |
| --- | --- | --- | --- | --- |
| TQS | 4.2 | 222 | 11.4 | 12.5 |
|  | 1.9 | 239 | 12.3 | 13.6 |
| TQC | 4.2 | 215 | 11.2 | 13.0 |
|  | 1.9 | 233 | 12.1 | 14.1 |

| Magnet | Top [K] | Gss [T/m] | Bss(body) [T] | Iss [kA] |
| --- | --- | --- | --- | --- |
| TQS | 4.2 | 245 | 12.6 | 13.9 |
|  | 1.9 | 264 | 13.5 | 15.1 |
| TQC | 4.2 | 239 | 12.4 | 14.4 |
|  | 1.9 | 255 | 13.2 | 15.5 |

-  Ic data from _extracted strands determine common performance reference_ for TQS/TQC
-  Issue: relatively wide range of extracted strand Ic (TQ01: 1862-1984 A/mm2 @12T, 4.2K)
-  _*Reference magnet performance limits*_ for a given test run are adjusted for measured Tbath
-  Actual _*conductor-limited quench levels*_ may be lower due to other degradation effects

## Coil Stress Comparison (2D FEA)

-  Main differences: _warm pre-load, cool-down effect, stress uniformity (pole to mid-plane)_
-  Peak stresses are high & no consensus on degradation limits  cable testing required
-  Peak stress ~20 MPa difference: stress-relief slot, different Gss & pole stress range at Gss
-  Mechanical review recommendations: perform cable tests; add pole-stress relief in TQS
-  Detailed FEA shows that _3D effects have a significant impact_ on actual coil stresses

- TQC Layer 1 stress - 

- TQS Layer 1 stress - 

## TQS 3D FEA

-  Interfaces for integrated use of CAD, mechanical and electro-magnetic packages
-  Studies of the effects of friction among interfaces (coil-pole, coil-pads, yoke-shell)
-  Design goal: _*maintain contact between coil and structure at all steps and locations*_

- 13 kA (<Iss)

- Uniform coil-pole
- displacements

## TQC 3D FEA

- _Modeling of epoxy bonding_:
- The coils and parts are initially bonded
- Bonded interface releases for tensile stress beyond 30 MPa
- Interface elements with stresses above σt are removed allowing surfaces to separate

- Lorentz forces are calculated using a ANSYS magnetic model (SOURC36 elements) and then transferred to the nodes of a structural model (SOLID45 elements) with same mesh
- Calculated effects (end gaps) depend on collar and iron axial stiffness, and slip-or-stick assumptions at interfaces (collar/iron/skin)

## TQC Mechanical Models and Assembly

- Understand coil size, effect of mid-plane shims and collar-yoke shims
- Check FEA analysis predictions for assembly and cool-down pre-loads
- Optimize collaring and yoke welding process for brittle Nb3Sn coils

_*Five TQC mechanical models were built and tested between October 2005 and April 2006*_

- _Goals:  _

**TQC01 Collared Coil**

## TQS Mechanical models and Assembly

- Coil-pad and yoke-shell sub-assembly        Transverse pre-load	              Axial pre-load

-  MM#1: first check of quad assembly steps, LN cool-down (dummy coil, no axial rods)
-  MM#2: full assembly and LN cool-down test (practice coils, shell/rods gauges)
-  MM#3: full assembly and controlled cool-down (real coils, full set of gauges)
- _Findings_:
-  Developed assembly procedure and measured cool-down effects for shell and rods
-  Strain gauges on bronze pole provided useful data on stress conditions, homogeneity
-  Friction among structural elements plays crucial role: improved FEA models

## TQS01 Performance Analysis

- Calculated axial stress at pole gap (3D FEA)

- Quench current and origin (first cycle, 4.5K)

- _Analysis findings_:
-  Performance limit in the “pole-gap” area of coil 6
-  FEA results: coil axial tension spike in gap area
-  Post-test inspection shows epoxy tearing (all coils)
- _Corrective actions_:
-  TQS01b: replace coil 6 and check reproducibility
-  TQC02:  eliminate co-planar gaps in the two layers
-  TQS02:   change materials for pole and/or structure

*Only 1 quench in end segments*

- Iref     = 12.3 kA
- Gref  = 218 T/m

## Progress since DOE Technical Review

** ****Coil fabrication:**
-  TQS01 + TQC01 production coils and 2 spare coils completed
-  Further optimization is needed, but no major design changes
-  **Mechanical design:**
-  Mechanical review: designs are consistent with Nb3Sn experience & FEA
-  Constantly improving FEA models based on prototype measurements
-  Already starting to converge towards an optimal set of design features
** ****Feedback from TQS01 test:**
-  First quench > 0.80 Iss; Imax= 0.87 Iss; second cycle starts at 84%
-  Axial support: minimal end quenching, no degradation (up to 87% level)
-  _***Excellent result for first prototype of a challenging, new design***_* *
** ****Next steps:**
-  Complete TQC01 assembly and replace limiting coil in TQS01
-  TQC01 & TQS01b tests in July-August
-  TQC02 coil fabrication starting in June, TQS02 starts in September

