Early Müller-Philips “Metalix” Tube (Type D)
in the mid-twenties by Pr. Albert Bouwers of the
Philips Company, in
This tube of the “Coolidge Type” built
on the Media Line Focus principle was
initially sold under the brand name of “Müller
Media-Metalix” and later as “Philips
Metalix”. Its cylindrical central part (the canister) was made of
chrome-steel alloy, fused on either side to the glass tubing forming the rest
of the body of the tube. The canister is surrounded by a protective layer of
lead covered by the exterior visible metal parts.
X-rays come out of the tube through a round
glass window fused to the center of the canister, and then through an
aluminium filter. A thick cylindrical housing, of what is described as
“special bakelite” protects the rest of the tube.
Unfortunately this tube was received broken.
But looking inside, the glass seemed too fragile for the disproportionately
heavy anode. The tungsten target embedded in
copper is at a low angle, and the focal spot is a virtual 3mm square. This particular
tube is water-cooled, but similar tubes were also sold with metal radiators. Some tubes were even jet-air cooled (Go to“Philips Metalix Tube”).
This “Type D” tube boasted 100 mA at up to 70 kVp and 40 mA up to 100 kVp (for short
exposures only), or 6 mA at 125 kVp
continuously. Later models of the “Metalix” were
better protected, larger in size and with an improved output, and were even manufactured
in different parts of the world.
To the left are two old advertisements of
the Metalix tube, one under the name of “Müller-Media-Metalix”, water-cooled, and the other under
the name of “Philips-Metalix”, with a metal
In order to go around the G.E. Coolidge
patent covering hot cathode tubes in vacuum, the Metalix tube had a Helium
filling at a pressure of at
least 1/1000 mm of Mercury. This Helium inclusion had practically no effect
on the efficiency of the tube and soon
diffused out of its glass wall.
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