JPS5844662A - X-ray tube with encircling ceramic case - Google Patents

Abstract

PURPOSE:To obtain an X-ray tube, the encircling ceramic case of which can be handled easily and the creeping discharge of the inner surface of which is suppressed, by causing small electric discharge by coating the inner wall of the encircling ceramic case with a cover coat, and scattering fine metal particles over the surface of the cover coat at minute intervals. CONSTITUTION:As a cover coat 10, a glass member having high insulating resistance is used in order to maintain its insulating performance and to prevent any dirt from entering among the ceramic particles of an encircling ceramic case 1. By scattering a fine metal particle group 11 over the cover coat 10, any high electric-potential difference, which might be caused due to a large amount of electric charges which might be accumulated in local parts of the inner wall of the case 1, is prevented from developing between the above local parts and from growing into intensive electric discharge. The above metal particle group 11 is formed by scattering metal particles, for example, copper particles with a grain diameter of around 10-100mum at intervals equal to the diameter of the metal particles, by a slow sputtering or other proper means.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external ceramic X-ray tube in which the f8Wi voltage resistance of the internal ceramic external X-ray tube is improved.

Glass was often used for the outside 1111 of the X-ray tube, but in recent years, Cefox, which has better mechanical strength than glass, has come to be used.

Figure 1 shows an example of a conventional non-ceramic 5is X-ray tube.
At both ends of the cella-built ivy envelope l, respectively.

A cathode terminal 31 to which the cathode 2 is attached. The 111m terminal 6 on which the anode tube 4 is attached is hemlocked. shadow@! filament 6 is II! It emits electrons when heated with electricity. The iew so 4 IC is provided with an anode 7, and a target 8 is embedded in the negative electrode opposite the cathode. The electrons Il emitted from the filament y) 6 are accelerated by the high voltage applied between the cathode and anode and are irradiated to the target 8 (11).
L, emit X-rays from here. This xIl is the anode tube 4
The X-ray radiation provided at - is taken out to the outside and used. It is desirable for the X-ray tube to be as small as possible in one step, but a high voltage is applied between the cathode and the anode, and the Cerasec envelope 1
must be able to withstand this high voltage. High voltage
Although the outer surface of the container must be kept clean, it is unavoidable that some dirt may get on the surface of the glass container. Dirt is removed by washing. However, the occasion of SIS outside of Setsutsuku,
Because the inner surface remains as it is, dirt gets in between the particles of the ceramics, but the outside surface of the ceramics is 5.
Compared to iinc, it is difficult to remove dirt even if you use the conventional cleaning method for outside glass, and due to this dirt, the creepage of the inner surface of the ceramic envelope is There was a problem in that it was difficult to maintain a sufficiently high withstand voltage.

Furthermore, scattered electrons and secondary electrons are generated within the X-tube during operation. Many of these scattered electrons and secondary electrons are captured on the inner surface of the single envelope, and are accumulated therein as electric charge. On the other hand, depending on the speed and angle of incidence when the scattered electrons are concentrated in the ceramic envelope, there are some locations where the secondary electron emission ratio becomes 1 or more, and the electrons become positively charged there. After 5K, the inner surface of the envelope has negatively charged parts, parts that are hardly charged, and positively charged parts, and when the potential difference between these parts reaches a certain limit or more, There are many cases in which an avalanche of electron movement, ie, discharge, occurs, and as a result, the outer MS wall is damaged. This phenomenon occurs because the inner surface of the envelope has high insulation properties, making it difficult for charged charges to move. Even though it is difficult to remove dirt when it adheres to the inner surface of the envelope of a conventional double-walled envelope X-ray tube, it does not mean that all the dirt is uniformly KFj and the insulation deteriorates uniformly. It may be 1, but this discharge iK phenomenon is outside of Ichihata's tsutsuden tsuta.
This also occurs in SX-ray tubes.

An object of the present invention is to provide a ceramic envelope or tube which does not have the above-mentioned problems, is easy to handle, and suppresses creeping discharge on the inner surface.

In order to achieve the above object, the present invention includes:

As in the case of the inside of the ceramic envelope, the inside of the ceramic envelope is smooth and easy to clean, as is the case with the outside of the glass. Either by scattering them at intervals and causing micro discharges so that the charge moves before a high potential difference charged area is generated, or
Alternatively, a material having an appropriate low conductivity was selected for use.

FIG. 3 shows an embodiment of the present invention.
11 inner surface ICi! , over its eating surface, Yuyu 10
Further, fine metal particle groups 11 are scattered on the ψ@10 at minute intervals. Incidentally, in the same figure, the numerals are the same as in the case of iml.

In this case, Yu@10 uses a vitreous material with high insulation resistance to prevent dirt from entering between the ceramic particles of the ceramic envelope 1, and the fine metal particles 11 are used to maintain insulation performance. By interspersing it on top of it,
This prevents a large amount of charge from accumulating in one local part of the inner surface of the seven insulator envelope 1, causing a high potential difference between each local part, and developing into an intense discharge.

This metal particle group 11 is made by sputtering gently or by other appropriate means, and particles of metal such as copper having a particle diameter of 10' to 100 sm are scattered at intervals of the same degree as the metal particle diameter. By doing this, the ceramic envelope 1 can be cleaned in the same manner as a conventional glass envelope, and the inner surface of the ceramic envelope 1 can be cleaned without causing a high potential difference due to electrical charges. (As a result, the creeping withstand voltage of the inner surface of the ceramic envelope 1 can be improved.

In the above embodiment, a highly insulating layer was applied and metal particles were scattered, but the layer was made to have some conductivity so as to be able to reach the required high voltage and to prevent strong local charging. (For example, insulation - drag force tlG" ~ 10" 1Ω・1ulF)
Even if a material with a
It can be immersed in electricity. It should be noted that Ichitani, who implemented the present invention, found that while a high voltage is applied between the cathode and the cathode, if a leakage current flows on the inside of the CERASEC envelope 1, the creepage leakage current The value is usually 1. For example, the beam current value required to emit X-rays is on the order of magnitude, but there is no problem at all because the three techniques, low voice AII change, are sufficient to accomplish the purpose.

As explained above, according to the original @, 5I outside of Sessettuta
IIx Wrapper Manufacturer 11-e Handling of the envelope is facilitated, and the 5iiiy withstand voltage of the inner surface of the envelope is improved during use.

WjAII's simple m@ Figure 1 shows an example of a conventional cellar-built ivy envelope
The second cabinet is a diagram of one embodiment of the present invention.

1-ceramic envelope, z-* pole, 3-cathode terminal, 4-
. . . Anode pole, toe pole terminal, 7-9 pole, 8 . . . target, lO . . . 5 legs, 11 . . . metal particle group.

Figure 1 Figure 2

Claims (1)

[Claims] 1. In a ceramic envelope X-ray tube, which has a cathode terminal with a cathode installed and an anode terminal with an anode tube installed at both ends of the ceramic envelope, the inside of the ceramic external phase vessel is A ceramic characterized in that the surface is coated with a thin layer, and fine metal particles are scattered at minute intervals on the surface of the layer 511, or a low conductive layer is coated on the inner surface of the ceramic envelope. Envelope X-ray tube.