The spread of the initial energy of electrons in a gyrotron due to the negative-mass instability developing in a magnetron-injector gun

The formation of an electron beam in a magnetron-injector gun of a gyrotron is investigated in the case when it is affected by the negative-mass insta bility due to the Coulomb repulsion and nonisochronous cyclotron rotation o f particles. A technique is proposed for calculating the spread of the init ial energy of electrons caused by the instability, which develops as the el ectron beam moves in the presence of a nonuniform magnetostatic field of th e magnetron-injector gun. It is demonstrated that this instability can be o ne of the main factors providing the energy spread in electron guns of gyro trons. (C) 2000 MAIK "Nauka/ Interperiodica".