Patent ID: 8193691

Claim:
An electron tube comprising: a microwave structure, an electron gun having a cathode-wehnelt assembly, with axis Zc,Zc′ for providing a linear electron beam along the same axis Zc,Zc′ in a circular cylindrical passage with axis Zs,Zs′ of the microwave structure, the cathode comprising a centre O of rotation of the beam on said axis Zc,Zc′ of the cathode, wherein the electron gun and the microwave structure each comprise portions of spherical surfaces in contact inscribed on one and the same sphere of radius R centred on the centre O of the cathode so as to form a swivel for angular adjustment of the axis Zc,Z′ of the cathode and to make the axis Zc,Zc′ of the electron beam coincide with the axis Zs,Zs′ of the said circular cylindrical passage of the microwave structure.