EPS 2019

I1.201 Relativistic nanophotonics: creating extreme plasma conditions from nanostructures with ultrafast lasers

8 Jul 2019, 16:30

30m

Aula U6-06, Building U6 (University of Milano-Bicocca UNIMIB)

BPIF BPIF

Speaker

J.J. Rocca (EPS 2019)

Description

See the full abstract here:
http://ocs.ciemat.es/EPS2019ABS/pdf/I1.201.pdf

The trapping of femtosecond laser pulses of relativistic intensity deep within ordered nanowire arrays can volumetrically heat dense matter into a new ultra-hot plasma regime [1]. Electron densities more than 100 times greater than the critical density with multi-keV temperatures are achieved using ultrashort laser pulses of only one Joule energy. Extraordinarily high degrees of ionization (e.g. 52 times ionized Au) are observed with gigabar pressures only exceeded in the laboratory in the central hot-spot of highly compressed thermonuclear fusion plasmas. The fundamental physics of relativistic laser pulse interactions with nanostructures and their promising applications will be reviewed. The large electron density, which shortens the radiative lifetime\combined with the large plasma volume that increases the hydrodynamic cooling time allow for greatly increased conversion into x-rays. Recent experiments in which gold nanowire arrays were heated by ultra-high contrast pulses at intensities of ~ 4 x 10^19 W cm^-2 produced record 20 percent conversion efficiency into picosecond x-ray pulses [2]. In a different set of experiments the acceleration of deuterons from a dense deuterated nanowire array to MeV energies resulted in a record number of monochromatic fusion neutrons per Joule for a compact laser. The neutron production was 500 times larger than that obtained irradiating flat solid targets of the same material (CD2) with the same laser pulses [3]. Results of the first experiments conducted at an increased intensity of ~ 5 x 10^21 W cm^-2 with ultra-high contrast pulses from a frequency-doubled petawatt-class laser will be presented and compared with 3-D relativistic particle-in-cell simulations.
Work supported by the U.S. Department of Energy, Fusion Science program of the Office of Science and by the Air Force Office of Scientific Research.

1. M.A. Purvis, et al., "Relativistic plasma nano-photonics for ultra-high energy density physics," Nature Photonics 7, 796, (2013).
2. R. Hollinger et al., "Efficient picosecond x-ray pulse generation from plasmas in the radiation dominated regime". Optica. 4, 1344, (2017).
3. A. Curtis, et al. , "Micro-scale fusion in dense relativistic nanowire array plasmas". Nature Communications. 9, 1077, (2018).