| (11) | EP 0 209 963 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Improvement in or relating to ignitron devices |
(57) An ignitron device is provided in which a permanent annular magnet (4) at least partly surrounds the region between the ignitron anode (3) and the surface of a mercury pool (2) connected to the cathode terminal, the magnet being effective to create an axial magnetic field in the aforementioned region which tends to constrain the discharge arc of the device towards the centre of the pool and away from the envelope walls of the device. |