React

1
React Wind Results Summary and Common Coil
Status

• A. Zlobin
• Outline
• RW program goal
• Test result summary
• Lessons learned
• Common coil status
• Next steps

2
RW Program Goals

• The goal was to test and optimize
• Magnet components cable, insulation
• RW technology cable reaction, cable insulating,
  winding and impregnation procedures,
  instrumentation, coil prestress
• In order to reach the best possible results and
  understand the limitations of Nb3Sn conductor and
  RW technology

3
Test Result Summary

• We have tested three racetracks, HFDB01, 02 and
  03, based on the react and wind technique
• First racetrack demonstrated poor quench
  performance due to conductor instabilities
• In the last two racetracks
• We reached 75-78 of predicted short sample limit
  
• Results are quite similar and reproducible
• It is not bad, but certainly is not enough to
  consider the problem solved and recommend RW
  technology for real magnets

4
What Did We Learn?

• We learned that
• Present Nb3Sn strands are unstable, they show
  significant Ic degradation at low fields
• The cable used for react wind technique may
  have additional stability problems due to high Ra
• Racetrack mechanical structure is not perfect and
  may be a cause of Ic degradation
• Two of these effects do not allow us to address
  our major questions
• What is the level of Ic degradation of reacted
  cable in a magnet?
• What is the reproducibility of this technology?

5
What to Do Next?

• We need to
• Study and improve the strand stability with
  Conductor Development Group and industry
• Study and improve the stability of cable for RW
  technology, optimizing Ra
• Improve our test tool racetrack, or develop
  another way of testing cable degradation in a
  real coil fabrication process
• Only after resolving these problems could we
  return to our main question what are the
  possibilities and limitations of RW technology
  for Nb3Sn magnets

6
How to Proceed?

• Strand testing and stability calculations
• Cable testing using well developed robust
  techniques ? LBNL-type racetrack coils
• ? Some results and plans for this will be
  presented by Emanuela
• Optimize the racetrack design
• ? Giorgio has presented a plan to do this

7
Common Coil Model Status

• The first short model has been fabricated and is
  ready for tests
• Tests are planned for June-July 2003, after
  finishing the tests of the present racetrack and
  mirror magnet
• Details of the design and fabrication procedure
  for the common coil model will be presented
  during the tour by Igor Novitski

8
What Do We Learn From CC Tests?

• The common coil model use the same or similar
  components and procedures as the racetracks
• Strand the same
• Cable 59 vs. 41 strand (similar)
• Insulation the same
• Coil winding and impregnation procedures the
  same
• Mechanical structure is more robust in the common
  coil design

9
What Do We Learn From CC Tests?

• If the limiting factor is the racetrack
  mechanics, we will see some improvements in the
  common coil model
• This would advance us in understanding the
  limitations of RW technology
• If the limiting factor is conductor stability we
  should expect similar results
• This would confirm the importance of the
  stability problem for this technology. In
  addition we will be able to study field quality
  including the coil magnetization effect, quench
  protection issues, collar mechanics, etc

10
Next Step

• Based on the test results of this common coil
  model we will decide
• Whether
• We will continue studying this design in
  parallel with conductor development
• Or
• We will focus on the conductor development issue
  and resume magnet tests after success in that
  area is achieved