发散磁场中等离子体加速和推进性能数值研究

Numerical Investigation on Plasma Acceleration Process and Propulsion Performance on Divergence Magnetic Field

关键词:  等离子体推力器  发散磁场  能量转化  数值模拟

Key words:  Plasma thruster  Divergence magnetic field  Energy conversion  Numerical simulation

摘要:

稳态螺旋波等离子体推力器中，源室放电获得的一定能量的等离子体经过磁喷管加速产生预定的推力和比冲。为了分析在发散磁场约束下，等离子体的运动受约束磁场和内能变化的影响规律及其推进性能，引入了考虑电子和离子不同响应的二维轴对称数值模型。计算了入口中心磁感应强度[B0]为100～500G、电子温度[Te0]为3.0～10.0eV时等离子体的运动。结果表明，入口等离子体的内能增加，[B0]保持100G不变时，其最终膨胀的绝对速度增加，比冲从400s提高到约为580s；内能变化对比冲[Isp]的影响大于磁感应强度。不考虑等离子体与磁场相互作用情况下，文中计算的磁场范围可以最大限度地将内能转化为等离子体的轴向定向动能；为了提高[Isp]，应适当增加电离段等离子体获得的能量，且可以适当降低对产生约束磁场的电流线圈输入能量要求。

Abstract:

In the stable helicon plasma thruster，the plasma with certain energy generated in the discharge cavity is accelerated by the magnetic nozzle to generate the pre-conditioned thrust and specific impulse. To analyze the impact of the confinement magnetic field and internal energy on the acceleration process，the two dimensional axisymmetric numerical model，incorporating the distinct response of the ions and electrons，is introduced，and the magnetic inductive intensity[B0]ranging from 100G to 500G and the electron temperature[Te0]ranging from 3.0eV to 10.0eV are investigated. The results show that，as the inlet internal energy increases at constant[B0]of 100G，the resulting expansion velocity improves，and the specific impulse[Isp]raises from 400s to 580s; meanwhile，the[Isp]is more influenced by the internal energy variations，compared with the magnetic inductive intensity. The internal energy can be transformed into the axial kinetic energy to the limit within the[B0]considered，under the condition that the interaction between the plasma and magnetic field is neglected. The requirement on the magnetic inductive intensity can be lowered，while the plasma energy obtained in the discharge section should be enhanced to increase[Isp].