Air-breathing electric propulsion: mission characterization and design analysis

Crandall, Patrick; Wirz, Richard E.

doi:10.1007/s44205-022-00009-8

Cited by 10 publications

(3 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, when a satellite passes over, it becomes visible and there exists a strong LoS component. Additionally, the distances and velocities of the satellites comply with the records in [43], [44]. On the other hand, since the most important variables are the transmit power P , as wel as the number of antennas L, and the number of RIS elements N , we will mainly provide numerical results versus these variables.…”

Section: Numerical Resultsmentioning

confidence: 99%

Secrecy-Rate Optimization of Double RIS-Aided Space–Ground Networks

Hoang

Vahid

et al. 2023

IEEE Internet Things J.

View full text Add to dashboard Cite

The physical layer security (PLS) of a space-ground communication system is examined. To improve the security performance, a pair of reconfigurable intelligent surfaces (RISs) is integrated into the system and benchmarked against a scheme, where there is only a single RIS close to the ground station. As for the double-RIS scenario, we formulate a secrecy rate maximization problem, and then propose an alternating optimization (AO) algorithm for jointly optimizing three vectors, namely the beamformer of the ground station and the reflecting vectors of two different RISs. Similarly, as for the single-RIS case, we also propose another AO algorithm for optimizing a pair of vectors, namely the beamformer of the ground station and the reflecting vector of the single RIS. Both the double-RIS and the single-RIS AO algorithms are developed on the basis of the first-order Taylor expansion and the Dinkelbach's method, which allow us to approximate non-convex optimization problems by convex ones. Our results demonstrate that the proposed double-RIS scheme outperforms the single-RIS benchmark scheme in terms of its security.

show abstract

Section: Numerical Resultsmentioning

confidence: 99%

Secrecy-Rate Optimization of Double RIS-Aided Space–Ground Networks

Hoang

Vahid

et al. 2023

IEEE Internet Things J.

View full text Add to dashboard Cite

show abstract

“…Several recent mission analysis studies of the ABEP scenario conclude that high specific impulse (I sp ) is a key desired characteristic of the thruster, with a minimum I sp requirement of at least around 3000 s [1,2,5]. This is driven primarily by the tangential drag of the spacecraft and solar array surfaces, which is significant even if these surfaces are aligned with the VLEO air flow.…”

Section: Introductionmentioning

confidence: 99%

Influence of applied magnetic field in an air-breathing microwave plasma cathode

Tisaev,

Karadag,

Fabris

2023

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The air-breathing electric propulsion (ABEP) concept refers to a spacecraft in very-low Earth orbit (VLEO) ingesting upper atmospheric air as propellant for an electric thruster. This compensates atmospheric drag and allows the spacecraft to maintain its orbital altitude, removing the need for on-board propellant storage and allowing an extended mission duration which is not limited by propellant exhaustion. There is a need for development of a robust, high current density and long life cathode (or neutralizer) for air-breathing electrostatic thrusters as conventional thermionic hollow cathodes are susceptible to oxygen poisoning. An Air-breathing Microwave Plasma CAThode (AMPCAT) is proposed to overcome this issue through the use of a microwave plasma discharge, producing an extracted current in the order of 1 A with 0.1 mg/s of air. In this paper, the effect of varying magnetic-field strength and topology is investigated by using an electromagnet coil, which reveals a significantly different behaviour for air compared to xenon. The extracted current with xenon increases by 3.9 times from the zero-field value up to a peak around 150 mT magnetic-field strength at the antenna, whereas an applied field does not increase the extracted current with air at nominal conditions. A non-zero magnetic-field with air is however beneficial for current extraction at reduced neutral densities. A distinct increase in extracted current is identified at low bias voltages with air for a field strength of around 50 mT at the internal microwave antenna, consistent across varying field topologies. The effect of a lowered magnetic-field strength in the orifice region is investigated through the use of a secondary coil, resulting in an extracted current increase of 25 % for a relaxation from 6 mT to 1 mT, and demonstrating the beneficial impact of a locally reduced field strength on electron extraction.

show abstract

“…Several recent ABEP studies suggest a high thruster specific impulse (I sp ) is needed, of at least around 3000 s, due to the considerable shear drag of the solar array area required, even if these surfaces are oriented edge-on to the airflow. [9][10][11] This suggests that a thruster based on electrostatic acceleration is suitable for an ABEP system, which requires an airbreathing neutralizer (or cathode) to support the thruster discharge.…”

Section: Introductionmentioning

confidence: 99%

Performance and plasma diagnostics of the Air-breathing Microwave Plasma CAThode (AMPCAT) coupled to a cylindrical Hall thruster

Tisaev,

Karadag,

Masillo

et al. 2023

Journal of Applied Physics

View full text Add to dashboard Cite

The Air-breathing Microwave Plasma CAThode (AMPCAT) has been developed for air-breathing electric propulsion in very-low Earth orbit. In this study, the standalone AMPCAT plasma characteristics are analyzed by means of several diagnostic tools and operation on xenon is compared to a conventional hollow cathode. A transition of AMPCAT extracted current from a lower (<0.1 A) to higher-current (>0.5 A) mode, triggered by increasing the negative cathode bias voltage, is accompanied by a significant rise in internal electron density and external electron temperature. The AMPCAT is coupled with a cylindrical Hall thruster in the 100–300 W power-level running on 0.5–0.7 mg/s of xenon, and the thrust is directly measured for cathode operation with both xenon and air. Stable thruster operation is demonstrated for the AMPCAT running on both propellants. For xenon, the performance is compared to a hollow cathode, which reveals matching discharge current profiles but a significantly higher thrust for the AMPCAT at low discharge voltages, approximately two times higher at 200 V. Langmuir probe measurements highlight a 30–40 V lower plasma potential in the cathode vicinity for the AMPCAT with xenon compared to both the hollow cathode and AMPCAT with air. This indicates a significantly improved coupling of cathode electrons to the thruster discharge, yielding an increased degree of ionization. Faraday probe and Wien filter results show that a larger current utilization efficiency drives the observed performance difference at low discharge voltages, rather than a significant change in ion acceleration or plume divergence.

show abstract

Air-breathing electric propulsion: mission characterization and design analysis

Cited by 10 publications

References 24 publications

Secrecy-Rate Optimization of Double RIS-Aided Space–Ground Networks

Secrecy-Rate Optimization of Double RIS-Aided Space–Ground Networks

Influence of applied magnetic field in an air-breathing microwave plasma cathode

Performance and plasma diagnostics of the Air-breathing Microwave Plasma CAThode (AMPCAT) coupled to a cylindrical Hall thruster

Contact Info

Product

Resources

About