# Presentation: 161408

## TQ Results

*LARP CM11*
*October 27-28, 2008*
- Gian Luca Sabbi

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

## TQC and TQS Designs

-  Aluminum shell over iron yoke
-  Assembly with bladders and keys
-  Full preload after cool-down
-  Rods/plates for high axial pre-load

- TQC (Collar)

- TQS (Shell)

-  Stainless steel collars and skin
-  Control spacers to limit pre-load
-  Full pre-load at room temperature
-  End support plates, low pre-load

## TQ Short Sample Limit

**MJR strand (TQ01 Models)**
- Jc = 1.9 kA/mm2
*(12 T, 4.2 K)*

**RRP strand (TQ02 models)**
- Jc = 2.7 kA/mm2
*(12 T, 4.2 K)*

| Magnet | Top [K] | Gss [T/m] | Iss [kA] |
| --- | --- | --- | --- |
| S01a,b,c | 4.4 | 216 | 12.1 |
|  | 1.9 | 234 | 13.2 |
| C01a (b) | 4.4 | 209 (201) | 12.6 (12.1) |
|  | 1.9 | 228 (218) | 13.7 (13.1) |

| Magnet | Top [K] | Gss [T/m] | Iss [kA] |
| --- | --- | --- | --- |
| S02a,b,c | 4.4 | 239 | 13.6 |
|  | 1.9 | 260 | 14.9 |
| C02a,e | 4.4 | 224 | 13.6 |
|  | 1.9 | 244 | 14.8 |

-  TQC iron yoke is located further away from the coil than TQS (SS collar)
*- Causes shallower load line, lower short sample gradient *
-  From TQC01b, iron yoke was extended above the ends for mechanical reasons
*- End peak field increase causes further loss of short sample gradient *

*Same fraction of short sample results in ~6% lower gradient for TQC than TQS*

## TQC Tests

| Magnet | Conductor | Coils | Island | Temperature | Test |
| --- | --- | --- | --- | --- | --- |
| TQC01a | MJR | 9,10,12,13 | Bronze | 4.4 K & 1.9K | August 2006
FNAL |
| TQC01b | MJR | 7,8,10,12 | Bronze | 4.4 K & 1.9K | August 2007
FNAL |
| TQC02e | RRP | 20, 21, 22, 23 | Titanium | 4.4 K & 1.9 K | October 2007
FNAL |
| TQC02a | RRP | 17, 19, 24, 27 | Bronze | 4.4 K & 1.9 K | January 2008
FNAL |
| TQC02b | MJR/RRP | 10, 12, 17, 19 | Bronze | 4.4 K & 1.9 K | Aug 2008
FNAL |

- New models & virgin coils are in **bold font. **Rebuilt models & pre-trained coils are in *italic font.*** **

## TQS Tests

| Magnet | Conductor | Coils | Island | Temperature | Test |
| --- | --- | --- | --- | --- | --- |
| TQS01a | MJR | 5, 6, 7, 8 | Bronze | 4.4 K | April 2006
LBNL |
| TQS01b | MJR | 14, 15, 7, 8 | Bronze | 4.4 K | Nov. 2006
LBNL |
| TQS01c | MJR | 5, 15, 7, 8 | Bronze | 4.4 K & 1.9 K | March 2007
FNAL |
| TQS02a | RRP | 20, 21, 22, 23 | Titanium | 4.4 K & 1.9 K | June 2007
FNAL |
| TQS02b | RRP | 22, 23, 28, 29 | Titanium | 4.4 K & 1.9 K | March 2008
CERN |
| TQS02c | RRP | 22, 23, 28, 20 | Titanium | 4.4 K & 1.9 K | Jun & Sep 08
CERN |

- New models & virgin coils are in **bold font. **Rebuilt models & pre-trained coils are in *italic font.*** **

##  TQ Quench Performance Summary

| Model | First Training at 4.4K |  |  | First Training at 1.9K |  |  | Highest Quench* |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | GStart
(T/m) | GMax 
(T/m) | Gmax/Gss
(%) | GStart
(T/m) | GMax 
(T/m) | Gmax/Gss
(%) | GMax 
(T/m) | GMax quench
conditions |
| TQC01a | 131 | 154 | 72 | 151 | 196 | 87 | 200 | 1.9K, 100A/s |
| TQC01b | 142 | 178 | 86 | 179 | 200 | 90 | 200 | 1.9K |
| TQC02E | 177 | 201 | 87 | 198 | 199 | 79 | 201 | 4.4K |
| TQC02a | 124 | 157 | 68 | 145 | 164 | 65 | 169 | 1.9K, 50 A/s |
| TQC02b | 141 | 173 | 85 | 158 | 173 | 78 | 175 | 3.6K, 50A/s |
| TQS01a | 180 | 193 | 89 | n/a | n/a | n/a | 200 | 3.2K |
| TQS01b | 168 | 182 | 84 | n/a | n/a | n/a | 182 | 4.4K |
| TQS01c | 159 | 176 | 81 | 176 | 191 | 82 | 191 | 1.9K |
| TQS02a | 182 | 219 | 92 | 214 | 221 | 85 | 222 | 2.2K |
| TQS02b | 190 | 200 | 84 | 196 | 205 | 79 | 205 | 1.9K |
| TQS02c | 216 | 222 | 93 | 205 | 209 | 80 | 231 | 2.7K |

