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Transport of energy by ultraintense laser-generated electrons in nail-wire targets

2009; American Institute of Physics; Volume: 16; Issue: 11 Linguagem: Inglês

10.1063/1.3261810

1527-2419

T. Ma, M. H. Key, R. J. Mason, K. U. Akli, R. L. Daskalova, R. R. Freeman, J. S. Green, K. Highbarger, P. A. Jaanimagi, J. A. King, K. L. Lancaster, S. P. Hatchett, A. J. Mackinnon, A. G. MacPhee, P. A. Norreys, P. K. Patel, R. B. Stephens, W. Theobald, L. D. Van Woerkom, M. S. Wei, S. C. Wilks, F. N. Beg,

Fusion materials and technologies

Nail-wire targets (20 μm diameter copper wires with 80 μm hemispherical head) were used to investigate energy transport by relativistic fast electrons generated in intense laser-plasma interactions. The targets were irradiated using the 300 J, 1 ps, and 2×1020 W⋅cm−2 Vulcan laser at the Rutherford Appleton Laboratory. A spherically bent crystal imager, a highly ordered pyrolytic graphite spectrometer, and single photon counting charge-coupled device gave absolute Cu Kα measurements. Results show a concentration of energy deposition in the head and an approximately exponential fall-off along the wire with about 60 μm 1/e decay length due to resistive inhibition. The coupling efficiency to the wire was 3.3±1.7% with an average hot electron temperature of 620±125 keV. Extreme ultraviolet images (68 and 256 eV) indicate additional heating of a thin surface layer of the wire. Modeling using the hybrid E-PLAS code has been compared with the experimental data, showing evidence of resistive heating, magnetic trapping, and surface transport.