This exhibit is a sectioned X-Ray tube housing with tube installed and working, except for the HV connection. The motor coils for spinning the tungsten anode is on the right. The tube is in the centre with a void on the left before a set of bellows. In use the housing is filled with oil. The oil provides insulation and a means of over temperature protection in this 1950's piece of medical apparatus. As the oil heats and expands it compresses the bellows. Eventually a micro-switch is activated and this signals a shut-down.
Diagram of basic structure. A is the rotating anode with T the target spot. The anode can be solid tungsten or more likely a molybdenum core with a tungsten outer layer. R is the copper rotator with S the motor coils. H is the outer casing with O as the oil filling which expands to compress the bellows B when too hot. E is the glass envelope with C the cathode which is a filament in a cup to limit the beam spread. Finally W is the output window for the X-Ray beam. The high voltage supply is most likely in the range of 40-150 kV. The beam current can reach 450 mA which delivers around 5 kW to a 1 mm diameter spot on the target. Temperatures can rise to over 1,000 °C.
The Mullard logo and the end of the bellows section.
The three filament leads. The brown structure is the clamp holding the working tube.
Here tha anode is spinning and the filament running. The brightness of the filament suggests pure tungsten. The bearings of the motor are plated ball bearings and the friction is very low such that the anode spins for several minutes after the current is switched off.
The spinning anode with filament off. The circular hole in the foreground is the exit window for the X-Ray beam.
The motor windings and laminations.
Here the top filament can be seen to be running.
The pure white light of the tungsten filament.
An enlargement showing the form of the lower filament.
The apparatus is mm in diameter, and excluding the base pins is mm tall.
References: Observation, wikipedia (diagram) & www.frankshospitalworkshop.com (pdf file).
PDF scanned from an original document held by the museum