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Emission of electromagnetic pulses from laser wakefields through linear mode conversion
Zheng-Ming Sheng1, Kunioki Mima, Jie Zhang
1Laboratory of Optical Physics, Institute of Physics, CAS, Beijing 100080, China.
Physical Review Letters
|March 24, 2005
Summary
Powerful terahertz radiation is generated from laser wakefields via mode conversion in inhomogeneous plasmas. This tunable emission, with high field strengths, is suitable for advanced applications and diagnostics.
Area of Science:
- Plasma Physics
- Laser-Plasma Interactions
- Electromagnetic Wave Generation
Background:
- Laser wakefield acceleration relies on plasma oscillations.
- Controlling emission properties is crucial for applications.
- Linear mode conversion offers a pathway to coherent emission.
Purpose of the Study:
- To investigate the generation of coherent emission from laser wakefields.
- To analytically determine the emission spectrum and conversion efficiency.
- To explore the potential of this emission as a tunable radiation source.
Main Methods:
- Analytical derivation of emission spectrum and conversion efficiency.
- Utilizing linear mode conversion of laser wakefields.
- Validation through particle-in-cell simulations.
Main Results:
- Powerful coherent emission is produced around the plasma oscillation frequency.
- Oblique incidence of laser pulses on plasma density gradients drives the conversion.
- Tunable terahertz emission with field strengths up to GV/m is achieved.
Conclusions:
- Linear mode conversion is an effective mechanism for generating tunable, high-field terahertz radiation.
- The emission is suitable for high-field applications and as a diagnostic for wakefields.
- This method offers a straightforward approach to controlling laser-plasma emission properties.