柱对称等离子体中逃逸概率近似表达式

APPROXIMATE EXPRESSION FOR ESCAPE PROBABILITY IN A CYLINDRICALLY EXPANDING MEDIUM

摘要: 柱对称等离子体中谱线逃逸概率公式含有五重复杂的数值积分.采用源缓交近似又速度线性近似,对多普勒线型,由中间值定理给出逃逸概率近似表达式.近似表达式为含误差函数的一重高斯型积分,数值计算大大化简.对物理上感兴趣的速度常数项与线性项之比绝对值<1,且逃逸概率>0.1的情况,近似表达式误差最大不超过7%;速度常数项为零时,误差<1%.

Abstract: An approximate expression for escape probability for Doppler Profile lines in a cylindrically expanding medium is obtained in this paper. The complicated quintuple integral griving escape probability is approximated by a simple integral which has a Gauss-shaped integrand. The largest error is no more than 7%.