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CASE STUDY 4

DENTAL X-RAY TUBE HEAD: THE INSIDE OUT STORY
(Start the Story All Over Again.)

 

You were here:

We have entered the tube head from the back. The rubberized pouch was lifted out. The thin, yellowish oil filling the tube head makes the images of the plastic container and other components a little hazy.

 


 

 

 

The plastic container and it's contents were next lifted out.

THE INSIDE IS FINALLY OUT!

The x-ray tube, where all the action takes place, is seen in it's pristine glory resting on the coils of a step-up transformer. The white shining armour seen on the top is the insulating paper, while the thermal cut-out (light blue round) can be seen peeping from the left top corner of the picture. The yellow wires form the low-tension circuit (coming out at the lower end of the glass envelope), while the high-tension circuit is formed by the red and the white wires (on the left and the right of the envelope).

 

The tube head opened up so far was preserved for display and teaching purpose. Yet another tube (defunct, of course!) was similarly opened up and dissected further (seen below).

The glass envelope containing cathode and anode was separated from the circuitry and cut open (not very cleanly, though!). Infact, when an attempt was made to cut it, it exploded, shattering into pieces.


The cut ends were rounded off and the cathode and anode photographed. The picture below shows the cathode end of the glass envelope.


Two yellow leads of the low-tension circuit went to a resistor (seen as a green tube in a picture above).The red lead is a part of the high-tension circuit. The circuit is completed by a white lead (in a plastic sleeve) seen entering the step-up transformer in a picture above.

The anode, made up of copper stem and tungsten focal spot is seen through the glass envelope. The round opening in the copper stem is the 'window' through which the x-ray beam emerges. Through this 'window', the sloping surface of the tungsten focal spot is visible. Yet another opening is seen in the face of the copper stem (facing the cathode). This opening allows the high-speed electrons coming from the cathode to reach the focal spot.

   
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