Electromagnetic propulsion (EMP) requires two primary components: an electromagnet to generate the magnetic field and a propulsion component. EMP uses a current from the magnetic field to accelerate the object. Through Lorenz Force, the electrified conductor encounters a force in a perpendicular direction to the magnetic field and the current. If a liquid or gas is used for propulsion instead of a conductor, this force is called Magneto Hydro Dynamic drive.
The concept of electric propulsion is gaining popularity in the aerospace industry for use as a spacecraft thruster. For decades, the aerospace industry has led research into electric propulsion, focusing on electric propulsion diagnostics. The aerospace industry has long applied advanced diagnostics to thruster characterization, and now it is using various plasma probes to analyze the electric potential, density, and electron temperature of plasma. Aerospace researchers were the first to characterize electric propulsion thrusters using various diagnostic tools, including electromagnetic radiation measurement.
How Electromagnetic Propulsion Will Work
While space travel has thus far been limited to chemically-propelled rocket engines, in the early 21st century, antimatter, nuclear fusion, and light propulsion techniques are becoming promising means for space travel. New spacecraft without a means of propellant are also being introduced. These spacecraft would be moved through space using electromagnets.
At very low temperatures, electromagnets exhibit unique behavior—once electricity is applied, they vibrate for a few nanoseconds. Researchers hypothesize that if the vibrations are contained in a single direction, the jolt could propel the spacecraft further and faster than any other propulsion method can.
Types of Thrusters Used in Space Applications
Space applications rely on the following types of thrusters:
- Field Emission Electric Propulsion: This type of propulsion relies on indium, cesium, or another metal ion. It applies a potential difference of several kilovolts between accelerator electrodes and an emitter, accelerating the ions at high speeds. Satellites use field emission electric propulsion for precision direction and altitude control.
- Gridded Ion Thruster: This is a thrust system that uses electrostatic forces to accelerate ions. Negatively charged electrodes on the thruster’s downstream end create the electric field to facilitate acceleration. Coaxial apertures on the electrode function as lenses by focusing the ions. Positively charged upstream electrodes act as an accelerator grid, which attracts the ions and creates numerous ion jets. The amount of voltage applied affects the ions’ exhaust velocity in the beam.
- High-Efficiency Multistage Plasma Thruster: THALES Electron Devices in Germany developed this thruster, based on the ion thruster principle. It consumes propellant at a rate below 20% of the chemical system. The magnetic exit cusp confines low-energy neutralizer electrons to maintain a reduced plasma potential toward the thruster end, resulting in only a few electrons reaching the discharge channel’s exit cusp. The electrons that escape get trapped along the bent magnetic flux lines in spirals. The strong magnetic field gradient acts like a mirror, reflecting electrons in a radial direction.
- Hall Effect Thruster: This thrust system depends on electrostatic potential to accelerate ions. At the thruster’s open end, plasma creates a negative charge. A radial magnetic field equal to approximately 0.03 Tesla confines the electrons, while xenon gas or other propellant is fed through an anode and diffuses into the thruster’s channel, where the electrons ionize it. The propellant ions are accelerated between the cathode and anode.
- Magneto Plasma Dynamic Thruster: Based on the principle of Lorenz Force, Magneto Plasma Dynamic Thrusters eliminate the need for fuel combustion. Xenon, argon, neon, or another gas is ionized as it is fed into the accelerator chamber. The power source creates an electric and magnetic field, and the ionized gases are propelled out of the exhaust chamber, generating thrust.
- Pulse Plasma Thruster: As the most simple electric propulsion system, the pulse plasma thruster was used in 1960s Soviet-era spacecraft. An arc sent through fuel turns into plasma, which then travels between two capacitor-charged plates, charging the plasma and creating an electron flow. A strong electromagnetic field is created, exerting Lorenz Force and exhausting the accelerated plasma at high velocities. It functions on similar principles to a railgun.
- Quad Confinement Thruster: Using eight electromagnets, quad confinement thrusters generate a convex magnetic field with a central cusp and four outer cusps on the periphery. Accelerated ions pass through a Hall Effect static field to create thrust.
Contact Custom Coils for Your Electromagnet Needs!
Many applications depend on electromagnetic propulsion, including spacecraft and military aircraft. Electromagnetic propulsion is being researched for missile launches, long-range artillery, and direct-fire tank guns. It is also an essential technology in enabling all-electric submarines and naval ships in the future.
Custom Coils has been developing, testing, and manufacturing specialty coils since 1978. We specialize in creating custom coils for challenging applications, such as vacuum, zero gravity, and extreme temperature conditions typical to the aerospace industry. Contact us or request a quote to learn more about our capabilities.