Title :
Plasma channels for multi-GeV laser-plasma accelerators using discharges in structured gas cells
Author :
Lopes, N.C. ; Russo, C. ; Bendoyro, R.A. ; Hilbert, M. ; Jiang, J. ; Clayton, C.E. ; Fang, F.
Author_Institution :
Grupo de Lasers e Plasmas, Inst. de Plasmas e Fusao Nucl., Lisbon, Portugal
Abstract :
Summary form only given. Laser-plasma accelerators use intense laser pulses to produce relativistic plasma density structures that can trap and accelerate electron bunches. The energy gain can be strongly enhanced by extending the acceleration length, where the laser stays focused to high intensity, to a distance much longer than the Rayleigh length. This can be achieved by propagating the laser in a preformed and fully-ionized cylindrical plasma with a parabolic density profile acting as a "graded-index optical plasma fiber". In this work we present a method to produce plasma channels adequate for compact multi-GeV electron acceleration. It uses a high-voltage and high-current discharge between two hollow conical electrodes, through a structured gas cell. This fast discharge produces a plasma line that evolves to a plasma channel by free radial expansion of the plasma inside the gas cell. We also present new experimental results demonstrating a significant improvement of the plasma smoothness and reproducibility over the previous work, by using a low-current simmer discharge to partially pre- ionize the interaction zone. The plasma channels are 2 cm long but this length may be extended to about 10 cm by increasing the length of the plasma cell. The plasma can be made of low Z gases (H2 or He) so full ionization can be achieved to avoid ionization induced defocusing of the intense laser pulses. Plasma channels with axial electron densities in the range 1 - 5times1017 cm-3 can be produced making this a potential target for multi-GeV accelerators with current technology high-power lasers.
Keywords :
electron accelerators; electron density; linear accelerators; plasma accelerators; plasma density; plasma electromagnetic wave propagation; acceleration length; axial electron density; electron bunch acceleration; electron bunch trapping; free plasma radial expansion; fully ionized cylindrical plasma; graded index optical plasma fiber; high voltage high current discharge; hollow conical electrodes; intense laser pulses; interaction zone preionisation; low Z gases; low current simmer discharge; multiGeV electron acceleration; multiGeV laser plasma accelerators; parabolic plasma density profile; plasma channels; plasma line; relativistic plasma density structures; structured gas cell discharges; Acceleration; Electron accelerators; Electron traps; Fiber lasers; Gas lasers; Ionization; Optical propagation; Optical pulses; Plasma accelerators; Plasma density;
Conference_Titel :
Plasma Science - Abstracts, 2009. ICOPS 2009. IEEE International Conference on
Conference_Location :
San Diego, CA
Print_ISBN :
978-1-4244-2617-1
DOI :
10.1109/PLASMA.2009.5227317