中文摘要：

为了使读者对气体放电相似性有一个全面的了解,对气体放电相似性的研究进行综述.Townsend首先阐述了气体放电相似性原理,von Engel给出了气体放电相似性的定义、主要相似关系,相似放电允许和不允许的物理过程.两个气隙放电相似的必要条件是p1d1=p2d2和E1（px）/p1=E2（px）/p2（p1、d1、E1和p2、d2、E2分别为两个气隙的气压、气隙长度、电场强度）.前者表明电子跨越整个气隙期间所发生的平均碰撞次数相同,而后者表明电子的平均动能相同,即每次碰撞原子时的电离能力相同.随后介绍了放电相似性的使用范围在高频放电和脉冲放电研究领域的扩展,并简单介绍了3个放电相似性的应用例子：清洗ITER装置的超大尺度辉光放电、分析化学中的超小尺度放电、大气中间层的超大尺度放电.

英文摘要：

To provide a general idea of similarity in gas discharges, we reviewed the related researches. The similarityprinciple was first noticed and demonstrated by Townsend. Then yon Engel presented the definition of the similar dis-charge and the parameter relations between two similar discharges, as well as the allowed processes and the forbiddenprocesses of similar discharges. Similar discharge is defined by two conditions, namely, pldl =p2d2 and El（px）/pl=E2（Px）/p2, where pl, dl, E1 andp2, d2, E2 are the pressures, lengths, and electric field intensities at the point x in two gaps.We also summarized the extended application of the similarity law in high-frequency discharge and pulsed discharge, aswell as three examples, namely, the glow discharge in extra-large dimension for cleaning ITER devices, the discharge inextra-small dimension used in analytical chemistry, and the discharge in ultra-large dimension in the atmosphere.