Pressler Ion Tube
Ref. B21
During the first half of the 20th century, the brothers Otto and Rudolf Pressler, in Leipzig and in Cursdorf, Germany, were world known manufacturers of Crookes tubes, Geissler tubes, Holtz tubes, X-ray tubes, etc. They made tubes essentially for teaching and demonstration purposes as well as for laboratory work.
The above tube is undated. It is a two electrode tube (a concave aluminium cathode and a tungsten faced anti-cathode, without any other anodal structure). It is about 14” (35cms) long with a 4” (10cms) bulb, and bears the Pressler (Cursdorf) label, with a faded “No. 2520”.
Of particular interest is the regeneration device, consisting of a small carbon inclusion freely moving in a small side-chamber communicating through a narrow neck with the main tube cavity. When the tube becomes hard with use, due to high vacuum, heating this carbon material liberates some of the adsorbed gas and the right vacuum is re-established.
Note the glass sheaths surrounding the stems of both the cathode and the anti-cathode and the small radial glass arms fixing them in a constant position inside the tube necks. Nevertheless, in this particular tube, the focal spot on the tungsten target is visibly off-center.