TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 DEF

An X-ray tube providing rectification of the high voltage by itself.  1, fiche 1, Anglais, - self%2Drectifying%20tube

Record number: 1, Textual support number: 1 OBS

This is accomplished when an X-ray tube is connected directly to the secondary windings of the high voltage transformer without any intervening rectifier. When the cathode is negative with respect to the anode, electrons will flow from the cathode filament to the anode and produce X-rays. During the next half of the electrical cycle, the anode is negative with respect to the cathode, and electrons could flow in the opposite direction. However, as long as the anode is kept cool, no electrons will be emitted from the anode, and no current will flow. The result is that of half wave rectification, where only half of the cycle of the high-voltage current is used to produce X-rays.  1, fiche 1, Anglais, - self%2Drectifying%20tube

Record number: 1, Textual support number: 2 OBS

An obvious disadvantage of self-rectification, as opposed to supplying the X-ray tube with an already rectified direct current, is that exposure times must be increased since X-ray production occurs during only half of the time the current is applied. Secondly, repeated exposures could heat the anode to such an extent that electrons are also emitted from the anode. This could result in a reverse flow of electrons in the X-ray tube with excessive heating and destruction of the filament.  1, fiche 1, Anglais, - self%2Drectifying%20tube

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 OBS

[...] ce tube, étant auto-redresseur, n'utilise que la phase positive du courant alternatif; en d'autres termes lorsque la cathode est positive et l'anode négative aucun courant ne traverse le tube. Lorsque la polarité change, l'anode devient positive et la cathode négative; les électrons sont dès lors projetés sur l'anticathode avec émissions de rayons X.  1, fiche 1, Français, - tube%20auto%2Ddresseur

Fiche 1,  Justifications,  Espagnol