Abstract: This invention relates to electron guns, each comprising of an indirectly heated cathode, a gate electrode and an anode, for generating electron beams of various shapes and power that are preferably used to machine workpieces. Thus cathodes can be used with various geometric designs. Thus cathodes of the most varied geometrical shapes can be used. Along with band cathodes and band cathodes with bodies attached to them, massive cathodes such as bolt-type cathodes can also be applied. Using massive bodies results in a longer service life of the cathode as compared to band cathodes. Another benefit is that the service life of the heat source for the cathode is identical to the service life of the laser used. It is particularly advantageous to place the laser outside the housing, which ensures a very long service life of this source of heat. At the same time, the solution according to the invention is distinguished by an indirect temperature measurement of the cathode.