Topological approach for laser acceleration investigation

An approach using topology reveals a new understanding and knowledge of laser particle acceleration. Laser pulse irradiation on a thin-foil target is examined using two-dimensional particle-in-cell simulations. Through topology, laser ion acceleration schemes are classified depending on whether the deformed target shape after laser irradiation is homeomorphic with respect to the initial target. High energy ions are generated with high-efficiency when the deformed target shape is non-homeomorphic. In this case, the target thickness greatly affects the obtained ion energy. However, when the deformed target shape is homeomorphic, the obtained ion energy is low, and the effect of the target thickness is small.