Abstract: As the first section of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR)， the high power helicon plasma source directly affects the performance of the rocket. For increasing the plasma density and the propellant ionization rate of the helicon plasma source， the ion density and the electron temperature of the helicon plasma source with 4kW power have been tested by a radio-frequency compensated probe. The results show that， under the condition of strong magnetic field， the discharge mode jumps twice as the applied power increased， and the helicon discharge mode is obtained. With the helicon discharge mode， the ion density is over 1×1012cm-3 in the plume region， and is over 2×1014cm-3 in the antenna region. The ion density is higher in the central area of the discharge tube， and decreases along the radial direction. The results provide evidence for the development of the VASIMR with 30kW power.

Key words: Helicon plasma；Radio-frequency compensated probe；Ion density；Diagnostics

摘要： 高功率螺旋波等离子体源作为可变比冲磁等离子体发动机(?Variable Specific Impulse Magnetoplasma Rocket，VASIMR)的第一级，其参数直接影响发动机的性能。为提高螺旋波源的等离子体密度和工质电离率，以4kW螺旋波等离子体源为研究对象，利用射频补偿Langmuir探针诊断等离子体的离子密度和电子温度。试验结果表明，在强磁场条件下，随着功率的升高，螺旋波等离子体源内部共出现两次放电模式转换，最终进入了螺旋波放电模式。在达到螺旋波放电模式后，羽流区域的等离子体密度超过1×1012cm-3，初步评估，放电天线区域的离子密度超过2×1014cm-3，离子密度在放电管中心区域较高，沿径向逐渐降低。研究结果为30kW磁等离子体发动机的研制提供依据。

关键词: 螺旋波等离子体源；射频补偿探针；离子密度；诊断