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Isotrace Radial Beam Pulse Tetrode

The tetrode is mounted on a silver metal base. On the bottom of this base are five cylindrical metal pins, arranged in a circle. There are several circular holes on the bottom of the base as well. This base is designed to fit snugly into a fixture.
Secured to this base is a large, dark grey, metallic object with long fins. It is wide, but narrows at the top, where it connects to a thin blue cylindrical piece. All of this is covered by a glass casing, which forms the vacuum tube. Above the casing is the plate, a metal cap with a point on top which receives the charge from the apparatus within the vacuum tube and carries it to the rest of the machine.
This glass casing is mostly clear, but it has been darkened somewhat, and a particularly pronounced dark band has formed in a circle at the midpoint of the tube. This tetrode is designed to operate at temperatures between one and two hundred degrees, and the marks might be the result of burns from sustained heating.

Accession Number:

Alternative Name:

Primary Materials: Glass, Thoriated Tungsten, Metal


Dimensions (cm): Height = 24.46, Diameter = 13.34.


The object is a tetrode, a type of high-Voltage power regulator used to control the flow of current to large electronic devices. This particular tetrode was used to power the University of Toronto’s Isotope and Rare Atom Counting Equipment (ISOTRACE) linear accelerator.


Very Good. A pronounced dark band has formed on the glass case of the tetrode, likely the result of burning, but otherwise the tetrode has no visible blemishes or damage.

Associated Instruments:


Eimac, then a division of Varian Associates, San Carlo, California; currently a division of Communications and Power Industries, Palo Alto, California

Date of Manufacture: 1980s or later


Purchased by the University of Toronto Department of Physics to power the particle accelerator. It was acquired by the University of Toronto Scientific Instruments Collection in 2017.

Additional Information and References:

Datasheet for the tetrode:

Historical Notes: