Product Category
Space-Grade RF Generators for Plasma Thrusters
A 13.56 MHz RF generator that works on a laboratory bench is not a flight unit. This explains the requirements that make a generator space-grade, and why re-qualifying an industrial supply is usually the wrong path.
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The generator's role in the PPU
Inside an RF power processing unit, the RF generator is the stage that produces the high-power radio-frequency carrier the thruster antenna needs. It sets the frequency, usually 13.56 MHz, amplifies the signal to the operating level, and delivers it to the matching network. Generator efficiency sets the floor for the whole unit's efficiency, so it is the stage where architecture choices matter most.
Industrial versus space-grade
13.56 MHz RF generators are a mature industrial product. Semiconductor fabrication and surface-treatment plasma tools use them by the thousand, from suppliers such as MKS Instruments and Advanced Energy. Those units are well engineered for a factory: rack mounted, mains powered, water cooled, and maintained on the ground.
A plasma thruster needs the same core function in a completely different envelope. There is no rack, no mains, no water loop, no maintenance, and the unit has to survive launch and years of radiation and thermal cycling. The gap between the two is what "space-grade" describes.
The space-grade requirements delta
| Dimension | Industrial 13.56 MHz generator | Space-grade generator |
|---|---|---|
| Input power | Single or three-phase mains | Unregulated low-voltage spacecraft bus |
| Cooling | Forced air or water loop | Conduction to a baseplate, radiative only |
| Efficiency priority | Moderate; heat is easy to reject | Critical; every lost watt drives radiator mass |
| Mass and volume | Not constrained | Tight budget, shared with payload |
| Environment | Climate-controlled room | Vibration, vacuum, total ionising dose, single-event effects, wide temperature range |
| Lifetime | Serviceable | Years of unattended operation, no repair |
| Control interface | Ethernet or analogue front panel | Spacecraft data bus, autonomous fault handling |
The efficiency and thermal rows are the ones that reshape the design. An industrial unit can afford a linear or lightly optimised power stage because a chiller carries the loss away. In orbit that loss becomes radiator area, so a space-grade generator is built around a high-efficiency switch-mode stage, commonly Class-E or a related topology, using GaN transistors for their power density and low switching loss. Sourcing those parts in Europe also keeps the unit free of United States export control.
Why re-qualifying an industrial unit rarely works
- Wrong input. Industrial units expect mains. Adapting them to a low-voltage bus means an added front-end converter, more mass, more loss.
- Wrong cooling. A design that assumes forced air or water has no conduction path to a baseplate. Re-hosting the thermal design is a redesign.
- Uncontrolled parts. The bill of materials is chosen for cost and availability, not radiation tolerance or upscreening, and is not classified for export.
- Efficiency ceiling. If the topology was not chosen for efficiency, no amount of qualification testing raises it.
- Mass. Rack-oriented mechanical design carries structure a spacecraft does not want.
By the time each of these is addressed, little of the original unit remains. A purpose-built space-grade generator is usually the shorter path.
Design targets for the MHz Labs unit
MHz Labs is developing its RF power processing unit as a purpose-built space-grade generator plus adaptive matching network. The unit is in development along a TRL 4 to 6 roadmap. It has no flight heritage yet. Current design targets:
| Parameter | Design target |
|---|---|
| RF output power | 50 to 500 W |
| Operating frequency | 13.56 MHz ISM |
| Conversion efficiency | Not published while unmeasured |
| Power stage | GaN, switch-mode (Class-E family) |
| Bus input | Unregulated low-voltage spacecraft rail |
| Cooling | Conduction to baseplate |
| Matching | Integrated real-time adaptive network |
| Supply chain | Fully European |
Frequently asked questions
Can I use an MKS or Advanced Energy generator on a thruster?
On a laboratory model or a ground test, yes, that is common practice. For flight, no: those units assume mains power, active liquid or air cooling, and a commercial parts list, none of which survive the transition to a spacecraft.
What does "space-grade" actually require?
Operation from the spacecraft bus, conduction cooling, a high-efficiency power stage, a radiation-tolerant and export-classified bill of materials, autonomous fault handling, and qualification for launch vibration, vacuum and thermal cycling.
Why is efficiency more important in space than in a fab?
A fab rejects waste heat into a chiller at almost no cost. A satellite rejects it only by radiating to space, so every watt of loss adds radiator area and mass to the whole spacecraft.
Is the MHz Labs generator available now?
It is in development along a TRL 4 to 6 roadmap. Engineering engagement, design targets and integration discussion are open now; contact the team for current status.
Sources and further reading
- MKS Instruments, ELITE 13.56 MHz RF plasma generators, an example of the industrial baseline.
- Goebel and Katz, Fundamentals of Electric Propulsion, NASA JPL DESCANSO, for the power-budget context.
Specifying a space-grade RF generator?
MHz Labs builds the RF power processing unit so your propulsion team does not have to. Request the current design targets and integration guidance.
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