Laser-induced fluorescence measurements of acceleration zone scaling in the 12.5 kW HERMeS Hall thruster
Laser-induced fluorescence measurements of acceleration zone scaling in the 12.5 kW HERMeS Hall thruster
复制标题
12.5 kW HERMeS 霍尔推进器加速区缩放的激光诱导荧光测量
DOI：
10.1063/1.5040388
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发表时间：
2018
影响因子：
3.2
通讯作者：
R. Hofer
中科院分区：
文献类型：
--
作者：
V. Chaplin;B. Jorns;A. Lopez Ortega;I. Mikellides;R. Conversano;R. Lobbia;R. Hofer
我们在 NASA 具有磁屏蔽的 12.5kW 霍尔效应火箭中，对加速区缩放与放电电压 (V d)、磁场强度 (B) 和设施背景压力 (P B G) 进行激光诱导荧光测量。在固定放电电流下，放电电压为300~600V的等离子体电位分布在等离子体电位小于300V的区域大致重叠；由于电位梯度陡峭的区域更宽，离子加速在更高的 V d 处开始更上游。通道外半部和羽流附近的平均离子速度矢量的径向散度随着 V d 的减小而增大。在固定 V d 时，加速区位于更高 B 和更高 P B G 处的更上游。在高放电电压下，沿着加速区的通道中心线测量双峰离子速度分布函数 (IVDF)；这种效应归因于大振幅放电电流振荡期间加速区运动的时间平均。在较低的放电电压下，加速区内的电离不能完全解释近羽流中 IVDF 的展宽。这些结果对于理解前极腐蚀具有重要意义，前极腐蚀可能是磁屏蔽推进器长寿命期间的重要磨损机制，并且它们为验证交叉场电子传输的第一原理模型提供了基线数据。我们在 NASA 的 12.5kW 磁屏蔽霍尔效应火箭中，提出了加速区随放电电压 (V d)、磁场强度 (B) 和设施背景压力 (PB G) 变化的激光诱导荧光测量。在固定放电电流下，放电电压为300~600V的等离子体电位分布在等离子体电位小于300V的区域大致重叠；由于电位梯度陡峭的区域更宽，离子加速在更高的 V d 处开始更上游。通道外半部和羽流附近的平均离子速度矢量的径向散度随着 V d 的减小而增大。在固定 V d 时，加速区位于更高 B 和更高 P B G 处的更上游。在高放电电压下，沿着加速区的通道中心线测量双峰离子速度分布函数 (IVDF)；这种效应归因于加速区运动的时间平均......
We present laser-induced fluorescence measurements of acceleration zone scaling with discharge voltage ( V d), magnetic field strength ( B), and facility background pressure ( P B G) in NASA’s 12.5 kW Hall Effect Rocket with Magnetic Shielding. At fixed discharge current, the plasma potential profiles at discharge voltages from 300 to 600 V approximately overlapped in the region with plasma potential less than 300 V; ion acceleration began further upstream at higher V d because the region with a steep potential gradient was broader. The radial divergence of mean ion velocity vectors in the outer half of the channel and near plume increased with decreasing V d. At fixed V d, the acceleration zone was located further upstream at higher B and at higher P B G. Bimodal ion velocity distribution functions (IVDFs) were measured along the channel centerline in the acceleration zone at high discharge voltages; this effect was attributed to time-averaging over movement of the acceleration zone during large-amplitude discharge current oscillations. At lower discharge voltages, the broadening of the IVDFs in the near plume could not be fully explained by ionization within the acceleration region. These results have implications for understanding front pole erosion, which can be an important wear mechanism over the long lifetimes of magnetically shielded thrusters, and they provide baseline data for validating first principles models of cross-field electron transport.We present laser-induced fluorescence measurements of acceleration zone scaling with discharge voltage ( V d), magnetic field strength ( B), and facility background pressure ( P B G) in NASA’s 12.5 kW Hall Effect Rocket with Magnetic Shielding. At fixed discharge current, the plasma potential profiles at discharge voltages from 300 to 600 V approximately overlapped in the region with plasma potential less than 300 V; ion acceleration began further upstream at higher V d because the region with a steep potential gradient was broader. The radial divergence of mean ion velocity vectors in the outer half of the channel and near plume increased with decreasing V d. At fixed V d, the acceleration zone was located further upstream at higher B and at higher P B G. Bimodal ion velocity distribution functions (IVDFs) were measured along the channel centerline in the acceleration zone at high discharge voltages; this effect was attributed to time-averaging over movement of the acceleration zone ...