Optical detection method of discharge mode transition of inductively coupled plasma in an atmosphere-breathing electric propulsion system

Plasma discharge stability is an important problem in atmosphere-breathing electric propulsion system when maintaining long-term missions at ultra-low earth orbit.This paper designed an inductively coupled plasma source to imitate the ionization section.The effect of inflow rate and Radio Frequency(RF)power on the plasma discharge mode transition is experimentally studied.A discharge mode detection method is proposed,which determines the discharge mode by identifying the morphology of the plasma core.By using the method,the discharge mode transition is quantified and a control model based on the parameter sensitivity is constructed.To verify the method,the spectra are measured and the electron temperature spatial distribution is calculated.And the method has been proven effective.The results show that the inductively coupled discharge contains capacitive components affected by the mass flow rate and the radio frequency power.The plasma characteristics can be maintained stably by controlling the radio frequency power when the mass flow rate randomly changes in a certain range.It is demonstrated that the application of detection method effectively identifies the discharge mode,which is a promising active control method for the plasma discharge mode.

A brief review of alternative propellants and requirements for pulsed plasma thrusters in micropropulsion applications

Technological miniaturization has enabled the development of small satellites weighing as little as 1 kg.Unfortunately,there is still a lack of suitable efficient micropropulsion systems at these scales.The pulsed plasma thruster is a structurally simple form of electric propulsion.This simplicity also makes it ideally suited for miniaturization.Its history can be traced back to applications in satellites that are much larger than micro/nano-satellites.The vast majority of modern pulsed plasma thrusters use solid polytetrafluoroethylene(PTFE)as a propellant.Unfortunately,at lower discharge energy levels such as those necessitated by the power limitations of micro/nano-satellites,PTFE has a tendency to exhibit carbon deposition,which can ultimately lead to thruster failure.In this new era of small satellites,it is important to consider alternative propellants in the miniaturization of pulsed plasma thrusters.This brief review discusses the needs and limitations of small satellites and alternative propellants that may be able to meet these needs.Such propellants may be able to offer advantages such as a longer thruster lifetime,a higher specific impulse,or a higher thrust-topower ratio.This would enable the development of different types of pulsed plasma thrusters that can be tailored towards specific mission requirements.

An atmosphere-breathing propulsion system using inductively coupled plasma source

CubeSats have attracted more research interest recently due to their lower cost and shorter production time.A promising technology for CubeSat application is atmosphere-breathing electric propulsion,which can capture the atmospheric particles as propulsion propellant to maintain longterm mission at very low Earth orbit.This paper designs an atmosphere-breathing electric propulsion system for a 3 U CubeSat,which consists of an intake device and an electric thruster based on the inductively coupled plasma.The capture performance of intake device is optimized considering both particles capture efficiency and compression ratio.The plasma source is also analyzed by experiment and simulation.Then,the thrust performance is also estimated when taking into account the intake performance.The results show that it is feasible to use atmosphere-breathing electric propulsion technology for CubeSats to compensate for aerodynamic drag at lower Earth orbit.

1A级射频感性耦合等离子体中和器电子引出特性研究

为解决低轨道吸气式离子电推力器的电中和问题,设计了一套抗氧化能力强、长寿命的1 A级氙工质感性耦合等离子体中和器,实验研究了发射孔径对其电子引出特性的影响。实验结果表明:发射孔径的变化,会对中和器电子引出电压、饱和电流和工质利用系数产生较大的影响,且在部分孔径下发现了电子束流随引出电压上升时出现二次跃变现象,根据工质利用系数和电子引出功耗比确定出中和器最优发射孔径为1.5 mm;电子束流引出为1 A时,工质利用系数达到27.7,电子引出功耗比为94.6 W/A。同时,测试了中和器温度对工作稳定性的影响,中和器热平衡状态下与点火初期相比中和器电子引出性能下降约10%。

The plume diagnostics of 30 cm ion thruster with an advanced plasma diagnostics system

In order to achieve a better understanding of plume characteristics of LIPS-300 ion thruster,the beam current density,ion energy and electron number density of LIPS-300 ion thruster plume are studied with an Advanced Plasma Diagnostics System(APDS)which allows for simultaneous in situ measurements of various properties characterizing ion thruster,such as plasma density,plasma potential,plasma temperature and ion beam current densities,ion energy distribution and so on.The results show that the beam current density distribution has a double‘wing'shape.The high energy ions were found in small scan angle,while low energy ions were found in greater scan angle.Electron number density has a similar shape with the beam current density distribution.

