Kinetic model of spontaneous magnetic fields in laser-plasma interactions with electrons taking a super-Gaussian velocity distribution

The quasistatic magnetic fields in laser-plasma interactions are investigated using a kinetic model for electrons with super-Gaussian velocity distributed in laser-produced plasmas. These fields are excited by low-frequency nonlinear currents, which arise from wave–wave and wave–particle interactions. The dispersion equation for transverse perturbations is derived from a set of self-consistent governing equations that describe high-frequency transverse electromagnetic waves, ion-acoustic motion, and self-generated magnetic fields. Numerical results indicate that increased laser intensity and a lower super-Gaussian index lead to a higher growth rate of the spontaneous magnetic field, while reducing the magnetic field scale. In fact, the super-Gaussian index has a minimal effect on the properties of the self-generated magnetic field. This means that its characteristics for electrons with a super-Gaussian velocity distribution closely resemble those for Maxwellian-distributed electrons. Both the characteristic length scales and the rapid growth rate support the experimental observations, indicating that the magnetic fields can grow to measurable levels.