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* Home > Defence  > Solutions for Defence > Space > Electric Propulsion > 7mm Diameter Hollow Cathodes *
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7mm Diameter Hollow Cathodes

QinetiQ currently produces four sizes of hollow cathode, each with different operating current ranges:

  • T5 and T6 gridded ion thrusters (0.5 - 3.6A)
  • ROS-2000 Hall Effect Thruster (or 'HET' developed by Astrium under contract to ESA) (3 - 20A)
  • 5.0 kW HET (2 - 10A)
  • Miniaturised HET (0.5 - 5A)



The T6 design has been extensively tested to 35A, and an earlier version was used successfully in the UK-25 300mN ion thruster, where currents of 30A were routinely employed. QinetiQ has also developed a device rated for continuous operation at 30A with extended operation at up to 50A.
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7mm Diameter cathodes can be configured for many applications
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7mm Diameter cathodes can be configured for many applications.
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The 7 mm cathodes have been qualified for the ESA/Astrium ROS-2000 Hall effect product and are undergoing qualification for the QinetiQ T6 and further European Hall effect systems. This has included the following:

  • Environmental qualification to 43 grms.
  • 2 x cathodes successfully completed 5500 rapid on/off cycles for the ROS-2000 thruster.
  • 1 x cathode successfully completed 18,000 rapid on/off heater cycles.
  • 1x cathode successfully completed 5500 rapid on/off heater cycles followed by 4200 hours of operation at 18 A.
  • Life testing of two cathodes to be completed as part of the Astrium EADS ROS-2000 lifetest.
  • 7 mm cathodes successfully passed accelerated contamination tests. This used artificially high levels of gas impurities to demonstrate compliance with required total in-service impurity levels.
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7mm Diameter Hollow Cathodes technical data:
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Mass: 120 gm
DC Ampere hours: > 15,000 hours @ 15 A
NC Ampere hours: > 15,000 hours @ 3 A
DC and NC cycle life: > 5,500.
Emitter technology: BaO based
In-orbit life: No degrading effects from space exposure.
Ground storage: No shelf life or need to flush with shield gas (e.g. dry nitrogen).
Propellant quality: > 4.7 grade (see data on 3 mm cathode)
Vibration / shock: 43 g rms, 1000 g.
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> Hollow Cathode Technology Factsheet [PDF]
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