The measurement of exhaust velocity of pulsed plasma thruster

Pang, Hui; Zhang, Z.-Y.

doi:10.2514/6.1985-2023

Cited by 2 publications

(2 citation statements)

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“…To study the plasma propagation process, a triple Langmuir probe was used to measure the ion saturation current of the local plasma plume [30,31]. This method has previously been used for PPT plasma diagnostics [32][33][34].…”

Section: Langmuir Probe Measurementsmentioning

confidence: 99%

Diagnostics of ion and electron diffusion in pulsed plasma thrusters using neutral gas injection

Zhang

Tang

et al. 2020

Plasma Sources Sci. Technol.

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Pulsed plasma thrusters (PPTs) have been widely used in space flight applications due to their low cost and robustness. Recently, it has been observed that during the operation of a PPT, the plasma plume exhibits an in-plume acceleration phenomenon where the leading-edge ions continue to accelerate in the plume even in the absence of electromagnetic forces. The physical mechanism behind the phenomenon may be ambipolar diffusion in nature. However, details regarding the propagation of electrons within the plume are still unknown. To better understand the complete plasma diffusion process, it is important to understand the behavior of both ions and electrons. To investigate this mechanism, a diagnostic method using neutral gas injection is proposed to estimate the velocity of fast electrons within the plasma plume. This is a new method where neutral gas is injected at the plasma plume edge to increase the local visible light emission and ionization rate of electrons. In addition to this, a triple Langmuir probe, bandpass filter, and spectrometer were also used to study the plume characteristics. From the experimental results, we estimate that the exhaust velocity of the electrons is over 200 km s −1 , roughly an order of magnitude higher than the ion velocity (26 km s −1 ). The acceleration of ions and the corresponding deceleration of electrons with downstream distance was observed using time-of-flight probe data. Furthermore, the spectral data was also used to identify electron deceleration within the plume. These results further suggest that ambipolar diffusion of electrons and ions may exist in the PPT plume, and that the in-plume acceleration of ions is due to the ambipolar electric field in the plume. Another implication is that depending on the length scales, the plasma plume of the PPT can be non-quasineutrally distributed during the initial period of plume formation.

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Section: Langmuir Probe Measurementsmentioning

confidence: 99%

Diagnostics of ion and electron diffusion in pulsed plasma thrusters using neutral gas injection

Zhang

Tang

et al. 2020

Plasma Sources Sci. Technol.

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“…For simplification, most models are based on the assumption that the plasma plumes are distributed quasi-symmetrically along the thruster's exit direction [12]. This assumption has been widely used in simulation studies that use methods such as the view factor method [13], two-dimensional axisymmetric simplification [14], the Abel inversion method [15], etc. At the same time, the axisymmetric plume assumption is also adopted in the plume diagnostics and divergence angle measurements of ion thrusters, Hall thrusters, and magnetoplasmadynamic thrusters [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Time-resolved investigation of the asymmetric plasma plume in a pulsed plasma thruster

Zhang¹,

Zhang²,

Ling³

et al. 2020

J. Phys. D: Appl. Phys.

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Electric propulsion (EP) has become one of the most promising options for the motion control of small satellites. The physics behind the ejected plasma plumes of EP thrusters has attracted significant interest due to their interactions with the critical components of satellites. Axisymmetric plume assumptions are widely used in simulations and plume diagnostics. However, we show here that the plasma plume of a parallel-plate pulsed plasma thruster (PPT) is asymmetrically distributed along the centerline of the electrodes, contrary to the inherent axisymmetric assumption. To study this asymmetric plume structure in depth, a triple Langmuir probe was used to obtain the electron density of a two-dimensional plume area over the operating period of a PPT. The electron density results show that the plasma forms an 'I' shape plume at 2 µs after the initial main discharge. However, over time, the plume appears to cant significantly towards the cathode. The physical mechanism behind the asymmetric plume structure is studied through inter-electrode magnetic probe measurements and plasma trajectory analyses. The successive magnetic profiles indicate that the plasma is accelerated by a non-symmetrical electromagnetic force between the electrodes, which results in the plasma exhausting out with an entirely asymmetric distribution shifted upwards towards the cathode. This was also verified using varying sets of discharge voltage experiments. This work also indicates that care must be taken in the selection of the measurement points in PPT plume diagnostics. The measurement points should be chosen above the centerline of the PPT exit as the plasma parameters along the centerline may not be the most energetic part as previously believed. Furthermore, the asymmetric acceleration component of the electromagnetic force between the electrodes can enlighten us in the design of electromagnetic field configurations for future discharge channel optimization.

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The measurement of exhaust velocity of pulsed plasma thruster

Cited by 2 publications

References 0 publications

Diagnostics of ion and electron diffusion in pulsed plasma thrusters using neutral gas injection

Diagnostics of ion and electron diffusion in pulsed plasma thrusters using neutral gas injection

Time-resolved investigation of the asymmetric plasma plume in a pulsed plasma thruster

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