JPS61171034A - Highly-efficient helix traveling-wave tube - Google Patents

Abstract

PURPOSE:To provide speed inclinations which enable the suppression of backward wave oscillation and the realization of a high efficiency not lower than that of a helix traveling-wave tube of relatively low electricity consumption. CONSTITUTION:An electron beam 3 emitted from an electron gun 1 interacts with electromagnetic waves entered through an electromagnetic wave input portion 5, so that the electromagnetic waves are amplified, and the electron beam advances to a collector 2 while being modulated. In a part extending from an input-side wave delay circuit 7 to an output-side wave delay circuit 8 and having a circuit period P1, the phase velocity of the electromagnetic waves is increased so as to improve the phase distortion of a helix traveling- wave tube and suppress the dispersion of the speed of the electron beam 3. In a speed inclination part following the above-mentioned part, many electrons are uniformly synchronized with the electromagnetic waves to serve to improve the efficiency of the helix traveling-wave tube. The speed inclination in the input-side wave delay circuit 7 serves to suppress backward wave oscillation, while that in the output-side wave delay circuit 8 serves to improve the efficiency and suppress backward wave oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a helical traveling wave tube, and particularly to a helical slow wave circuit type provided with a velocity taper for improving efficiency and suppressing backward wave oscillation.

[Conventional technology]

As is well known, a helix traveling wave tube consists of an electron gun section for emitting an electron beam, a helix slow wave circuit section where the electron beam and electromagnetic waves interact, and a helix slow wave circuit section that collects the electrons that have finished interacting with the electromagnetic waves. an electromagnetic wave input section for guiding electromagnetic waves to a slow wave circuit, an electromagnetic wave extraction section for taking out electromagnetic waves to an external circuit, and a collector section for focusing electrons and beams to a predetermined beam diameter in the slow wave circuit. Consists of a magnetic field device. Among these, the helix slow wave circuit obtains an amplification effect by reducing the phase velocity of the electromagnetic wave to approximately the same velocity as that of the electron beam and maintaining a synchronous relationship between the two.

Helix traveling wave tubes have a simpler structure than coupled cavity traveling wave tubes and other traveling wave tubes.
Although they are already widely used as high-frequency amplifier tubes with relatively low or medium power, in recent years, with the increase in communication capacity and the rise of solid-state devices, there has been a demand for even higher output.

[Problem that the invention seeks to solve]

When increasing the output of a helical traveling wave tube, J
The most serious problem is backward wave oscillation caused by the coupling of the (n=-1) order spatial harmonic and the electron beam. The inventor previously proposed a method of providing a speed taper in the center of the circuit with a small change in circuit period as a method for suppressing this backward wave oscillation. (Special application 1977-101
450. Patent Application No. 167840/1972) is proposed.

Therefore, if this method is used, a high-power helical traveling wave tube with suppressed backward wave oscillation can be produced, but the efficiency is approximately the same as that of the conventional tube.

On the other hand, in order to improve the efficiency of the helical traveling wave tube,
There are two methods: applying a velocity taper to improve beam efficiency (Japanese Patent Application No. 52-50375) and applying a multi-stage potential drop collector to improve collector efficiency. Normally, these two methods are used in parallel to realize a highly efficient helical traveling wave tube. However, this speed taper for improving efficiency reduces the phase speed of the circuit wave in the region very close to the electromagnetic wave extraction part in accordance with the speed of the electrons reduced by the interaction, which reduces the backward wave oscillation mentioned above. Problems have limited its applicability to relatively low power helical traveling wave tubes.

[Means for solving problems]

The present invention suppresses backward wave oscillation in a high-power helical traveling wave tube, and moreover has a velocity taper that is approximately the same level or higher than the velocity taper for the sole purpose of improving efficiency, which is applied to the above-mentioned relatively low-power helical traveling wave tube. This provides a speed taper that can achieve high efficiency.

The speed taper according to the present invention changes the output side slow wave circuit between the electromagnetic wave attenuator and the electromagnetic wave extraction part to the electromagnetic wave input part side circuit period (P6) of the input side slow wave circuit between the electromagnetic wave input part and the electromagnetic wave attenuator. It consists of three parts: a slow wave circuit with a larger circuit period (P1), a slow wave circuit with a smaller circuit period (P2), and a speed taper section that changes from a larger circuit period to a smaller circuit period. The circuit period (P(Z)) at direction position 2 is p (z) = p, e-a I z-z1), where zl is the axial position of the speed taper starting point.
(l) (a is a constant determined by P, , P, , the length of the speed taper section by lT), and the circuit length of the speed taper section (lT) is a slow wave circuit with a large circuit period. The ratio (Lr/L) to the sum (L) of the length (l1), the circuit length of the speed taper section, and the circuit length (l2) of the slow wave circuit with a small circuit period is in the region of P,
The ratio (Pt/Pt > of The present invention provides a high-output helix traveling wave tube with high efficiency and suppressed backward wave oscillation.

