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Padmore, H. A.

Paper Title Page
TUPMN109 A High Repetition Rate VUV-Soft X-Ray FEL Concept 1167
 
  • J. N. Corlett, J. M. Byrd, W. M. Fawley, M. Gullans, D. Li, S. M. Lidia, H. A. Padmore, G. Penn, I. V. Pogorelov, J. Qiang, D. Robin, F. Sannibale, J. W. Staples, C. Steier, M. Venturini, S. P. Virostek, W. Wan, R. P. Wells, R. B. Wilcox, J. S. Wurtele, A. Zholents
    LBNL, Berkeley, California
  
  Funding: This work was supported by the Director, Office of Science, High Energy Physics, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, and wavelength; utilization of harmonics to attain shorter wavelengths; and precise synchronization of the x-ray pulse with laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FELs, each producing high average brightness, tunable over the soft x-ray-VUV range, and each with individual performance characteristics determined by the configuration of the FEL SASE, enhanced-SASE (ESASE), seeded, self-seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands. FELs would be tailored to specific experimental needs, including production of ultrafast pulses even into the attosecond domain, and high temporal coherence (i.e. high resolving power) beams.

 
TUPMN116 Numerical Study of Coulomb Scattering Effects on Electron Beam from a Nano-tip 1185
 
  • J. Qiang, J. N. Corlett, S. M. Lidia, H. A. Padmore, W. Wan, A. Zholents, M. S. Zolotorev
    LBNL, Berkeley, California
  • A. Adelmann
    PSI, Villigen
  
  Funding: This work was supported by the U. S. Department of Energy under Contract no. DE-AC02-05CH11231.

Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The Coulomb scattering near the tip can significantly degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emittance growth and energy spread, due to Coulomb scattering, can be significantly enhanced with respect to mean-field space-charge calculations in different parameter regimes.