arXiv subjects

G. Andonian

Publications and source records attributed to G. Andonian.

22 records · Page 2Linked to original sources

arXiv2017

Experimental characterization of electron beam driven wakefield modes in a dielectric woodpile Cartesian symmetric structure

The use of photonic structures in the terahertz (THz) spectral region may enable the essential characteristics of confinement, modal control, and electric field shielding for very high gradient accelerators based on wakefields in dielectrics. We report here an experimental investigation of THz wakefield modes in a 3D photonic woodpile structure. Selective control in exciting or suppressing of wakefield modes with non-zero transverse wave vector is demonstrated by using drive beams of varying transverse ellipticity. Additionally, we show that the wakefield spectrum is insensitive to the offset position of the strongly elliptical beam. These results are consistent with analytic theory and 3D simulations, and illustrate a key advantage of wakefield systems with Cartesian symmetry, the suppression of transverse wakes by elliptical beams.

physics.acc-ph↗

arXiv2014

Tunable Electron Multibunch Production in Plasma Wakefield Accelerators

Synchronized, independently tunable and focused $μ$J-class laser pulses are used to release multiple electron populations via photo-ionization inside an electron-beam driven plasma wave. By varying the laser foci in the laboratory frame and the position of the underdense photocathodes in the co-moving frame, the delays between the produced bunches and their energies are adjusted. The resulting multibunches have ultra-high quality and brightness, allowing for hitherto impossible bunch configurations such as spatially overlapping bunch populations with strictly separated energies, which opens up a new regime for light sources such as free-electron-lasers.

physics.plasm-ph↗

arXiv2010

Transverse Beam Size Effects on Longitudinal Profile Reconstruction

The use of coherent transition radiation autocorrelation methods to determine bunch length and profile information is examined with the compressed electron beam at the BNL ATF. A bi-gaussian fit is applied to coherent transition radiation auto-correlation data to extract the longitudinal current distribution. The effects of large transverse beam sizes are studied in theory and compared to experimental results. A suitable form of the correction factor is derived for beams with large transverse-longitudinal aspect ratios.

physics.acc-ph↗

arXiv2010

Teravolt-per-meter plasma wakefields from low-charge, femtosecond electron beams

Recent initiatives in ultra-short, GeV electron beam generation have focused on achieving sub-fs pulses for driving X-ray free-electron lasers (FELs) in single-spike mode. This scheme employs very low charge beams, which may allow existing FEL injectors to produce few-100 as pulses, with high brightness. Towards this end, recent experiments at SLAC have produced ~2 fs rms, low transverse emittance, 20 pC electron pulses. Here we examine use of such pulses to excite plasma wakefields exceeding 1 TV/m. We present a focusing scheme capable of producing ~200 nm beam sizes, where the surface Coulomb fields are also ~TV/m. These conditions access a new regime for high field atomic physics, allowing frontier experiments, including sub-fs plasma formation for wake excitation.

physics.plasm-ph↗