Schuh K, Hader J, Moloney J V, Koch S W
Arizona Center for Mathematical Sciences, Department of Mathematics, University of Arizona, Tucson, Arizona 85721, USA and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA.
College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA and Department of Physics and Material Science Center, Philipps-University, 35032 Marburg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Mar;89(3):033103. doi: 10.1103/PhysRevE.89.033103. Epub 2014 Mar 12.
The excitation of atomic gases by short high-intensity optical pulses leads to significant electron ionization. In dilute systems, the generated distribution of ionized electrons is highly anisotropic, reflecting the quantum mechanical properties of the atomic states involved in the many photon transitions. For higher atomic densities, the Coulomb interaction in the electron-ion system leads to the development of an isotropic electron plasma. To study the ionization process in the presence of the many-body interaction, a fully microscopic model is developed that combines a generalized version of the optical Bloch equations describing the optical excitation with a microscopic description of the many-body interactions. The numerical evaluation shows that the Coulomb interaction significantly modifies the distribution anisotropy already during the excitation process. Whereas a reduced anisotropy is still present after the pulse for low ionization degrees and pressures, it is completely absent for elevated gas densities. An ionization degree is predicted that is significantly enhanced by the many-body interactions.
短高强度光脉冲对原子气体的激发会导致显著的电子电离。在稀薄系统中，产生的电离电子分布高度各向异性，反映了多光子跃迁中所涉及原子态的量子力学性质。对于更高的原子密度，电子 - 离子系统中的库仑相互作用会导致各向同性电子等离子体的形成。为了研究多体相互作用存在时的电离过程，开发了一个完全微观的模型，该模型将描述光激发的光学布洛赫方程的广义版本与多体相互作用的微观描述相结合。数值评估表明，库仑相互作用在激发过程中就显著改变了分布的各向异性。对于低电离度和低气压情况，脉冲之后仍存在各向异性的降低，而对于升高的气体密度，这种各向异性则完全不存在。预测多体相互作用会显著提高电离度。
