General Electric SRT-2 X-ray Tube (ca. 1950s)
The General Electric SRT-2 seen here was a hooded anode X-ray tube used for therapy. The SRT designation stood for "self-rectified therapy." The "2" indicates that this a fine to medium focus tube. The two projecting connections on the left end of the tube would seem to indicate that it was water-cooled.
As seen in the photo to the right, the anode (target) is surrounded by a cylindrical copper hood. The latter plays several possible roles: it minimizes the number of stray electrons that impinge on the glass envelope, it shields stray X-rays, and it increases the heat capacity of the target.
The X-ray beam escapes the hood through a square beryllium (?) window (facing upwards in the photo). The photo shows how the portion of the envelope adjacent to the port in the copper hood has been ground down in order to minimize the attenuation of the beam.
As seen in the photo to the right, a particularly interesting feature of this tube is the fact that the cathode is a flat spiral coil similar to that used in the early "Universal" X-ray tubes rather than the more common "Benson" style coil.
Size: Approximately 19" long, 4.5" diameter (max)
Price: $595 in 1953-1954 GE catalog
Quoting the 1953-1954 GE catalog: "The SRT-2 follows the same design as the SRT and is supplied for replacement in the Maximar 220 and 250, now discontinued, and the current Maximar 250 III. Its range is 80 to 250 kvp at 15 ma."
Kindly donated by Margie Wheaton in memory of her father Dr. Julius E. Marfy.
General Electric Catalog. X-ray Supplies and Accessories. 1953-1954.