3mm 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)

3mm Diameter cathodes can be configured for many applications

The principal features of this scaleable hollow cathode design include:

• Robust and lightweight mechanical design
• Wide propellant flow rate range; at present, 0.03 to 1.2 mg/s
• Wide emission current range possible from single cathode design
• Low temperature operation and hence long life; e.g. 20 A at 1200 ºC
• Reliable low work function dispenser technology with extensive application heritage in commercial applications i.e. colour television production
• Range of enclosures for different applications

The 3mm diameter Hollow Cathode has been subjected to extensive qualification, life testing and characterisation (performed by QinetiQ) in support of a range of national and international programmes including five cathodes (4 x T5 discharge cathode configuration + 1 x T5 neutraliser configuration) successfully completing a life test of 15,000 hours operation and 5,500 On/Off cycles without any observed degradation in performance.

3mm Diameter Hollow Cathodes technical data:

Mass: 60g
DC Ampere hours: > 15,000 hours @ 3.6 A
NC Ampere hours: > 15,000 hours @ 1.6 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), during storage or spacecraft Assembly, Integration and Verification (AIV).
Propellant quality: > 4.7 grade, H₂ < 1 ppm, N₂ < 10 ppm, O₂ < 3 ppm, H₂O < 3 ppm, CO₂+CO < 5 ppm, C_nH_m < 1 ppm (no external getters required)
Vibration / shock: qualified to 22 g rms (random), 1000 g (shock).