The Cathode Ray Tube site
History and Physics Instruments
Ion X-Ray tubes
William David Coolidge 1873-1975
Triple cascade X-ray tube in the lab of Dr. Coolidge 1928
In this lab model every bulb is fed with 300KV, the tube was 2,4 meter long with bulb diameters of 30cm!
Lodge X-ray High Tension Valve ca 1912
This rare rectifier tube invented by the physicist Sir Oliver Lodge prevented reverse currents which occurred using Ruhmkorff coils. The inversed voltage had a negative effect on the pressure in the Ion tubes. These rectifier valves prevented these inversed voltages. The valves were used in series with the X-ray tube.
The Cathode inside the tube is an aluminum spiral which creates a larger surface for handling high currents. The distinctive red colored glass is the result of a specific exhaustion method which keeps the vacuum stable under all conditions.
Pictures courtesy of Alastair Wright.
From Ion X-ray tubes to Hot Filament tubes
In the early times Crookes or Hittorf tubes consist of a few simple electrodes projecting into a
glass bulb. With one of these tubes Wilhelm Röntgen made his discovery for which he was
awarded for the first Nobel Prize. The classic cold cathode ion X-ray tube was born. A tube with two
electrodes. The tube developed qiuck into a three electrode tube with an anticathode and platinum
target (due to the high melting point of this metal).
Soon after the discovery of Conrad Röntgen the production of these tubes started, not only in the
German factories of Gundelach, Müller, Pressler and Siemens. But also Andrews in England.
In the US by Victor and General Electric. But these ion tubes had many disadvantages like unstable
vacuum and cooling. Some described them as unpredictable as a woman.
The great breakthrough came in 1913 when William Coolidge and Lilienfeld made there first hot filament
cathode X-ray tube, he replaced the cold cathode with a heated spiral filament cathode and tungsten
anode. The third anticathode disappeared, the angle of the anode in his tube was set at 45º. X-rays
could now be better controlled and were more reliable. The only practical problem was cooling the
Anode, (which got extremely hot) this was a huge problem due to its small size. New designs were
developed, a heavy copper base to the anode, sometimes with water or air cooling, this conducted the
heat away and therefore increased the capacity of the tube to withstand a high current.
Philips developed in 1924 the Metalix tube. The glass tube was fitted in a metal housing and also
incorporated the principle of line focus. This tube had sufficient shielding for physician and patient and
was safe to use with the high voltage.
The anode face was changed to an angle of 19º in respect to the cathode.
X-ray demonstration tube for Gaede pump use.
Leybolds Nachfolger 1910-1930
This tube has blue glass terminals.
Picture from the Leybolds Nachfolger catalogue 1911.
Leybold sold many types of tubes for the use on a
Gaede vacuum pump.
This picture comes from the Leybolds Nachfolger catalogue from 1929.
In this catalogue the tube is only printed in combination with the Gaede pump and not available anymore as a separate item. The reference number points at a new type. This dates this tube before 1929.
Another X-ray demonstration tube
for use on a Gaede pump.
ca 1910-1930 Height 30cm
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Didactical and Toy X-ray Tubes
Hot filament Coolidge X-Ray Tubes
With a bulb diameter of only 4,5cm dates from early 1900. It was probably part of a German experiment box sold by Bing or Meiser&Mertig
Advert from the Bing 1912 toy catalogue.
Around 1900 many educational different Physics boxes were sold for amusement or Christmas gift. Many kids were experimenting with the newly discovered techniques like electricity and even X-rays without warning!
Home entertainment X-ray tubes.
These rather small X-ray tubes were
used in school and for home
entertainment sold as part of Physics
experiment boxes together with small
Ruhmkorff coils or Wimshurst
static machines. The drawings from the
original catalogues show how
the tubes were used.
Page from the 1909 German
von Dr. C. Richard Schultze.
Huge water cooled C.H.F. Müller Rapid X-ray tube (1926).
This tube is a result of many years of development, the first Müller Rapid tubes date back to 1911 and were patented. The copper block connection of the anti-cathode to the glass is special in this tube. The anode is hollow for optimum cooling of the electrode with water.
The target is made of Tungsten (Wolfram)
The Bauer air valve regulator.
This regulator was used to regulate the vacuum to the optimum pressure. Inside is a folded thin glass tube containing a bit of mercury. Attached to the rubber hose was a pneumatic piston to move the amount of mercury allowing a bit of air slipping into the tube softening the hardness of the X-ray tube.
Small Gundelach Ion tube for school demonstrations ca1910
The iconic Gundelach Moment tube
lenght 40cm This model is made around 1910-1912.
On the sphere there is a J etched, this was used by Gundelach for marking tubes made for rectified alternating voltages, probably for use with the "Ideal Apparat" made by Reiniger Gebbert & Schall.
The Gundelach vacuum regulator for regulating the " hardness" of the tube.
Smallest working X- ray setup ever seen, sold for child use!
Working tube on the smallest
German coil I know.
Due to it's age the tube is gassy
and no harmfull x-rays are produced.
A small 15cm fluoroscope screen made by the German company Heyden ca1910, an Ampere meter made by the French maker C.G de Radiologie and an English indicator tube ca 1910.
The indicator tube was placed in series with the X-Ray tube to see if there was a reverse current present.
The working of an indicator tube shows the typical reversed current of a Ruhmkorff coil, Ionisation around both wires, there is a bit more forward current than reversed. Due to this phenomena most early X-ray tubes degraded and eventually were not useful anymore.
Placing a valve tube in series with the X-ray tube prevented this negative effect. With a true DC current only one wire will ionize.
A viewing device with a fluorescent screen in the front.
X-ray tube ca 1910 likely from the French Giaffe & Pilon company. Bulbsize 15cm.
A complete toy X-ray setup from early 1900 with a 5cm X-ray tube
In front a German DIY X-ray booklet for kids.
An indicatortube made by CHF Müller.
Ion X-ray tube (ca 1910)
This primitive X-ray tube has a bulb diameter of 10cm and has white glass terminals. Etched in the glass the serial number 58689
The anode has clear signs of use, the glass envelope has a purple deposit which shows heavy use of the tube in the past.
Stages of hardness
Glass makers added manganese dioxide to the glass for the distinct green fluorescence which helped the x-ray operators to judge the correct hardnees for optimum results.
X-ray tube production in England
Cuthbert Andrews (1882-1972) was a leading English manufacturer of X-ray
tubes in the early days. C.H.F Müller a large German X-ray tube maker,
wanted to produce and sell X-ray tubes in Britain. In 1909 Andrews
came in contact with Mr. Müller and by 1912 Andrews started producing X-ray
tubes for the English market. Andrews his company was virtual the only
manufacturer of conventional X-ray tubes in Britain after 1930.
His company produced over more than 30.000 tubes of 75 different shapes.
This text is extracted from an article which can be found on site of RHHCT.