Field Quality

7/6/99

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Table of Contents

Field Quality 

Why field Quality is important?

Sources of Field Errors

Impact of Cable Thickness on Field Quality

Results from Present Day Magnets (Real Magnets) What has a major impact on random field errors? Is it cable thickness or some thing else?

Results from Present Day Magnets (Real Magnets) What has a major impact on random field errors? Is it cable thickness or some thing else?

Conventional Wisdom: Increasing Aperture Reduces Standard Deviation at 2/3 of the Coil Radius.

Influence of magnet components on field errors (From: R. Gupta, LHC Collective Effects Workshop, Montreux, 1995. Published in Particle Accelerators)

Field Quality in SSC Magnets (Lab built prototype dipoles)

Field Errors in SSC dipoles How off we were from reality?

Why were we so wrong in estimating field errors in SSC dipoles?

Measured Current Dependence in Sextupole in SSC Magnets

Influence of Lorentz Forces

Feedback in design from HERA experience: The Real Magnet Vs. Paper Design

Feedback in design from HERA experience A Method to Adjust Integral Field and Skew Quad

Three magnets with similar apertures Tevatron, HERA and RHIC

Comparison of Field Quality in three similar aperture magnets

Comparison of Field Quality in Tevatron, HERA and RHIC dipoles

Relaxation of Tolerances

Errors in Modern Measurement System

Different Size Cable (within spec) from Two Different Vendors

Flexible Design (Adjustment in b5 During Production in Q1)

Saturation in RHIC Arc Dipoles

Saturation Control in RHIC Dipoles Variation in |B| in Iron Yoke

Average Field Errors on X-axis

Lessons Learnt from the RHIC Dipole Production

RHIC 100 mm Aperture Insertion Dipole: The first magnet gets the body harmonics right

Average Field errors ~10-4 up to 80% of the coil radius

Tuning Shims for 10-5 Field Quality at 2/3 of coil radius

Field Quality Improvements with Tuning Shims (Skew Harmonics)

Ultimate Field Quality in SC Magnets

Field Quality in Common Coil Design

Common Coil Design

Field Quality Optimization in Common Coil Design (Magnet Body- Geometric)

Field Quality Optimization in Common Coil Design (Magnet Body- Yoke Saturation)

Field Quality Optimization in the Common Coil Design (Magnet Ends)

Persistent Current-induced Harmonics (may be a problem in Nb3Sn magnets, if nothing is done)

Persistent Current-induced Harmonics Traditional solution: work on the superconductor

PPT Slide

Summary and Conclusions

Author: Ramesh Gupta

Email: gupta@bnl.gov

Home Page: http://www.bnl.gov/magnets/Staff/Gupta/

Other information:
Presented at the Annual VLHC Meeting at Monterey, CA, June 28-30, 1999. 

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