DE1093920B - High compression electron beam generation system with combined electrostatic and magnetic focusing, especially for travel time tubes - Google Patents

Description

GERMAN

In high-compression beam generation systems, a combined electrostatic and magnetic compression applied.

The electrostatic compaction, as it has so far z. B. in Wanderfeidwendelröhren in the production a so-called Brillouin jet has been used, has several disadvantages, e.g. B. increased noise, Great sensitivity of the beam generation system to installation tolerances, strong dependency on the gain of the magnetic field strength xo and decreasing output power with increasing magnetic Leading field strength as well as a strong increase in the filament leakage current when it rises more sharply Input signal.

Beam generation systems with combined electrostatic and magnetic compression, on the other hand, do not show these deficiencies, but also have the Advantage of a higher degree of efficiency and enable a more intensive one due to the more precise beam guidance Coupling.

The realization of a beam generation system with combined electrostatic and magnetic Compaction can be done in a number of ways. For example, around the beam generation system a magnetic cylinder are placed, the opening cross-section is chosen so large that a certain part of the magnetic field required to focus the electron flow up to the cathode is effective and the strength of the magnetic field from the cathode in the electron flow direction gradually increases to the full value of the magnetic guide field strength. Sufficient for lower compression it is to achieve the desired increase in field strength through ferromagnetic rings.

In the book "Advances in High Frequency Technology", Vol. 3, Leipzig 1954, p. 294, electron beam generation systems are described with combined electrostatic and magnetic focusing, in which the magnetic field interacts is generated with an elongated focusing coil, namely by means of a perforated disc made of magnetic Material, of a cylinder made of magnetic material surrounding the electron gun or a magnetic auxiliary coil with opposing field.

In all of the known arrangements, only the edge electrons or the central electrons are essentially The electrons emerging from the cathode are fully focused, while the remaining electrons are imperfect be bundled. The ones required in high-compression beam generating systems large convergence angles cannot be achieved with the known beam generation systems.

In the case of very high compression, the

generating system with combined

electrostatic and magnetic

Focus, in particular

for transit time tubes

Applicant:
Standard electrical system Lorenz

Corporation,

Stuttgart-Zuffenhausen,

Hellmuth-Hirth-Str. 42

Dipl.-Ing. Dr. Werner Klein, Korntal (Württ),

and Dipl.-Ing. Walter Friz, Stuttgart,

have been named as inventors

avoidable distortion errors that produce the desired Expand the intersection point of the electron flow lines to an intersection area. In order to achieve a usable focus despite these inevitable distortion errors and to achieve that both the edge and the central electrons are equally well focused, whereby a much smoother jet boundary is achieved, especially with high compression, beats the invention in a high-compression, coaxial of at least one ferromagnetic cylinder enclosed electron gun in which the electrons emitted by a concave cathode by means of electrostatic and magnetic focusing fields are bundled to form an electron beam, especially for time-of-flight tubes, propose that the ferromagnetic (s) surrounding the electron gun Cylinder is (are) designed and arranged in such a way that, viewed from the cathode, it is cylindrical Forms zones with opening cross-sections that increase in the electron flow direction.

In a further development of the subject matter of the invention, it is proposed that two be used ferromagnetic cylinders one cylinder inside and the other cylinder outside the vacuum vessel to arrange the tube. Due to the separation, the two cylinders can operate on different magnetic Potential. Due to the distance between the two cylinders and their axial overlap

009 650/385

the necessary degrees of freedom are given. A particular advantage of this version is the possibility of Compensate for the specimen variance that always occurs by simply readjusting the outer cylinder to be able to.

1 shows schematically a high compression beam generation system according to the invention with combined electrostatic and magnetic focusing, the concave cathode 1 being surrounded by the focusing electrode 2 and an acceleration anode 3 being provided. A ferromagnetic cylinder 4 coaxially surrounds the radiation generating system. Part 5 of this cylinder enables the above-mentioned additional increase in field strength. The beam generation system itself, including the magnetic cylinder, is arranged in a magnet that generates a homogeneous magnetic guide field Φ.

In Fig. 2, a beam generation system with two ferromagnetic cylinders 4 and 6 is shown schematically. As in FIG. 1, the concave cathode 1 is surrounded by a focusing electrode 2. 3 is again an acceleration anode. The ferromagnetic cylinders coaxially enclose the beam generation system. The cylinder 6, which axially overlaps the cylinder 4 by a certain amount and is at a certain distance from it, provides the additional field strength increase. It is advantageous to place the vacuum envelope between the cylinders 4 and 6. Then the cylinder 6 can be adjusted from the outside; With this, the most favorable amount of the field strength increase can be set for a given magnetic field Φ.

With the help of these two exemplary embodiments Build beam generation systems with combined electrostatic and magnetic compression, which have a particularly high compression, whereby the convergence angle can be greater than 30 °.

Claims (5)

Patent claims: substantially in the direction of the electron flow lines extending electrostatic and magnetic focusing fields are of a Konkavkathode electrons emitted by bundled into an electron beam, in particular for velocity-modulated tubes, characterized in that the (s) of the electron gun enclosing (n) ferromagnetic cylinder (s) so constructed and arranged is (are) that he (they), seen from the cathode, forms cylindrical zones with opening cross-sections which increase in the electron flow direction. 2. electron gun according to claim 1 for generating an omnidirectional beam, characterized characterized in that the electron gun and the ferromagnetic ^) The cylinder is (are) designed to be rotationally symmetrical and the ferromagnetic cylinder (s) represents (represent) a structure widening in a step-like manner in the electron flow direction. 3. Electron gun according to claim 1 for generating a flat beam, characterized characterized in that the electron gun and the ferromagnetic ^) The cylinder is axially symmetrical and the ferromagnetic cylinder (s) represents (represent) a structure widening in a step-like manner in the electron flow direction. 4. electron gun according to one of claims 1 to 3, characterized in that that when using two ferromagnetic Cylinders one of the cylinders inside and the other cylinder outside the vacuum vessel of the Tube is arranged. 5. electron gun according to one of claims 1 to 4, characterized in that that the convergence angle of the electron beam is greater than 30 °. 1. High density, from at least one 40 publications considered: ferromagnetic cylinder coaxially enclosed "Advances in High Frequency Technology", Vol. 3, Leipzig Electron gun, in which the zig 1954, p. 294. 1 sheet of drawings © 009 650/385 11.