*(*) Highest Quench value includes all Training, Ramp Rate & Intermediate Temperature Quenches*

## Discussion Points

- _TQC-specific_:
-  Are the coil stress levels known and understood?
-  Is there sufficient tolerance to assembly parameters?
- _TQS-specific_:
-  Which factors determined the TQS plateau levels at 4.5K & 1.9K?
- _Overall results vs expectations_:
-  Did the TQ program achieve its original objectives?
-  Are there additional TQ objectives, and what is their priority?

## TQC Coil Stress

- Preload at inner pole in TQC models (MPa)
- TQC01b data is listed separately for coils with glued/non-glued outer poles.

## TQC Models Analysis

- _TQC01a_:
- Viability of collaring process demonstrated
- Low preload limited the quench plateau in TQC01a at 4.5K and resulted in outer layer mid-plane damage at 1.9K at the end of magnet test.
- _TQC01b_:
- Analysis incorporated plastic coil behavior, resulting in appropriate preload.
- Reached 88% of its short sample gradient at 4.5K and 92% at 1.9K.

- _TQC02E_:
- Coils re-used from TQS02a, collared without damage.
- Achieved 90% of its short sample gradient at 4.5K and 81% at 1.9K
- After disassembly, coils were re-used in TQS02b/c, with no indication of degradation during assembly, testing or disassembly of TQC structure.

## TQC Models Analysis (2)

- _TQC02a_:
- TQC02a was first collared in March 2007: results from strain gauges as well as collar deflection measurements were consistent with analysis.
- The magnet was re-assembled in November 2007 with increased preload during the collaring phase.
- The reassembled magnet included two new coils, replacing two that may have been damaged due to a misplaced mid-plane shim during the initial assembly.
- Limited quench plateau in the new coils indicates probable degradation during construction due to higher collaring preload and large increments during early collaring steps.
- _TQC02b_:
- Return to TQC01b preload parameters and additional early collaring steps in TQC02b will allow return to TQC02E/TQC01b performance or better.

## TQS01 – Analysis of Plateau Quenches

-  TQS01 plateau quenches are very repeatable (all segment dV/dt are overlays)
-  Quench propagation velocity along pole turn can be correlated with local Ic
-  Calculated “gap” Ic in coil 6 consistent with ~87% quench level (already in Q#4)
-  TQS01b & TQS01c limit also consistent with Ic degradation (in different coils)

- SQ02 Measured Quench Velocities

- Iq/Iss

## TQS01 – Coil Stress near Pole Gaps

- Differential _measurements_ of coil axial strain in TQS01b

- 1. Assembly

- 2. Cool-down

- 4. Warm-up

- 3. Training

-  3D ANSYS calculations and TQS01b measurements
-   indicate high longitudinal tension in coil across gaps,
-   possibly leading to conductor degradation
-  This effect depends on the interfaces between coil,
-   pole (bronze or titanium) and *outer support elements*

## TQS02a Quench Analysis

-  All plateau quenches in coil 21 (coil 21 participates in initial training)
-  Quenches start in the pole turn and the multi-turn of the outer layer
-  Voltage signal overlays indicate same origin and evolution
-  Proximity of quench onsets indicates start is near the pole turn
-  FEA shows very high stress with Ti poles in outer pole turn
-  Comparison of 1st and 2nd plateau shows further training occurred at 1.9K
-  At 1.9 K, same limiting coil and same segments/sequence as 4.5K

## TQS02b Quench Analysis

-  All quenches (4.5K & 1.9K) start in coil 29 at same location (pole turn)
-  At 1.9K, 20A/s ramps resulted in lower quench current than at 4.5K
-  At 1.9K, higher ramp rates resulted in higher quench currents
-  Quench location correlates with “kinks” after un-winding/re-winding

## TQS02c-TC1 Quench Analysis

- All Quenches are in coil 23 B6A10 (_ramp between inner and outer layer_)
* **4.5K start is at about 110 mm from the V tap A10 (20A/s ramp rate)*
* **1.9K start is at about 210 mm from the V tap A10 (20A/s ramp rate)*

