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Ng, K. Y.

Paper Title Page
MOPAS011 Uniform Longitudinal Beam Profiles in the Fermilab Recycler Using Adaptive RF Correction 458
 
  • M. Hu, D. R. Broemmelsiek, B. Chase, J. L. Crisp, N. E. Eddy, P. W. Joireman, K. Y. Ng
    Fermilab, Batavia, Illinois
  
  Non-uniformity in longitudinal beam profiles due to potential well distortion have been observed in the Fermilab Recycler Ring. The main source of distortion, the analysis, and the experimental verification of a solution are presented. An adaptive algorithm has been developed to remove the distortion. This algorithm has been implemented in a custom FPGA-based module, which has been integrated into the current Low Level RF system.  
TUZAAB03 Emittance Measurement and Modeling for the Fermilab Booster 799
 
  • X. Huang
    SLAC, Menlo Park, California
  • S.-Y. Lee
    IUCF, Bloomington, Indiana
  • K. Y. Ng
    Fermilab, Batavia, Illinois
  
  Funding: DOE/NSF

We systematically measured the emittance evolution of a fast cycling proton accelerator on a turn-by-turn basis under various beam intensities via an ionization profile monitor (IPM). The vertical emittance growth rate was derived and phenomenologically analyzed. The transverse and longitudinal components in the horizontal beam size were separated by making use of their different evolution behaviors. The quadrupole mode beam size oscillation after transition crossing is also studied and explained. We found a considerable space-charge-induced emittance growth rate component in the vertical plane but not as much for the horizontal plane. We carried out multiparticle simulations to understand the mechanism of space-charge-induced emittance growth. The major sources of emittance growth were found to be the random skew-quadrupole and dipole field errors in the presence of large space-charge tune spread.

PRSTAB 9, 014202 (2006)

 
slides icon Slides  
TUPAS014 Fast Beam Stacking using RF Barriers 1682
 
  • W. Chou, D. Capista, E. Griffin, K. Y. Ng, D. Wildman
    Fermilab, Batavia, Illinois
  
  Funding: Work supported by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Dept. of Energy.

Two barrier rf systems were fabricated, tested and installed in the Fermilab Main Injector.* Each can provide 8-10 kV rectangular pulses (the rf barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector (MI), which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology.

* W. Chou, D. Wildman and A. Takagi, "Induction Barrier RF and Applications in Main Injector," Fermilab-Conf-06-227 (2006).

 
THPAN099 Direct Space-Charge Calculation in Elegant and Its Application to the ILC Damping Ring 3456
 
  • A. Xiao, M. Borland, L. Emery, Y. Wang
    ANL, Argonne, Illinois
  • K. Y. Ng
    Fermilab, Batavia, Illinois
  
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

A direct space-charge force model has been implemented in the tracking code elegant. The user can simulate transverse space-charge effects by inserting space-charge elements in the beamline at any desired position. Application to the International Linear Collider damping ring is presented in this paper. We simulated beam under equilibrium conditions, as well as the entire damping cycle from injection to extraction. Results show that beam halo is generated due to space charge effects. This would be a significant concern for the ILC damping ring and a detailed follow-up study is needed.

 
THPAN117 Electron Cloud Studies at Tevatron and Main Injector 3501
 
  • X. Zhang, A. Z. Chen, W. Chou, B. M. Hanna, K. Y. Ng, J.-F. Ostiguy, L. Valerio, R. M. Zwaska
    Fermilab, Batavia, Illinois
  
  Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000

Estimates indicate that the electron cloud effect could be a limiting factor for Main Injector intensity upgrades, with or without a the presence of a new 8 GeV superconducting 8GeV Linac injector. The effect may turn out to be an issue of operational relevance for other parts of the Fermilab accelerator complex as well. To improve our understanding of the situation, two sections of specially made vacuum test pipe outfitted for electron cloud detection with ANL provided Retarding Field Analyzers (RFAs), were installed in the Tevatron and the Main Injector. In this report we present some measurements, compare them with simulations and discuss future plans for studies.

 
FRPMS010 Electron Cloud in the Fermilab Booster 3895
 
  • K. Y. Ng
    Fermilab, Batavia, Illinois
  
  Simulations reveal a substantial build up of electron cloud in the Fermilab Booster ramping cycle, both inside the unshielded combined-function magnets and the beam pipes joining the magnets. The neutralization can be appreciable depending on the second-emission yield of the magnet pole faces and the beam pipe surfaces. The implication of the electron-cloud effects on the beam emittances and collective instabilities is discussed.