# Presentation: 297650

## HQ Design Study

- (WBS 2.1.4.1)
*LARP Collaboration Meeting*
*April 26-28, 2006*
- N. Andreev, E. Barzi, S. Caspi, D. Dietderich,
- _P. Ferracin_, A. Ghosh, _V. Kashikhin_, I. Novitski,
- GianLuca Sabbi, A. Zlobin

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

## HQ Design Study Goals & Milestones

- 1. Develop HQ design and R&D plan in preparation for model fabrication:
- 	- Magnetic, mechanical and quench analysis
- 	- R&D issues, magnet parameters and features
- 2. Provide input to LHC IR quad conceptual design and analysis:
- - Optics, IR layout, radiation deposition, cryogenics studies

- FY06:
- Focus on
- coil

- FY07:
- Focus on
- structure

## HQ Design Issues

_*Conductor*_*:* 	- strand (optimal design, critical current at high field)
- 		- cable (limits on maximum width & keystone angle)
_*Magnetic*_*:* 	- number of layers (cable design, winding issues)
- 		- use of wedges, conductor grading, end field optimization
- 		- Lorentz stresses
_*Mechanical*_*:* 	- collar-based vs. shell-based structure
- 		- structure and coil alignment
- 		- end axial support
_*Integration*_*:*	- coordination with model magnet, supporting R&D
- 		- coordination with IR magnets study
- 		- fabrication, cost and schedule considerations
- 		- target parameters, design features, R&D plan

## Cross-section analysis and selection

-  Same current density. How to account for cabling/stress degradation
-  Strand parameters (diameter, cu/sc): consistent (same) and practical
-  Cable parameters (no. str., angle, compact.): consistent (same) & approved
-  Iron yoke: same distance from coil and magnetic properties

- _Pre-conditions for comparison_:

- _Criteria for comparison_:

-  Maximum gradient
-  Coil stress distributions
-  Practicality, cost and schedule: strand procurement, use of TQ tooling (coils)
-  Winding/Fabrication issues: minimum radii, spacer design, radial placement
-  Complications vs. R&D interest/features
-  Coil volume, Quench protection, Field quality, ...

## Critical current assumptions

## Reference strand parameters

| B, T | T=4.2K |  | T=1.9K |  |
| --- | --- | --- | --- | --- |
|  | Jc(B,T), A/mm2 | dJc(B,T)/dB,
A/mm2/T | Jc(B,T), A/mm2 | dJc(B,T)/dB,
A/mm2/T |
| 12.0 | 3000 | -591 | 3827 | -663 |
| 12.5 | 2716 | -547 | 3507 | -617 |
| 13.0 | 2452 | -507 | 3209 | -575 |
| 13.5 | 2208 | -470 | 2931 | -536 |
| 14.0 | 1982 | -435 | 2672 | -500 |
| 14.5 | 1772 | -403 | 2431 | -466 |
| 15.0 | 1579 | -372 | 2206 | -435 |
| 15.5 |  |  | 1996 | -405 |
| 16.0 |  |  | 1800 | -377 |
| 16.5 |  |  | 1618 | -351 |
| 17.0 |  |  | 1449 | -326 |

- Assumed Cu/Sc ratio: 0.87 (based on RRP 54/61)

## Cable parameters

## Number of Layers

*Compared 2, 3, and 4-layer coil designs from the design and fabrication standpoint*
- _2-layer design_:
-  smallest number of parts and fabrication steps (+)
-  requires a cable with large aspect ratio (-)
-  difficulties in design of the end parts and in coil winding (-)
- _3-layer design:_
-  reduce the cable width (+)
-  maintain a continuous winding in each quadrant, minimize joints (+)
-  constraints to the coil design: more axial space for the coil ends (-)
- _4-layer design:_
-  twice as many coils, tooling and fabrication steps as to 2-layer design (-)
-  can reach 40 mm coil width while limiting the cable width (+)
-  allows grading of the outer two layers at small extra cost (+)
-  Allows re-use of some TQ tooling (and perhaps coils) (+)

## Yoke Parameters

- _Assumptions for preliminary magnetic optimization:_
-  Yoke OD 250 mm
-  Coil-yoke distance 10 mm
-  Non linear B-H curve

## Selected 4-layer cross-sections

**Note: gradients are in quotes because they are not all computed in a consistent manner**

## Coil Stress Analysis

- _Cross-section designs considered_:
-  “TQ” inner layer, not graded
-  Paolo graded
-  Vadim graded (# 7)
- _Magnetic assumptions_:
-  Real iron
-  Rin iron = Rout coil + 5 mm
-  Rout iron = 280 mm
-  Gradient = 300 T/m
- _Mechanical Assumptions_:
-  Layer 1-2 and Layer 3-4 bonded
-  Layer 2-3 sliding

## “TQ” Inner Layer, not graded

**108**

**126**

**173**

**152**

## “TQ” Inner Layer, not graded

**108**

**126**

**173**

**152**

## Paolo Graded

**119**

**172**

**124**

**118**

## Paolo Graded

**119**

**172**

**124**

**118**

## Vadim graded (#7)

**135**

**128**

**135**

**107**

## Vadim graded (#7)

**135**

**128**

**135**

**107**

## Reference cross-sections

- “TQ” inner layer

- Graded

- 307 T/m

- 317 T/m

## Summary

-  Two reference cross-sections were selected
-  Next steps:
- Magnetic:
-  Refine cable parameters (feedback from materials R&D)
-  Preliminary design of coil ends; peak field issues
-  Complete magnetic cross section (2 options)
-  Mechanical
-  More detailed comparison of preload requirements
-  Design of structure
-  Comparison with larger aperture designs
-  Magnetic, mechanical, quench
-  Cost and schedule