〔Example〕

FIG. 1 shows an embodiment of the invention. 1 is an electron gun, 2 is a collector, 3 is an electron beam, 4 is an electromagnetic wave attenuator, 5 is an electromagnetic wave input section, 6 is an electromagnetic wave extraction section, 7 is an input side slow wave circuit, and 8 is an output side slow wave circuit.

The overall configuration of the circuit period of the slow wave circuit is as follows: The circuit period of the electromagnetic wave input $5 side of the input side slow wave circuit 7 is Po, and the circuit period of the electromagnetic wave attenuator 4 side of the input side slow wave circuit 7 and the output side slow wave circuit 8. The circuit period P1 on the electromagnetic wave attenuator 4 side is P. The circuit period P on the electromagnetic wave extraction section 6 side of the output slow wave circuit 8 is set smaller than Po.

Further, the speed taper of the input side slow wave circuit is a linear taper, and the speed taper of the output side slow wave circuit is an exponential function taper as shown in equation (l).

In the figure, the electron beam 3 generated and emitted from the electron gun 1 interacts with the electromagnetic waves that have entered through the electromagnetic wave input section 5, the electromagnetic waves are amplified, and the electron beam 3 is modulated and sent to the collector 2 side. proceed. On the way, most of the electromagnetic waves are attenuated by the electromagnetic wave attenuator 4, but at the J side end of the attenuator of the output slow wave circuit 8, the electromagnetic waves are induced by the modulated electron beam, and the electromagnetic waves interact with the electron beam 3 again. The electromagnetic wave then proceeds to the collector 2 side, is amplified, and finally is extracted to the outside through the electromagnetic wave extraction section 6.

At this time, in the part where the circuit period is P from the input side slow wave circuit 7 to the output side slow wave circuit 8, the phase velocity of the electromagnetic wave becomes faster, improving the phase distortion of the P1 Hessox traveling wave tube and improving the electron beam. Velocity dispersion is suppressed and many electrons uniformly synchronize with electromagnetic waves in the subsequent velocity taper section, contributing to efficiency improvement. Of the two speed tapers, that of the input slow wave circuit 7 acts to suppress backward wave oscillation, and that of the output slow wave circuit 8 acts to improve efficiency and suppress backward wave oscillation. The speed taper of the output side slow wave circuit 8 is determined by the following formula, where the circuit period P (z) at the axial position 2 is s''+t as the position of the taper start point (a constant determined from the taper length t-1) It changes with an exponential function as shown in (l), and the phase velocity of the circuit wave decreases as the electron beam velocity decreases, resulting in high efficiency.

The inventors performed computer simulations on the configuration of the present invention as described above, confirmed that backward wave oscillation was suppressed and high efficiency was obtained, and discovered the optimal dimensional relationship for obtaining high efficiency.

Figure 2 shows a helix voltage of 7 kV and a collector current of 120 kV.
Taking a 12 GHz imperial helix traveling wave tube with mA as an example,
In the configuration of the present invention, the horizontal axis represents the ratio (lT/L) of the length tT of the speed taper part to the total length (c) of the output side slow wave circuit, and the lower circuit period is expressed as the ratio of the length tT of the speed taper section to the total length (c) of the output side slow wave circuit. Ratio of (P2) (Pt/Pt) The t-9 axis indicates a region where an efficiency of 28 cm or more can be obtained. Here, L
is normally set so that the gain of the output side slow wave circuit is 26 dB or more.

From the figure, the region where efficiency of 28% or more can be obtained is and .

