Author: Tennant, C.
Paper Title Page
TUXAUD03
 ERL Cooling Ring Concepts for the MEIC  
 
  • S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, F. Marhauser, R.A. Rimmer, C. Tennant, H. Wang, H. Zhang, Y. Zhang
    JLab, Newport News, Virginia, USA
  
  Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150
The MEIC design at Jefferson Lab will collide electrons in a storage ring with ions in a separate ring. In order to enhance the luminosity, the ions must be cooled in a cooling channel. The required current and charge necessary to cool the ions is on the order of 200 mA and 420 pC at an electron energy as high as 55 MeV. This is too high for a DC accelerator such as a pelletron and so the electron beam must be provided by an Energy Recovery Linac (ERL). This presentation will discuss two options for such an ERL and show some early results of modeling and simulation for these designs. At least at the highest energy, the beam quality seems to be good enough to provide a reasonable cooling rate for the ions. 		 
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TUPF13
 Microbunching Instability in Recirculation Arcs  
 
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • S.V. Benson, D. Douglas, R. Li, C. Tennant, C.-Y. Tsai
    JLab, Newport News, Virginia, USA
  
  Microbunching instability is one of the most challenging issues in the design of the transport lines for recirculating or energy recovery linac machines. We have developed a linear Vlasov solver to incorporate relevant collective effects, including coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) impedances, for a general linear beamline analysis. With application of this code to two specially designed recirculation arcs * and a circulating cooler ring design of MEIC at Jefferson Lab **, the resultant microbunching gain functions are presented. Some underlying physics with inclusion of these collective effects are discussed. We expect that the analysis can help illustrate the microbunching gain evolution and its spectral response, and further improve the advanced beamline designs.
* D. Douglas et al., http://arxiv.org/abs/1403.2318
** MEIC Design Summary, http://arxiv.org/abs/1504.07961
 
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WEXAUD03
 Space Charge and CSR Microwave Physics in a Circulated Electron Cooler  
 
  • R. Li, S.V. Benson, Y.S. Derbenev, D. Douglas, C. Tennant, Y. Zhang
    JLab, Newport News, Virginia, USA
  • E.W. Nissen
    CERN, Geneva, Switzerland
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  
  Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Circulator cooler ring (CCR) was proposed * as a scheme to alleviate the high demand for the average current of the cooling beam from the electron source. However, transporting the high-brightness cooling beam through CCR for multiple turns, while preserving the phase space quality of the beam, presents significant challenges for the CCR design **. In this presentation, we describe our studies on the microbunching instability (uBI) induced by the CSR and longitudinal space charge interactions, and present results of microwave physics for a non-magnetized beam circulating in an early design of CCR *** of MEIC. It is envisioned that CCR designed for a magnetized beam will have much reduced microbunching effects. A future plan for such study will be discussed.
* R. Brinkmann, et al., Proc. of EPAC98, p345 (1998)
** C. Tennant and D. Douglas, JLAB-TN-12-027 (2012)
*** C. Tsai et al., this workshop (2015)
 
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