title: Time-resolved characterization of the formation of a collisionless shock.
abstract: We report on the temporally and spatially resolved detection of the precursory stages that lead to the formation of an unmagnetized, supercritical collisionless shock in a laser-driven laboratory experiment. The measured evolution of the electrostatic potential associated with the shock unveils the transition from a current free double layer into a symmetric shock structure, stabilized by ion reflection at the shock front. Supported by a matching particle-in-cell simulation and theoretical considerations, we suggest that this process is analogous to ion reflection at supercritical collisionless shocks in supernova remnants.
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Ahmed
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: M E
authors.initials: ME
authors.lastname: Dieckmann
authors.affiliation: LULI, École Polytechnique, CNRS, CEA, UPMC, F-91128 Palaiseau, France.
authors.forename: L
authors.initials: L
authors.lastname: Romagnani
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Doria
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Sarri
authors.affiliation: Institute for Laser and Plasma Physics, University of Düsseldorf, D-40225 Düsseldorf, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Cerchez
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom and Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Ianni
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: I
authors.initials: I
authors.lastname: Kourakis
authors.affiliation: Institute for Laser and Plasma Physics, University of Düsseldorf, D-40225 Düsseldorf, Germany.
authors.forename: A L
authors.initials: AL
authors.lastname: Giesecke
authors.affiliation: Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Notley
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Prasad
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: K
authors.initials: K
authors.lastname: Quinn
authors.affiliation: Institute for Laser and Plasma Physics, University of Düsseldorf, D-40225 Düsseldorf, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Willi
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom and Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, 18221 Prague, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Borghesi