Author: Shin, Y.-M.
Paper Title Page
TUPPC045 Modeling Investigation on a Deflecting-Accelerating Composite RF-cavity System for Phase Space Beam Control 1266
 
  • Y.-M. Shin, M.D. Church, P. Piot
    Fermilab, Batavia, USA
 
  Phase space manipulations between the longitudinal and transverse degree of freedoms hold great promise toward the precise control of electron beams. Such transverse-to-longitudinal phase space exchange have been shown to be capable of exchanging the transverse and horizontal emittance or controlling the charge distribution of an electron bunch, for beam-driven advanced accelerator methods. The main limitation impinging on the performance of this exchange mechanism stems from the external coupling nature of a realistic deflecting cavity, compared to a thin-lens model. As an extended idea from *, this paper presents the design of a composite 3.9-GHz RF-system consisting of a deflecting- and accelerating-mode cavities. The system design analysis is discussed with particle-in-cell (PIC) simulations of the device performance.
* A. Zholents, PAC'11.
 
 
WEPPP026 Dielectric-plate-implanted Higher Order Mode (HOM) Waveguide for High Intensity Multi-beam Device Application 2781
 
  • Y.-M. Shin
    Fermilab, Batavia, USA
 
  A mode-selective oversized RF-beam channel has been investigated for high intensity multi-beam devices. Implanting the equi-spaced dielectric plates at the transverse positions where longitudinal electric fields of a HOM are minimal in the micro-metallic structure strongly suppresses all lower energy modes and other wakefield modes. The dielectric lattice captures only a single HOM of the wavelengths that correspond to the plate spacing. Electromagnetic simulations have shown that the lower energy modes, TE10 and TE20 modes, are suppressed down to < ~ -60 dB by two plate loads, while TE310-mode prominently propagates through the 2 mm long waveguide only with –4 dB (= -2dB/mm) at 1 THz. The numerical calculation indicated that the TE30 mode has ~ a few times higher Q than the lower energy modes. The strong single mode selectivity has been extensively looked into with a more highly overmoded structure. Feasibility analysis of the HOM structure for multi-beam device application is under investigation. Particle-in-cell (PIC) simulation has shown coherent beam bunching and energy gain from THz driving signal.  
 
WEPPP027 PBG-slab Embedded Traveling Wave Structure for Planar Beam Accelerator Application 2784
 
  • Y.-M. Shin
    Fermilab, Batavia, USA
 
  The oversized traveling wave (TE10-mode) channel integrated with the photonic-band-gap (PBG) slab arrays have been investigated for planar beam accelerator application. Simulation analysis showed that the slab arrays allow only the PBG-modes (5-6 GHz) to propagate with ~ 2 dB of insertion loss, corresponding to ~ 1.14 dB/cm attenuation, which thereby effectively suppresses trapped non-PBG modes down to ~ -14.3 dB/cm. It will enable monochromatic propagation of fundamental acceleration modes along the heavily over-moded planar waveguide without anomalous excitation of unstable trapped HOMs. The saturated maximum field gradients of the accelerating structure have been analyzed with respect to operational frequency bands corresponding to structural sizes. The field gradient of the guided PBG-mode has been investigated with finite-integral-method (FIM) simulations at W-band. This mode-filter could be utilized for HOM dampers in high aspect ratio (HAR) planar beam accelerators. An experimental test is currently under consideration.