JPS606065B2 - Direct heating type magnetron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a directly heated magnetron in which the cathode is composed of a thorium tungsten spiral, and is intended to prevent abnormal oscillations from occurring due to the end cooling effect of the cathode.

Generally, a directly heated magnetron uses a cathode 1 made of a thorium-tungsten spiral as shown in FIG. 1, and this cathode 1 is coaxially arranged at the center inside an anode cylinder (not shown).

Note that the cathode 1 has a first disc-shaped metal plate forged on its upper end.
A second end plate 3 of disk-shaped metal is forged to the lower end of the end plate 2 and the cathode 1, and is forged to the first end plate 2 by penetrating the central hole 4 of the second end plate 3 without contacting it. Together with the first rod-shaped conductor 5 and the second rod-shaped conductor 6 forged to the second end plate 3, it constitutes a cathode horizontal body. Reference numeral 7 denotes a large number of anode vanes arranged radially inside the anode cylinder and fixed to the inner circumferential surface of the anode cylinder.

By the way, in the directly heated magnetron as described above, when the cathode 1 is energized, the temperature rise at both ends of the cathode 1 is lower than the temperature rise at the center. In other words, the distribution of thermionic radiation from the cathode 1 is maximum at the center of the cathode and minimum at both ends. The amount of heat flowing into the terminal is small. Due to this non-uniformity, the central part of the anode vane becomes locally high in temperature, causing a large amount of gas to be released and lowering the emission, which causes abnormal oscillation. The present invention has been made in view of the above-mentioned points, and according to the magnetron of the present invention, as shown in FIGS. 2 and 3, the anode cylinder 8
The thickness of the numerous anode vanes 9 protruding from the inner circumferential surface of the anode 1 toward the cathode 1 is minimized at both ends and gradually increases toward the center.

Note that since the anode vane 9 is usually made of copper, it can be relatively easily formed by forging. According to this structure, the thickness of the anode vane 9 is maximum at the center where the thermionic emission of the cathode 1 is maximum, and the thickness of the anode vane 9 is the maximum at both ends where the thermionic emission of the cathode 1 is minimum. As a result, the amount of electron inflow per unit cross-sectional area of the anode vane 9 is made uniform, and as a result of increasing the heat capacity of the anode vane central portion, the anode vane is locally heated to a high temperature. Therefore, the occurrence of abnormal oscillation can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a portion of a conventional magnetron, FIG. 2 is a cross-sectional view of a magnetron embodying the present invention, and FIG. 3 is a perspective view of the main parts of the magnetron. 1... Cathode, 7, 9... Anode vane, 8... Anode cylinder. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. The thickness of the numerous anode vanes protruding toward the cathode from the inner circumferential surface of the anode cylinder surrounding the cathode made of a thorium tungsten spiral is made minimum at both ends, and gradually increases toward the center. A direct heating type magnetron that is characterized by: