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Ng, K.Y.

Paper Title Page
MPPP044 Impedance Calculation for Ferrite Inserts 2818
 
  • S.-Y. Lee, S. Breitzmann
    IUCF, Bloomington, Indiana
  • K.Y. Ng
    Fermilab, Batavia, Illinois
  
  Funding: NSF PHY-0244793; DOE DE-FG02-92ER40747.

Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. We study the narrowband longitudinal impedance of these ferrite inserts. We find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. We also provide a receipe for truly passive space charge impedance compensation and, at the same time, avoiding the narrowband microwave instabilities.

 
TPAT018 Stability of Barrier Buckets with Short or Zero Barrier Separations 1589
 
  • K.Y. Ng
    Fermilab, Batavia, Illinois
  
  A barrier bucket with small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and rf phase. Application is made to those barrier buckets used in the process of momentum mining on the issues of bunch-distribution distortion and particle loss.