Draft:

Present:

James, Riccardo, Dominique, Gunn

Discussion:

1. Presentation Overview:

   • Dominique presented the attached slides, providing an introduction to the HL-LHC BGI project and outlining the magnetic field requirements for the triplet magnet configuration.
   • A table summarizing the B-field harmonic values from the magnetic field calculations was also presented.

2. Magnetic Field Harmonics:

   • It was observed that the third harmonic value is relatively high (approximately 20) for both the new (instrument) magnet and the MDX (trim) magnet. However, due to the opposite signs of the B-fields, these contributions should cancel each other out.
   • Dominique will supply additional calculations to confirm the cancellation of the B3 harmonics.

3. Power Converter Noise and Mitigation:

   • Riccardo highlighted that noise ripple from power converters (measured in ppm) can affect the beam. This issue will be investigated further with the SY-EPC team at power converter level
   • He also suggested that applying a thin copper coating or layer on the instrument’s vacuum chamber could suppress these B-field ripples, offering a more cost-effective alternative to purchasing expensive, high-precision power converters.

4. Action Items:

   • Dominique: Provide further calculations to verify the cancellation of the B3 harmonics, and supply:
     1. The inductance values of the magnets.
     2. Measurements of the stray field affecting the adjacent beam pipe.
   • Gunn: Coordinate with the SY-EPC team to assess the impact of power converter noise ripple on the beam.