CHF Müller Tube

Ref. B12

Being 14” (35 cm) long and having a five-inch (12.5 cm) bulb, this tube is of the “light anode” type. It first appeared in the CHF Müller Catalog in 1904. But this particular tube, bearing No. 74071, was most probably manufactured early in 1909, the CHF Müller factory having celebrated its 75000th tube in May of that year. (Willi Stamer,“100 Years of X-ray Tubes”, p.23, Philips Medical Systems, 1999).

The target is a platinum disc embedded in the nickel anti-cathode and held in place by four small metal claws. The aluminium cathode is of the typical concave shape, and the aluminium anode is of the rod type. The regeneration is by a Mica Disc device.

Of particular interest, is the sticker in German on the cathode side of the glass tube wall that reads “Härtegrad 4-5 Walterscale” (Hardness grade 4-5 on the Walter Scale). This scale was introduced by Professor Bernhard Walter (see below), based on the size of the spark gap of the induction coil.

“…by setting the hinged wire at any given distance from the cathode end, the tube will regulate itself to the vacuum corresponding to that distance, for as the resistance of the path between the proper electrodes increases, current passes around by the mica discs down the wire and jumps across to the negative end, setting free a minute quantity of gas from the mica, and the vacuum is lowered, allowing the current to pass in the usual way.”
(“A Text-Book of Radiology”, E. R. Morton, 1918, p.51)

Professor Bernhard Walter worked in close cooperation with CHF Müller, and as early as 1898 or 1899 had proposed the use of a water-cooled anti-cathode.

(Willi Stamer“100 Years of X-ray Tubes”, p.16, Philips Medical Systems, 1999)