JPS6026440Y2 - Magnetron indirectly heated cathode structure - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an indirectly heated cathode structure for a magnetron.

Conventionally, the cathode structure of a high-power pulsed magnetron is constructed as shown in FIG. 1, in which a cathode layer 3 is formed around the outer periphery of a cathode sleeve 2 which is of a so-called indirect heating type and has a heater 1 built therein.

End hats 4 and 5 are provided at both ends of the cathode layer 3 in the axial direction, respectively, and are attached to the cathode sleeve 2 by welding.

However, in the conventional cathode structure as described above, since the inner peripheral surfaces of the end hats 4 and 5 are in close contact with the outer periphery of the cathode sleeve 2, the temperature of the end hat 4.5 increases due to heat conduction, and the emitter from the cathode layer 3 evaporates. Emitter operation is performed again from the end hats 4 and 5 to which objects are attached.

Therefore, there are drawbacks such as unstable pulse rise, poor oscillation spectrum, frequent arcing, and short life.

The object of this invention is to provide an indirectly heated cathode assembly for a magnetron that eliminates the above-mentioned conventional drawbacks.

Hereinafter, one embodiment of this invention will be described in detail with reference to the drawings.

The cathode structure of this invention is constructed as shown in FIGS. 2 to 4, and a cathode layer 8 is formed to a predetermined length around the outer periphery of a cathode sleeve 7 containing a heater 6.

At both ends of the cathode layer 8 in the axial direction, end collars 9 and 10 are provided, respectively, and are fixed to the cathode sleeve 7.

In this case, in this invention, out of the outer periphery of the cathode sleeve 7,
At least three (four in this embodiment) band-like protrusions 11 are integrally formed in the axial direction at locations corresponding to the end hats 9 and 10.

This protrusion 11 serves as a heat dam that inhibits heat conduction between the end hats 9, 10 and the cathode sleeve 7, and the protrusion height is 0.1 to 0.3rrrrIL.

At this protrusion 11, the end hats 9 and 10 are welded (as shown in Figures 2 and 3), caulked (as in Figure 4),
Brazing is fixed by etc.

Because of the presence of the protrusion 11 in this manner, at least half of the inner circumferential surfaces of the end hats 9 and 10 are not in contact with the cathode sleeve 7 in this invention.

The indirectly heated cathode structure of this invention is constructed as described above and shown in the drawings, and a protrusion 11 is provided on the outer periphery of the cathode sleeve 7, and the protrusion connects the sleeve and the end hat.
Because of this protrusion 11, at least half of the inner peripheral surfaces of the end hats 9, 10 are not in contact with the cathode sleeve 7.

In other words, it has a heat dam structure that inhibits heat conduction.

As a result, the temperature of the end hats 9 and 10 is lower than that of the cathode sleeve 7 by about 150°C to 200°C.

Therefore, even if the evaporated material of the emitter material (such as barium) from the cathode 8 adheres to the end hats 9 and 10, the amount of emissions from the end hats 9 and 10 will be reduced because the temperature is low.

Furthermore, according to this invention, the pulse rise is stable and the oscillation spectrum is good.

Furthermore, arcing is reduced and the lifespan can be extended.

In the above embodiment, Z is attached to the end hats 9 and 10.
End hat emissions due to emitter material adhesion can be further reduced by applying a surface treatment of R or using a material such as hafnium.

Further, in the above embodiment, a protrusion 11 is provided on the outer periphery of the cathode sleeve 7.
However, conversely, as shown in FIG. 5, protrusions 12 may be provided on the inner periphery of the end hats 9 and 10, and the same effect as in the above embodiment can be obtained.

As explained above, according to this invention, it is possible to provide an indirectly heated cathode structure for a magnetron that has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing a conventional cathode structure, FIGS. 2 and 3 are perspective views and longitudinal sectional views showing a cathode structure according to an embodiment of the invention, and FIGS. It is a longitudinal cross-sectional view showing a modification of the invention. 6...Heater, 7...Cathode sleeve, 8...Cathode layer, 9, 10...End hat, 11...Protrusion.

Claims (1)

[Scope of utility model registration request] In an indirectly heated cathode structure for a magnetron, an electron-emitting cathode layer is formed on the outer periphery of a cathode sleeve that has a built-in heater inside, and an end hat is fixed to the outer periphery of the sleeve at the end of the cathode layer. Alternatively, an indirectly heated cathode structure for a magnetron, characterized in that the end hat has at least three or more protrusions on the inner periphery, and the sleeve and the end hat are joined only by the protrusions.