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Particle Simulation Research on the Detailed Process of Bubble Generation

The detailed process of bubble generation in laser-plasma interaction has been studied by particle simulation. During the interaction between laser and plasma, a strong electrostatic field caused by charge separation is observed, whose structure looks like a potential well. Electrons are accelerated to 10 MeV within some tens of femtoseconds when the laser intensity is 5×1018W/cm2. After many electrons escape from the potential-well-like structure, electron cavitons are generated. Because of laser filamentation, the intensity of the laser becomes very asymmetric, the caviton structure is squeezed and deformed, and then electron bubbles are generated, which finally results in ion bubble formation. It is the electron caviton and laser beam filamentation that cause bubble generation. The 10 MeV superthermal electron generation accompanied by the electron caviton is attributed to E∇·E heating, which is a locally oscillating electron heating mechanism.