# Presentation: 682005

## Long Quad (LQ) & High Gradient (HQ) Series Alexander Zlobin

***bnl - fnal- lbnl - slac***

_**US LHC Accelerator Research Program**_

**DOE LARP review **
**Fermilab, June 12-14, 2006**

## LARP Magnet Program Goals

- Demonstrate by 2009 that Nb3Sn magnet technology is a viable choice for an LHC IR upgrade
- Predictable and reproducible performance
- TQ models (1 m, 90 mm aperture, Gnom > 200 T/m, Bcoil > 12 T)
- Long magnet fabrication
- LQ models (4 m, 90 mm aperture, Gnom > 200 T/m, Bcoil > 12 T)
- High gradient in large aperture
- HQ models (1 m, 90+ mm aperture, Gnom > 250 T/m, Bcoil > 15 T)

- 1.

- LQ and HQ magnet fabrication and test is planned for FY2007-09
- FY2006-07 – design studies

## LQ and HQ Design Studies

- LQ and HG design studies include:
- - Analysis of magnetic, mechanical, quench protection, technology and conductor issues
- -  Integration of results from
- Model Magnet R&D (TQ technology, conductor and magnet performance)
- Supporting R&D (long coil technology, long magnet testing)
- Materials (strand and cable parameters)
- Lab’s core programs
- - Development of magnet target parameters, design and technology concepts, R&D plan

- FNAL and LBNL
- Core HFM Programs

## LQ Design Study Goals and Issues

- Goals:
- LQ conceptual design studies to determine their optimal design, technology and parameters
- R&D plan development
- Baseline design:
- TQ cross-section
- Target parameters:
- Aperture 90 mm
- Gmax > 200 T/m (Bmax>12 T)
- Length ~4 m
- Key R&D issues:
- Mechanical structure
- Conductor design and parameters
- Quench protection
- Technology

## Mechanical Structure

- LQ mechanical structures is being selected based on:
- TQC and TQS mechanical analysis and model performance
- 2D and 3D analysis in progress
- TQS and TQC model test in FY06-07
- LR fabrication and test in FY07
- LM fabrication and test in FY06-07

- LQX

- LR

- TQS

- LM

- TQC

## Strand, Cable and Insulation

- strand parameters to unsure its stability and protection (design, longitudinal uniformity, critical current at high and low fields, RRR, Cu:nonCu ratio)
- baseline strand: RRP 54/61with Df~70 mcm
- alternative strands: RRP 60/61 with larger spacing and Df~65 mcm, RRP 84/91 or 108/127 with smaller Df
- R&D at OST sponsored by DOE CDP and Fermilab core program
- cable (long length, longitudinal uniformity)
- baseline design: N=27, keystone angle of 1 deg
- insulation
- braiding the insulation on the cable (same small thickness as sleeve, and much easier application to long cable units)
- sample made at NEEW is being prepared for electrical tests
- turn-to-ground, layer-to-layer, turn-to-turn test of a TQ practice coil
- effect of thicker cable insulation (tape with overlap) on coil design and magnet parameters
- Gmax reduction by 6%

## Technology and Tooling

- Define key fabrication steps for long coils (winding, curing, reaction, impregnation, measurements, handling)
- CTD has developed a new ceramic binder to replace the present ceramic binder (1008) at significantly _lower cost_ and also _shorter procurement time_
- Qualification tests (compatibility with coil fabrication process, electrical strength, coil sample mechanical properties, thermal conductivity) of cable stacks fabricated with this new binder are underway
- Develop concept of segmented reaction and impregnation tooling
- 1 m long tooling has been developed and tested
- 2 m and 4 m segmented tooling is being
-    developed at Fermilab for LM models

## LQ Design Study Milestones

**FY2006:  **
- Analysis of long coils during heat treatment and cooldown (Q1-Q4)
- Quench protection analysis of LQ based on TQ coils (Q2-Q3)
- Specification of strand and cable parameters for the LQ practice coils and first model to procure in FY2007 (Q4)
- LQ coil conceptual design finalization (Q4)
**FY2007:**
- Development of LQ coil fabrication technology (Q2)
- Selection of LQ mechanical structures based on TQ performance (Q3)
- Develop technical proposal for LQ R&D including model design parameters, baseline technology, cost estimates and schedule
- draft proposals for FY2008 at LARP collaboration meeting (Q2)
- final proposals for FY2008 (Q4)

## HQ Design Study Goals

- Goals:
- Perform studies (magnetic, mechanical and quench protection) and develop HQ design concept (magnet parameters and features) and R&D plan in preparation for model fabrication.
- Provide input to LHC IR quad conceptual design and analysis:
- Optics, IR layout, radiation deposition, cryogenics studies
- HQ target parameters:
- Aperture 90 mm
- Bmax ~15 T (G~300 T/m)
- Length ~1 m
- HQ is a precursor to larger aperture

## 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
- 	- coil radial and axial support
_*Quench Protection:*_
- 	- conductor parameters (Cu:nonCu ratio, RRR)
- 	- quench heaters (size, position, electrical parameters)

## Cross-section Analysis

- In FY2006 HQ design study concentrates on _*coil design*_ issues, to allow starting a detailed engineering design of the coil and tooling in FY2007.
- The FY2007 design study effort will concentrate on _*mechanical support*_ issues and further _*design optimization*_.
- _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 shape, radial placement
- Complications vs. R&D interest/features
- Coil volume, quench protection, field quality, ...

## Strand & Cable Parameters

- Based on OST RRP strand performance Jc(12T, 4.2K)=3 kA/mm2.
- Large spectrum of strand and cable designs and parameters have been studied:
- Strand D: 0.7-1.0 mm
- Number of strands: 23-38
- Cable aspect ratio:
- Keystone angle: 0.7-1.4

## Coil Design Analysis

- _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 (+)
-  allows re-use of some TQ tooling (and perhaps coils) (+)

## HQ Coil and Yoke Selection

-  Two reference 4-layer coil cross-sections were selected:
- “TQ” inner layer, not graded – Gmax=307 T/m
- Graded – Gmax=317 T/m
- Preliminary yoke analysis:
- yoke OD 250 mm
- coil-yoke distance 10 mm

- 307 T/m

- 317 T/m

## Mechanical Analysis 

- 307 T/m

- 317 T/m

- Preliminary coil mechanical analysis for both coil designs:
- Pmax~170 MPa – effect on conductor degradation?

## 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)
-  Mechanics:
-  More detailed comparison of preload requirements
-  Design of structure
-  Comparison with larger aperture designs:
-  Magnetic, mechanical, quench
-  Cost and schedule

## LQ and HQ DS Budget

- FY2006:
- LQ budget was increased by 21%, ~50% spent.
- HQ budget did not change, ~50% spent.
- FY2007:
- LQ budget is planned to grow by 53%.
- HQ budget is planned to grow by 17%.

## Summary

- HQ and LQ conceptual design studies are the key DS tasks in FY2006-2007.
- Good collaboration and coordination of DS works inside the LARP collaboration and with Labs core programs was established.
- Good progress in the first part of FY2006.
- We will be ready to start LQ and HQ model magnet R&D in FY2007:
- Focus on coil tooling and technology
- Work on DS task plans and budgets for FY2007 is in progress:
- LQ and HQ budget request was prepared