To provide a space thruster with which energy transfer becomes more efficient.

A thruster 1 has a main chamber 6 defined within a tube 2. The tube has a longitudinal axis which defines an axis of thrust. An injector 8 injects ionizable gas at one end of the main chamber within the tube. An ionizer 124 is adapted to ionize the injected gas within the main chamber 6. A first magnetic field generator 12, 14 and an electromagnetic field generator 18 are configured to generate a magnetized ponderomotive accelerating field downstream of the ionizer 124 along the direction of the thrust axis. The thruster 1 ionizes the gas, and subsequently accelerates both electrons and ions by the magnetized ponderomotive force.