Abstract-Dark hollow beams originating terahertz radiation in corrugated plasma under magnetic field

Physics of Plasmas

Hitendra K. Malik,  Sheetal Punia,

Deviation of normalized THz field for different beam orders with collisional frequency orders by taking parameters: b = 0.001 cm, na/no = 0.3, ω = 1.5*ωp, and external magnetic field B = 4 T.

https://aip.scitation.org/doi/abs/10.1063/1.5090814

In the present process, two laser beams having the same doughnut profiles but different frequencies are explored in space-periodic nonlinear plasma to produce nonlinear oscillatory current that resonantly excites the terahertz (THz) radiation. The interactions are assumed to be under the effect of external magnetic field and electron-neutral collisions. The intensity gradient of the considered dark hollow beams has a doughnut-shaped distribution, which is responsible for the multifocal field profile of the emitted THz radiation. The present scheme is capable of producing laser-to-THz energy conversion efficiency up to ∼10−3 with the optimization of various laser and plasma parameters even in the presence of electron-neutral collisions.

Abstract-Terahertz radiation for medical application

Reenu Gill, Sheetal Punia, Hitendra K. Malik,

http://iopscience.iop.org/article/10.1209/0295-5075/123/65003

Terahertz (THz) radiations focused at multiple positions are quite useful for their medical application. For this, we propose to employ beating of dark hollow Gaussian laser beams (DHGBs) of different beam orders in plasma. In view of realistic situations, we also include the collisions between the electrons and the neutrals. Because of a special intensity gradient distribution in DHGBs, the emitted THz radiation is found to have a unique field profile with multiple focii. The dependence of plasma density, order of the beams and collision frequency on the THz field amplitude is discussed. The important feature to consider hollow Gaussian laser beams is having the same power at different beam orders. It is found that the amplitude of the emitted radiation is highly sensitive to the beam order of the incident lasers. An optimization of the plasma parameters and the lasers characteristics can lead to the enhancement in the THz intensity and the efficiency of the mechanism.