This study investigates terahertz (THz) radiation generation through the interaction of two laser beams with a mixture of graphite nanoparticles with different shapes and orientations in the presence of external fields. The interaction induces a nonlinear ponderomotive force, creating a nonlinear oscillating current when the laser beat frequency ( \(\omega _1 - \omega _2\) ) matches the surface plasmon resonance frequency of the nanoparticles. The presence of an external wiggler magnetic field significantly enhances the efficiency of THz radiation by providing the necessary phase matching and momentum, resulting in an approximately sixfold increase in the enhancement of terahertz amplitude. Additionally, applying a transverse static electric field further enhances the amplitude of THz radiations, but to a lesser degree. This study aims to address the limitations of traditional THz generation methods and provides new insights into optimizing the efficiency of THz generation by utilizing amplitude-modulated laser beams, nanoparticle configurations, and the application of external fields. The findings of this study pave the way for compact, high-power THz sources with enhanced efficiency and tunability for practical applications.
