Cathode heaters for ion thrusters

These systems have the great advantage of needing very little fuel to provide long-term orbital adjustments and acceleration in space.

Kamet is a proud supplier of thermionic cathode heaters for electric propulsion systems in leading edge aerospace industries. Through a process called ionization, a solid fuel propellant (mostly xenon) is bombarded by electrons to create ions. It is the streaming of these ions at high speeds that creates a plasma flow which provides thrust for the spacecraft, hence the name ‘ion thrusters’. Our cathode heaters ensure the correct temperature is reached for the excitation energy required to initiate the plasma flow (up to 1600°C). Furthermore, a second neutralizer cathode assembly is usually present on the outside of the spacecraft to neutralize the emitted beam, thus avoiding damage to the external structure. Each of these critically important thermionic cathodes require a heater for operation.

The following are examples of different (electrostatic) ion thruster types and the space program/crafts that utilize them. In all these examples, multiple cathode heaters can be found:

  • Gridded, such as NASA’s programs NEXT (Evolutionary Xenon Thruster) and NSTAR (Solar Technology Application Readiness)
  • Hall thrusters, such as the Starlink program from SpaceX
  • Field-emission, such as the scientific spacecraft LISA Pathfinder by ESA/NASA

Cathode heater design, features and properties

Kamet, in partnership with our suppliers ARi Industries and Okazaki, has succeeded in developing prized and highly miniaturized cathode heaters that utilize the latest materials and technological trends. We have found the refractory (exotic) alloys to be the most suitable, with Tantalum usually being the alloy of choice.

Our Tantalum cathode heaters are essentially a specialized microheater coiled around the cathode. Micro heaters are part of our mineral insulated heating elements range.

Kamet’s cathode heaters are designed to withstand the extreme environmental challenges of deep space (temperature, pressure, vacuum), while being durable enough for thousands of heat cycles at the required temperatures for plasma ignition (up to 1600 °C). In fact the lifetime and durability of an ion thruster is for a large part dependent on its cathode heaters.

Technical drawing of a cathode heater

Kamet’s cathode heaters

In this highly specialized field, there is seldom one standard solution. Kamet Heating can guide you during the entire process of designing, developing and testing customized cathode heater assemblies. The quality of the end product is ensured, partly due to the full traceability but also on account of the wide range of recognized tests that we can perform in house. These include:

  • Insulation compaction density
  • Burn-in test
  • Dielectric strength
  • Weight
  • First Article Inspection Report
  • Final Manufacturing Report
  • Vibration
  • Acceleration
  • Material certificate
  • Helium leak
  • Radiographic analysis
  • Lead attachment strength (pull test)
  • Visual & mechanical examination
  • Conductor resistance
  • Insulation resistance
  • Mechanical shock
  • Pyrotechnic shock
  • Humidity
  • Hot firing
  • Electrical cycling
  • Thermal cycling
  • Destructive visual analysis

Why choose Kamet to do business with?

Over the years Kamet has sold over a thousand cathode heaters to Europe’s leading aerospace companies. We are the exclusive distributor for the European market of two leading mineral insulated heating solutions manufacturers: Okazaki Manufacturing Company and ARi Industries.

We bring not only our own extensive experience and knowhow to each project, but we also have the full support and partnership of these manufacturers. Thanks to our joint commitment to innovation, Kamet can bring our clients the certainty that our cathode heaters keep up with the very latest developments. An example would be the way in which ARi are pushing the boundaries for the maximum number of heat cycles as well as raising the cathode heater temperatures from 1400°C to 1600°C. Truly a leading edge manufacturer.

Our team of experts are on hand to answer all your queries. You can rely on us to respond within 24 hours. Although we are leading technical experts in this field, our team prides themselves on being approachable and ‘easy to do business with’. We look forward to hearing from you.


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