Bulletin of the American Physical Society
76th Annual Gaseous Electronics Conference
Volume 68, Number 9
Monday–Friday, October 9–13, 2023; Michigan League, Ann Arbor, Michigan
Session HR2: Electric Propulsion IV |
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Chair: Yevgeny Raitses, Princeton Plasma Physics Laboratory Room: Michigan League, Michigan |
Thursday, October 12, 2023 10:00AM - 10:15AM |
HR2.00001: Simulations of the effect of neutral dinamics in magnetic nozzle expansions. Diego García, Mario Merino, Eduardo Ahedo Electrodeless plasma thrusters (EPTs) promise several advantages over traditional electric propulsion devices. However, this kind of thrusters is still underperforming in terms of efficiency in comparison with more mature technologies and, despite the multiple efforts in understanding the underlying physics of plasma acceleration in magnetic nozzles, many questions about their operation are still open. |
Thursday, October 12, 2023 10:15AM - 10:30AM |
HR2.00002: PIC-MCC Simulation of ExB Discharge in High-Frequency Excited Plasmas for Air-Breathing Electric Propulsion in VLEO Mammadbaghir Baghirzade, Laxminarayan L Raja The present work concerns a magnetized high-frequency (HF) excited plasma discharge as an ionization source for extremely rarefied N2 environments (≤ 0.1 mTorr) encountered in Air-Breathing Electric Propulsion (ABEP) for Very Low Earth Orbits (VLEO) satellites. The goal is to analyze the complex physics of high frequency ExB discharge under rarefied N2 gas conditions, which involves phenomena such as a cyclotron orbit, collision events, and radio frequency (RF) excitation. This analysis is particularly crucial as the precise mechanisms that govern the breakdown of molecular nitrogen and the sustainment of the plasma within these conditions remain unclear. To understand this phenomenon, a high-fidelity computational modeling based on 1D-3V Particle-In-Cell/Monte-Carlo Collision (PIC-MCC) method coupled with Maxwell’s equations is carried out. The model adopts a fully kinetic approach and resolves inter-electrode gap distance of 10 cm in the 1D computation. All three components of particle velocity (3V) are considered to precisely capture the complex effects of magnetic fields on particle dynamics and the scattering events that arising during collisions within high frequency ExB discharge. The design incorporates a parallel-plate configuration, with a steady magnetic field of 100 G applied parallel to the electrodes for effective plasma confinement. An examination of the parameter space, i.e., 100 V – 10 kV, at high excitation frequencies, 100 MHz - 1 GHz, and initial seed electron densities 2.5x1013 - 2.5x1017m-3 is investigated at background gas (N2) pressure of ≤ 0.1 mTorr, (≤ 1018 m-3). Furthermore, by tracking a trajectory of a selected electron, the dynamics of an individual electron and the collision events it experiences are analyzed under magnetized and unmagnetized conditions. It is observed that in the absence of a magnetic field, no ignition occurred regardless of the initial plasma density, excitation voltages or background pressure. At the lowest background pressure of 0.1 mTorr that has been studied, the ionization of N2 is achieved at the higher initial plasma densities of 2.5x1016 #/m3and 2.5x1017 #/m3 with excitation voltages of 2 kV, 5 kV, and 10 kV, excitation frequency of 100 MHz and magnetic field strength of 100 G. |
Thursday, October 12, 2023 10:30AM - 10:45AM |
HR2.00003: Characterization of electron density fluctuations in the plasma of an ECR thruster Victor Desangles, Federico Boni, Julien Jarrige Electron density fluctuations are commonly observed in magnetized plasma discharges. They can be generated by different types of instabilities. In the specific case of electric propulsion, plasma instabilities have been mostly characterized in Hall Effect thrusters. In these devices, a large number of different instabilities, leading to various fluctuations’ frequencies and wavelengths, have been characterized [1]. They are shown to influence ionization processes and formation of the accelerating E field with a critical role in the thruster operation. In electron cyclotron resonance thrusters (ECRT), in which a magnetic nozzle is the acceleration stage, plasma fluctuations have been only recently observed [2]. While their exact characterization and their role in the thruster operation was only scarcely studied, it was concluded that plasma fluctuations may be related to anomalous electron transport phenomena [2]. This talk proposes to use two diagnostics, a microwave resonant probe and fast camera imaging, to characterize the plasma fluctuations in the source and in the plume of an ECRT. Such a characterization will open new scopes of analysis for the understanding of ECRTs. |
Thursday, October 12, 2023 10:45AM - 11:00AM |
