Multi-Anodal Crookes Tube

Ref. A3

The laboratory demonstration of Crookes tube has one concave cathode (unlike early Crookes tubes where the cathode was flat), and three short, spherically tipped anodes. It is undated (20^th Century).

Under high vacuum, the cathode ray beam (the electron beam) would hit the glass wall of the bulb opposite the cathode, irrespective of the position of the activated anode. With a lower vacuum, the electron beam would deviate towards the activated anode, or split into three beams when the three anodes are simultaneously connected.