From AMS Glossary
Magnetrons are characterized by high peak power, small size, efficient operation, and low operating voltage. Emitted electrons interact with an electric field and a strong magnetic field to generate microwave energy. Because the direction of the electric field that accelerates the electron beam is perpendicular to the axis of the magnetic field, magnetrons are sometimes referred to as crossed-field tubes. Unlike a klystron, a magnetron is not a coherent transmission source, but has a randomly changing phase from pulse to pulse. A coaxial magnetron uses a different architecture and has better stability, higher reliability, and longer life. Magnetrons are used in inexpensive radars and microwave ovens.