# Presentation: 142419

## IRQ R&D - Introduction A.V. Zlobin

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

_**US LHC Accelerator Research Program**_

- LARP collaboration meeting
- 19-21 October, 2004
- Napa, CA

## LHC Inner Triplet Designs

- LHC IR optics based on single-bore inner triplet with large-aperture quads

- LHC IR optics based on double-bore inner triplet with 100 mm quads

*The key elements of these approaches are separation dipoles and then double bore IRQ *

*The key elements of this approach are large-aperture high-gradient quads*

## Approaches and Challenges

- At present time the IRQ R&D program is focused on the large-aperture quadrupoles based on Nb3Sn superconductor for the single-bore inner triplet and double-bore inner triplet with parallel apertures.
- We will push magnet parameters above the present state-of-the-art:
- Jc(12T,4.2K) ~3 kA/mm2 in the coil
- the Bmax in the coil at quench ~15 T
- Bmax exceeds the level reached in Nb3Sn accelerator magnets to date
- the maximum stress in the coil, induced by Lorentz forces, approaches to the level which may cause significant degradation or even damage of brittle Nb3Sn conductor
- Nb3Sn is brittle => new technologies for accelerator magnets:
- W&R is the baseline technology

## IRQ R&D Phases

- Program starts with Conceptual Design Studies of IR and magnet designs.
- A series of short models has to address the issues of magnet technology, quench performance, field quality, mechanics, quench protection, reproducibility, long term performance, etc.
- Length dependent effects will be studied with 4-m long quadrupole coils, as soon as we achieve acceptable quench performance on short models.
- Model R&D will be followed by the construction of one or more quadrupole prototypes containing all of the features required for use in the LHC.

## IRQ design studies summary and open issues

- IRQ conceptual design studies and preparation to the short model R&D were started few years ago at Fermilab and LBNL.
- They included:
- magnetic analysis on different IRQ designs
- mechanical analysis of different IRQ mechanical structures
- Nb3Sn IRQ thermal analysis
- IRQ quench protection
- studies of structural material properties
- The summary of recent results will be presented and discussed at this meeting:
- preliminary answers on some R&D questions

## IRQ design studies in FY2005-2007

- We will continue IRQ design studies in FY2005-2007 focusing on analysis and discussions of:
- IR design parameters, IRQ aperture/gradient/length issues, field quality tables (with AP group and CERN)
- quadrupole magnetic designs, mechanics, operation temperature and temperature margin, quench protection issues, etc.
- the experimental data from the model magnet R&D  feedback to magnet development and AP groups
- the LHC IR commissioning and operation performance (when available)  feedback to model magnet R&D
- At this meeting we need to discuss the issues and questions to be addressed in FY2005.

## First phase of IRQ short model R&D

- The final answers on most of these questions can be provided only by model magnet R&D.
- The first 3-year phase of the short model R&D program focuses on the 90 mm shell-type technological quadrupoles (TQ).
- TQ models will serve as a tool for both quadrupole technology development and magnet performance studies:
- 2-, 3- and 4-layer coil designs and fabrication technologies
- different mechanical designs
- different assembly techniques
- This choice, in addition to the technical considerations, reduces cost and risks of this important phase of the program.
- In the future based on the results of this phase and program needs we could optimize the magnet aperture size and the nominal field gradient.

## FY2005-FY2007 short model R&D goals

- The main goals of the first 3-year IRQ R&D phase are:
- fabricate, test and evaluate two shell-type coil designs: 2(3)-layers and 4-layers
- fabricate, test and evaluate two alternative mechanical structures based on *bladder-key-Al shell* or *collar-yoke-skin*
- develop and study narrow and wide cables for both coil designs
- study and optimize strand parameters for quadrupole models
- develop and evaluate coil fabrication technologies
- develop and build tooling to perform short model (1-m long) R&D
- develop infrastructure for fabrication and test of long (up to 4-m long) quadrupole coils
- By the end of this phase we are planning to choose the optimal conductor, coil aperture and design and mechanical structure for the next phase of the short model R&D which will have to address the *field quality* and *reproducibility* issues.

## TQ design considerations

- In order to provide internal consistency and compatibility of this phase of the program, optimize program cost and reduce the development time we decided to:
- unify as much as possible the coil fabrication tooling
- distribute responsibilities among the groups for
- tooling development and procurement
- coil and magnet component design and procurement
- magnet fabrication and test

- The primary goal of FY2005 is fabrication and test of first simplified quadrupole technological model TQ4L1a by collaborative efforts of 3 Labs.
- Starting from FY2006 two coil designs and two mechanical structures will be studied, one at Fermilab and another one at LBNL to compare technologies and magnet performance.
- By the end of FY2007 we are planning to choose the optimal conductor, coil aperture and design and mechanical structure for the next phase of the short model R&D based on the model technologies and performances as well as to develop infrastructure for fabrication and test of long (up to 4-m long) quadrupole coils.
- At this meeting we need to discuss the details of FY2005 short model R&D plan, milestones, coordination of efforts, etc.

- FY2005-FY2007 short model R&D milestones

## Session agenda

- 01:30 Introduction, A. Zlobin
- 01:40 IR Quad Design Study Summary & Open Issues, V.Kashikhin
- 02:05 IR Quad Design Study Summary & Open Issues, G. Sabbi
- 02:30 IR Quad Model Magnet R&D, S. Caspi
- 03:15 *break - 1/2 hr*
- 03:45 IR Quad Model Magnet R&D, A. Zlobin
- 04:15 Sub-Scale Quad, P. Ferracin
- 05:00 General Discussion - open
- 06:00 Adjourn