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Mihalcea, D.

Paper Title Page
TUP103 Analysis of Halo Formation in a DC Photoinjector 645
 
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
 
 

Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
We discovered, by modeling the AES/JLab direct-current photoinjector with several beam-simulation codes, that nominal injector settings would create a large diffuse beam halo as a consequence of the internal space-charge force in the beam. The injector-induced halo is sensitive to the injector settings, but if the settings are judiciously chosen, it can be largely circumvented. We present an exploration of the parameter space for the AES/JLab photoinjector. Measurement of beam halo will be a crucial aspect of commissioning this machine.

 
TUP104 A High-Brightness Low-Energy Photoinjector Option for the Fermilab Electron Accelerator Facility 648
 
  • P. Piot, D. Mihalcea
    Northern Illinois University, DeKalb, Illinois
  • M. Church, S. Nagaitsev, Y.-E. Sun
    Fermilab, Batavia
  • I.V. Pogorelov
    LBNL, Berkeley, California
 
 

Funding: Work supported by Fermi Research Alliance LLC. Under DE-AC02- 07CH11359 with the U.S. DOE and by the Department of Education under contract P116Z010035 with Northern Illinois University
Fermilab is currently constructing a GeV-scale electron accelerator test facility. The accelerator will serve as a backbone for several Fermilab R&D programs, e.g., to test subsystem associated to project-X, ILC and the muon collider program. It is also anticipated that this facility will support beam physics and accelerator R&D programs such as testing of novel acceleration techniques, beam diagnostics and radiation sources concepts. In this paper we describe a possible option for the electron injector based on a photoemission rf gun. Optimization and performance studies of this ~50 MeV photoinjector are performed with various tracking programs (Astra, GPT, Impact-T, Impact-Z). We explore the performances of the magnetic bunch compressor which is extremely challenging at 50 MeV due to strong phase space dilution via collective effects (space charge and coherent synchrotron radiation). We also investigate the generation of flat beams with very high transverse emittance ratio using a round-to-flat beam transformer.

 
TUP105 Simulation of the Upgraded Photoinjector for the 10 kW JLAB IR-FEL 649
 
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
  • C. Hernandez-Garcia, S. Zhang
    JLAB, Newport News, Virginia
 
 

Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
The photoinjector of the JLab 10 kW IR FEL was recently upgraded: a new photocathode drive laser was commissioned and the booster section was replaced with 7-cell cavities. In this paper we present numerical simulation and optimization of the photoinjector perform with ASTRA, IMPACT-T and IMPACT-Z beam dynamics codes. We perform these calculations for two operating voltage of the dc gun: the nominal 350 keV and the planned 500 keV operating points.

 
TUP106 Simulation of Field-Emission Cathodes for High Current Electron Injectors 652
 
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
 
 

Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
From the prospect of the high average current electron injectors, the most important advantage of the field-emission cathodes is their capability to generate very large current densities. Simulation of field-emission cathodes is complicated by the large range of spatial dimensions: from sub-micron scale, for a single field-emission tip, to millimeter scale, for a field-emitter array. To overcome this simulation challenge our numerical model is split in two steps. In the first step, only electrons emitted by a single tip are considered. In the second step, the beams originating from many single emitting tips are merged together to mimic the field-emitter array configuration. We present simulation results of injector based on field array emitters cathodes.

 
TUP107 Longitudinal Beam Diagnostics for the ILC Injectors and Bunch Compressors 655
 
  • P. Piot
    Fermilab, Batavia
  • A. Bracke, T.J. Maxwell, D. Mihalcea, M.M. Rihaoui
    Northern Illinois University, DeKalb, Illinois
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio
  • J.G. Power
    ANL, Argonne
 
 

Funding: Work supported by US. Department of Energy, under Contract No. DE-FG02-06ER41435 with Northern Illinois University.
We present a diagnostics suite and analyze techniques for setting up the longitudinal beam dynamics in ILC electron injectors and bunch compressors. Techniques to measure first order moment and recover the first order longitudinal transfer map of the injector intricate bunching scheme are presented. Coherent transition radiation diagnotics needed to measure and monitor the bunch length downstream of the ~5 GeV bunch compressor are investigated using a vector diffraction model. We finally introduce a new diagnostics capable of measuring time-transverse correlation along a single bunch. Such a diagnostics should be valuable for controlling emittance dilution via transverse wakefield and for properly setting the crab cavities needed for maximizing luminosity for non-zero crossing angle at the interaction point.