Physics, Techniques and Procedures

Filament circuit

the electric circuit to produce the heating current, in the region of 5 A at the voltage of 12 V, to the filament wire of an X ray tube. The circuit is basically a step down transformer from the mains e.g. 220 V supply to low voltage but high current. The primary and secondary windings must be sufficiently insulated to withstand the high potential difference between the cathode and earth (see X ray tube, item 5). The stability of the filament current must be carefully regulated because the tube current is very sensitive to changes in the filament temperature. See also X ray generator.

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