Mode Transitions in Hall-Effect Thrusters Induced by Variable Magnetic Field Strength

Sekerak, Michael J.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.

doi:10.2514/1.b35709

Cited by 55 publications

(43 citation statements)

References 19 publications

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“…The peak-topeak values of the thruster discharge current did not vary as a function of axial or radial plate bias for either krypton or xenon operation. It is important to note that an increase in discharge current peak-to-peak was observed between axial plate biases of 10 and 20 Vand at a radial plate bias of 100 V. This seemingly discontinuous jump in discharge current peak-to-peak values resembled one of the characteristics identified by Sekerak et al to be indicative of a mode transition [56]. However, to meet the full definition of a mode transition outlined by Sekerak et al, a concomitant discontinuity would also have to be observed in the mean discharge current and peak frequency [56].…”

Section: Discharge Current Oscillationssupporting

confidence: 59%

“…It is important to note that an increase in discharge current peak-to-peak was observed between axial plate biases of 10 and 20 Vand at a radial plate bias of 100 V. This seemingly discontinuous jump in discharge current peak-to-peak values resembled one of the characteristics identified by Sekerak et al to be indicative of a mode transition [56]. However, to meet the full definition of a mode transition outlined by Sekerak et al, a concomitant discontinuity would also have to be observed in the mean discharge current and peak frequency [56]. However, no such changes in either of these parameters were observed and, as such, this shift was unlikely to be due to a mode transition but, rather, may be more emblematic of the oscillatory nature of the thruster when operating with krypton.…”

Section: Discharge Current Oscillationssupporting

confidence: 59%

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Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

Frieman

Brown

Liu

et al. 2018

Journal of Propulsion and Power

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Section: Discharge Current Oscillationssupporting

confidence: 59%

Section: Discharge Current Oscillationssupporting

confidence: 59%

Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

Frieman

Brown

Liu

et al. 2018

Journal of Propulsion and Power

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“…The externally loaded magnetic field is the most important factor to ensure the efficient and stable operation of the Hall thruster . As the electrons are magnetized inside the channel, the magnetic field lines are approximatively equipotential; the most basic principle that guides the design of the magnetic field configuration is thereby shaping an electric field profile that can facilitate efficient acceleration of non‐magnetized ions.…”

Section: Introductionmentioning

confidence: 99%

Particle‐in‐cell simulation of the effect of curved magnetic field on wall bombardment and erosion in a hall thruster

Liu

Hu³

et al. 2019

Contributions to Plasma Physics

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A curved, convex towards the channel bottom magnetic field is an important feature of an advanced Hall thruster that allows confining the plasma flow in the channel center, reducing the divergence angle of the ejected ion beam, and improving the discharge performance. In this article, the discharge behaviour of a Hall thruster in magnetic fields with different degrees of curvature is simulated with a particle‐in‐cell numerical method, and the effect of curved magnetic field on the ion bombardment and wall erosion and the associated mechanisms are studied and analysed. The results show that, as the curvature of the magnetic field increases, the propellant ionization becomes more confined at the channel center, the potential drop inside the channel decreases, and the acceleration region shifts outside the channel, which lead to the attenuation of the ion energy bombarding the wall and the deviation of the bombardment angle from the optimal sputtering angle. Conversely, the ion flux bombarding the wall near the channel exit increases. Nevertheless, the bombardment energy and angle are the dominant factors for the wall erosion, and the wall erosion rate clearly decreases with the increasing curvature of the magnetic field. These findings are closely related to the behaviour of electron conduction under a curved magnetic field; the relevant mechanisms are clarified in this article.

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“…The nominal mode can be characterized by a high ionization of the neutral gas, a maximum ratio between ion and discharge currents to maintain a low electric power, and a minimum of the amplitude of current oscillations (necessary for the architecture of power processing unit and cathode operation). Mode transitions have been established through experimental campaigns for variable discharge voltages and magnetic field strengths for a SPT-100 together with calculations Hara et al 2015) and for variable magnetic field strengths for the 6kW H6 (Sekarak et al 2016). New studies have been reinforced by the implementation of time-resolved diagnostics including CCD fast camera and optical fibers (e.g.…”

Section: Operating Regimes and Wall Effectsmentioning

confidence: 99%

“…New studies have been reinforced by the implementation of time-resolved diagnostics including CCD fast camera and optical fibers (e.g. Bouchoule et al 2001, Ellison et al 2012Sekarak et al 2016;) that are capable to offer a new insight of the plasma dynamic in the 5-30 kHz range.…”

Section: Operating Regimes and Wall Effectsmentioning

confidence: 99%

Latest progress in Hall thrusters plasma modelling

Taccogna

Garrigues

2019

Rev. Mod. Plasma Phys.

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In the last thirty years, numerical models have revealed different physical mechanisms involved in the Hall thruster functioning leading to a bridge between analytical prediction / empirical intuition and experiments. For this reason, modeling effort is continuously increasing in the domain of Hall Thrusters. Two basic approaches exist: one based on fluid/hybrid simulation where the distribution of electrons is assumed Maxwellian and the plasma inside the thruster, considered as quasineutral, is described with macroscopic quantities (density, velocity and energy); the second approach is based on kinetic description for charged particles where no approximation is made for the distribution of particles. Fluid or hybrid approaches offer the advantage of demanding low run times and computational resources. They are very useful to perform parametric studies but actually the anomalous phenomena responsible for electron transport across the magnetic field barrier have not been selfconsistently modeled. Kinetic approach is able to better capture phenomena originating on the Debye scale length like the lateral sheaths, ExB electron drift instability, important to explain the anomalous electron transport, but it requires very long run times. For this latter, the progress in computer science offers the advantage to describe conditions more and more close to the thruster operation. In this review, we will present the two approaches emphasizing on numerical schemes used with assumptions and approximations and on main results obtained. Future directions on the Hall thruster modeling will finally outlined.

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Mode Transitions in Hall-Effect Thrusters Induced by Variable Magnetic Field Strength

Cited by 55 publications

References 19 publications

Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

Particle‐in‐cell simulation of the effect of curved magnetic field on wall bombardment and erosion in a hall thruster

Latest progress in Hall thrusters plasma modelling

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