Unique X-ray emission characteristics from volumetrically heated nanowire array plasmas
Abstract
Highly anisotropic emission of hard X-ray radiation (h ν >10 keV) is observed when arrays of ordered nanowires (50 nm diameter wires of Au or Ni) are volumetrically heated by normal incidence irradiation with high contrast 50-60 fs laser pulses of relativistic intensity. The annular emission is in contrast with angular distribution of softer X-rays (h ν >1 KeV) from these targets and with the X-ray radiation emitted by polished flat targets, both of which are nearly isotropic. Model computations that make use the electron energy distribution computed by particle-in-cell simulations show that the unexpected annular distribution of the hard x-rays is the result of bremsstrahlung from fast electrons. Volumetric heating of Au nanowire arrays irradiated with an intensity of 2 x 10 19 W cm-2 is measured to convert laser energy into h ν>1KeV photons with a record efficiency of >8 percent into 2 π, creating a bright picosecond X-ray source for applications.
Work supported by the Office of Fusion Energy Science of the U.S Department of Energy, and the Defense Threat Reduction Agency. A.P was supported by DFG project TR18.- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2015
- Bibcode:
- 2015APS..DPPTO4002R