3(a) and 3(b) show the slow-wave circuit configuration at every point of entry within the region of FIG. 2 and the axial change in efficiency according to a computer simulation at that time. In the figure, the solid line represents the case of a slow wave circuit configuration according to the present invention, and the dotted line represents the case of a uniform circuit period. From (b) in the figure, the beam efficiency in the case of the slow wave circuit configuration according to the present invention is 29.4%, which is an improvement of 1.86 times compared to the 15°8 inch in the case of the uniform circuit period. There is. Furthermore, if we compare (a) and (b) t, it can be seen that a portion with a circuit period of P on the output extraction section side is necessary in order to obtain high efficiency. The length differs somewhat depending on the design conditions, but in most cases the maximum efficiency was obtained within the range of . Furthermore, the computer simulation result of the oscillation starting current of backward wave oscillation in the slow wave circuit configuration shown in (a) is 5QQmA, which is sufficiently suppressed compared to the operating current of 120mA.

It is clear that the condition values ) to (l2) obtained from the analysis results of the 12 GHz band helical traveling wave tube described above generally hold true in a normal helical traveling wave tube.

In this example, a two-segment helical traveling wave tube in which the electromagnetic wave attenuator is located in one place has been described.
It is clear that this also holds true when there is more than a force.

However, at this time, the circuit period P0 is the circuit period on the electromagnetic wave manual section side of the slow wave circuit before the output side slow wave circuit.

〔Effect of the invention〕

As explained above, the present invention provides a slow wave circuit with a larger circuit period (P2) and a circuit period with a smaller circuit period (P2) than the circuit period (P0) on the electromagnetic wave input section side of the input slow wave circuit.
) and a speed taper section that changes from a large circuit period to a small circuit period, and the change in circuit period in the axial direction in the speed taper is given by equation (l), The dimensional relationship of the valley is expressed by the formula 2〇)~(
The wax traveling wave tube is characterized by the characteristics given by 12) and provides a wax traveling wave tube that is highly efficient and produces high output with suppressed backward wave oscillation.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a helical traveling wave tube of the present invention and a configuration diagram of a slow wave circuit.
A characteristic diagram showing the region where the maximum efficiency is obtained with s as the vertical axis. Figure 3 (a) is a diagram of the slow wave circuit configuration of the present invention used for calculation. Figure 3 (b) is the beam efficiency versus axial distance. FIG. 1...Electron gun, 2...Collector, 3.
...electron beam, 4...electromagnetic wave attenuator,
5... Electromagnetic wave input section, 6... Electromagnetic wave extraction section, 7... Input side slow wave circuit, 8...
...Output side slow wave circuit. Agent: Susumu Uchihara, patent attorney 7.・\1,
, “−゛茅 2 times (α) (b) 3rd drunkenness

Claims (1)

[Scope of Claims] 1. In a traveling wave tube having an electron gun, a collector, an electromagnetic wave input section, an electromagnetic wave extraction section, and a helical slow wave circuit divided in high frequency by an electromagnetic wave attenuator in the middle, the electromagnetic wave attenuation The slow wave circuit between the electromagnetic wave input section and the electromagnetic wave attenuator is configured to have a circuit period (P_1) larger than the circuit period (P_0) on the electromagnetic wave input section side of the slow wave circuit between the electromagnetic wave input section and the electromagnetic wave attenuator. Wave circuit section and small circuit period (
It consists of three parts: the slow wave circuit part of P_2) and the speed taper part that changes from a large circuit period to a small circuit period,
The circuit period P(z
) is the axial position of the speed taper starting point as z_1, and P (z) = P_1e^-^a^(^re^-^^re^_^0
^) (a is P_1, P_2 and the length of the speed taper part l
_T (constant determined from T), and the circuit length of the speed taper section (
The circuit length (lT) of the slow wave circuit with the large circuit period is
_1), the sum (L_T) of the speed tapered portion and the circuit length (l_2) of the slow wave circuit with the small circuit period.
), the ratio ([l_T]/L) of 0.24≦(l_T)/L≦0.5. 2. The small circuit period (P_1) with respect to the small circuit period (P_1) with respect to the large circuit period (P_1)
2) ratio ([P_2]/[P_1]) is 0.7≦(P
_2)/(P_1)≦0.9. The helical traveling wave tube according to claim 1. 3. The ratio of the circuit length l_2 of the slow wave circuit with the small circuit period (P_2) to the total length (L) of the output side slow wave circuit (
The helical traveling wave tube according to claim 1, characterized in that l_2/L) satisfies 0.07≦(l_2)/L≦0.24. 4. The ratio (l_2/L) of the circuit length (l_2) of the slow-wave circuit with the small circuit period (P_2) to the total length (L) of the output-side slow-wave circuit is 0.07≦(l_2)/L≦0 .24. The helical traveling wave tube according to claim 2, characterized in that: .24.