Magnetized laser-plasma interactions for photonics and fusion
Magnetized plasmas have rarely been studied as nonlinear photonics media, yet they possess unique properties: Compared to unmagnetized plasmas, magnetization introduces additional resonances, which can mediate processes that are not possible without a magnetic field. On the other hand, compared to crystals and other non-ionized media, plasmas have a substantially larger bandwidth and damage threshold, making them viable for processing ultra-intense and ultra-short pulses. In addition, magnetized laser-plasma interactions are important in magneto-inertial fusion concepts, which strive to achieve fusion with the combined advantages of magnetic and inertial confinements. In magnetized implosion experiments, externally imposed seed magnetic fields are compressed, reaching strengths at which laser-plasma interactions become affected. For example, with the mediation of cyclotron-like waves, laser crossbeam energy transfer can occur at different growth rates and wavelength detuning. Processes like this need to be better understood and controlled to achieve high-performance magnetized implosions. Our research investigates magnetized laser-plasma interactions using theories, simulations, and experiments.
Magnetized plasmas support a unique variety of nonlinear interactions. In this example, a pump laser in the L mode decays to two daughter waves in P and F modes. The frequency difference between L and P waves is shown in (a), and the normalized coupling coefficient is shown in (b). The anisotropic nature of magnetized three-wave coupling is apparent. Unlike the unmagnetized case, backscattering is no longer the strongest, and special angles exist where the coupling is either enhanced or suppressed. []