JPS5834544A - Multi-stage collector type traveling wave tube - Google Patents

Abstract

PURPOSE:To saturate magnetism in a pole piece and obtain a strong focusing magnetic field in a collector without restricting cooling process by making the thickness of the pole piece that is arranged at an end nearest to the collector thinner than that of other pole pieces. CONSTITUTION:The thickness of a pole piece 9 nearest to the first collector 10 is made thin up to approximately a half of the remaining pole piece 8 . Thus, magnetic saturation takes place in the pole piece 9 and leaked magnetism generates an intense inverse magnetic field at the inner part of the first collector 10. This intense inverse magnetic field prevents the sudden diffusion of an electron beam that flows in the collector, guides the electron beam up to the lower potential second collector 11, and improves the overall efficiency. Suppose that the thickness of the pole piece 8 is t1 and that of the pole piece 9 is t2, a condition of 0.5 t1>=t2 is required to generate magnetic saturation effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to traveling wave tubes, and more particularly to multi-R collector traveling wave tubes using periodic permanent magnet focusing devices.

To improve the efficiency of traveling wave tubes, there is a method to increase the conversion efficiency from the electron beam to the high-frequency circuit, and a method to decelerate the electron beam flowing into the collector after giving energy to the high-frequency circuit using a DC electric field to reduce the kinetic energy of the electron beam. 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 voltage to the collector that is lower than the voltage applied to the high frequency circuit. Since the kinetic energy of the electron beam flowing into the collector has a large dispersion, the collector electrode is divided into multiple parts, and by sequentially applying lower voltages as the distance from the high-frequency circuit increases, the energy is 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 usually weakens within the collector, the electron beam diverges in the radial direction, and before reaching the collector electrode to which a lower voltage is applied, the electron beam reaches the collector electrode to which a relatively high voltage is applied. ;1kliii was trapped in the rectifier electrode, resulting in a decrease in overall efficiency.

In Utility Application No. 55-6091, the first circuit closest to the high frequency circuit is
It is stated that a periodic permanent magnet focusing device is provided around the collector to prevent the electron beam from spreading and to increase the overall efficiency. However, in this conventional technique, since the focusing device is provided around the collector, the diameter of the jll:i collector is small and flJ@ is not possible, and the first:I collector cannot be cooled sufficiently.

It has the disadvantage of requiring a periodic permanent magnet made of gold for the collector, and its application has been limited to small-power traveling wave tubes.

The object of the present invention is to obtain a strong focusing magnetic field in a multi-stage collector type traveling wave tube using a periodic magnet focusing device without being limited by the shape of the collector and without limiting cooling. The goal is to provide a means for achieving this goal.

According to the present invention, in the periodic magnet focusing device provided at *W of the high frequency circuit, the thickness of the pole piece disposed at the roundest end of the collector is made thinner than the thickness of the other pole pieces. Magnetically saturated within the piece,
The increased reversal leakage magnetic field within the collector is used to focus the electron beam.

High frequency circuit output section of helix traveling wave tube according to the present invention and 2
9=y The configuration of the letter section is shown in FIG. In the two-stage flexor-type helix traveling wave tube l, 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 vacuum-tight window 5. It is connected to the coaxial line 6 via. The periodic permanent magnetic field focusing device has a structure in which permanent magnets 7 and pole pieces 8 and 9 are alternately arranged along a pipe-shaped vacuum external device 2.

The second stage collector section is the first reflector 10 near the high frequency circuit section.
It has a structure in which the second collector 11 which is further away from the collector 11 is supported by the insulator 12 inside the Lucta vacuum outside ff1113,
If the voltage applied to helix 3 is V, then the first
Collector 10 has 0.5V.

A voltage of 0.25V is applied to the second collector 11.

Here, the thickness of the pole piece 9 closest to the It:i rector 10 is reduced to about half the thickness of the remaining mail piece 8. By doing this, magnetic saturation occurs in the pole piece 9, causing leakage. The magnetic field generated by the first collector lO
generates a strong reversal magnetic field inside. This strong reversal magnetic field prevents the rapid divergence of the electron beam entering the collector,
The electron beams are guided to the second collector 11, which has a lower potential, thereby increasing the overall efficiency.

The thickness of the bolt heath 8 is tl, and the thickness of the pole piece 9 is 1. In order to effectively generate magnetic saturation, the following condition is required: s Q, 5 tl>h.

2nd!1iiiI shows the axial magnetic flux density distribution when the thickness of the pole piece 9 is changed. BB is a point corresponding to the first collector starting point person-person in FIG. Curve 21 is tl
shows the axial magnetic flux density distribution in the case of mt, and the song 41122
indicates the case of 0.4 tl = Lt. Curve 21.2
From the comparison in 2, it can be seen that if t is made thinner than tl, the focusing magnetic field in the high frequency circuit section will decrease a little, but in the area of the jli:x register 10, it will be strong enough to prevent the rapid divergence of the electron beam. It can be seen that a reversal magnetic field can be obtained.

In the present invention, it is only necessary to reduce the thickness of the pole piece at the end of the collector of a one-period permanent magnet focusing device, and the shape of the collector can be freely designed, as well as heat dissipation blades and heat sinks can be freely installed on the outside of the collector. It can also be applied to high-power traveling wave tubes.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of the high-frequency circuit output part and collector part of a two-stage collector type traveling wave tube in which the present invention is implemented, and Figure 2 shows the structure of the pole piece closest to the collector when the thickness is changed. FIG. 3 is a diagram showing an axial magnetic flux density distribution. DESCRIPTION OF SYMBOLS 1... Two-stage collector type traveling wave tube, 2... Pipe-shaped envelope, 3... Helix, 4... Ij electric body axis, 5...
... Vacuum sealed room, 6... Coaxial line, 7... Permanent magnet, 8... Pole piece, 9... Pole piece, 10
...first collector, 11...s2 collector, 12-
... Insulator, 13 ... Collector vacuum envelope, 21.
... On-axis magnetic flux density distribution when i, = gt, 22...
・On-axis magnetic flux density distribution when 0.4t, = t.

Claims (1)

[Claims] In a traveling wave tube having a beam focusing device using a periodic permanent magnet and am collector electrodes, the thickness of the one ruby closest to the collector is % of the periodic permanent magnet beam focusing device. A multi-stage; register type traveling wave tube characterized by being thinner than the thickness of the pole piece.