Author: Kishek, R.A.
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WEA2IO02
 Proposed Experimental Validation of Hamiltonian Perturbation Theory in IOTA  
 
  • D.L. Bruhwiler, N.M. Cook, C.C. Hall, R.A. Kishek, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • S. Nagaitsev, A.L. Romanov, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  The Integrable Optics Test Accelerator (IOTA) is a small ring under construction to explore advanced concepts in beam dynamics, initially with electron pencil beams to emulate single-particle dynamics and later with low-energy proton beams including significant space charge tune depression. Hamiltonian perturbation theory and simulations with Synergia, Warp and other codes are being used to develop an experimental program for beam dynamics, including the highly nonlinear 'elliptic' magnet originally proposed by Danilov and Nagaitsev. The results suggest a number of experiments that could be performed at IOTA. For example, small changes in the linear tune and the strength of the elliptic magnet can be used to control dynamic aperture. Both electron and proton beams can be used to measure the tune spread as a function of the elliptic magnet strength, for comparison with theory. Space charge driven halo formation due to envelope oscillations can be measured over a range of elliptic magnet strengths. Theoretical and computational results will be presented to guide future decisions regarding experimental diagnostics for IOTA.  
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WEA4CO02
 Impact of Space Charge on Beam Dynamics and Integrability in the IOTA Ring  
 
  • C.C. Hall, D.L. Bruhwiler, N.M. Cook, R.A. Kishek, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.L. Romanov, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0011340.
Modern hadron accelerators such as spallation sources and neutrino factories must push the intensity limits to meet increasingly challenging goals. The Integrable Optics Test Accelerator (IOTA) is a small ring, currently under construction at Fermilab, which will explore advanced concepts in beam dynamics with low-energy proton beams with high space charge tune depression. Through use of a special nonlinear magnet insertion, large tune spread with amplitude can be achieved while preserving two integrals of motion for the single particle behavior. The tune shift and spread induced by space charge can disrupt the stability of these invariants. In this work we examine the behavior of these invariants in the presence of space charge. Simulations of a modified IOTA lattice that accounts for the space charge tune depression are shown, and the behavior of the invariants is examined. 		 
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MOPOB53 Simulation of Ping-Pong Multipactor with Continuous Electron Seeding 181
SUPO41   use link to see paper's listing under its alternate paper code  
 
  • M. Siddiqi, R.A. Kishek
    UMD, College Park, Maryland, USA
  
  Funding: National Science Foundation grant No. PHY1535519
Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics *. In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented.
*R.A. Kishek, Physics of Plasmas 20, 056702 (2013). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB53  
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