Experimental observations of transport of picosecond laser generated electrons in a nail-like target

• Published in: Physics of plasmas 2007-12, Vol.14 (12), p.120701-120701-4
• Main Authors: Pasley, J., Wei, M., Shipton, E., Chen, S., Ma, T., Beg, F. N., Alexander, N., Stephens, R., MacPhee, A. G., Hey, D., Le Pape, S., Patel, P., Mackinnon, A., Key, M., Offermann, D., Link, A., Chowdhury, E., Van-Woerkom, L., Freeman, R. R.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CHARGED-PARTICLE TRANSPORT; COPPER; ELECTRONS; EV RANGE; EXTREME ULTRAVIOLET RADIATION; FLUORESCENCE; LASER-PRODUCED PLASMA; LASERS; LAWRENCE LIVERMORE NATIONAL LABORATORY; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PULSES; RELATIVISTIC PLASMA; RELATIVISTIC RANGE; TITANIUM; WIRES
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.2815790

The transport of relativistic electrons, generated by the interaction of a high intensity ( 2 × 10 20 W ∕ cm 2 ) laser, has been studied in a nail-like target comprised of a 20 μ m diameter solid copper wire, coated with ∼ 2 μ m of titanium, with an 80 μ m diameter hemispherical termination. A ∼ 500 fs , ∼ 200 J pulse of 1.053 μ m laser light produced by the Titan Laser at Lawrence Livermore National Laboratory was focused to a ∼ 20 μ m diameter spot centered on the flat face of the hemisphere. K α fluorescence from the Cu and Ti regions was imaged together with extreme ultraviolet (XUV) emission at 68 and 256 eV . Results showed a quasiexponential decline in K α emission along the wire over a distance of a few hundred microns from the laser focus, consistent with bulk Ohmic inhibition of the relativistic electron transport. Weaker K α and XUV emission on a longer scale length showed limb brightening suggesting a transition to enhanced transport at the surface of the wire.