A vacuum arc thruster (VAT) is an electric spacecraft propulsion system. It is a type of electric propulsion system used for spacecraft propulsion. It is also known as a VASIMR (Variable Specific Impulse Magnetoplasma Rocket). To generate thrust, a vacuum arc discharge across an insulator between two electrodes is used. Micrometer-sized cathodic spots generate metal plasma. In a VAT, the metallic cathode is consumed as propellant, whereas the insulator is used as propellant in a pulsed plasma thruster. It is intended to provide efficient and high-thrust propulsion in space.
One of the most important characteristics of a vacuum arc thruster is its ability to vary the specific impulse (Isp), which is a measure of a rocket engine’s efficiency. The VASIMR can change its Isp by adjusting its power and magnetic field strength to optimize performance for different mission requirements. It can operate in low-thrust, high-Isp mode for long-duration missions, or in high-thrust, low-Isp mode for quick maneuvers or acceleration.
The vacuum arc thruster works by ionizing a propellant, typically a noble gas like xenon, within a magnetic field using radio frequency (RF) energy. To generate thrust, the ionized gas, or plasma, is accelerated and expelled at high speeds. Magnetoplasma propulsion is the name given to this process.
Advantages
Compared to traditional chemical rockets, the vacuum arc thruster has several advantages. It can deliver significantly higher specific impulses, resulting in increased fuel efficiency and mission duration. VASIMR engines can also run for long periods of time, making them suitable for applications such as station-keeping, orbit transfers, and interplanetary travel.
However, it is important to note that vacuum arc thrusters are still in development and have not yet been widely deployed for space missions. Several research organizations and companies, including Ad Astra Rocket Company, are working to advance this technology and conduct tests to validate its performance and feasibility for various space applications.
In summary, a vacuum arc thruster, or VASIMR, is an electric propulsion system that generates thrust in space using plasma and magnetic fields. It has the potential for high efficiency, variable specific impulse, and long-duration missions, but it requires more research and development to fully realize its capabilities.
