A New Design For A Plasma Engine Fuels On Only Thin Air

A new design for a plasma engine was developed by Francesco Romano, aiming to fuel satellites in Very Low Earth Orbit (VLEO) using only thin air. The engine, called a RF Helicon Plasma Thruster, uses atmospheric molecules to generate thrust without relying on traditional fuel sources like Xenon. It is part of a category known as Atmosphere-Breathing Electric Propulsion (ABEP) systems. The thruster was tested in a vacuum chamber to simulate VLEO conditions, and it generated steady streams of plasma with only 50-60W of RF power, well within the capabilities of standard spacecraft solar panels. The system was found to be highly efficient, collecting ~94.3% of the air particles in the test, with only a 8% efficiency drop when subjected to a 15° tilt. The design uses a specular intake, a parabolic mirror coated with graphite or silicon dioxide, to bounce particles directly into the engine.

The thruster was tested with three different intake versions: an enhanced funnel design, a diffuse intake, and a specular intake. The specular intake was the most effective, collecting 94.3% of the particles and maintaining high efficiency even when tilted. The thruster uses a birdcage antenna, similar to those in MRI machines, to ensure 99% of the electrical power enters the thruster, achieving an extremely high efficiency. The thruster uses a solenoid wrapped around the engine to create a magnetic field that pushes the plasma out the back in a quasi-neutral jet, eliminating the need for a neutralizer. The system was validated in a vacuum chamber and showed reliability in simulating VLEO conditions. The engine could operate indefinitely between 190 and 250 km with less than 1.6 kW of power, which is within the generation limits of standard spacecraft solar panels. The design has potential for future use in space missions, including Mars, where the engine could support spacecraft above the Red Planet at a height of 120-160 km.

The work is part of a PhD thesis and is available in arXiv. The design has potential for commercial applications if it can be de-risked and proven to work on an actual mission. The idea is intriguing, and there are plenty of potential applications for the thruster if it can be successfully tested in real-world scenarios. The design has shown promise in laboratory tests, but there is no guarantee it will see use outside of a lab. The system could revolutionize how satellites are fueled in VLEO, reducing the reliance on expensive gases and improving efficiency.

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