Microwave ovens do not use rotating magnetrons. Instead, they use a fixed magnetron, which is a type of vacuum tube that generates the microwaves used for cooking. The magnetron operates at a fixed frequency, typically around 2.45 gigahertz (GHz), and it does not rotate during the cooking process.
The rotation you might observe inside a microwave oven is not related to the magnetron but rather to the turntable or rotating plate found at the bottom of the microwave's interior. The turntable's purpose is to rotate the food being cooked, ensuring more even exposure to the microwave energy and thus more uniform cooking. Some microwave models also feature a rotating antenna or stirrer, which helps distribute the microwaves more evenly throughout the oven cavity, further improving cooking uniformity. However, these components are not magnetrons and do not rotate at high speeds. The rotation speed of the turntable and other components is usually quite slow, usually a few revolutions per minute (RPM).