JPS5999646A - Microwave tube - Google Patents

Abstract

PURPOSE:To widen the variable range of the degree of coupling by inserting a coupling loop from a coupling hole into a cavity while mounting said loop on the inward end of a coaxial line, and making the degree of the insertion of said loop variable by making use of the forward and backward movement or rotation of a flange. CONSTITUTION:A variable input coupling part 36 is provided on the first cavity (input cavity) 25 facing to a tuner 32, and a coupling hole 56 extending in the axial direction of the cavity is bored in the wall 50 of the cavity 25. And, a coupling loop 57 bent in approximately ? character-shape is arranged in the cavity 25 such that said loop passes in a non-contact manner through said coupling hole. An RF terminal 58, a coaxial line 58c, and a coupling loop 57 are fixed on a RF terminal mounting flange 60, and although the flange 60 is attached to the cavity wall 50 via a bellows 61 to keep its airtightness, it is movable prependicularly to a tube axis as shown by an arrow P. Accordingly, when the flange 60 is brought near to the tube axis, the effective area of the coupling loop 57 within the first cavity 25 becomes large, thus allowing the coupling to become large. On the contrary, when it is moved away from the tube axis, the coupling becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to improvements in microwave tubes having resonant cavities.

[Technical background of the invention and its problems]

Typical types of tubes that use a resonant cavity and an electron beam to amplify and oscillate microwaves include a straight talistron, a traveling wave tube, and a gyrotron.

For example, a linear high-power klystron consists of an electron gun, an electron action section in which an input cavity, an intermediate cavity, and an output cavity are connected by a drift tube, and a collector. speed modulated by an input signal introduced into the
The intermediate cavity and drift tube gradually modulate the density, and the density-modulated electron beam passes through the gap in the output cavity to obtain amplified microwaves from the output cavity. The resulting electron beam is collected by the collector.

In such a microwave tube, it is necessary to provide a high frequency coupler to add an excitation signal to the input cavity, and an external high frequency absorber is electrically connected to the intermediate cavity to reduce the Q of the cavity. It is necessary to provide a high frequency coupler to adjust the Furthermore, in the case of relatively low power, a coaxial waveguide may be coupled to the output cavity. As for the structure of such a high frequency coupler that couples the cavity and an external circuit, it is rare that the degree of coupling is made variable. Generally, the coupling loop is rotated. However, a coupler having a rotating structure is difficult to employ if its vicinity is placed in a vacuum region because the structure is complicated.

Furthermore, there is a tendency that the variable range of the degree of bonding cannot be made very large.

[Object of the Invention] The object of the present invention is to provide a microwave tube having a high-frequency coupler that has a wide variable range of coupling degree and can obtain stable high-frequency coupling characteristics with respect to a resonant cavity kept in a vacuum. This is what we provide.

[Summary of the invention]

In this invention, a coupling hole is formed in a part of the cavity mold of a resonant cavity whose interior is kept in a vacuum, and a bellows and a flange are attached to the outside of the coupling hole to create a vacuum interior space. Insert the coaxial line and support it on the above flange,
A coupling loop is attached to the inner end of the coaxial line and inserted into the cavity through the coupling hole, and the degree of insertion can be varied by moving back and forth or rotating the flange. This makes it possible to widen the variable range of the degree of coupling, and by using a coaxial line, it is possible to stabilize the coupling characteristics with external circuits.

[Embodiments of the invention]

An outline of an example in which the present invention is implemented in an ultra-high power linear klystron device with an output of 1 megawatt (MW) class will be explained with reference to FIG. This Talistron device has an electron gun section 11.
．． High frequency amplification section Lm output waveguide section 171. and a tube body having a collector section L (an insulating oil-filled tank 15 in which the electron gun section is housed and connected to a power source), a focusing magnet device 16 disposed around the high frequency amplification section, and a focusing magnet device 16 attached around the collector. It is combined with a boiler 17 for evaporative cooling.

The electron gun part has a concave electron emitting cathode 18, a first anode 19, a second anode 2o, and an insulating cylinder 2.
1F1.21b maintains vacuum tightness, and a metal exhaust pipe 22 is provided at the lower end of FIG. A power source is connected through the filament, the cathode terminal 23.14, and the first anode terminal 19m. These are placed in insulating oil in a tank and operated. The high-frequency amplification unit L1 includes a first cavity 25, a second cavity 26, and a third cavity 2, which are resonant cavities for high-frequency input from the upstream side of the electron beam.
7, the fourth cavity 28, the fifth cavity 29, and the sixth cavity 30, which is an output cavity, are arranged in a column, and are connected by drift pipes 31, 31, . . . .

Each cavity has a tuner 3 with a capacitive plate for varying the tuning frequency.
2.32... are provided, and these are driven by drive shafts 33, 33... extending parallel to the tube axis by a drive body provided on the upper part of the collector side pole piece 34 and a suitable gear mechanism. be done.

