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Title: Direct thrust measurement of a permanent magnet helicon double layer thruster

Abstract

Direct thrust measurements of a permanent magnet helicon double layer thruster have been made using a pendulum thrust balance and a high sensitivity laser displacement sensor. At the low pressures used (0.08 Pa) an ion beam is detected downstream of the thruster exit, and a maximum thrust force of about 3 mN is measured for argon with an rf input power of about 700 W. The measured thrust is proportional to the upstream plasma density and is in good agreement with the theoretical thrust based on the maximum upstream electron pressure.

Authors:
; ; ; ;  [1]; ;  [2]; ; ; ;  [3]
  1. Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)
  2. ASTRIUM-EADS, 6 rue Laurent Pichat, 75016 Paris (France)
  3. Surrey Space Centre, University of Surrey, Guildford GU2 7XH (United Kingdom)
Publication Date:
OSTI Identifier:
21518370
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 98; Journal Issue: 14; Other Information: DOI: 10.1063/1.3577608; (c) 2011 American Institute of Physics
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; ARGON IONS; BALANCES; ELECTRONS; ION BEAMS; LASER RADIATION; LAYERS; PERMANENT MAGNETS; PLASMA DENSITY; SENSITIVITY; SENSORS; THRUSTERS; BEAMS; CHARGED PARTICLES; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; ELEMENTS; EQUIPMENT; FERMIONS; FLUIDS; GASES; IONS; LEPTONS; MAGNETS; MEASURING INSTRUMENTS; NONMETALS; RADIATIONS; RARE GASES; WEIGHT INDICATORS

Citation Formats

Takahashi, K., Lafleur, T., Charles, C., Alexander, P., Boswell, R. W., Perren, M., Laine, R., Pottinger, S., Lappas, V., Harle, T., and Lamprou, D. Direct thrust measurement of a permanent magnet helicon double layer thruster. United States: N. p., 2011. Web. doi:10.1063/1.3577608.
Takahashi, K., Lafleur, T., Charles, C., Alexander, P., Boswell, R. W., Perren, M., Laine, R., Pottinger, S., Lappas, V., Harle, T., & Lamprou, D. Direct thrust measurement of a permanent magnet helicon double layer thruster. United States. doi:10.1063/1.3577608.
Takahashi, K., Lafleur, T., Charles, C., Alexander, P., Boswell, R. W., Perren, M., Laine, R., Pottinger, S., Lappas, V., Harle, T., and Lamprou, D. Mon . "Direct thrust measurement of a permanent magnet helicon double layer thruster". United States. doi:10.1063/1.3577608.
@article{osti_21518370,
title = {Direct thrust measurement of a permanent magnet helicon double layer thruster},
author = {Takahashi, K. and Lafleur, T. and Charles, C. and Alexander, P. and Boswell, R. W. and Perren, M. and Laine, R. and Pottinger, S. and Lappas, V. and Harle, T. and Lamprou, D.},
abstractNote = {Direct thrust measurements of a permanent magnet helicon double layer thruster have been made using a pendulum thrust balance and a high sensitivity laser displacement sensor. At the low pressures used (0.08 Pa) an ion beam is detected downstream of the thruster exit, and a maximum thrust force of about 3 mN is measured for argon with an rf input power of about 700 W. The measured thrust is proportional to the upstream plasma density and is in good agreement with the theoretical thrust based on the maximum upstream electron pressure.},
doi = {10.1063/1.3577608},
journal = {Applied Physics Letters},
number = 14,
volume = 98,
place = {United States},
year = {Mon Apr 04 00:00:00 EDT 2011},
month = {Mon Apr 04 00:00:00 EDT 2011}
}
  • A small helicon source, 5 cm in diameter and 5 cm long, using a permanent magnet (PM) to create the DC magnetic field B, is investigated for its possible use as an ion spacecraft thruster. Such ambipolar thrusters do not require a separate electron source for neutralization. The discharge is placed in the far-field of the annular PM, where B is fairly uniform. The plasma is ejected into a large chamber, where the ion energy distribution is measured with a retarding-field energy analyzer. The resulting specific impulse is lower than that of Hall thrusters but can easily be increased to relevant valuesmore » by applying to the endplate of the discharge a small voltage relative to spacecraft ground.« less
  • A current-free electric double layer is created in a helicon double layer thruster operating with xenon and compared to a recently developed theory. The Xe{sup +} ion beam formed by acceleration through the potential drop of the double layer is characterized radially using an electrostatic ion energy analyzer. For operating conditions of 500 W rf power, 0.07 mTorr gas pressure, and a maximum magnetic field of 125 G, the measured beam velocity is about 6 km s{sup -1}, the beam area is about 150 cm{sup 2}, and the measured beam divergence is less than 6 deg.
  • The ion beam generated by a helicon double layer has been electrically steered up to 20 deg. off axis by using a solenoid placed normal to the two axial solenoids of the helicon plasma source without significantly changing the beam exhaust velocity.
  • An ion beam generated by an annular double layer has been measured in a helicon thruster, which sustains a magnetised low-pressure (5.0 × 10{sup −4} Torr) argon plasma at a constant radio-frequency (13.56 MHz) power of 300 W. After the ion beam exits the annular structure, it merges into a solid centrally peaked structure in the diffusion chamber. As the annular ion beam moves towards the inner region in the diffusion chamber, a reversed-cone plasma wake (with a half opening angle of about 30°) is formed. This process is verified by measuring both the radial and axial distributions of the beam potential and beammore » current. The beam potential changes from a two-peak radial profile (maximum value ∼ 30 V, minimum value ∼ 22.5 V) to a flat (∼28 V) along the axial direction; similarly, the beam current changes from a two-peak to one-peak radial profile and the maximum value decreases by half. The inward cross-magnetic-field motion of the beam ions is caused by a divergent electric field in the source. Cross-field diffusion of electrons is also observed in the inner plume and is determined as being of non-ambipolar origin.« less
  • Helicon discharges are known for their ability to produce high densities of partially ionized plasma, their efficiency arising from an unusual mechanism of rf coupling. However, the requirement of a dc magnetic field has prevented their wide acceptance in industry. The use of permanent magnets greatly simplifies helicon sources, and arrays of small sources extend the use of helicons to the processing of large substrates. An eight-tube array was designed and constructed, and its density uniformity measured in a 53x165 cm{sup 2} chamber. Three innovations involved (a) the remote field of ring magnets, (b) a low-field density peak, and (c)more » rf power distribution. High-density plasmas uniform over large areas requires compatibility in all three areas.« less