title: Weibel-induced filamentation during an ultrafast laser-driven plasma expansion.
abstract: The development of current instabilities behind the front of a cylindrically expanding plasma has been investigated experimentally via proton probing techniques. A multitude of tubelike filamentary structures is observed to form behind the front of a plasma created by irradiating solid-density wire targets with a high-intensity (I ~ 10(19) W/cm(2)), picosecond-duration laser pulse. These filaments exhibit a remarkable degree of stability, persisting for several tens of picoseconds, and appear to be magnetized over a filament length corresponding to several filament radii. Particle-in-cell simulations indicate that their formation can be attributed to a Weibel instability driven by a thermal anisotropy of the electron population. We suggest that these results may have implications in astrophysical scenarios, particularly concerning the problem of the generation of strong, spatially extended and sustained magnetic fields in astrophysical jets.
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, The Queen's University of Belfast, Belfast BT7 1NN, United Kingdom.
authors.forename: K
authors.initials: K
authors.lastname: Quinn
authors.forename: L
authors.initials: L
authors.lastname: Romagnani
authors.forename: B
authors.initials: B
authors.lastname: Ramakrishna
authors.forename: G
authors.initials: G
authors.lastname: Sarri
authors.forename: M E
authors.initials: ME
authors.lastname: Dieckmann
authors.forename: P A
authors.initials: PA
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Fuchs
authors.forename: L
authors.initials: L
authors.lastname: Lancia
authors.forename: A
authors.initials: A
authors.lastname: Pipahl
authors.forename: T
authors.initials: T
authors.lastname: Toncian
authors.forename: O
authors.initials: O
authors.lastname: Willi
authors.forename: R J
authors.initials: RJ
authors.lastname: Clarke
authors.forename: M
authors.initials: M
authors.lastname: Notley
authors.forename: A
authors.initials: A
authors.lastname: Macchi
authors.forename: M
authors.initials: M
authors.lastname: Borghesi