一、引言 1875年,Kundt等人首先发现了低压下气体分子在固体表面的“光滑现象”(即在固体表面上它们的平均速度不为零)。1898年,Smoluchowski又发现在一定的压力下,气体分子在固体表面附近存在“温度跃变”,而“光滑现象”和“温度跃变”现象都是分子和固体表面碰撞中不完全适应的结果。为了研究气体分子和固体表面的适应现象,1911年克努曾首先引入了适应系数的定义,并用热丝法测量了总能量适应系数,按照克努曾的定义,总能量适应系数可定义为: I. INTRODUCTION In 1875, Kundt and others first discovered the “smooth phenomenon” of gas molecules on solid surfaces at low pressure (ie, their average velocity on solid surfaces is not zero). In 1898, Smoluchowski also found that under certain pressure, gas molecules have “temperature jump” near the solid surface, and “smooth phenomenon” and “temperature jump” phenomenon are the result of imperfect adaptation in molecular and solid surface collisions . In order to study the adaptation phenomena of gas molecules and solid surfaces, in 1911 Knud firstly introduced the definition of fitness coefficient and measured the total energy fitness coefficient by hot wire method. According to Knudsen’s definition, the total energy fitness coefficient can be defined as: