基于Monte-Carlo方法模拟分析NBI真空压力分布的研究

Simulative analysis based on Monte Carlo method for vacuum pressure distribution in NBI

中性束注入装置是产生高能中性粒子以加热托卡马克等离子体的装置。NBI真空压力分布是影响中性束传输效率特别是再电离损失的关键因素之一。研究分析了超导托卡马克实验装置中NBI的工作原理和结构特点,建立了EAST NBI的几何与物理模型,利用Monte-Carlo方法建立NBI主真空室内分子运动及碰撞的数学模型,并运用Matlab软件编程实现对NBI主真空室内真空压力分布的模拟计算,得到主真空室内三段区域在进气过程中的气体分子三维分布图和平均压力变化曲线。研究可为EAST NBI主真空室内的中性化室、偏转系统、低温抽气系统的结构设计提供指导。

Neutral Beam Injector （NBI） is used to generate high-energy neutral particles so as to heat the tokamak plasma. The vacuum pressure distribution in NBI is one of the key influcing factors on the efficiency of neutral beam transmission especially the loss due to reionization during the transmission. Analyzing the operating principle and constructional characteristics of NBI applied in the Experimental Advanced Superconducting Tokamak （EAST）, the relevant geometric and physical models were developed. Then, based on the Monte Carlo method, a mathematical model of molecular movement and collision in the main vacuum chamber of NBI in EAST was developed. And the software Matlab was used for programming to implement the simulative calculation of the pressure distribution in NBI＇s main vaeuum chamber. As a result, the 3-D molecular distribution of gas and variation of average pressure in the intake process of the three zones in main vacuum chamber were obtained, thus providing the reference to the constructional design of neutralizer,deflecting system and cryopumping system.