Neutron transport and diffusion in inhomogeneous media. I
Neutron transport and diffusion in inhomogeneous media. I
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非均匀介质中的中子输运和扩散。
DOI：
10.1063/1.522714
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发表时间：
1975
影响因子：
1.3
通讯作者：
E. Larsen
中科院分区：
文献类型：
--
作者：
E. Larsen
中子输运方程的渐近解对于具有细胞状近周期结构的大的近临界区域D获得。D中的典型平均自由程被认为与单元直径具有相同的数量级，并且与D的典型直径相比，这些被认为是小的（e级）。解对于小参数e是渐近的。它是两个函数的乘积，一个由详细的细胞计算确定，另一个作为随时间变化的扩散方程的解获得。扩散方程包含前体（缓发中子）密度，方程推导。扩散方程中的系数，这是确定使用的细胞计算的结果，不同于那些现在在工程应用中使用。导出了扩散方程的初始条件，讨论了边界条件的确定问题。
The asymptotic solution of the neutron transport equation is obtained for large near‐critical domains D which possess a cellular, nearly periodic structure. A typical mean free path in D is taken to be of the same order of magnitude as a cell diameter, and these are taken to be small (of order e) compared to a typical diameter of D. The solution is asymptotic with respect to the small parameter e. It is a product of two functions, one determined by a detailed cell calculation and the other obtained as the solution of a time dependent diffusion equation. The diffusion equation contains precursor (delayed neutron) densities, equations for which are derived. The coefficients in the diffusion equation, which are determined using the results of the cell calculation, differ from those now used in engineering applications. The initial condition for the diffusion equation is derived, and the problem of determining the boundary condition is discussed.