The Research Of Terahertz Signal Source Based On Multi-electron Excitation

Terahertz refers to the frequency range of 0.1THz to 10 THz electromagnetic waves.Terahertz wave is between microwave electronics and infrared photonics.It is a new frequency band in electromagnetic spectrum which has yet to be developed and has great scientific significance and application prospect.Terahertz has a wide range of applications in biomedical,security and communications.As a key device for the development of the entire terahertz,the development of high-power and highly efficient terahertz sources is an imminent scientific and technical problem.At present,the development of high power,high efficiency,compact terahertz source plays a key role in promoting the development of terahertz.In recent years,scientists have made great efforts to develop terahertz sources.However,with the further increase in frequency,due to the size of the transition effect,the traditional terahertz source performance is limited.The Smith-Purcell radiation source has become a hotspot in the study of terahertz sources at home and abroad because it reduces the requirements for machining accuracy and SP super-radiation can be combined with quasi-optical resonators.In this paper,the multi-electron homogeneous coherent Smith-Purcell(SP)terahertz radiation is combined with the quasi-optical resonant mode to enhanced SP super-radiation.Mainly divided into the following aspects:(1)The dispersion of the grating is analyzed by boundary condition and field matching.Then the mathematical tool draws the theoretical deduced dispersion curve.The interaction between electron injection and grating is studied,and the influence of the physical parameters of the structure on the periodic structure is analyzed then.(2)The electromagnetic properties of the staggered double electron bunch were studied.it was found that the staggered electrons could enhance the second harmonic components of the electron bunch.Then we studied a two-stage high-frequency structure of the electromagnetic radiation source.The first section is mainly used for pre-modulation of DC electronic injection,so that it produces staggered electronic two groups;the second paragraph is used to generate electromagnetic radiation,the modulation frequency is the second harmonic of the cycle of electrons.The results show that the continuous electron beams are modulated and clustered into two pairs of staggered electrons due to the interaction between the surface slow waves and the continuous electrons in the double grating structure.The terahertz radiation is excited when the modulated electrons pass through the single-raster structure of the later stage.The results show that the simulation results are in good agreement with the theoretical analysis.Finally,we compare the staggered electron bunch with the symmetrical electrons and find that the radiation intensity of the staggered double electron bunch is higher than that of the symmetric electron bunch.(3)A terahertz source with dual electron excitation and symmetric dual grating SP super radiation is studied.By combining the SP radiation and the quasi-optical mode to achieve the effective enhancement of the SP harmonic radiation,and the quasi-light oscillation on the second harmonic electron radiation energy to form a feedback system,making the injection wave interaction has been effectively enhanced.The results show that radiation field strength increased by nearly 3 times.