Huge Early CGR Thyratron

A thyratron is a gas filled electronic tube used as a high energy electrical switch or relay. Most thyratrons are of the triode design where the different elements are enclosed inside a metal shield assembly. The gas inside the tube is usually at a fraction of the pressure of the ambient air (15-30 millibars). Gases used include mercury vapor, xenon, neon, argon or even hydrogen, with hydrogen generally used in very high-voltage applications.

The oil-immersed tube shown above dates probably to the thirties, coming from the high-tension control unit of a radiotherapy set-up. It is 18” (45cms) long with a 5” (12.5cms) bulb, and a smudged stamp on the tube base reading “Cie Gle de Radiologie” standing for “Compagnie Générale de Radiologie”, better known as the “CGR”, presently owned by General Electric.

No other technical information is available.

The internal structure of this thyratron is masked by the black cylindrical shield which is losing its outer layer in a black powdery form depositing inside the glass wall of the tube. This shield is in connection with the small rectangular mesh-like metallic inclusion in the lower part of the tube probably intended for gettering.

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