Investigation on plasma structure evolution and discharge characteristics of a single-stage planar-pulsed-inductive accelerator under ambient fill condition

The physical process of a single-stage planar-pulsed-inductive accelerator is investigated.Measurements include the waveforms of circuit current,capacitor voltage,plasma radiation intensity,and temporal plasma structure photos captured by a high-speed camera.Experiments are conducted under static ambient fill condition using argon as propellant.Varied values of capacitor voltage and gas pressure are compared.Further discussions quantify the EM interaction between circuit and plasma,as well as their energy deposition and current sheet acceleration.Based on the results of experiments,physical mechanisms of the initial ionization phase and the following acceleration phase are analyzed theoretically.

Electron population properties with different energies in a helicon plasma source

The characteristics of electrons play a dominant role in determining the ionization and acceleration processes of plasmas.Compared with electrostatic diagnostics,the optical method is independent of the radio frequency(RF)noise,magnetic field,and electric field.In this paper,an optical emission spectroscope was used to determine the plasma emission spectra,electron excitation energy population distributions(EEEPDs),growth rates of low-energy and highenergy electrons,and their intensity jumps with input powers.The 56 emission lines with the highest signal-to-noise ratio and their corresponding electron excitation energy were used for the translation of the spectrum into EEEPD.One discrete EEEPD has two clear different regions,namely the low-energy electron excitation region(neutral lines with threshold energy of13–15 eV)and the high-energy electron excitation region(ionic lines with threshold energy?19 e V).The EEEPD variations with different diameters of discharge tubes(20 mm,40 mm,and 60 mm)and different input RF powers(200–1800 W)were investigated.By normalized intensity comparison of the ionic and neutral lines,the growth rate of the ionic population was higher than the neutral one,especially when the tube diameter was less than 40 mm and the input power was higher than 1000 W.Moreover,we found that the intensities of low-energy electrons and high-energy electrons jump at different input powers from inductively coupled(H)mode to helicon(W)mode;therefore,the determination of W mode needs to be carefully considered.

Experimental investigation on the evolution of plasma properties in the discharge channel of a pulsed plasma thruster

Pulsed plasma thrusters(PPTs)are an attractive form of micro-thrusters due to advantages such as their compactness and lightweight design compared to other electric propulsion systems.Experimental investigations on their plasma properties are beneficial in clarifying the complex process of plasma evolution during the micro-second pulse discharge of a PPT.In this work,the multi-dimensional evolutions of the light intensity of the PPT plasma with wavelength,time,and position were identified.The plasma pressure was obtained using an iterative process with composition calculations.The results show that significant ion recombination occurred in the discharge channel since the line intensities of CII,CIII,CIV,and FII decreased and those of CI and FI increased as the plasma moved downstream.At the center of the discharge channel,the electron temperature and electron density were in the order of 10000 K and 1017 cm-3,respectively.These had maximum values of 13750 K and 2.3?×?1017 cm-3 and the maximum temperature occurred during the first half-cycle while the maximum number density was measured during the second half-cycle.The estimated plasma pressure was in the order of 105 Pa and exhibited a maximum value of 2.69?×?105 Pa.

