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采用Langmuir探针方法对氢等离子体中电子密度和电子能量概率函数随射频功率的变化进行研究，发现电子密度在射频功率增加过程中出现两次跳跃。通过发射光谱法测得氢等离子体Hα、Hβ和Hγ三条谱线强度比值的变化，进一步验证了密度跳跃现象。该现象说明氢等离子体的放电模式发生了从电感耦合到电容耦合再到螺旋波模式的转变。从电子与氢分子的相互作用和Nagoya type Ⅲ型(N-型)天线电场耦合作用两方面解释密度跳跃现象。随着输入功率的增加，电子与氢分子相互作用增强，使电子密度发生跃变；当天线横向电场Ey取最大值，螺旋波轴向波矢kz分别为π/la和3π/la时天线与等离子体耦合最好，分别产生两次密度跳跃。

Study of density jump in helicon-wave induced H2 plasma

Hydrogen plasmas electron density and electron energy distribution function EEDF were studied with Langmuir probe.Two jumps were observed in the variation of the electron density with the radio frequency power.The relative intensity ratio of hydrogen plasmas spectrum line Hα,Hβ and Hγ validated this phenomenon.Two density jumps illuminated the transition of discharge mode,which labeled as capacitive,inductive and helicon-wave mode.In this work,the density jumps are explained from two sides,one is the interaction between electrons and hydrogen molecules,the other is Nagoya type Ⅲ(N-type) antenna-plasma coupling.With the increase of radiofrequency power,the interaction between electron and hydrogen molecule has been enhanced which causes the electron density jumps.The antenna couples well to plasmas when transverse field Ey is maximum,and the wave vector of kz locates at π/la or 3π/la,corresponding to the first and second density jump.