Victor X-ray Tube with Focusing Ring (ca. 1905-1915) |
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The focusing ring located midway between the cathode and the anode helped ensure that the electrons from the cathode were directed to a small area (a few square millimeters) in the center of the target. A buildup of static charge on the glass of the tube could cause the focal point to wander and the ring helped combat this phenomenon. At least that is one explanation. The following is taken from the Sweet and Lewis catalog "Coils and X-ray Tubes" (copyright 1903): "Many users of tubes claim that the insertion of a ring of metal between the cathode and anode, and attached to the latter, will give the tube greater penetration at a low degree of vacuum." This particular tube belonged to M. J. Gross who worked with Dr. Coolidge at General Electric in Schenectady N.Y. Gross later became Vice President of the GE X-ray Company. During the 1930s and 1940s, Gross and Zed Attlee formed the core of Coolidge's research and design team. Size: approximately 7" diameter bulb, 20" long Kindly donated by Linda Sinrod in memory of Malvern J Gross |
