# Presentation: 671265

## Quadrupole Models: TQ and HQ

*LHC IR Upgrades Workshop*
- October 3-4, 2005
- Gian Luca Sabbi

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

## LARP Magnet Program Goals

***FY09 Milestone:***_ _
**       **_**Demonstrate viability of Nb**__**3**__**Sn technology for “Quad-first” option **_

***1. Capability to deliver predictable, reproducible performance:***
**	****TQ ****	****(Technology Quads): ****	****D = 90 mm, L = 1 m, G****nom**** > 200 T/m**
***2. Capability to scale-up the magnet length:***
**       ****LQ (Long Quads) :****	****	****D = 90 mm, L = 4 m, G****nom**** > 200 T/m**
***3. Capability to reach high gradients in large apertures:***
**	****HQ (High Gradient Quads): ****	****D = 90 mm, L = 1 m, G****nom**** > 250 T/m**

***Overall goal:***
**      **_**Provide options for future upgrades of the LHC Interaction Regions**_

## Model Magnet Parameters: Aperture

- A) It is directly applicable to the LHC IR upgrade:
-  IR upgrade scenarios using ~90 mm quads have been developed
- B) It is sufficient to investigate the critical magnet R&D issues:
-  Conductor/cable designs and performance
-  Magnetic design: peak fields in the coil up to 15 Tesla
-  Mechanical design: conductor stress up to 150-200 MPa
- C) Larger apertures would lead to more costly, less effective R&D:
-  Cross-section area increases ~linearly with aperture
-  Conductor requirements for 4-m long and high gradient models
-  Several models for each type are needed, with practice & spare coils
-  Larger aperture also impacts cost for tooling, structures, testing etc.

-  Optimal aperture for the LHC IR upgrade may be larger than 90 mm
-  Difficult to finalize choice until several more years
-  A 90 mm aperture was chosen for the quadrupole models, because:

## Model Parameters: Gradient, Length

-  Quadrupole magnets are generally characterized in terms of gradient
-  For magnet R&D the coil peak field is a better performance indicator
-  Goal of “high gradient” models is to demonstrate  ~15 Tesla coil field
-  Results can help determine the maximum performance characteristic
-  Quad aperture/gradient will be scaled following IR optimization
-  Benefits of “moderate” aperture choice apply to high field model R&D

- _Gradient/coil field:_

- _Scale-up to long Nb__3__Sn magnets is a major R&D issue:_

-  fabrication of long lengths of conductor/cable with uniform properties
-  stress control during coil reaction; handling of reacted coils
-  support structures, magnet assembly

*A 4 meter length is considered adequate for technology proof *
*Magnetic parameters will be the same for LQ as for TQ*

## Technology Quads (TQ)

***Objective: contribute to developing the technology base for LQ & HQ:***
-  evaluate conductor and cable performance: stability, stress limits
-  develop and select coil fabrication procedures
-  select the mechanical design concept and support structure
-  ***demonstrate predictable and reproducible performance***
***Implementation: ***_***two series, same coil design, different structures***_***:***
-  TQS models: shell-based structure
-  TQC models: collar-based structure
***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

## Conductor & Coil Design

- _Conductor_:
-  Strand diameter: 0.7 mm
-  Cable: 27 strands
-  1.0 degrees keystone
-  Width: 10.05 mm
-  Mid-thickness:1.26 mm
-  Insulation: S-2 glass sleeve
- _Coil_:
-  double-layer shell
-  one (inner layer) wedge/octant

- TQ1a/2a coil cross-section

## TQS01: Shell-based Structure

- _Concept_:
-  Aluminum shell over yoke and pads
-  Assembly based on bladders and keys
- _Advantages_:
-  Can deliver very high pre-stress
-  Large pre-stress increase at cool-down
-  Easy assembly/disassembly/reassembly
- _R&D issues_:
-  Coil alignment, field quality
-  Long vs. segmented shells

*TQS01 test expected to take place in February-March 2006*

## TQC01: Collar-based Structure

- _Concept_:
-  Support by thick SS collars
-  Assembly w/external press
- _Advantages_:
-  Proven coil positioning
-  Proven length scale-up
- _R&D issues_:
-  Deliver required pre-stress
-  Pre-stress overshoot
-  Flexibility for R&D

*TQS01 test expected to take place in April-May 2006*

## High-Gradient Quads (HQ)

- Goal: achieve ~15 T coil field (~300 T/m in the 90 mm aperture)

- 3-layer: G=260-290 T/m

- 4-layer: G=280-310 T/m

## 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
_*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

## IR Quad Design Space