Results
- Showing results for:
- Reset all filters
Search results
-
Journal articleFabris AL, Young C, Knoll A, et al., 2022,
Evidence of a free-space ion acceleration layer in the plume of a quad confinement plasma source
, Journal of Applied Physics, Vol: 131, Pages: 1-11, ISSN: 0021-8979The Quad Confinement Plasma Source is a novel plasma device developed for space propulsion applications, whose core is an E×Bdischarge with open electron drift. The magnetic field is produced by independently powered electromagnets able to generate different magnetic field topologies with the ultimate aim of manipulating the ion flow field for achieving thrust vectoring. In this work, we map the ion velocity in the plasmaejected from the Quad Confinement Thruster with different magnetic configurations using non-intrusive Laser-Induced Fluorescence diagnostics. Measurements show asteep ion acceleration layer located 8 cm downstream the exit plane of the discharge channel, detached from any physical boundary of the plasma source. In this location, the ion velocity increases from 3 km/s to 10 km/s within a 1 cm axial region. The ion acceleration profile has been haracterised under multiple testing conditions in order to identify the influence of the magnetic field intensity and topology on this peculiar ion acceleration layer.
-
Journal articleSchwertheim A, Knoll A, 2022,
Low power thrust measurements of the water electrolysis Hall effect thruster
, CEAS Space Journal, Vol: 14, Pages: 3-17, ISSN: 1868-2502We propose that a Hall effect thruster could be modified to operate on the products of water electrolysis. Such a thruster would exploit the low cost and high storability of water while producing gaseous hydrogen and oxygen in-situ as they are required. By supplying the anode with oxygen and the cathode with hydrogen, the poisoning of the cathode is mitigated. The water electrolysis Hall effect thruster (WET-HET) has been designed to demonstrate this concept. The dimensions of the WET-HET have been optimized for oxygen operation using PlasmaSim, a zero-dimensional particle in cell code. We present the first direct thrust measurements of the WET-HET. A hanging pendulum style thrust balance is used to measure the thrust of the WET-HET while operating in the Boltzmann vacuum facility within the Imperial Plasma Propulsion Laboratory. For this test the beam was neutralized using a filament plasma bridge neutralizer operating on krypton. We find thrust, specific impulse, and thrust efficiency all increase linearly with power for values between 400 and 1050 W. Increasing the mass flow rate from 0.96 to 1.85 mg/s increases thrust at the expense of specific impulse. Changing mass flow rate was found to have little impact on the thrust efficiency over this range. An optimal radial magnetic flux density of 403 G at the exit plane is found. Further increases to the magnetic field beyond this point were found to decrease the thrust, specific impulse and thrust efficiency, whereas the discharge voltage increased monotonically with increasing magnetic field for a given input power. It was found that the experimental thruster performance was lower than the simulation results from PlasmaSim. However, the general trends in performance as a function of power and propellant mass flow rate were preserved. We attribute a portion of this discrepancy to the inability of the simulation to model the energy absorbed by the covalent bond of the oxygen molecule. For the powers and mass flow rat
-
Conference paperStaab D, Longhi E, Garbayo A, et al., 2021,
ICE: A MODULAR WATER ELECTROLYSIS PROPULSION SYSTEM
, SPACE PROPULSION CONFERENCE 2020+1 -
Conference paperMasillo S, Lucca Fabris A, Karadag B, et al., 2021,
EXPERIMENTAL CHARACTERISATION OF THE NOVEL HALO PLASMA THRUSTER FOR SMALL SATELLITE APPLICATIONS
, SPACE PROPULSION 2020+1 -
Conference paperSchwertheim A, Knoll A, 2021,
PERFORMANCE CHARACTERISATION OF THE WATER ELECTROLYSIS HALL EFFECT THRUSTER (WET-HET) USING DIRECT THRUST MEASUREMENTS
, SPACE PROPULSION 2020+1 -
Conference paperMuir C, Ma C, Knoll A, 2021,
The design, fabrication and test progress summary of the iridium catalysed electrolysis thruster
, Space Propulsion 2020+1 -
Conference paperRosati Azevedo E, Tirila V, Schwertheim A, et al., 2021,
Magnetic Field Enhancement of the Quad Confinement Thruster (QCT): Design and Early Development of the QCT Phoenix
, The 7th Space Propulsion Conference -
Journal articleSchwertheim A, Rosati Azevedo E, Liu G, et al., 2021,
Interlaboratory validation of a hanging pendulum thrust balance for electric propulsion testing
, Review of Scientific Instruments, Vol: 92, Pages: 1-11, ISSN: 0034-6748A hanging pendulum thrust balance has been developed by Imperial College London in collaboration with the European Space Agency (ESA) to characterize a wide range of static fire electric propulsion and chemical micro-propulsion devices with thrust in the range of 1 mN to 1 N. The thrusters under investigation are mounted on a pendulum platform, which is suspended from the support structure using stainless steel flexures. The displacement of the platform is measured using an optical laser triangulation sensor. Thermal stability is ensured by a closed loop self-compensating heating system. The traceability and stability of the calibration are ensured using two separate calibration subsystems: a voice coil actuator and a servomotor pulley system. Two nearly identical thrust balances have been constructed, with one being tested in the Imperial Plasma Propulsion Laboratory and the other in the ESA Propulsion Laboratory. Both balances show a high degree of linearity in the range of 0.5 mN–100 mN. Both instruments have demonstrated a stable calibration over several days, with an estimated standard deviation on thrust measurements better than 0.27 mN for low thrust measurements. The same electric propulsion test article was used during both tests: a Quad Confinement Thruster (QCT) variant called QCT Phoenix. This thruster differed from previous QCT designs by having a newly optimized magnetic topology. The device produced thrust up to 2.21 ± 0.22 mN with a maximum specific impulse of 274 ± 41 s for an anode power range of 50 W–115 W.