电子回旋共振离子推力器研究与应用综述

电子回旋共振离子推力器(ECRIT)以电子的无碰撞加热机制产生等离子体,具有推力范围宽、下限低、可精确控制的特点。本文从原理和工作过程出发,分析了ECRIT对当今空间飞行任务的适用性。围绕这些适用范围,综述了当前原理可行的10cm低推力、2cm微推力ECRIT在不同工质驱动下的研究和应用现状,总结了这些推力器性能的重要特征,分析了制约推力器进一步发展的关键问题。结果表明,ECRIT因为独特的原理和物理过程以及成功的飞行实例,被证明适用于当今深空与近地小行星及引力波探测、微小卫星控制以及地球极低轨道飞行器的阻力补偿。

应用于电推进的碘工质电子回旋共振等离子体源

电子回旋共振(electron cyclotron resonance,ECR)源具有无需内电极、低气压电离、等离子体密度较高和结构紧凑等优点,适用于小功率电推进.因此,研究小功率碘工质ECR等离子体源具有重要意义.本文首先设计了一套耐腐蚀且可以均衡稳定输出碘蒸汽的储供系统;然后完成了耐碘腐蚀ECR推力器设计,利用耐腐蚀的同轴谐振腔结构将微波馈送到推力器,并将通道磁场变为会切型磁场以产生更多ECR层;最终联合点火实验成功,成为国际上首个可以用于电推进的ECR电离碘工质等离子体源.分析实验和静磁场、微波电场分布发现,小功率、低流量下的不稳定等离子体羽流闪烁由寻常波电子等离子体共振加热和非寻常波ECR加热模式之间的转化引起.高流量下电离率下降是由电子损失、壁面损失和碘工质电负性导致.并依据此原理提出了改进方案.放电后等离子体源没有明显损伤,说明具备长寿命潜力.此项工作初步证实了小功率碘工质ECR电推进方案可行.

低气压离子风推进器仿真与实验

离子风动力具有无需机械旋转部件、低功耗及低噪声等优点,在平流层飞艇和太阳能飞机上具有重要的应用潜力。模拟临近空间的低气压环境,采用“线-柱”电极结构电晕放电装置产生离子风,实验测量不同放电条件下离子风推进器产生的推力和推功比,研究了气压、放电电压、电极间隙对离子风动力的影响。仿真和实验结果表明,气压的降低会导致推进器推功比的下降,具体表现为:当电极间隙为2.0 cm,最大推功比由1 atm(1 atm=101325 Pa)时的17.70 mN/W降低至0.02 atm时的0.24 mN/W;而推功比的损失可以通过增大电极间隙来补偿,当电极间隙增加至14 cm,在0.02 atm的气压环境下,推功比由0.24 mN/W升至0.70 mN/W。通过优化离子风推进器结构,增加电极间隙,离子风动力具备低气压环境下的应用潜力。

微型氙气供给模块性能研究及在轨应用

传统氙气供给系统由于系统复杂、重量体积大、价格昂贵、生产周期长等劣势,已无法适应低轨互联网卫星星座对低功率霍尔电推进系统的轻质化、低成本及快速研制的发展要求。本文提出一种基于复杂流体通道先进成型和微型化流体控制部件相结合的Bang-Bang控制型微型氙气供给模块,对其结构组成和工作原理进行了介绍。基于Matlab与AMESim联合仿真方式搭建了其系统动态仿真模型,并采用Peng-Robinson方程考虑了氙气的超临界特性,对其Bang-Bang压力控制特性进行仿真研究。对微型氙气供给模块与600W霍尔推力器的在轨数据进行了分析,产品在轨工作稳定,在轨数据与仿真结果相吻合。

空间电推进技术发展及应用展望

我国空间电推进技术已进入成熟和全面应用的新阶段。为进一步促进电推进技术发展,加速推动空间动力领域技术进步,采用调研、对比分析的方法,以功率为划分标准,重点结合未来空间任务对电推进的应用需求,针对电推进各技术方向的特点,从“中、微、超”3个功率区间对空间电推进进行了分类综述。总结了国内外电推进技术的发展现状和存在的不足,提出了需要攻克的关键难点,研判了发展的主要趋势,归纳了存在的共性问题,提出了未来10年空间电推进技术的发展建议,供我国卫星用户、总体单位和空间电推进专业技术单位参考。