## Preliminary FY07 Plan

| Model | Features | FY07 activities | Budget |
| --- | --- | --- | --- |
| TQC01b | Re-assemble & test with tabbed collars | Test  | 55 |
| TQC01c | Adjust pre-load configuration | Fabricate & test | 205 |
| TQC02 | New conductor, structure optimization | Fabricate & test | 359 |
| TQS02 | New conductor, structure optimization  | Fabricate & test | 430 |
| TQ03 | LQ reference or TQ02 backup | Fabricate coils | 800 |

- _MSC Guidance_:

-  Model magnet R&D effort continues at FY06 funding levels
-  Meet TQ milestones to support critical decisions for LQ
-  Design/procure LQ tooling and start practice coil fabrication
-  Start HQ engineering design and tooling design

- _Preliminary TQ plan_:

## Basis for the FY07 Plan

** ****Schedule information from TQS01 an TQC01**
-  More accurate information on sub-task requirements
-  **Feedback from TQS01 test**
-  First quench above 80% of 4.5 K short sample; max quench at 87%
-  Maximum gradient achieved (197 T/m @ 3.2K) is close to TQ reference
-  Test results and FEA analysis indicate a clear optimization strategy
-  We are on track to meet the LARP Magnet R&D objectives
** ****TQS01 & TQC01 coil fabrication approach was successful**
-  Good quality and consistency of fabricated coils
-  Efficient use of resources and facilities; program and team integration
**TQS01 test information is available before start of TQC02 winding**
-  Optimization: pole piece design near gaps and layer transition; end parts
** ****Recommendations from TQ the mechanical review**
-  Extract maximum information at each step; explore variants

## Q1-06  Q2-06  Q3-06  Q4-06  Q1-07  Q2-07  Q3-07  Q4-07  Q1-08

**Q1-06  Q2-06  Q3-06  Q4-06  Q1-07  Q2-07  Q3-07  Q4-07  Q1-08**

**TQ01**

**TQ01R**

**TQ02**

**TQ03**

- Complete
- 8/2006

- Complete
- 4/2007

**TQ Plan – Updated June 12, 2006**

## TQ Milestones FY06-08

| 02/2006 | Mechanical Design | Compare design objectives & FEA results
Evaluate results from mechanical models
Assess readiness to assemble/test magnets |
| --- | --- | --- |
| 08/2006 | TQ01 evaluation |  Evaluate TQ01 coil fabrication results
 Compare test results with expectations
 Demonstrate control of strand stability (for MJR)
 Provide a basis for the LQ coil design |
| 04/2007 | TQ02 evaluation |  Evaluate conductor performance (for RRP)
 Evaluate mechanical design optimization results
 Provide a basis for LQ structure design
 Assess if TQ goals have been achieved |
| 01/2008 | TQ03 evaluation |  Assess if TQ goals have been achieved
  (backup for TQ02)
  and/or
 Validate LQ design, analysis and fabrication
 Define performance reference for LQ |

## TQ Evaluation Criteria 

- TQ Evaluation Criteria

- _Technology demonstration and characterization:_
*consistently achieve G>200 T/m after training and thermal cycle *
*evaluate the mechanical performance of different models*
*determine the required design margins (fraction of short sample)*
* *
- _Selection of optimal design features and fabrication methods:_
- LQ models:
*Provide the *_*optimized coil design*_* and *_*tooling*_* for LQ*
*Feedback on *_*coil fabrication methods*_* (integrate with LR)*
*Input for *_*structure selection*_* (integrate with DS)*
* *
- HQ models:
_*Design methods*_*, *_*coil technology, possibly re-use coils*_* *
*Input for *_*structure selection*_* (integrate with DS)*

## Summary

-  Some delay, but overall good progress on TQ models
-  Excellent result from first TQS prototype: a solid basis to build on
-  Good understanding of prototype performance and limitations
-  Established a reference and developed strategy for optimization
-  First TQC prototype is near completion – test in July
-  Updated R&D plan takes into account the new information
-  _TQ goal #1_: provide a basis for the LQ coil design
-  _TQ goal #2_: provide a basis for the LQ structure design
-  Modularity of TQ tooling should allow smooth transition to LQ
-  TQ also provides a basis for HQ design and fabrication