JPS5830039A - Multi-stage collector type traveling wave tube - Google Patents

Abstract

PURPOSE:To increase leakage magnetism into a collector and focus an electron beam by means of an intense reversal magnetic field by making an end nearest the collector consist of only magnets and removing a pole piece in a periodic permanent magnet focussing device. CONSTITUTION:A two-stage collector section supports the primary collector 10 that is adjacent to a high frequency circuit section and the secondary collector 11 that is far from it in a collector vacuum enclosure 13 using an insulator 12. Suppose that the voltage applied to a helix 3 is V, 0.5V and 0.25V voltages are applied to the primary and secondary collectors 10 and 11, respectively. In this case, a permanent magnet 7 is located nearest the primary collector 10 and a pole piece 8 is removed. Thus leakage magnetism is increased toward the collectors from the permanent magnet 7 and an intense reversal magnetic field is generated within the primary collector 10. This intense reversal magnetic field prevents the sudden divergence of the electron beam which flows into the collector, guides the electron beam to the lower potential secondary collector 11, and improves overall efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to traveling wave tubes, and more particularly to multi-stage collector traveling wave tubes using periodic permanent magnet focusing devices. To improve the efficiency of traveling wave tubes, there are two methods: increasing the conversion efficiency from the electron beam to the high-frequency circuit, and decelerating the electron beam that flows into the collector after giving energy to the high-frequency circuit using a DC electric field to reduce the kinetic energy of the two electron beams. There is a way to increase the overall efficiency by circulating it back into the DC power supply. The latter method can be realized by applying a lower voltage to the collector than the voltage applied to the high frequency circuit. Since there is a large dispersion in the kinetic energy of the electron beam flowing into the collector, the collector electrode is divided into multiple parts and lower voltages are sequentially applied as the distance from the high-frequency circuit increases, allowing the energy to be refluxed according to the energy distribution of the electron beam. can be achieved, further increasing overall efficiency. However, because the magnetic field that focuses the electron beam normally weakens within the collector, the electron beam diverges in the radial direction, and before reaching the collector electrode where a lower voltage is applied, the electron beam reaches the collector electrode where a relatively high voltage is applied. There was a problem in that it was trapped in the collector electrode, resulting in a decrease in overall efficiency. Japanese Utility Model Application No. 55-6091 describes the provision of a periodic permanent magnet focusing device around the first collector closest to the high frequency circuit to prevent electron beam diffusion and improve overall efficiency. However, in this conventional technology, the diameter of the first collector is limited due to the structure in which a focusing device is provided around the collector, the first collector cannot be cooled sufficiently, and an extra periodic permanent magnet is required for the collector. However, its application has been limited to low-power traveling wave tubes.

An object of the present invention is to obtain a strong focused magnetic field within the collector without being limited by the shape of the collector and without limiting cooling in a multi-stage collector type traveling wave tube using a periodic permanent magnet focusing device. It is to provide the means. According to the present invention, in a periodic permanent magnet focusing device provided around a high frequency circuit, by using only the magnet at the end closest to the collector and removing the pole piece,
FIG. 1 shows the configuration of a high frequency circuit output section and a two-stage collector section of a helical traveling wave tube according to the present invention, which increases the magnetic leakage into the collector and focuses the electron beam by a strong reversal magnetic field. Two-stage collector type helix traveling wave tube 1
The high-frequency circuit section has a structure in which a helix 3 is supported by a dielectric rod 4 in a pipe-shaped vacuum envelope 2, and the output end of the helix 3 is connected to a coaxial line 6 through a vacuum-tight window 5.
It is connected to the. The periodic permanent magnetic field focusing device has a structure in which permanent magnets 7 and pole pieces 8 are alternately arranged along a pipe-shaped vacuum envelope 2. The two-stage collector section has a structure in which a first collector 10 near the high-frequency circuit section and a second collector 11 farthest from the high-frequency circuit section are supported within a collector vacuum envelope 13 by an insulator 12, and a voltage is applied to the helix 3. If the voltage is V, then a voltage of 0.5 V is applied to the first collector 10 and a voltage of 0.25 V is applied to the second collector 11. Here, the permanent magnet 7 is placed closest to the first collector IO, and the pole piece 8 is removed. By doing so, magnetic leakage from the permanent magnet 7 toward the collector increases, and a strong reversal magnetic field is generated at the base of the first collector 100. This strong reversal magnetic field prevents the electron beam that has entered the collector from rapidly diverging, guides the electron beam to the second collector 11 with a lower potential, and increases the overall efficiency. In the present invention, it is only necessary to remove the pole piece at the end of the collector of the periodic permanent magnet focusing device, and not only can the shape of the collector be freely designed, but also heat dissipation blades, heat sinks, etc. can be freely attached to the outside of the collector. , it is also applicable to high power traveling wave tubes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a high frequency circuit output section and a collector section of a two-stage collector type traveling wave tube in which the present invention is implemented. 1: Two-stage collector type traveling wave tube, 2: Vibe-shaped envelope, 3
: Helix, 4: Dielectric rod, 5: Vacuum sealed window, 6: Coaxial line, 7: Permanent magnet, 8: Pole piece, 10: First
Collector, 11: Second collector, 12: Insulator, 13;
Collector vacuum envelope. degree

Claims (1)

[Claims] A traveling wave tube having a beam focusing device using a periodic permanent magnet and a plurality of collector electrodes, wherein the collector end of the periodic permanent magnet beam focusing device is a multi-stage collector type traveling wave tube.