Investigations On On-chip Particle Accelerator Based On Laser-driven Dielectric Prism

Particle accelerators are critical scientific tools and industrial equipment in many fields,such as probing the fundamental structure of matter,industrial radioisotope production,medical radiation therapy,safety scanners,environmental governance and food irradiation processing.However,conventional particle accelerators are limited in their application due to their large size and expensive construction costs.Therefore,future particle accelerators must be more compact and cost-effective to enable broader applications than what is currently possible.This thesis uses mature laser technology to induce high acceleration gradient(GV/m)surface evanescent waves on the surface of on-chip microstructures manufactured through micro/nano processing technology,replacing the low acceleration gradient(10-100 MV/m)microwave of traditional RF accelerators to accelerate particles.The acceleration field generated by lasers with high acceleration gradient shortens the distance required for particles to accelerate to the same energy by 1-3 orders of magnitude compared to RF accelerators.In this way,we can deploy and apply particle accelerators in a low-cost and small-scale way,which is of great value and significance for basic science,medicine,industry and agriculture.Dielectric laser accelerators based on laser-driven micro dielectric structures are an effective solution for developing miniaturization and even on-chip accelerators.This thesis proposes and studies an inverse Cherenkov dielectric laser accelerator based on prism structure.The main works are as follows:(1)We study the acceleration theory of the acceleration unit under single-sided and double-sided prism structures and provided the electromagnetic field distribution and particle tracking simulation results and analysis of the electron beam under both structures.The research results verify that the double-sided prism structure has both longitudinal acceleration and transverse focusing characteristics within a specific phase range.After utilizing this characteristic to achieve single-stage acceleration of the electron beam,the effects of different initial charge levels and transverse emittance on the quality of the electron beam were further discussed.(2)We propose three kinds of cascade acceleration schemes of double-sided prismstructure dielectric laser accelerators.The scheme solves the problem that the electron beam velocity does not match the phase velocity of the acceleration field in the longrange acceleration by changing the laser incidence angle and the refractive index of the dielectric structure.The simulation results verify the feasibility of the cascade acceleration scheme of the electron beam.In the study,it was found that adjusting the laser incidence angle and incidence time of each stage can effectively solve the phase slip phenomenon between the electron beam and the acceleration field,improve the average acceleration gradient of the electron beam,and maintain low transverse emittance and beam size during long-range acceleration.On this basis,other cascade schemes and more stages cascade acceleration schemes were discussed.(3)We achieve the prebunching of the electron beam based on the double-sided dielectric prism structure.The electron beam is compressed in the longitudinal direction.We perform single stage acceleration and cascade acceleration simulations on the compressed electron beam.The results show that the prebunched electron beam is increased by 3-4 times in charge during single stage acceleration and cascade acceleration,improving the beam current intensity.(4)We propose a preliminary scheme of dielectric laser acceleration experiment based on laser-driven dielectric prism.We design and fabricate the microstructure of on-chip particle accelerators based on the laser-driven dielectric prism.We measure the damage thresholds at different positions on the microstructure.We design three sets of electron sources with ultra-low emittance and beam size based on the photocathode microwave electron gun.Through simulation research,we find transverse truncated Gaussian driven lasers are more conducive to obtaining high-quality beams.In general,this thesis investigates the on-chip particle accelerator based on the laser-driven dielectric prism,which provides a theoretical and experimental reference for the miniaturization of dielectric laser accelerators.