Varian High Power Tube

Ref. K14

This unmarked glass-metal rotating anode Varian tube, of unknown model number, dating probably to around the turn of the century, is one of a series of Varian high power X-ray tubes (50 to 100 kW) equipped with two focal spots (03 to 06 sq. mm for the small, and 1 to 1.2 sq. mm for the large, depending on the particular model).

This glass-metal tube has a round, beryllium covered X-ray window of about 4.5 cm. The anode disc is of the Rhenium-Tungsten type on a Molybdenum base, rotates at 9000 rpm,and measures 13 cm in diameter.

Note the deep copper indentations affixed to the anode side of tube body (to the right in the pictures) possibly intended for providing better cooling in contact with the surrounding oil.

The metal part of the tube body is most probably made of “kovar”, a metal alloy of iron, nickel and cobalt, designed to have substantially the same thermal expansion characteristics as borosilicate glass in order to allow a tight mechanical joint between the two materials over a range of temperatures.