Magnetoplasma thrusters, also known as magnetoplasmadynamic (MPD) thrusters, are a type of electric propulsion system that uses magnetic and electric fields to ionize and accelerate propellant to generate thrust. Similar to ion thrusters, they are known for their high specific impulse and propellant efficiency.
Magnetoplasma thrusters use a magnetized plasma as the propellant. The propellant is ionized and accelerated by electromagnetic forces, generating a high-velocity exhaust. These thrusters are capable of achieving high specific impulse, making them suitable for long-duration space missions where continuous low-thrust maneuvers are needed.
The propulsive efficiency is a crucial parameter in evaluating the performance of a rocket engine, indicating how well it converts propellant energy into useful thrust. Practical rocket engines often have propulsive efficiencies less than 100% due to factors like incomplete combustion, heat losses, and other inefficiencies in the propulsion system.
The propulsive efficiency () is defined by the following formula:
where,
- is the propulsive efficiency,
- is the thrust produced by the rocket engine,
- is the effective exhaust velocity of the rocket,
- ṁ is the mass flow rate of the propellants,
- is the specific impulse of the rocket engine,
- g0 is the acceleration due to gravity (approximately 9.81 m/s²).