HR2.00004: Numerical Study of a Novel Resonant Plasma localization approach for Microwave Electrothermal Thrusters Juyeon Lee, Laxminarayan L Raja Microwave electrothermal thrusters (METs) are promising propulsion systems for space missions due to their high specific impulse and power compatibility. METs use microwave energy to heat propellant to generate thrust. However, a challenge in METs is the plasma discharge deviating from the nozzle entrance, leading to energy losses and inefficient conversion of microwave energy. This behavior is primarily attributed to their electrodeless configurations. To address this challenge, we propose the integration of all-dielectric resonators into METs. These resonators are comprised of solid dielectric materials that efficiently localize and manipulate electromagnetic wave energy. In this study, we examine different configurations of a 2D planar computational model, focusing on the impact of varying shapes and sizes of the dielectric resonators on the operation of METs. The electric field distribution within METs is crucial for electron Joule heating, which is the primary mechanism for gas heating. Concentrating the highest electric field strength near the nozzle throat enables the gas flowing through it to be heated, resulting in higher nozzle exit velocity. This study aims to understand the interactions between the resonator and propellants, particularly focusing on microwave energy absorption, and how they affect thrust generation and exhaust characteristics. The goal is to demonstrate how these interactions contribute to achieving higher specific impulse and enhanced efficiency in METs. |
Thursday, October 12, 2023 11:00AM - 11:15AM |
HR2.00005: Oscillations and instabilities in a propulsive magnetic nozzle Mario Merino, Davide Maddaloni, Matteo Ripoli, Jaume Navarro-Cavallé, Filippo Terragni, Eduardo Ahedo
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Thursday, October 12, 2023 11:15AM - 11:30AM |
HR2.00006: Experimental measurements of ion trajectories and plasma detachment in the magnetic nozzle of an ECR thruster Romain PIOCH, Victor Désangles, Pascal Chabert Several electric propulsion devices currently under development use a diverging magnetic field, called magnetic nozzle (MN), to accelerate and eject plasma and produce thrust. The processes at stake in the demagnetization phenomenon, called detachment, of the plasma expanding in the MN are a key to optimize the design of those devices. We introduce a new electrostatic probe, the directional Faraday probe, inspired from the classic Faraday cup design. This probe is able, thanks to the geometry of its collectors, to measure the local angular distribution of ion current density. Therefore, it gives access to the ions trajectories in the plume of electric propulsion devices. Measurements made with this diagnostic in the MN of an ECR thruster are compared with the magnetic field topology. This analysis yields valuable information on the location of the plasma detachment which can be confronted to theoretical models. Preliminary results showed that several centimeters away from the thruster source, the ion trajectories remain collinear to the magnetic field lines at the center of the plume while a converging detachment occurs at the edges of the MN. Moreover, plasma parameters seem to have a strong influence on the plasma expansion and detachment. |
Thursday, October 12, 2023 11:30AM - 11:45AM |
HR2.00007: Electron velocity distribution function measurement in microwave cathode plume by incoherent laser Thomson scattering Takuya Koiso, Yusuke Yamashita, Ryudo Tsukizaki, Kazutaka Nishiyama In this work, we conducted an incoherent laser Thomson scattering (incoherent LTS) to measure the electron velocity distribution function at the plume region of a microwave cathode. The result obtained from incoherent LTS shows the electron density of 10^18 m^-3 and the electron temperature of 2-4 eV, which is validated by the comparison with a Langmuir probe measurement. Additionally, the incoherent LTS shows the EVDF is non-Maxwellian EVDF at a low propellant flow rate, whereas Maxwellian EVDF at a high propellant flow rate, indicating that the electron heating and cooling mechanism depends on the propellant flow rate. |
Thursday, October 12, 2023 11:45AM - 12:00PM |
HR2.00008: Nanosecond dielectric barrier discharge aircraft ice protection system Andrey Starikovskiy, Nickolay Aleksandrov, Manny Rios The Earth's atmosphere contains lots of water vapor at every level. Liquid water droplets in clouds can be below the freezing point, a matter phase state with the thermodynamic name of "supercooled". It so happens that all aircraft flying at subsonic speeds into clouds in these conditions collect ice on every forward exposed structure. The big engineering challenge is to design and develop ice protection systems that use the least amount of engine power, which at this point is why, numerically, the number of ice-protected aircraft is the minority compared to overall global number of aircraft. This paper presents results of numerical modeling of nanosecond surface dielectric barrier discharge (ns-SDBD) for aircraft ice protection system using a heat release in highly nonequilibrium pulsed plasma. The major attention is paid to the effects based on ultrafast (on nanosecond time scale at atmospheric pressure) local heating of the gas, since at present the main successes in ice protection using gas discharges are associated with namely this thermal effect. The mechanisms of ultrafast heating of air at high electric fields realized in these discharges, as well as during the decay of discharge plasma, are analyzed. |
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