摘要
2 cm电子回旋共振离子推力器具有高比冲、长寿命的特点,其应用于引力波探测的可行性已经过初步探索.然而,在探究离子源推力下限的过程中发现,在极低功率(0.5 W)和极低流量(0.1 sccm,1 sccm=1 L/min)的极限工作状态下,过度施加栅极电压可能引发离子源猝灭.采用实验手段对猝灭现象进行观测的难度很大,一方面因为猝灭现象具有随机性和瞬时性;另一方面,介入式诊断对弱放电水平的等离子体干扰很大,而光学诊断又有栅极系统阻挡.为此本文采用全粒子数值模型对离子源进行了一体化模拟,复现了猝灭现象.模拟结果表明,天线和放电室之间的双极扩散是导致离子源猝灭的最根本原因.明晰了猝灭机理后,本文提出了相应的改进措施,并用一体化模拟进行了理论验证.对猝灭机理的研究将为离子源的设计和应用提供理论依据,保障离子源安全稳定工作,满足引力波探测任务的推力需求.
A 2-cm electron cyclotron resonance ion source has the advantages of long life and high specific impulse,which can meet the requirements for space gravitational waves detection.In the experiment on finding the lower limit of thrust,it is found that when the ion source operates under the extreme condition of 0.5-W microwave power and 0.1-sccm gas flow rate,increasing the voltages of grid system excessively may cause flameout.The plasma discharge level is controlled by the gas supply,microwave,and power supply system,and their small disturbances will make experimental results different,thus the flameout of the ion source appears randomly and transiently.Besides,it is difficult to observe the flameout phenomenon experimentally,because the probe diagnosis has big interference to low-density plasma,and the optical diagnosis is blocked by the grid system.Therefore,the integrative simulation with the full particle-in-cell method is used to simulate the operating process of the ion source,whose calculation range includes the discharge chamber,grid system,and plume.Through simulating the processes of plasma discharge and ion beam extraction continuously in space and time,the flameout phenomenon can be reproduced artificially after increasing the voltages of grid system.The simulation results show that the ambipolar diffusion between the antenna and discharge chamber is the fundamental reason for the flameout of the ion source.In the circuit,the antenna does not touch the discharge chamber but for bulk plasma,which makes its surface gradually accumulate charges until it reaches the floating potential.Because the increase of the voltage of antenna lags behind that of grid system,a strong electric field will appear between the antenna and chamber.Then,electrons and ions respectively move toward the chamber and antenna,the ambipolar diffusion helps the antenna reach the floating potential rapidly.When the plasma density inside the chamber is low,the ambipolar diffusion will cause flameout.In order to avoid the flameout of the
作者
付瑜亮
杨涓
王彬
胡展
夏旭
牟浩
Fu Yu-Liang;Yang Juan;Wang Bin;Hu Zhan;Xia Xu;Mu Hao(School of Astronautics,Northwestern Polytechnical University,Xi’an 710072,China;Innovation Academy for Microsatellites of Chinese Academy of Sciences,Shanghai 201203,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第8期229-235,共7页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2020YFC2201000)
国家自然科学基金(批准号:11875222)资助的课题~。
关键词
电子回旋共振离子源
粒子模拟
猝灭
electron cyclotron resonance ion source
particle-in-cell simulation
flameout phenomenon
