Shaping a stationary tubular electron beam of high perveance in a longitudinal magnetic field

A description is given of an electron gun that produces a stationary tubular beam, whose perveance is close to the limit for such a beam in a cylindrical drift chamber. The cathode and anode of the gun are made as two coaxial cylinders, while the magnetic field is shaped in such a way that all the force lines passing through the emitting surface intersect a ring of small thickness at the exit from the gun. A beam bearing a maximum current of 10 A has been produced at an anode voltage of 3kV in a magnetic field of 500 G. A beam with this perveance can be transported over a distance of 1.5 m in a sufficiently strong magnetic field without shape deviation