The first cavity 25 is provided with a variable manual high-frequency coupling section 36 whose degree of coupling can be adjusted using gears.

The second cavity 26 is similarly provided with a variable high frequency coupling section L1, to which an external high frequency absorber (not shown) is connected.

Note that a cathode pole piece 38 is integrally connected to the second anode below the input cavity. The drift tube section between the fourth cavity and the fifth cavity is equipped with an axis adjustment device υ for finely adjusting the axes of each of the upper and lower cavities and the drift tube.
is provided. A bent tapered waveguide 40 is coupled to the output cavity 30, which passes through the collector side pole piece 34 and extends laterally from the space between this and the collector and boiler to maintain vacuum tightness. It is integrated with the output waveguide section 13 having a dielectric plate 41. The focusing magnet device 16 has a yoke 42 and a plurality of electromagnetic coils 43, 43, . . . provided inside the yoke, and is magnetically connected to both pole pieces 34, 311. Note that the high-frequency amplifying section 11 is covered with a cylindrical cover 44, and a magnet device is disposed outside of the cylindrical cover 44. The collector portion 14 is formed into a conical shape, and the outer periphery thereof is formed with unevenness.

The boiler L that surrounds this collector section has a water inlet 45 at the bottom.
A drain port 46 is provided at the top, and a steam outlet 42 is formed in the ceiling. Drain port 4
An open end of a drain pipe 48 is provided protruding inside the collector part 6 so that water is always filled to a predetermined height above the tip of the collector part 14. Note that each drift tube, each cavity outer wall, the collector bottom, the collector side pole piece portion, and the output waveguide portion are forced to be water cooled.

Now, a case will be described in which the multi-cavity high-power klystron as described above is adjusted to a wide band.

As mentioned above, the Q of the cavity is adjusted by connecting an external load to the second cavity 26, which is an intermediate cavity, and the resonance frequency of each cavity is shifted from each other to adjust the bandwidth. Adjust flatness (stagger tuning).

Since the optimum value of the Q of the output cavity 30 is determined from the viewpoint of output conversion efficiency, it is not made variable for band adjustment. In addition, the higher the Q of one or more intermediate cavities near the output cavity, the higher the output conversion efficiency. and an intermediate cavity near the input cavity.

FIG. 2 illustrates a frequency band characteristic diagram obtained by adjusting the coupling degree of each cavity. The number marked on the horizontal axis (11
-(6) show cavities from input cavity 1 to output cavity 6, and their positions indicate the tuning frequency setting values of the cavities. Δf has a 3 dBFtF bandwidth.

Next, the structure of the variable high frequency coupler will be explained. The case of the input cavity 25 will be explained, and the case of the intermediate cavity 26 is different only in that the size of the coupling hole and the coupling loop are slightly smaller, so the description of other parts will be omitted. do.

The embodiment shown in FIGS. 3 to 5 has the following structure. The first cavity (input cavity) 25 is provided with a variable manual power coupling part L1 facing the tuner 11. That is, the cavity wall 50 of the first cavity 25 is provided with an elongated coupling hole 56 in the axial direction of the cavity. A coupling loop 67 bent into a substantially square shape is provided in the first cavity 25 so as to pass through the coupling hole 56 without contact.

One end of this coupling loop 57 is fixed to the inner end of the inner conductor 6811 of the coaxial line 58C integrated with the high frequency coaxial terminal 58 (hereinafter simply referred to as RF terminal), and the other end is fixed to the inner end of the inner conductor 6811 of the coaxial line 58C integrated with the high frequency coaxial terminal 58 (hereinafter simply referred to as RF terminal).
is fixed to the inner end of the

The inner conductor 581N and the outer conductor 58b are coaxial and are made of ceramic
9, and the outer conductor 58b is R,
It is hermetically fixed to the F terminal mounting flange 60 and mechanically held. This flange 60 is attached to the cavity wall 50 via a conductive vacuum bellows 61.

Therefore, the area surrounded by the flange 60, the RF terminal 58, and the bellows 61 is a vacuum internal space 6 similar to the inside of the cavity 25.
2. And in this internal space 62 there is a coaxial line S.
SC is inserted.

In this way, the RF terminal 5 is attached to the RF terminal mounting flange 60.
8 and the coaxial line 58C1 coupling loop 51 are fixed, and the RF terminal mounting flange 60 is attached to the cavity wall 50 via a bellows 61 and kept vacuum-tight, but It can be moved as shown by arrow P. Therefore, if the flange 60 is brought closer to the tube axis direction, the first cavity 2
The effective area (loop width W x loop insertion amount e) of the coupling loop 57 within 5 becomes large.

