Anisotropic Energetic Ion Emission from Explosion of Intense Laser Irradiated Argon Clusters in a Jet

The interaction of an intense femtosecond laser field (～ 10¹⁶W/cm²) with argon clusters in a dense jet has been studied by measuring the energy and angle distributions of emitted ions. A directional anisotropy in the ion explosion energies is observed. The experimental results indicate that the average ion energies are up to 40% in the detection direction parallel to the laser polarization higher than that perpendicular to it. The measured ion yield increases about 80%, correspondingly. The findings are interpreted by charge-dependent ion acceleration and explosion of elliptic microplasma spheres.