Study On The Plume Characteristics Of Pulsed Plasma Thruster

The plume distribution characteristics of the ablative pulse plasma thruster (APPT)with parallel plate electrode are systematically studied in this research based on boththeoretical and experimental analysis. Triple Langmuir probe diagnostic methods andmaterials analysis methods were adopted to describe the deposition pollutiondistribution characteristics at all positions in the APPT’s plume.In order to study the characteristics of the plasma in the plume of APPT, acurrent-based Triple Langmuir probe method is applied to diagnose the plume of APPT.For the sake of improving the electromagnetic compatibility and decreasing the errors inmeasurement, a diagnostic system with probe, collection circuit and glow cleaningdevice is elaborately designed. A FIR digital filter based on Matlab is designed and thesoftware for calculation is compiled using a developed calculation method by Labview.Therefore, bulk solving of the plume’s characteristics parameters is realized. Throughthis system, the diagnostic experiment takes the plasma characteristics in differentpositions that have disparate axial angle (0°to40°) and axial distance (8cm to20cm) intwo planes which is perpendicular or parallel with the discharging plate in the plume ofAPPT discharging in five different energies(6J,10J,13.5J,17J,24J). The result showsthat electron temperature and electron density of the plasma in APPT plume decreasesas the axial angle and axial distance increases; and increases as the discharge energyincreases. The plasma in the plane perpendicular with the pad having a non-symmetricalcharacteristic, and the each attenuating trend of electron temperature and electrondensity value from center to boundary in perpendicular plane and parallel plane showsdifferent.In order to study the APPT plume pollution characteristics, the plume of APPTwith13.5J discharge energy in different positions deposition sample is collected. Itssurface morphology is observed using scanning electron microscopy and atomic forcemicroscope, the structural components of the film is analyzed adopting Fouriertransform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS), and theoptical characteristics of the film is tested employing UV-visible spectrophotometer on.The result shows that the samples deposited in different positions in APPT’s plumegenerate a low-fluorocarbon film. And the microstructures of the deposited filmcollected in disparate region of the plume transform in different trends. Affected by thefilm properties, the deposition film has the characteristics of low transmittance againstthe light whose wavelength is less than500nm and the film can also enhance thereflectance. The sample’s optical characteristic shows a great angle dependency.In this paper, the methods and conclusions of the research in the APPT plumecharacteristics provide favorable guidance for the APPT plume characteristics theoretical analysis and simulation research and discharge ablation mechanism.