LBNL, Berkeley, California
UCB, Berkeley, California
ANL, Argonne
The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a 10‐beamline soft x‐ray FEL array powered by a 2.4 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Beam is distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz, with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds.
BNL, Upton, Long Island, New York
BNL plan to build 5-to-30 GeV energy recovery linac for its future electron-ion collider, eRHIC. In past few months the laboratory turned its attention to FEL potential of this unique machine, which was initially assessed in our early paper [1]. In this talk we present current vision of a possible FEL farm and narrow-band FEL-oscillators driven by this accelerator.
[1] Potential Use of eRHIC's ERL for FELs and Light Sources, V.N. Litvinenko, I. Ben-Zvi, Proceedings of FEL'2004 http://jacow.org/f04/papers/WEBOS04/WEBOS04. PDF
Vanderbilt University, Nashville, TN
We report recent advances in the development of electron sources of extreme brightness approaching the quantum degenerate limit. These cathodes comprise either a diamond field emitter or carbon nanotube and an individual adsorbed atom or molecule. Both emitters are covalent carbon structures and thus have the benefits of high activation energy for atomic migration, chemical inertness, and high thermal conductivity. The single adsorbate produces surface states which result in dramatic resonant enhancement of the field emission current at the allowed energies of those states. The result is a beam with a narrow energy spread that is spatially localized to roughly the size of a single atom. Thus far, we have observed short lived (~1 sec) beams from residual gases of ~6 microamps corresponding to a normalized transverse brightness of ~3·1018 A/m2-str. Whereas conventional field emitters have a quantum degeneracy of <10-4, we estimate the degeneracy of our observed beams to be ~0.1. The use of metal adsorbates should stabilize the effect, allow higher current operation, and provide a long lived source whose brightness approaches the quantum limit.
SLAC, Menlo Park, California
This talk is about the experience gained in commissioning the X-Ray diagnostics at the LCLS over the past year. Though the designs of the diagnostics are based largely on technology from synchrotron light sources, the high intensity and high brightness of LCLS X-Ray beam are well outside of the range of parameters for synchrotron light sources, so the diagnostics must perform in essentially new territory. It turned out that some capabilities of the diagnostics were not utilized because the FEL beam was so strong right from the beginning. On the other hand, in some cases the diagnostics were used to perform novel measurements that were not envisioned in the original design. The talk will cover each of the diagnostics systems, how it performed, and what it told us about the FEL beam.
ANL, Argonne
European XFEL GmbH, Hamburg
Free-electron lasers for hard x-rays can be constructed in oscillator (XFELO) configuration, providing ultra-high spectral purity and brightness [1]. The average brightness is expected to be several orders of magnitude higher than, and peak brightness comparable to that of SASE XFELs. XFELOs can enable revolutionary scientific opportunities as well as drastically improve experimental techniques developed at third-generation x-ray facilities. Low-loss x-ray crystal cavity and ultra-low-emittance electron beams are two major technical challenges in the realization of XFELOs. The requirements to x-ray cavity components are demanding: diamond crystals and curved grazing incidence mirrors must have near-perfect reflectivity, negligible wave-front distortions, and are subject to very tight tolerances on angular, spatial, and thermal stability under high heat load of the XFELO radiation. This paper gives an overview on the recent progress [2-4] and future plans in the R&D on the feasibility of x-ray cavities for XFELOs. The experimental and simulation studies results provide strong evidence for the feasibility of the x-ray cavities.
1. K-J. Kim, et al, PRL 100 (2008) 244802
2. Yu. Shvyd'ko, et al, Nature Phys. 6 (2010) 196
3. S. Stoupin, Yu. Shvyd'ko, PRL 104 (2010) 085901
4. S. Stoupin et al, Rev. Sci. Instr. 81 (2010) 055108