CERN Accelerating science

Article
Title	Simulations of Laser Pulse Coupling and Transmission Efficiency in Plasma Channels
Author(s)	Giacone, Rodolfo ; Bruhwiler, David L ; Cary, John R ; Dimitrov, Dimitre ; Esarey, Eric ; Geddes, Cameron G R ; Leemans, Wim ; Messmer, Peter
Affiliation	(LBNL, Berkeley) ; (Tech-X, Boulder, Colorado)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.2179
Subject category	Accelerators and Storage Rings
Abstract	Optical guiding of the laser pulse in a laser wakefield accelerator (LWFA) via plasma channels can greatly increase the interaction length and, hence, the maximun energy of trapped electrons.* Energy efficient coupling of laser pulses from vacuum into plasma channels is very important for optimal LWFA performance. We present 2D particle-in-cell simulations of this problem using the VORPAL code.** Some of the mechanisms considered are enhanced leakage of laser energy transversely through the channel walls, enhanced refraction due to tunneling ionization of neutral gas on the periphery of the gas jet, ionization of neutral gas by transverse wings of the laser pulse and effect of the pulse being off axis of the channel. Using power spectral diagnostics,*** we are able to differentiate between pump depletion and leakage from the channel. The results from our simulations show that for short (&#8776;&#0955;<sub><font size="-1">p