强激光与粒子束
彊激光與粒子束
강격광여입자속
HIGH POWER LASER AND PARTICLEBEAMS
2008年
12期
2067-2072
,共6页
史密斯-帕塞尔辐射%自由电子激光%THz源%PIC模拟%后处理
史密斯-帕塞爾輻射%自由電子激光%THz源%PIC模擬%後處理
사밀사-파새이복사%자유전자격광%THz원%PIC모의%후처리
Smith-Purcell radiation%free electron laser%THz source%particle-in-cell simulation%post processing
采用模拟和数值计算的方法,研究了THz波段的受激史密斯-帕塞尔辐射特性.实验装置以"上海电子束离子阱"为原型,采用紧凑型设计以便最终实现其可移动性.束流动力学模拟表明,此装置采用强磁场,可以得到平均流强为0.2 A、束流半径为75μm的高品质电子束,为电子束工作在自由电子激光模式下创造了条件.基于Andrews和Brau的理论,优化了光栅参数,保证了辐射角度在60°.其中消散场的计算频率为0.365 9 THz.采用particle-in-cell(PIC)程序模拟了光栅表面的辐射场以及电子的动力学特性.模拟结果表明电子有群聚效应,且二次谐波(0.723 THz,约为消散频率的2倍)得到增强.采用后处理方法计算了史密斯-帕塞尔辐射的功率空间分布.计算显示辐射角度与理论角度相一致,表明了方法的有效性.输出的功率约为2 mW.
採用模擬和數值計算的方法,研究瞭THz波段的受激史密斯-帕塞爾輻射特性.實驗裝置以"上海電子束離子阱"為原型,採用緊湊型設計以便最終實現其可移動性.束流動力學模擬錶明,此裝置採用彊磁場,可以得到平均流彊為0.2 A、束流半徑為75μm的高品質電子束,為電子束工作在自由電子激光模式下創造瞭條件.基于Andrews和Brau的理論,優化瞭光柵參數,保證瞭輻射角度在60°.其中消散場的計算頻率為0.365 9 THz.採用particle-in-cell(PIC)程序模擬瞭光柵錶麵的輻射場以及電子的動力學特性.模擬結果錶明電子有群聚效應,且二次諧波(0.723 THz,約為消散頻率的2倍)得到增彊.採用後處理方法計算瞭史密斯-帕塞爾輻射的功率空間分佈.計算顯示輻射角度與理論角度相一緻,錶明瞭方法的有效性.輸齣的功率約為2 mW.
채용모의화수치계산적방법,연구료THz파단적수격사밀사-파새이복사특성.실험장치이"상해전자속리자정"위원형,채용긴주형설계이편최종실현기가이동성.속류동역학모의표명,차장치채용강자장,가이득도평균류강위0.2 A、속류반경위75μm적고품질전자속,위전자속공작재자유전자격광모식하창조료조건.기우Andrews화Brau적이론,우화료광책삼수,보증료복사각도재60°.기중소산장적계산빈솔위0.365 9 THz.채용particle-in-cell(PIC)정서모의료광책표면적복사장이급전자적동역학특성.모의결과표명전자유군취효응,차이차해파(0.723 THz,약위소산빈솔적2배)득도증강.채용후처리방법계산료사밀사-파새이복사적공솔공간분포.계산현시복사각도여이론각도상일치,표명료방법적유효성.수출적공솔약위2 mW.
The characteristics of stimulated Smith-Purcell radiation in THz region are simulated and nu-merically calculated. The experimental device is designed to be compact. The notion of the design for the experi-ment device is originated from the prototype of the Shanghai Electron Beam Ion Trap. Strong axial magnetic field is necessary to achieve high current and low emittance of electron beam. The simulation results of dynamic characteristics for the electron beam show that an average beam current can be as high as 0.2 A with an RMS beam radius of 75 μm, which is the precondition to work as free electron laser(FEL) while passing over the grating surface. Based on the theory of Andrews and Brau, we have optimized the parameters of grating to en-sure the emission angle is near 60°. And the calculated frequency of evanescent wave is 0.365 9 THz. The pa-rameters are then used in the particle-in-cell(PIC) simulation code. The simulation results show that beam bunc-hing occurs. Besides, the second harmonic is enhanced, whose frequency is 0.723 THz, about twice as that of evanescent wave. To calculate the exact emission power from simulation results corresponding to the Smith-Pur-cell(SP) radiation, we also present a new post processing method. With this method, we have obtained the space distribution of emission power. The calculation shows that the emission is centralized at the expected an-gle, which accounts for the validation of this method. And the extracted power is about 2 mW.
