The “Kesselring” Free Anti-Cathode Tube

Ref. B16

This tube, of the second decade of the 20th Century, is 25” (63 cm) long with a 6” (15 cm) bulb, was made by the Kesselring X-ray Tube Company, Chicago, Il., and was intended for use in conjunction with a high frequency high voltage generator (up to 100kV), such as a Tesla coil.

Compared to other gas discharge X-ray tubes, it presents two peculiar characteristics, namely the absence of any external electrical connection to the anti-cathode, and the presence of a conical copper funnel-shaped attachment on the rear side of the anti-cathode. The tungsten target is simply placed in the path of the electron stream flowing from the cathode towards the anode, and the conical attachment on the rear of the anti-cathode is there to presumably help shaping and increasing the efficiency of the electron beam hitting the target.

Note the concave shape of the anode, similar to, but smaller in size than the cathode, and placed in the small bulbar widening of the corresponding glass arm.

Regeneration is by the small cylindrical secondary chamber on the upper side of the bulb, containing a whitish fiber-like material, probably asbestos.