Extending plasma accelerators: guiding with capillary tubes |
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Authors: | Cros B Courtois C Malka G Matthieussent G Marques JR Dorchies F Amiranoff F Rebibo S Hamoniaux G Blanchot N Miquel JL |
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Institution: | LPGP UMR CNRS, Univ. de Paris-Sud, Orsay; |
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Abstract: | In order to extend plasma accelerators, the laser beam has to be guided inside gas or plasma over a distance of the order of the dephasing length, which is typically much larger than the diffraction length zR of the laser. A capillary tube can be used as a waveguide for high-intensity laser pulses over distances well in excess of zR. Experimental demonstration of monomode guiding over 100 zR of 1016 W/cm2 pulses has been obtained in evacuated capillary tubes (45-70-μm inner diameter). A drop of transmission has been observed when the intensity of the amplified spontaneous emission (ASE) is high enough to ionize the capillary tube entrance. Propagation in helium gas-filled (10-40 mbar) capillary tubes has been studied at intensities up to 1016 W/cm2; a plasma column with on-axis density of the order of 1017 cm-3 has been created on a length of the order of 4 cm. The use of a capillary tube for an extended accelerator is discussed for the ease of linear, resonant excitation of plasma waves by laser wakefield |
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