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Title: Theoretical and numerical analyses of a slit-masked chicane for modulated bunch generation

Density modulations on electron beams can improve machine performance of beam-driven accelerators and FELs with resonance beam-wave coupling. The beam modulation is studied with a masked chicane by the analytic model and simulations with the beam parameters of the Fermilab Accelerator Science and Technology (FAST) facility. With the chicane design parameters (bending angle of 18o, bending radius of 0.95 m and R56 ~ –0.19 m) and a nominal beam of 3 ps bunch length, the analytic model showed that a slit-mask with slit period 900 μ m and aperture width 300 μ m induces a modulation of bunch-to-bunch spacing ~ 100 μ m to the bunch with 2.4% correlated energy spread. With the designed slit mask and a 3 ps bunch, particle-in-cell (PIC) simulations, including nonlinear energy distributions, space charge force, and coherent synchrotron radiation (CSR) effect, also result in beam modulation with bunch-to-bunch distance around 100 μ m and a corresponding modulation frequency of 3 THz. The beam modulation has been extensively examined with three different beam conditions, 2.25 ps (0.25 nC), 3.25 ps (1 nC), and 4.75 ps (3.2 nC), by tracking code Elegant. The simulation analysis indicates that the sliced beam by the slit-mask with 3 ~more » 6% correlated energy spread has modulation lengths about 187 μ m (0.25 nC), 270 μ m (1 nC) and 325 μ m (3.2 nC). As a result, the theoretical and numerical data proved the capability of the designed masked chicane in producing modulated bunch train with micro-bunch length around 100 fs.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. Northern Illinois Univ., DeKalb, IL (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. (FNAL), Batavia, IL (United States)
Publication Date:
OSTI Identifier:
1234898
Report Number(s):
FERMILAB-PUB--15-454-APC
Journal ID: ISSN 1748-0221; arXiv eprint number arXiv:1511.02172
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Journal of Instrumentation
Additional Journal Information:
Journal Volume: 10; Journal Issue: 10; Journal ID: ISSN 1748-0221
Publisher:
Institute of Physics (IOP)
Research Org:
Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY accelerator modelling and simulations (multi-particle dynamics; single-particle dynamics); beam dynamics; instrumentation for FEL; beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors)