Non-invasive time-resolved measurements of anomalous collision frequency in a Hall thruster

Dale, Ethan T.; Jorns, Benjamin

doi:10.1063/1.5077008

Cited by 40 publications

(24 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The resulting profile of the anomalous collision frequency is presented in Figure 6. It is worth noting how this profile recovers values of the anomalous collisionality close to the ones obtained by other authors and calibrated on experimental data [29,46,61].…”

Section: Resultssupporting

confidence: 85%

“…Therefore, β could also be a function of time, i.e., β = β(z, t). While we have decided to fix the axial profile of the anomalous collisionality to limit the degrees of freedom in the model calibration, experimental investigations in the literature [46] have highlighted how β varies significantly during the breathing mode cycle.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, perturbations remain up to a certain degree and, as discussed by Jorns et al in Reference [42], a sharp transition of global plasma parameters and a downstream shift in plasma properties are observed upon probe insertion in the channel. Optical methods, such as Laser Induced Fluorescence (LIF) [44][45][46][47][48][49] and Thompson scattering [50], provide non-intrusive alternatives to fast moving ionic probes for the exploration of the steady and unsteady behavior of the near-plume plasma of Hall thrusters. In spite of being capable of providing useful information, these diagnostic systems can present signal-to-noise interpretation issues and, in most cases, require complex and expensive setups, limiting their extensive use.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

et al. 2021

View full text Add to dashboard Cite

One of the main oscillatory modes found ubiquitously in Hall thrusters is the so-called breathing mode. This is recognized as a relatively low-frequency (10–30 kHz), longitudinal oscillation of the discharge current and plasma parameters. In this paper, we present a synergic experimental and numerical investigation of the breathing mode in a 5 kW-class Hall thruster. To this aim, we propose the use of an informed 1D fully-fluid model to provide augmented data with respect to available experimental measurements. The experimental data consists of two datasets, i.e., the discharge current signal and the local near-plume plasma properties measured at high-frequency with a fast-diving triple Langmuir probe. The model is calibrated on the discharge current signal and its accuracy is assessed by comparing predictions against the available measurements of the near-plume plasma properties. It is shown that the model can be calibrated using the discharge current signal, which is easy to measure, and that, once calibrated, it can predict with reasonable accuracy the spatio-temporal distributions of the plasma properties, which would be difficult to measure or estimate otherwise. Finally, we describe how the augmented data obtained through the combination of experiments and calibrated model can provide insight into the breathing mode oscillations and the evolution of plasma properties.

show abstract

Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

et al. 2021

View full text Add to dashboard Cite

show abstract

“…An understanding of the velocity distribution of electrons also may help lead to refined expressions for relating measured wave properties to transport [181]. Similarly, there have been recent advances in techniques based on laser induced fluorescence that have allowed, for the first time, the noninvasive measurement of anomalous electron transport inside Hall thrusters [170]. This data will be crucial for providing "ground truth" for the local transport that can be used as a point of comparison to determine if the contributions from instabilities, if any, are sufficient to explain the electron dynamics.…”

Section: Advances In Science and Technology To Meet Challengesmentioning

confidence: 99%

Physics of E × B discharges relevant to plasma propulsion and similar technologies

et al. 2020

Self Cite

View full text Add to dashboard Cite

This paper provides perspectives on recent progress in the understanding of the physics of devices where the external magnetic field is applied perpendicularly to the discharge current. This configuration generates a strong electric field, which acts to accelerates ions. The many applications of this set up include generation of thrust for spacecraft propulsion and the separation of species in plasma mass separation devices. These "E×B" plasmas are subject to plasma-wall interaction effects as well as various micro and macro instabilities, and in many devices, we observe the emergence of anomalous transport. This perspective presents the current understanding of the physics of these phenomena, state-of-the-art computational results, identifies critical questions, and suggests directions for future research.

show abstract

“…On the other hand, low-frequency plasma oscillations include breathing mode oscillations (Boeuf & Garrigues 1998; Barral & Ahedo 2009; Hara et al. 2014 a , b ; Dale & Jorns 2019) and azimuthally rotating spokes (Ellison et al. 2012; Sekerak et al.…”

Section: Introductionmentioning

confidence: 99%

Theory of gradient drift instabilities in low-temperature, partially magnetised plasmas

2022

View full text Add to dashboard Cite

A fluid dispersion theory in partially magnetised plasmas is analysed to examine the conditions under which large-wavelength modes develop in Penning-type configurations, that is, where an electric field is imposed perpendicular to a homogeneous magnetic field. The fluid dispersion relation assuming a slab geometry shows that two types of low-frequency, gradient drift instabilities occur in the direction of the $\boldsymbol {E} \times \boldsymbol {B}$ and diamagnetic drifts. One type of instability, observed when the equilibrium electric field and plasma density gradient are in the same direction, is similar to the classic modified Simon–Hoh instability. A second instability is found for conditions in which (i) the diamagnetic drift is in the direction opposite to the $\boldsymbol {E} \times \boldsymbol {B}$ drift and (ii) the magnitude of the diamagnetic drift is sufficiently larger than the electron thermal speed. The present fluid dispersion theory suggests that the rotating spokes driven by such fluid instabilities propagate in the same direction as the diamagnetic drift, which can be in the same direction as or opposite to the $\boldsymbol {E} \times \boldsymbol {B}$ drift, depending on the plasma conditions. This finding may account for the observation, in some plasma devices, of the rotation of large-scale structures in both the $\boldsymbol {E} \times \boldsymbol {B}$ and $-\boldsymbol {E} \times \boldsymbol {B}$ directions.

show abstract

Non-invasive time-resolved measurements of anomalous collision frequency in a Hall thruster

Cited by 40 publications

References 27 publications

Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

Physics of E × B discharges relevant to plasma propulsion and similar technologies

Theory of gradient drift instabilities in low-temperature, partially magnetised plasmas

Contact Info

Product

Resources

About