Manipulation Of Ultraintense Laser Pulses With Microstructures

In this paper,the effects of different plasma micro-structures on laser pulses are studied.With the development of laser pulse,it has important applications in more and more fields.In different situations,the requirements for laser pulses are also different.In order for laser pulses to be better applied,this article explores the interaction of ultra-strong laser pulses with plasmas with different microstructures through the use of particle-in-cell simulations(PIC)under several demand conditions.There are three parts:Cascaded light confinement of relativistic laser pulses in multistage micro-channels;Plasma polarization grating lens for improving laser pulse contrast;Ultra-intense laser pulse guidance and laser wake-filed acceleration for Helium in the near critical density plasma.In the first part:In order to obtain ultra-high intensity laser pulses,the use of multistage micro-channels structure to manipulate the transmission of laser pulses is studied.When the laser pulse enters the plasma channel,it interacts with the plasma channel,and a large number of electrons are pulled out from the channel wall.Some of the electrons are affected by various forces and move to the center of the channel,which changes the electrons in the channel,which changes the density distribution of electrons in the channel and thus changes the refractive index.The laser pulse is continuously focused and amplified during the transmission process,and at the same time,it is continuously cut to form a pulse-chain.As the laser spot is reduced in focus,the inner diameter of the micro-channel structure also becomes smaller,and the intensity of the laser pulse can eventually be enlarged to?10²³W/cm~2.In the second part:With the development of laser pulse intensity,the requirement of laser contrast is higher and higher.By using a plasma polarization grating lens,the contrast of intense laser pulse can be optimized.When a linearly polarized laser pulse interacts with the grating lens,the prepulse of the laser pulse first interacts with the grating lens,most of the prepulses are reflected by the grating lens due to the polarization effect,and the intensity of the transmitted prepulses can be effectively reduced,and there is no obvious change in the structure before the laser main pulse arrives;When the Ultra-intensity laser main pulse arrives at the grating lens and interacts with it,since the thickness of the grating structure is very thin,the laser main pulse can effectively transmit through the grating lens,and its intensity change is small,and even can be enhanced to a certain extent.In the third part:An ultra-intense ultrashort laser pulse is used to interact with a near critical density hybrid plasma,The laser pulse can be effectively guided in the plasma channel,the intensity of the laser pulse can be increased,and the laser pulse can also be optimized to a certain extent.In the process,the helium ions in the mixed plasma can be accelerated by the laser wake field acceleration(LWFA)mechanism to obtain a higher acceleration gradient and acceleration distance to obtain a high-energy ion beam.When the parameters of the ultra-intense laser pulse match the parameters of the near critical density hybrid plasma,the electron density distribution changes correspondingly due to the pondermotive force and the electromagnetic force in the process of their interaction,forming the"Bubble"structure and wake field.By this method,the helium ion can be effectively accelerated.