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Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses
Published on: July 2, 2012
Effect of laser intensity on fast-electron-beam divergence in solid-density plasmas
J S Green1, V M Ovchinnikov, R G Evans
1Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom.
Physical Review Letters
|February 1, 2008
Summary
Electron acceleration in metal foils was studied using intense laser pulses. Results show electron divergence increases with laser intensity-squared, independent of pulse duration, suggesting a fundamental laser-plasma interaction property relevant to fast ignition fusion.
Area of Science:
- Plasma Physics
- Laser-Matter Interaction
- Inertial Confinement Fusion
Background:
- Fast ignition inertial fusion requires understanding electron acceleration.
- Laser-plasma interactions are crucial for efficient energy coupling.
Purpose of the Study:
- Investigate electron acceleration divergence in metal foils under intense laser irradiation.
- Determine the dependence of electron divergence on laser intensity and pulse duration.
Main Methods:
- Irradiation of metal foil targets with 1 µm wavelength, 5 ps laser pulses.
- Measurement of K-alpha X-ray emission for spatially resolved electron divergence.
- Transverse probing of plasma on the foil's back surface.
- Two-dimensional particle-in-cell simulations.
Main Results:
- Electron divergence increases with the parameter Iλ², where I is laser intensity and λ is wavelength.
- Electron divergence was found to be independent of laser pulse duration.
- Simulations successfully reproduced the experimental observations.
Conclusions:
- The observed electron divergence is a fundamental property of laser-plasma interactions.
- Findings are relevant to fast ignition inertial fusion requirements.
- The study provides insights into electron acceleration mechanisms in high-intensity laser-matter interactions.
