The through holes 25 satisfy the condition of uL/D>1 in the case the gas flow rate in the through holes is defined as (u), the substantial length of the holes as L, and the diffusioncoefficient of mutual gases as D. 貫通孔は、孔内でのガス流速をu、実質的な孔の長さをL、相互ガス拡散係数をDとするとき、uL/D>1の条件を満たす。 - 特許庁