- _Exceptions_:
- the beginning of the training for q1-q2 : quenches are in coil 28
- ramp rate >20A/s (4.2K) and ramp rate >140A/s (1.9K): quenches are in coil 23 A2A4
- ramp rate <20A/s (4.2K) when quenches are in coil 23 B4B3

## TQS02c-TC2 Quench Analysis

## TQS Summary

- _Structure performance_:
-  Demonstrated accurate, repeatable control of warm and cold pre-load
-  Delivered safe, fast assembly and disassembly for all 6 models
-  Training starts high and improves rapidly to maximum; no retraining
-  All TQ02 models surpassed target gradient, achieved up to 230 T/m
- _Coil Performance_:
-  TQS01:   Degradation due to high stress at pole gaps (several coils)
-  TQS02a: Degradation due to high stress in outer layer (coil 21)
-  TQS02b: Degradation due to unwinding/rewinding (coil 29)
-  TQS02c: Degradation in the inter-layer ramp region (coil 23)

## Conductor Stability

- _Question_: are instabilities observed in magnets induced by conductor damage at some step in the fabrication/test process?

-  No instabilities in SQ02 and TQ01 models  at 4.5 K & 1.9K (MJR)
-  No stability limitations in SR/LR at 4.5 K (RRP)
-  No stability limitations in TQ02 models at 4.5 K (RRP)
-  Signs of instability in TQC02 models at 1.9K (both MJR & RRP)
-  Signs of instability in TQS02 models at 1.9K (RRP)

-  We expected that conductor instabilities may affect SQ/TQ/LR/LQ
-  Conductor tests indicated limited margin at operating points
-  Cabling and HT parameters were optimized to maximize margin
-  Results?

## TQ Objectives (2005 Tech Review)

_**Phase 1 (TQ baseline):**_** TQS01 & TQC01**
- Develop and verify the coil fabrication technology
- Perform a consistent comparison among mechanical support concepts
*Same conductor/cable and same coil design*
*Same fabrication procedures for all coils*
*Consistent instrumentation and documentation*
- Lay groundwork for Lab collaboration
*Agree on coil module design and fabrication*
*Share fabrication and instrumentation practices*
*Integrate coil fabrication steps *
*Integrate design, fabrication and testing teams** *

## TQ Objectives (2005 Tech Review)

_**Phase 2 (mechanical & conductor studies):**_** TQS02, TQC02, TQE01**
- TQS02: reconfigure/optimize based on TQS01 results
*Adjust pre-load conditions, assembly sequence *
*If needed, replace one or more coils*
- TQC02: first TQ coils made with “baseline” 54/61 RRP strand
*No changes in the coil/cable design are expected*
*Optimization of mechanical structure w/TQC01 feedback*
- TQE01: disassemble TQC01 coil and test in TQS01 structure
*Compare coil performance in different structures*
*	**(evaluate based on TQS01 and TQC01 results)*
*Explore the feasibility of collared coil disassembly *

## TQ Objectives (2005 Tech Review)

_**Phase 3 (optimized models):**_** TQS03 and TQC03**
- _Demonstrate the TQ objectives:_
_*consistently achieve G>200 T/m after training and thermal cycle*_* *
*evaluate the required design margins (fraction of short sample) *
*characterize the mechanical performance of the two structures*
* *
- _Support the follow-on model magnet R&D:_
- LQ models:
*Provide the *_*optimized coil design*_* for LQ*
*Feedback on *_*coil fabrication methods*_* (integrate with LR)*
*Input for *_*structure selection*_* (integrate with DS)*
* *
- HQ models:
_*Design methods/tools*_* and *_*coil fabrication technology*_* *
*Input for *_*structure selection*_* (integrate with DS)*

## TQ Objectives Summary

-  Optimize/characterize cable design and heat treatment cycle
-  Evaluate conductor/cable performance and stability
-  Develop and optimize coil fabrication/handling procedures
-  Optimize and finalize the coil design for LQ
-  Develop/calibrate FEA models
-  Compare mechanical design concepts and support structures
-  Compare test data with expected (design) values
-  Evaluate and optimize quench protection parameters for LQ
-  Develop instrumentation and diagnostic techniques
-  Provide experimental feedback for LQ and HQ structure selection
-  _Consistently achive G>200 T/m after training and thermal cycle_

- Can we declare that these objectives have been achieved?

## Current & Future TQ Objectives

-  Evaluate new conductor on well-characterized coil/structure
-  Investigate role of end pre-load in shell-based models
-  Improve performance of collar-based models
-  Other?
-  Which priorities, in view of the main LARP milestones?