-
Journal articleWilliams RD, Fabris AL, Knoll A, 2020,
Insight into the plasma structure of the Quad Confinement Thruster using electron kinetic modelling
, Acta Astronautica, Vol: 173, Pages: 111-118, ISSN: 0094-5765The behaviour of plasma within the discharge channel of the Quad Confinement Thruster is studied on the basis of electron kinetics. Here we propose that E × B drift of electrons drives the formation of unusual quadrant dependent light emitting structures observed experimentally in the discharge channel of the Quad Confinement Thruster. This assertion is made on the basis of a theory-based analysis and a computational model of the Quad Confinement Thruster. A particle orbit model of electron motion under the influence of applied electric and magnetic fields was used to assess electron transport. Structures strongly resembling that of the observed visible emission regions were found in the electron density distribution within the channel. While the motion of electrons cannot be decoupled from the motion of ions, as in this simple electron kinetic approximation, the results of this analysis strongly indicate the physical mechanism governing the formation of the non-uniform density distributions within the Quad Confinement Thruster channel.
-
PatentKnoll A, Harle T, Peter S, et al., 2020,
Plasma generation
, US10595391B2A plasma torch having an open end from which a plasma plume is emitted in use is disclosed. The plasma torch includes a central cathode rod, a grounded conductive tube having an open end and being arranged around the cathode and spaced therefrom to form a first cylindrical cavity open at one end; and a high voltage electrode having a dielectric barrier material at a radially inward-facing surface thereof and being arranged around the grounded conductive tube and spaced apart therefrom to form a second annular cylindrical cavity open at one end. A constant direct current (DC) electrical power plus a high voltage pulsed electrical power is provided to the cathode producing an arc discharge in the first cavity between the cathode and grounded tube to generate a central thermal plasma emitted at an open end of the first cylindrical cavity. A high voltage alternating current electrical power or pulsed electrical power is provided to the high voltage electrode producing a dielectric barrier discharge in the second annular cylindrical cavity to generate a non-thermal plasma emitted from an open end of the second cavity as a halo around the central thermal plasma.
-
Conference paperKaradag B, Masillo S, Moloney R, et al., 2020,
Experimental Investigation and Performance Optimization of the Halo thruster
, 36th International Electric Propulsion Conference -
Conference paperMörtl M, Knoll A, Williams V, et al., 2020,
Enhancing Hall Effect Thruster Simulations with Deep Recurrent Networks
, 36th International Electric Propulsion Conference -
Conference paperSchwertheim A, Knoll A, 2020,
The Water Electrolysis Hall Effect Thruster (WET-HET): Paving the Way to Dual Mode Chemical-Electric Water Propulsion
, 36th International Electric Propulsion Conference -
Conference paperWilliams V, Argyriou V, Shaw P, et al., 2019,
Development of PPTNet a Neural Network for the Rapid Prototyping of Pulsed Plasma Thrusters
, 36th International Electric Propulsion Conference -
Journal articleMuir C, Knoll A, 2019,
Catalytic Combustion of Hydrogen and Oxygen for an Electrolysis Micro-Propulsion System
, Journal of the British Interplanetary Society, ISSN: 0007-084X -
Journal articleSchwertheim A, Knoll A, 2019,
In situ Utilization of Water as a Propellant for a Next Generation Plasma Propulsion System
, Journal of the British Interplanetary Society, ISSN: 0007-084X
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.