Hall-effect thruster (HET) technology
Electric propulsion (also known as EP, plasma propulsion, and ion propulsion) is as old as rocketry itself, being first proposed by pioneering Rocket Scientist Konstantin Eduardovich Tsiolkovsky in 1911.
In the last century, myriad devices with exotic-sounding names like magnetoplasmadynamic thruster, helicon thruster, ion engine, arcjet, RF plasma thruster, and electrospray thruster have been thoroughly investigated in laboratories across the globe. After decades of development, trial, and error one technology has distinguished itself time and again as the highest-performing, most reliable in-space propulsion solution: the Hall-effect Thruster (HET).
HET technology has evolved, stabilized, and now has been in use on spacecraft for nearly 30 years. It is trusted on the most demanding missions and has never failed in space. Historically, only government agencies have been able to afford the luxury of HET systems on their flagship spacecraft. With the Orbion Aurora propulsion system, private small-satellite owners and operators can enjoy the same high performance on commercial-sized budgets.
What is a Hall-effect thruster (HET)?
A HET is a type of ion, or plasma, thruster which accelerates propellant via an electric field. Trapped within an intense magnetic field, electrons ionize the propellent—in the case of the Aurora, inert xenon or krypton gas—creating ionized plasma. Electrostatic forces generated from the satellite’s on-board power system accelerate the ions to exhaust velocities of 20,000 meters per second.
Because of their incredibly high exhaust velocity, Hall thrusters demonstrate significant propellent mass savings over chemical propulsion-based systems, allowing spacecraft to do more with less.
How Hall-effect thrusters stack up against other options
EP systems require significantly less propellant mass than chemical propulsion systems, and thus are favored for the cost savings and performance increases they allow. However, high specific impulse and efficiency are necessary but not sufficient conditions for an EP flight system. Throughout nearly 100 years of laboratory development each new experimental EP device has exposed a new set of challenging problems that, often, don’t fully surface until 1,000s of hours of testing or, worse, on-orbit anomalies are discovered. The promise of new propellants, plasma acceleration schemes, and power processing components have a long and frustrating history of yielding to system-level complexities such as spacecraft contamination, spacecraft charging, electromagnetic noise, or vanishing mass margins when attempting to transition into a flight product.
Your EP solution must add value to the spacecraft as a system. Benefits such as cheaper propellant, lower pressure tank, or a few percent increase in specific impulse do not outweigh the risk of catastrophic failure that can accompany The Next New Thing. The Hall-effect thruster has proven over and over that its system-level performance benefits are unrivaled. In fact, over the past 15 years Hall thrusters have “robustly outperformed chemical thrusters in terms of reliability.” Hall thrusters are trusted by the largest and most-expensive government and commercial satellites and they have never caused a mission failure. In fact, Hall thrusters have occasionally rescued multi-$100M spacecraft (AEHF-1 and GEOStar 3) when less-reliable propulsion systems failed. In the current New Space era there are a number of variant technologies seeking to challenge the Hall thruster. While maturity of these systems are low, there’s sufficient data by which they can be compared against a HET system. This table is not exhaustive, but captures a side-by-side comparison of some systems-level implications of recent electric propulsion products.
|Product family||Xe/Kr HETs||Mercury / Iodine HETs||Indium & Gallium FEEP||Water EP Devices||Electro-spray||RF Plasma Thruster|
|Spacecraft contamination||None||Films on solar panels, optics, electrical systems||Conductive films on solar panels, optics, electrical systems||Condensation on cold surfaces||Conductive films on solar panels, optics, electrical systems||Depends on propellant|
|Propellant supply system||Proven / Simple||Unproven / Complex||Proven/ Simple||Potential for on-orbit freeze/expansion damage||Unproven||Depends on propellant|
|Flight heritage||> 1,000||O||10s||1s||1s||1s|
|Ground handling safety||Safe||Toxic / Highly Corrosive||Safe||Safe||Safe||Safe|
|Thrust/Power||High||Theoretically High||Very low||Low||Theoretically High||Very low|
|Specific Impulse||High||Theoretically High||High||Low||Theoretically High||Low|
The Engineers at Orbion have over 200 years of combined experience with HET technology and spacecraft electronics.
Orbion has re-invented the manufacturing process to provide high-reliability Hall thrusters on a commercial budget.Learn about our manufacturing
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