地月及深空探测先进电推进技术的发展

聚焦地月及深空探测关键技术之一——空间电推进技术,介绍了空间电推进的技术内涵和中国电推进应用现状,从任务特点、电推配置、应用效益等维度剖析了国际上典型的基于电推进的地月及深空探测任务。瞄准中国深空探测领域未来发展需求,针对月球探测、小行星探测、载人火星探测、太阳系边际探测和地月空间科学探测5种典型场景,分别介绍了电推进优化应用策略,梳理了面向深空探测的先进电推进关键技术体系和发展重点。最后,按照“一中一超一微”的发展思路给出了空间电推进技术发展建议,为后续空间电推进在地月及深空探测领域实现更加广泛的应用提供参考。

霍尔电推进空间应用现状及未来展望

对霍尔电推进的空间应用现状进行综述,并对其未来发展趋势进行展望。针对我国霍尔电推进在原始创新、研发效率、产品成熟度、在轨应用等方面与国外存在的差距,提出加强需求分析和任务牵引、加强工作机理研究、加快产品迭代、加强天地差异研究、加快生产线建设等发展建议,以更好地推动发展。

微小卫星用低功率电推进技术研究进展

随着微小卫星任务的不断拓展,轨道机动、位置保持、姿态控制、自主离轨等任务对低功率推进系统的需求日益增加。结合微小卫星对低功率推进系统高比冲、推力精确、结构紧凑等技术需求,综述了射频离子电推进、微波离子电推进和脉冲等离子体电推进技术的研究和应用现状;通过列举各国应用案例,对比了各推进系统的性能和技术特点,总结了各推进系统的关键技术;在此基础上,分析了我国微小卫星用电推进技术发展趋势及后续攻关方向。研究结果可为微小卫星推进系统方案选择提供参考。

Presheath formation and area design limit satellite-based Langmuir probes

In this article,the effect of the finite conductive surface area of a satellite on the use of satellite-based Langmuir probes is reviewed in light of the basic theory of asymmetric double Langmuir probes(ADLPs).Recent theoretical and experimental studies have discussed electron sheath/presheath formation and the electron Bohm criterion along with their implications for satellite-based Langmuir probes.The effects predicted by the latest theory of the electron Bohm criterion were not experimentally observed and the experimental results remain supportive of a critical area ratio(A_(L)/A_(S))_(crit)=(m_(i)/(2.3m_(e)))^(1/2)between the probe area A_(S)and the satellite area A_L as conventionally believed.A satellite-based Langmuir probe must satisfy this criterion to physically act as a single Langmuir probe.However,experimental investigations also found that high-energy electrons adversely affect(A_(L)/A_(S))_(crit)and a Langmuir probe's signal quality by giving additional electron current to A_(L).Based on these results,a number of limitations of the maximum probe area are derived when designing satellite-based Langmuir probes,with consideration of both the aim of the satellite and the plasma where the satellite-based probe works.These proposed measures are expected to only partially alleviate the effect of the inadequate satellite surface area on the application of satellite-based Langmuir probes.Using a larger satellite to carry a Langmuir probe remains the most viable means to obtain precise space plasma parameters.

螺旋波等离子体推进研究进展

螺旋波等离子体推力器是一种新概念磁等离子体推进装置,以其电离率高、无电极烧蚀、寿命长、比冲高等优点受到国内外学者的广泛关注,该新型推力器在未来长寿命深空探测器和卫星的动力系统中具有广阔的应用前景。概述了螺旋波等离子体推力器的系统组成和工作原理、重点介绍了该推力器的研究进展、现状和关键技术,总结了国外在研的四种典型的推力器结构类型,并根据实际情况,提出了国内螺旋波技术在电推进领域的研究方向和发展思路。

电推进研究的技术状态和发展前景

论述了各类电推进器的工作原理、研究状况 ,在分析其主要工作特点的基础上 ,并根据国外成功应用的实例 ,说明了各类电推进器的适用场合。并就电推进器的研究与应用发展前景进行了展望。

脉冲等离子体推力器研究综述

简要介绍了脉冲等离子体推力器(PPT)的基本工作原理;回顾了国内外脉冲等离子推力器的发展历史;阐述了它的优势与面临的挑战;分析了需要研究的关键技术与发展方向。