The plasma thrusters used in satellites could be much more powerful than previously thought


The plasma thrusters used in satellites could be even more powerful

Plasma glow from an H9 MUSCLE Hall thruster during a Kryptonian thruster test. Credit: Electric and Dynamic Propulsion Laboratory

It is believed that Hall thrusters, an efficient type of electric propulsion widely used in orbit, must be large to produce a lot of thrust. Now, a new study from the University of Michigan indicates that smaller Hall thrusters can generate much more thrust — making them candidates for interplanetary missions.


“People previously believed that you could only push a certain amount of current through the area of ​​the impulse, which in turn translates directly to the amount of force or thrust you could generate per unit area,” said Benjamin Jorns, associate professor at UCLA. Aviation Engineering Who led the study of the drive for the new hall to be introduced in AIAA SciTech Forum In National Harbor, Maryland today.

His team challenged this limit by running a 9 kW Hall impeller up to 45 kW, while maintaining nearly 80% of its nominal efficiency. This increased the amount of force generated per unit area by a factor of approximately 10.

Whether we call it a Plasma motive or ion engine, electric propulsion is our best bet for interplanetary travel — but science is at a crossroads. While Hall thrusters are a well-proven technology, an alternative concept, known as a magnetodynamic thrust, promises to pack more power into smaller engines. However, it has not yet been proven in many ways, including for life.

He believes that hall pushers are not competitive because of the way they work. the defendIt is usually a Noble gas Like xenon, it moves through a cylindrical channel where it is accelerated by a strong electric field. Thrust is generated in the forward direction as it exits from behind. But before the propellant can be accelerated, it needs to lose some electrons to give it a positive charge.

The electrons are accelerated by a magnetic field To run in a loop around that channel — which Jorns described as a “buzz saw” — knocks electrons off the fuel atoms, turning them into positively charged ions. However, calculations indicated that if the Hall impulse tried to force more fuel through the engine, the electrons scurrying around in a loop would break out of the configuration, breaking down the “buzzsaw” function.

“It’s like trying to bite off more than you can chew,” Jorns said. “A buzz saw couldn’t force its way through that much material.”

In addition, the engine will get very hot. The Jorns team put these beliefs to the test.

“We named our engine the H9 MUSCLE because basically, we took the H9 engine and made a muscle car out of it by turning it into an ’11’ — really up to a hundred, if we’re going by exact analogy,” Lian Su, a doctoral student in aerospace engineering will offer. studying.

They addressed the heat problem by cooling it with water, which allowed them to see how big of a problem a buzzsaw breakdown would be. Turns out nothing was too much trouble. The H9 MUSCLE engine runs on xenon, conventional fuel, up to 37.5 kW, with an overall efficiency of around 49%, not far from 62% efficiency when designed for its 9 kW power.

Using krypton, a lighter gas, they increased their power supply at 45 kilowatts. With an overall efficiency of 51%, they achieve a maximum thrust of around 1.8 N, on par with the larger X3 Hall engine in the 100 kW class.

The plasma thrusters used in satellites could be even more powerful

Doctoral student Will Hurley leaves the room where Hall’s new plasma propulsion device is being tested at PEPL Lab. Credit: Marcin Szczepanski/Michigan Engineering

“This is a kind of crazy result because typically krypton performs much worse than xenon on Hall engines. So it’s pretty cool and an interesting path forward to see that we can actually improve krypton’s performance relative to xenon by increasing the thruster. current densitySu said.

Telescopic thrusters such as the X3 — also developed in part by UM — have been explored for interplanetary cargo transport, but they are much larger and heavier, making it difficult for them to transport humans. Now, regular Hall engines are back on the table for manned flights.

Jorns says the cooling problem will need a space-worthy solution if Hall thrusters are to operate at such high powers. However, he is optimistic that individual thrusters can run from 100 to 200 kilowatts, arranged in arrays that provide megawatts of thrust. This could enable manned missions to reach Mars even on the far side of the sun, traveling 250 million miles.

The team hopes to pursue the cooling issue as well as the challenges in developing both Hall thrusters and magnetodynamic thrusters on Earth, since few facilities can test thrusters at the scale of a Mars mission. The amount of spent fuel motivation It comes too fast for vacuum pumps to maintain conditions inside the test chamber like space.

more information:
Leanne L. Su et al, Operation and performance of a magnetically shielded Hall detonator at ultrahigh current densities, AIAA SCITECH Forum 2023 (2023). DOI: 10.2514/6.2023-0842

Introduction of
University of Michigan

the quote: Plasma thrusters used in satellites could be much more powerful than previously thought (2023, January 24) Retrieved January 24, 2023 from https://phys.org/news/2023-01-plasma-thrusters-satellites-powerful -previously. html

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