Magnetron testing. Technician testing a magnetron, a device that creates microwave radiation. A magnetron consists of an electron tube surrounded by a magnet. As electrons are released from the heated cathode they are forced to take a spiral path to the anode by the magnetic field, creating microwaves. This magnetron will be used in a medical linear accelerator (Linac), a radiotherapy device used to treat cancer. The microwaves will be aimed at a cancerous tumour. The radiation will disrupt the tumour cells' DNA (deoxyribonucleic acid), either stopping their replication or killing them. This magnetron is produced by e2v Technologies.