Abstract: In order to study the effects of magnetic circuit on the performance of 30cm diameter ion thruster(LIPS-300)which matches the new type of GEO satellite platform，PIC-MCC numerical simulation method was used to study LIPS-300’s discharge loss and beam flatness under its typical operating point. The magnetic field input of PIC-MCC simulation was calculated using infinite element software Maxwell. It was also used to study the effects of different magnet sizes on the magnetic contour produced by side-wall magnet pair. The obtained results indicate that under LIPS-300’s typical operating point，4 pole field thruster’s discharge loss is higher than that of 3 pole field by 3%. They are 164W/A and 160W/A，respectively. The 4 pole field thruster’s beam flatness is larger than that of 3 pole field thruster by 30%. They are 0.65 and 0.50，respectively. More field free volume can be obtained by utilization of thicker and narrower magnet. So，the thruster can achieve better performance by applying 4 pole magnetic field and moderately large thickness/width ratio of the magnet is beneficial to the improvement of the beam flatness.

Key words: Ion thruster；Magnetic circuit；PIC-MCC；Discharge loss；Beam flatness

摘要： 为了研究磁路结构对与新型GEO平台配套的30cm离子推力器(LIPS-300)性能的影响，采用PIC-MCC数值模拟方法对LIPS-300在其典型工作点下的放电损耗和束流平直度进行了研究，其中输入磁场采用有限元软件Maxwell计算得到，另外还利用Maxwell研究了磁体尺寸对侧壁磁环对产生的磁场等值线的影响。结果表明在LIPS-300的典型工作点下，4极场推力器比3极场推力器放电损耗高3%，分别是164W/A和160W/A，束流平直度高30%，分别为0.65和0.50。利用较厚较窄的磁环能够获得更大的无场区体积。因此，采用4极场将获得更好的推力器性能，采用较大厚度/宽度比的磁体有利于推力器束流平直度的改进。

关键词: 离子推力器；磁路；PIC-MCC；放电损耗；束流平直度