UCLA, Los Angeles, USA
LBNL, Berkeley, California, USA
LANL, Los Alamos, New Mexico, USA
The HiRES beamline at Lawrence Berkeley National Laboratory (USA) is a state-of-the-art compact accelerator providing ultrafast relativistic electron pulses at MHz repetition rates, for applications in ultrafast science and for particle accelerator science and technology R&D. Using HiRES as testbed, we seek to apply recent developments in machine learning and computational techniques for machine-learning-based adaptive control, and eventually, a full control system based on global feedback. The ultimate goal is to demonstrate the benefits of such a suite of controls to UED, including increased temporal and spatial resolution. Concrete steps toward these goals are presented, including automatic, model-independent tuning for accelerators, and energy virtual diagnostics with direct application to improving UED temporal resolution.
… [continued from below] by the DOE Office of Science, Office of High Energy Physics under contract number 89233218CNA000001 and DE-AC02-05CH11231 and by the NSF under Grant No. PHY-1549132.
UCLA, Los Angeles, USA
RadiaBeam, Marina del Rey, California, USA
Free electron lasers are an attractive option for high average and peak power radiation in the THz gap, a region of the electromagnetic spectrum where radiation sources are scarce, as the required beam and undulator parameters are readily achievable with current technology. However, slippage effects require the FEL to be driven with relatively long and low current electron bunches, limiting amplification gain and output power. Previous work demonstrated that a waveguide could be used to match the radiation and e-beam velocities in a meter-long strongly-tapered helical undulator, resulting in 10\% energy extraction from an ultrashort 200 pC, 5.5 MeV electron beam. We present simulations for a follow-up experiment targeting higher frequencies with improvements to the e-beam transport including a permanent magnet chicane for strong beam compression. FEL simulations show >20\% extraction efficiency from a 125 pC, 7.4 MeV electron beam at 0.32 THz.
UCLA, Los Angeles, USA
RadiaBeam, Santa Monica, California, USA
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
Fermilab, Batavia, Illinois, USA
RadiaSoft LLC, Boulder, Colorado, USA
ANL, Lemont, Illinois, USA
In this paper we’ll describe the FAST-GREENS experimental program where a 4 m-long strongly tapered helical undulator with a seeded prebuncher is used in the high gain TESSA regime to convert a significant fraction (up to 10 %) of energy from the 240 MeV electron beam from the FAST linac to coherent 515 nm radiation. We’ll also discuss the longer term plans for the setup where by embedding the undulator in an optical cavity matched with the high repetition rate from the superconducting accelerator (3,9 MHz), a very high average power laser source can be obtained. Eventually, the laser pulses can be redirected onto the relativistic electrons to generate by inverse compton scattering a very high flux of circularly polarized gamma rays for polarized positron production.
UCLA, Los Angeles, USA
We present progress and an experimental plan for multi-MeV relativistic energy gain in a dielectric laser-driven accelerator (DLA). Using a 780 nm, 100 fs pulse-front-tilted laser, we achieve interaction with 6 MeV electrons over a 4 mm long structure with 800 nm period. To compensate for resonant defocusing effects, the laser pulse is imprinted with a phase mask, applied by a Spatial Light Modulator, which uses alternating phase focusing (APF) to achieve stable beam transport. The DLA is mechanically mounted with a variable sized gap (600-1200 nm) in order to maximize transmission while maintaining high gradient within the channel. The combination of high interaction length and use of APF confines and accelerates the electrons by up to 3.5 MeV.
UCLA, Los Angeles, USA