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Collimated γ-ray emission enabled by efficient direct laser acceleration
DOI:10.1088/1367-2630/adb3c1.png)
Abstract
En 中文
We investigate the mechanisms responsible for single-lobed versus double-lobed angular distributions of emitted gamma-rays in laser-irradiated plasmas, focusing on how direct laser acceleration (DLA) shapes the emission profile. Using test-particle calculations, we show that the efficiency of DLA plays a central role. In the inefficient DLA regime, electrons rapidly gain and lose energy within a single laser cycle, resulting in a double-lobed emission profile heavily influenced by laser fields. In contrast, in the efficient DLA regime, electrons steadily accumulate energy over multiple laser cycles, achieving much higher energies and emitting orders of magnitude more energy. This emission is intensely collimated and results in single-lobed profiles dominated by quasi-static azimuthal magnetic fields in the plasma. Particle-in-cell simulations demonstrate that lower-density targets create favorable conditions for some electrons to enter the efficient DLA regime. These electrons can dominate the emission, transforming the overall profile from double-lobed to single-lobed, even though inefficient DLA electrons remain present. These findings provide valuable insights for optimizing laser-driven gamma-ray sources for applications requiring high-intensity, well-collimated beams.
Keywords:
direct laser acceleration
particle-in-cell simulation
laser-driven gamma-ray source
high-intensity laser-plasma interactions
collimated gamma-ray emission
Journal
IF:
2.8
Papers:
580
Citations:
3.5W

