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Podobedov, B.

Paper Title Page
TUOCAB01 A New Code for Orbit Response Matrix Analysis 804
 
  • L. Yang, S.-Y. Lee
    IUCF, Bloomington, Indiana
  • X. Huang
    SLAC, Menlo Park, California
  • B. Podobedov
    BNL, Upton, Long Island, New York
 
  Funding: NSF PHY-0552389, DOE DE-FG02-92ER40747

The Orbit Response Matrix (ORM) has been successfully used extensively in accelerator modeling. However, in many cases, the existing codes can not find a correct model. We develop a new code that solve the convergence and coupling problems. We test our code by carrying out systematic study of accelerator models. Effects measurement errors and the completeness of information will be addressed in this study. Possible inclusion of phase information will be discussed.

 
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TUPMS007 NSLS VUV Ring Lifetime Study 1203
 
  • L. Yang, S.-Y. Lee
    IUCF, Bloomington, Indiana
  • S. L. Kramer, B. Podobedov
    BNL, Upton, Long Island, New York
 
  Beam lifetime at VUV ring of National Synchrotron Light Source(NSLS) at BNL is limited by Touschek effect. This effect is affected by momentum acceptance and beam density. The geometry near injection septum, dynamic aperture and the RF acceptance all can limit the over all momentum acceptance. Extensive experiments including coupling, gas scattering, RF acceptance, have been done for understanding the lifetime, and the result is confirmed with theoretical predictions.  
TUPMS074 Collective Effects in the NSLS-II Storage Ring 1344
 
  • S. Krinsky, J. Bengtsson, J. S. Berg, M. Blaskiewicz, A. Blednykh, W. Guo, N. Malitsky, C. Montag, B. Podobedov, J. Rose, N. A. Towne, L.-H. Yu
    BNL, Upton, Long Island, New York
  • F. Wang
    MIT, Middleton, Massachusetts
 
  Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.

A new high-brightness synchrotron light source (NSLS-II) is under design at BNL. The 3-GeV NSLS-II storage ring has a double-bend achromatic lattice with damping wigglers installed in zero-dispersion straights to reduce the emittance below 1nm. In this note, we present an overview of the impact of collective effects upon the performance of the storage ring. Subjects discussed include Touschek lifetime, intra-beam scattering, instability thresholds due to ring impedance, and use of a third-harmonic Landau cavity.

 
TUPMS078 IBS Effects in a Wiggler Dominated Light Source 1353
 
  • B. Podobedov
    BNL, Upton, Long Island, New York
  • L. Yang
    IUCF, Bloomington, Indiana
 
  Intra-beam scattering (IBS) is often thought of as a fundamental limitation to achieving lower emittance and hence higher brightness in modern storage ring light sources. However, as we show in this paper analytically and by simulations using SAD code, this limitation may no longer be relevant in a wiggler dominated 3rd generation light source. Instead, lowering the emittance by increasing the amount of wiggler radiation does not result in significant IBS induced emittance blow-up, as higher beam density (and IBS rates) is compensated by faster radiation damping. We show that under some practical assumptions the relative ratio of the emittance including the IBS effect to the emittance at zero current is emittance independent.  
WEOAC04 Impedance Minimization by Nonlinear Tapering 2006
 
  • B. Podobedov
    BNL, Upton, Long Island, New York
  • I. Zagorodnov
    DESY, Hamburg
 
  There exist analytical approximations that express the transverse geometric impedance of tapered transitions in the inductive regime as a functional of the transition boundary and its derivatives. Assuming the initial and final cross-sections and the transition length are fixed, one can minimize these functionals by appropriate choice of the boundary variation with the longitudinal coordinate. In this paper we numerically investigate how well this works for the cases of optimized tapered transitions in circular, elliptical and rectangular geometry by running ABCI, ECHO, and GDFIDL EM field solvers. We show that a significant reduction of impedance for optimized boundary compared to that of a linear taper is indeed possible in some cases, and then we compare this reduction to analytical predictions.  
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