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Absorption of subpicosecond UV laser pulses during interaction with solid targets
M Borghesi1, A J Mackinnon, R Gaillard
1The Blackett Laboratory, Imperial College of Science, Medicine and Technology, London SW7 2BZ, United Kingdom.
Summary
High absorption of ultraviolet laser pulses was observed in plasma. This absorption, up to 65%, is attributed to resonance and collisional processes at specific laser polarizations and incidence angles.
Area of Science:
- Plasma Physics
- Laser-Matter Interaction
- Ultrafast Optics
Background:
- Understanding laser energy absorption in plasma is crucial for inertial confinement fusion and other applications.
- High-intensity laser interactions with plasma can lead to complex absorption mechanisms.
Purpose of the Study:
- To measure and analyze the absorption of subpicosecond ultraviolet laser pulses at high intensities.
- To investigate the influence of polarization and angle of incidence on laser absorption.
- To elucidate the underlying physical mechanisms responsible for the observed absorption levels.
Main Methods:
- Experimental measurement of laser pulse absorption.
- Varying laser polarization (s and p) and angle of incidence.
- Analysis of absorption data in relation to plasma parameters.
Main Results:
- Observed high absorption levels, reaching up to 55% for s-polarized and 65% for p-polarized light.
- Absorption varied significantly with the angle of incidence and polarization.
- Results suggest a combination of resonance and collisional absorption mechanisms.
Conclusions:
- The study demonstrates significant laser energy absorption in plasma under specific conditions.
- Resonance and collisional absorption are identified as key processes.
- Plasma scale length is estimated to be a fraction of the laser wavelength.