Scientific Results

Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions

Year: 2017

Authors: Chatterjee G., Singh P.K., Robinson A.P.L., Blackman D., Booth N., Culfa O., Dance R.J., Gizzi L.A., Gray R.J., Green J.S., Koester P., Kumar G.R., Labate L., Lad A.D., Lancaster K.L., Pasley J., Woolsey N.C., Rajeev P.P.

Autors Affiliation: Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India; Central Laser Facility, STFC Rutherford Appleton Laboratory, Chilton-Didcot, OX110QX, United Kingdom; York Plasma Institute, University of York, Heslington, York, YO105DQ, United Kingdom; 0000000121138138 grid.11984.35 SUPA, Dept. of Physics, University of Strathclyde UK, Glasgow, G4 0NG, United Kingdom; Intense Laser Irradiation Laboratory, INO-CNR, Pisa, Italy; Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee, Hamburg, 22761, Germany

Abstract: The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-┬Ám thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~1020 W/cm2. The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

Journal/Review: SCIENTIFIC REPORTS

Volume: 7 (1)      Pages from: 8347-1  to: 8347-8

More Information: The authors acknowledge the excellent experimental support provided by the Vulcan/Experimental Science staff at CLF. G.R.K. acknowledges financial support from DAE, (Govt. of India) and a J.C. Bose grant (DST, Govt. of India) and G.C. and P.K.S acknowledge support from the \”Strong Field Science\” program (11P-1401) of DAE (Govt. of India) operated by TIFR. EPSRC support for the Fusion Doctoral Training Network is also gratefully acknowledged. P.K., L.L. and L.A.G. acknowledge financial support from MiUR project PRIN-2012AY5LEL. R.J.G. and R.J.D. acknowledge the grant EP/J003832/1. Part of this work was supported by the Newton-Bhabha Funds.
KeyWords: ION-ACCELERATION; PLASMA; PULSE; GENERATION; BEAM
DOI: 10.1038/s41598-017-08619-1

English