Research On Brain-organ Interaction Technology Based On EEG Signal Analysis And Processin

Laser stands for Light Amplification by Stimulated Emission of Radiation.The year 1960 marked a pivotal moment in technological history when physicist T.Maiman pioneered the development of the first-ever laser,igniting a widespread technological revolution.Distinct from conventional light sources,lasers are characterized by high monochromaticity,excellent coherence,remarkable directionality,and concentrated energy.From their theoretical conception to their first experimental demonstration,laser technology has advanced through numerous stages,profoundly driving the progress of physics and optics.It has also given rise to many important applications,such as inertial confinement fusion,high-energy particle source drivers,laser communication systems,laser mapping,minimally invasive surgery,and weapon guidance,becoming an indispensable force in the advancement of modern technology.This paper primarily investigates the physical problems associated with proton acceleration driven by the wakefield in a plasma using an optical laser spring and the suppression of stimulated Raman scattering by angularly incoherent laser pulse.The work of this paper is mainly divided into the following two aspects:1.Proton acceleration in a near-critical-density gas driven by a light spring(LS)pulse with a helical structure in its intensity profile is investigated by using three-dimensional particle-in-cell simulations.Due to the fact that the high-intensity focal point of the optical spring is concentrated on a very small segment of a ring,the light intensity at other positions on the ring,apart from the bright spot,is extremely low,almost zero.Compared with other pulse modes with the same laser power,such as the Gaussian pulse or the donut Laguerre–Gaussian(LG)pulse,the LS structure significantly enhances the peak intensity and drives a stronger longitudinal acceleration field and transverse focusing field.Both the high intensity and helical structure of the LS pulse contribute to the formation of a bubble-like structure with a fine electron column on the axis.The intense lateral momentum of LS laser rapidly expels electrons outward,forming an external bubble sheath,while inwardly converging electrons create an inner bubble sheath,resulting in a special bubble structure with an electron column along the central axis.The presence of this electron column generates a focusing field for the surrounding protons,continuously attracting them to oscillate near the axis.This structure is crucial in binding the proton beam within the bubble and providing sustained,stable acceleration over a longer period,essential for obtaining high-energy proton beams.Therefore,it is very promising to obtain ultrahigh-energy protons using LS pulses with a relatively lower power.For example,using LS pulses with the same power of 4.81 PW,the proton in the gas can be accelerated up to 8.7 Ge V,and the witness proton can be accelerated to 10.6 Ge V from 0.11 Ge V,which shows the overwhelming advantage over the Gaussian and LG pulse cases.2.Utilizing three-dimensional particle-in-cell(PIC)simulations,this study delves into the impact of azimuthally incoherent vortex light configurations on mitigating Stimulated Raman Scattering(SRS).The challenges in realizing high-gain,predictable,and reproducible fusion outcomes through laser-driven inertial confinement fusion(ICF)are primarily attributed to laser-plasma instabilities,including Stimulated Raman Scattering(SRS),Stimulated Brillouin Scattering(SBS),and Two-Plasmon Decay(TPD).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF studies.For the model used in our calculations,we compare the maximum field ratio between the stimulated Raman scattering and the driving pulses along the laser propagation direction for different cases of frequency spread,angular momentum spread and random relative phases.In particular,angular incoherence does not introduce extra undesirable hot electrons.This provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.