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English: Early Crookes x-ray tube from the Museum of Wilhelm Conrad Röntgen in Würzburg, Germany. These first generation 'cold cathode' x-ray tubes were used from the 1890s until about 1920. The electrode on the right was the concave cathode or negative electrode, which focused a beam of electrons on the angled platinum anode in the center of the bulb. When the electrons struck this they generated x-rays, which passed through the glass wall of the tube at top. The electrode to the left of the anode was called the auxiliary anode.The curved tube attached just above the cathode is an 'osmotic softener' device to adjust the pressure in the tube. Crookes tubes required some gas in them to operate, but as time passed the gas was absorbed by the walls of the tube and the pressure dropped, requiring higher voltage across the tube which generated 'harder' x-rays, until eventually the tube stopped working. The softener consists of a tiny palladium tube, closed on the outer end, which projects through the glass wall of the tube. It is protected by a glass cap. When the pressure got too low, the cap was removed and a flame was played over the palladium tube. Hydrogen ions from the flame diffuse through the palladium into the tube, raising the pressure. For more information see Frederick F. Strong, (1908) High Frequency Currents, Rebman Co., New York, p.192-200
|Date||May 8th 2008 (see EXIF)|
|Source||my own camera|
(Reusing this file)
GNU Free Documentation License
|Camera manufacturer||NIKON CORPORATION|
|Camera model||NIKON D80|
|Orientation of image||1|
|Image resolution in width direction||300|
|Image resolution in height direction||300|
|Unit of X and Y resolution||2|
|Exposure time||10/600 sec (0.016666666666667)|
|F number||f / 3.5|
|ISO speed rating||200|
|Compressed bits per pixel||4|
|Lens focal length||32 mm|
|Date and time original image was generated||2008:05:08 11:14:24|
|Date and time image was made digital data||2008:05:08 11:14:24|
|Meaning of each component|
|Maximum lens aperture||3.1|
|Supported Flashpix version||0100|
|Color space information||1|
|Exif image width||2842|
|Exif image length||2004|