High-order harmonics from solid targets as a probe for high-density plasmas.
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.
Hässner
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R
Theobald
W
W
Niedermeier
S
S
Schillinger
H
H
Sauerbrey
R
R