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Gao, F.

Paper Title Page
WEPMS086 Design of a 26 GHz Wakefield Power Extractor 2535
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • W. Gai, F. Gao, R. Konecny
    ANL, Argonne, Illinois
  • S. Kazakov
    KEK, Ibaraki
  High frequency, high output power, and high efficiency RF sources have compelling applications in accelerators for high energy physics. The 26 GHz RF power extractor proposed in this paper provides a practical approach for generating high power RF in this particular frequency range. The extractor is designed to couple out RF power generated from the high charge electron bunch train at the Argonne Wakefield Accelerator (AWA) facility traversing dielectric loaded or corrugated waveguides. In this paper we evaluate two different techniques for extracting the beam energy at the AWA: one is based on a completely metallic corrugated waveguide and coupler; and the other is based on a dielectric lined circular waveguide and coupler. Designs for both RF power extractors will be presented including parameter optimization, the electromagnetic modeling of structures and RF couplers, and the analysis of beam dynamics.  
THPMN088 C-Band High Power RF Generation and Extraction Using a Dielectric Loaded Waveguide 2912
  • F. Gao, M. E. Conde, W. Gai, R. Konecny, W. Liu, J. G. Power, Z. M. Yusof
    ANL, Argonne, Illinois
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio
  • T. Wong
    Illinois Institute of Technology, Chicago, Illinois
  Funding: Department of Energy

We report on the fabrication, simulation, and high-power testing of a C-band RF power extractor recently conducted at the Argonne Wakefield Accelerator (AWA) facility. Dielectric loaded accelerating (DLA) structures can be used for high-power RF generation [*,**] when a high-current electron beam passes through a DLA structure and loses energy into the modes of the structure due to self-wakefields. The AWA generates high charge (up to 100nC), short bunch length (1.5mm~2.5mm) electron beams, which is ideal for high-power RF generation. The generated RF power can be subsequently extracted with a properly designed extraction coupler in order to accelerate a second beam, or for other high power purposes. In this paper, the detailed design of a 7.8 GHz DLA power extractor, MAFIA simulations, and results of the high-power test are presented. Simulation predictions of an 79 MW, 2.2 ns long RF pulse (generated by a single 100 nC electron bunch) and a longer RF pulse of the same power (obtained from a 35 nC periodic bunch train) will be compared to experimental results.

* W. Gai, et al, Experimental Demonstration of Two Beam Acceleration Using Dielectric Step-up Transformer, PAC01, pp.1880-1882.** D. Yu, et al, 21GHz Ceramic RF Power Extractor, AAC02, pp.484-505.

FRPMN117 Pepper-pot Based Emittance Measurements of the AWA Photoinjector 4393
  • J. G. Power, M. E. Conde, W. Gai, F. Gao, R. Konecny, W. Liu, Z. M. Yusof
    ANL, Argonne, Illinois
  • P. Piot, M. M. Rihaoui
    Northern Illinois University, DeKalb, Illinois
  The Argonne Wakefield Accelerator (AWA) RF photocathode gun is a 1.5 cell, L-band, RF photocathode gun operating at 80 MV/m, with an emittance compensating solenoid, and a magnesium photocathode and generates an 8 MeV, 1 nC - 100 nC beam. In this paper, we report on a parametric set of measurements to characterize the transverse trace space of the 1 nC electron beam directly out of the gun. The entire experiment is simulated with PARMELA, from the photocathode, through the pepper pot, and to the imaging screen. The transverse trace-space is sampled with a 2-D pepper pot which allows for simultaneous, single-shot measurements, of both the x and y distributions. A series of pepper pots were available during the experiment to increase the dynamic range of emittance measurements. Realistic particle distributions are used for the simulations and are derived from actual laser profiles, which were captured from a virtual cathode and generated with MATLAB-based particle generator. We report both the second moment (emittance) and the detailed phase space distribution over a gun launch phase range of approximately 50 degrees.