The bond becomes larger. Conversely, if you move it further away, the bond will become smaller. The coupling hole 56 is formed to have a size as small as possible within a range where the coupling loop 57 and the coaxial line 58C connected thereto can both pass through without contact. Therefore, the inner end of the coaxial line 58C is also dimensioned to be inserted into the cavity 25. Conversely, the space 62 has a size that accommodates most of the coupling loop 57, and when the loop is pulled out from the coupling hole into this space, the degree of coupling is at its lowest.

In addition, in the first cavity 25, there is a C
A variable tuner 32 is provided. That is, a capacitance adjusting plate 49 is disposed opposite to the coupling loop 52, and since the height of the capacitance adjusting plate 49 is slightly larger than the interval between the drift tubes 31, it is formed in an arc shape. This capacity adjustment plate 49 is fixed to one end of a movable capacity adjustment plate support rod 51 that penetrates the cavity wall 50, and the other end of this support rod 5 is fixed to a support body 52 that also serves as an airtight member. There is. This support 52 is airtightly connected to the cavity wall 60 via a bellows 53.

Furthermore, an adjusting threaded rod 55 is screwed into the support body 52 by penetrating the frame 54. In this way, the capacity adjustment plate 4
g, capacity adjustment plate support rod 51, support body 52, bellows 53
, the tuner 32 is constituted by the adjusting threaded rod 55. When the adjustment threaded rod 55 rotates, the capacity adjustment plate support rod 51 moves toward the axis, and accordingly, the capacity adjustment plate 49 also moves in the radial direction of the ts1 cavity 25.

The capacitance adjustment plate is indicated by a dotted line 49a in FIG.

49b, they may be arranged symmetrically on both the left and right sides of the coupling loop 57 so that they can be inserted and retracted as a single unit.

This maintains the symmetry of the electromagnetic field modes within the cavity,
Moreover, the tuning variable range can be made even larger.

〔Effect of the invention〕

According to this invention, the amount of coupling is made variable by varying the amount by which the coupling loop 51 for the high-frequency magnetic field in the first cavity 25 is inserted into the first cavity 25, so the range of variation of the degree of coupling is made variable. It can be made large. In particular, a space is provided outside the coupling hole of the cavity by a bellows and a flange, and a coaxial line that can move forward and backward is provided in this space, and the coupling loop is provided so that it can move forward and backward as a whole, so the range of variable coupling degree is widened. Become. Since it has a coaxial line of a constant length, the characteristic conversion with the external circuit will not be disturbed even if it is varied. Moreover, since these are placed in a vacuum region, there is little risk of high frequency discharge occurring, making them suitable for relatively high power applications.

FIG. 6 shows a modification of the present invention. By rotating the flange 6° in the direction of arrow P while keeping the insertion amount e constant, and bending the direction of the connecting loop 52, the loop 57 can be changed. The effective binding area is changed.

In addition, the variable coupling loop mechanism may be constructed by combining the advancing and retracting directions as shown in FIGS. 3 to 5 and the rotating direction as shown in FIG. 6.

[Brief explanation of the drawing]

Fig. 1 is a schematic vertical cross-sectional view showing one embodiment of the present invention, Fig. 2 is a characteristic diagram thereof, Fig. 3 is a longitudinal cross-sectional view of the main part thereof, Fig. 4 is a cross-sectional view thereof, and Fig. 5 is a cross-sectional view thereof. 4 <51- (A side view of the main part in 51, FIG. 6 is a cross-sectional view showing another embodiment of the present invention. 12... High frequency amplification section, 25... First cavity, 31・
...Drift tube, 36...Variable human power coupling part, 50...
・Cavity wall, 56...Joining hole, 57...Joining loop, 58...F terminal, 5its...Inner conductor, ssb
...outer conductor, 58C...coaxial line, 60...RF
Terminal mounting flange, 61... bellows, 62...
vacuum space. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (2)

[Claims] (1) Forming the above-mentioned cavity in a microwave tube comprising a resonant cavity whose interior is kept in a vacuum, and a high-frequency coupler connected to an external circuit to this cavity and configured to have a variable degree of coupling. A coupling hole is drilled in a part of the cavity wall, and a conductive bellows and a coaxial terminal mounting flange are vacuum-tightly attached to the outside of this coupling hole, and the internal space surrounded by these bellows and flanges is A coaxial line is provided and integrally connected to the coaxial terminal of the flange to be mechanically held by the flange, and a coupling loop can be connected to the inner end of the coaxial line and inserted into the cavity through the coupling hole. A microwave tube characterized in that the flange is configured to be movable forward and backward or rotatable with respect to the cavity. (2) The microwave tube according to claim 1, wherein the coupling hole has a temple shape and dimensions through which the coaxial line and the coupling loop pass through without contacting each other.