Modeling on plasma energy balance and transfer in a hollow cathode

Cao, Shuai; Ren, Junxue; Tang, Haibin; Pan, Ruojian; Zhang, Zhe; Zhang, Kaiyu; Cao, Jinbin

doi:10.1088/1361-6463/ab197e

Cited by 16 publications

(14 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Discharge completion occurs in around 10 µs. Therefore, the transient plume generated by PPTs will exhibit different plasma propagation mechanisms when compared with the plume of stationary thrusters (such as ion and Hall thrusters) [30,31].…”

Section: Vacuum System and Pulsed Plasma Thrustermentioning

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.

View full text Add to dashboard Cite

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.

show abstract

Section: Vacuum System and Pulsed Plasma Thrustermentioning

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.

View full text Add to dashboard Cite

show abstract

“…Again, using the NSTAR cathode conditions, b = 0.5. Electric field work consists of two terms, namely, the ohmic heating and the electron pressure-gradient work [36]. The 0-D approach does not consider the spatial distribution of the electron's temperature, which means the electric field work actually equals the ohmic heating.…”

Section: Steady-state Modelmentioning

confidence: 99%

“…The energy brought in by ions from the orifice region, P ds , is much smaller than the other terms according to [36] and therefore can be neglected. The component power balance terms are expressed as follows:…”

Section: Steady-state Modelmentioning

confidence: 99%

Effect of low-frequency disturbance on the self-sustained discharge of hollow cathode

Liu

Ren

Cao

et al. 2020

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The existence of low-frequency disturbance can affect the discharge stability of a hollow cathode, and may even lead to the extinction of the discharge. In this paper, a semi-transient algorithm based on the classical 0-D theoretical model of an orificed hollow cathode was developed to study the discharge stability of a hollow cathode under a continuous low-frequency electric field disturbance. A laboratory experiment using an orificed BaO-W cathode was carried out to confirm the validity of transient analysis results and to determine an appropriate time step in the analysis. The theoretical evolution trend of the discharge current is largely in agreement with the experiment for a time step value of 12.5 µs although there is a 7% error in the discharge duration prediction. This study has identified the role of two emission enhancement mechanisms in the failure process of a self-sustained discharge, namely the Schottky effect and the sheath funneling effect. The presence of the sheath funneling effect induces larger amplitude oscillations and a sharp drop in discharge parameters when the effect ceases to exist, and this significantly weakens the discharge stability. The influence of operating conditions and disturbance parameters on transient discharge characteristics was examined for the NASA NSTAR cathode. Within the parameter range that was studied, findings show that higher xenon flow rates or lower discharge currents provide optimal duration as a result of higher electron temperatures and denser plasma at the initial state. For a fixed operation point, the discharge duration was found to decline exponentially with disturbance amplitude and quadratically with disturbance frequency.

show abstract

“…Two-dimensional models, both fluid [2], [3], [4], [5], particle in cell (PIC) [6] and Hybrid-PIC [7], have been proven to be essential in understanding the physics of hollow cathodes, and in particular the developing and dynamics of the external plume region. By solving the unsteady fluid equations along the axial and radial directions, these models are capable of investigating the plasma instabilities established in the plume region.…”

Section: Introductionmentioning

confidence: 99%