A cavity magnetron is a special tube used as a generator of microwave radiation. Czech Professor Augustin Zacek was the first to describe the principle of magnetron oscillation in 1924. The magnetron became the basis of the first US and British ground and airborne radars. The ability of magnetic waves to heat food was discovered by chocolate that accidentally melted in the pocket of one of the researchers working on the development of radar. Raytheon introduced the first microwave oven based on this principle in 1947.