title: High-order harmonics from solid targets as a probe for high-density plasmas.
abstract: The interaction of 100-fs Ti:sapphire laser pulses with thin foil targets was experimentally investigated at intensities exceeding 10(18) W/cm(2). High harmonics were observed in transmission through an overdense plasma in the direction of the incident beam. From the cutoff frequency of the harmonics an electron density of 1 x 10(24) cm(-3) is inferred, indicating a compression of the plasma by the ponderomotive force of the laser pulse.
authors.forename: R
authors.initials: R
authors.lastname: Hässner
authors.forename: W
authors.initials: W
authors.lastname: Theobald
authors.forename: S
authors.initials: S
authors.lastname: Niedermeier
authors.forename: H
authors.initials: H
authors.lastname: Schillinger
authors.forename: R
authors.initials: R
authors.lastname: Sauerbrey