MOA02
UCLA, Los Angeles, California, USA
UCLA, Los Angeles, USA
RadiaSoft LLC, Boulder, Colorado, USA
RadiaBeam, Santa Monica, California, USA
ANL, Argonne, Illinois, USA
RadiaSoft LLC, Boulder, Colorado, USA
RadiaBeam, Santa Monica, California, USA
UCLA, Los Angeles, USA
ANL, Argonne, Illinois, USA
The Linac Extension Area (LEA) is a new beamline planned as an extension of Argonne's APS linac. An S-band 1.6-cell copper photo-cathode (PC) RF gun has been installed and commissioned at the APS linac front end. The PC gun will provide a beam to the LEA for accelerator technology development and beam physics experiments, in interleaving with a thermionic RF gun which provides a beam for APS storage ring operations. Recently an experiment was proposed to demonstrate the TESSA high-efficiency concept at LEA. In support of this experiment, we have begun simulating the photo-injector using the code OPAL (Object-oriented Particle Accelerator Library). In this paper, we first benchmark OPAL simulations with the established APS photo-injector optimization using ASTRA and ELEGANT. Key beam parameters required for a successful high-efficiency TESSA demonstration are discussed.
Arizona State University, Tempe, USA
UCLA, Los Angeles, USA
SLAC, Menlo Park, California, USA
We report on experiments in nanopatterning electron beams from a photoinjector as a first step toward a compact XFEL (CXFEL). The nanopatterning is produced by Bragg diffraction of relativistic electron beams through a patterned Si crystal consisting of alternating thick and thin strips to produce nanometer-scale electron density modulations. Multi-slice simulations show that the target can be oriented for a two-beam condition where nearly 80% of the elastically scattered electron beam is diffracted into the 220 Bragg peak. An experiment at the two-beam condition measurement has been carried out at the SLAC UED facility showing this effect with 2.26 MeV electrons. We successfully proved a large portion of the main beam is diffracted into 220 spot by tuning the orientation of the sample. Future plans at UCLA are to observe the nanopatterned beam, and to investigate various grating periods, crystal thicknesses, and sample orientations to maximize the contrast in the pattern and explore tuning the period of the modulation. The SLAC measurement results will be presented along with design of the UCLA experiments.
FRA03
RadiaBeam, Santa Monica, California, USA
UCLA, Los Angeles, California, USA
Fermilab, Batavia, Illinois, USA
RadiaSoft LLC, Boulder, Colorado, USA
ANL, Argonne, Illinois, USA
Free Electron Lasers have achieved prominence as the X-ray light source technology for research applications, but their industrial potential remains largely unexplored, even though FELs could reach wavelength coverage and powers unattainable by active media sources. In response to this challenge, we developed the TESSA (tapering-enhanced stimulated superradiant amplifier) FEL scheme, which enables as much as 50% single-pass beam-to-light energy-conversion efficiency. With strongly tapered helical undulator and stimulated rapid deceleration, TESSA offers an order-of-magnitude improvement over all existing high-efficiency FEL paradigms and beyond the limit of many conventional lasers. The proof-of-concept was recently demonstrated by UCLA in a pilot experiment at 10-μm wavelength, where 35% deceleration efficiency has been achieved in a 50-cm wiggler. The next steps discussed herein, include: the ongoing development of the TESSA high gain amplifier at UV wavelength; a planned transition to SCRF linac driven TESSA oscillator to reach high average powers; and eventually a development of the EUV TESSA oscillator for industrial applications in the semiconductor industry.
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
UCLA, Los Angeles, USA
Ariel University, Ariel, Israel
In the context of radiation emission from an electron beam, Dicke's superradiance (SR) is the enhanced coherent spontaneous radiation emission from a prebunched beam, and Stimulated-Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave.* These processes are analyzed for undulator radiation in the framework of radiation field mode-excitation theory. In the nonlinear saturation regime the synchronicity of the bunched beam and an injected radiation wave may be sustained by wiggler tapering: Tapering-Enhanced Superradiance (TES) and Tapering-Enhanced Stimulated Superradiance Amplification (TESSA).** Identifying these processes is useful for understanding the enhancement of radiative emission in the tapered wiggler section of seeded FELs.***,**** The nonlinear formulation of the energy transfer dynamics between the radiation wave and the bunched beam fully conserves energy. This includes conservation of energy without radiation reaction terms in the interesting case of spontaneous self-interaction (no input radiation).
* A. Gover, Phys. Rev. ST-AB 8, 030701 (2005).
** J. Duris et al., New J.Phys. 17 063036 (2015).
*** E. A. Schneidmiller et al., PRST-AB 18, 03070 (2015).
**** C. Emma et al., this conference.