On the Poulsen Arc and its Theory

The paper deals with an experimental investigation of the Poulsen arc carried out by means of: 1. The ordinary electrical methods of testing, 2. Gehrcke's oscillograph for taking oscillograms of arc voltage, 3. Photographic side views of the arc, 4. Photographs of the arc and craters viewed in a rotating mirror, i. e., crater oscillograms. The chief results of the investigation are: The experimental values of ratio between radio frequency current and the direct current are satisfactorily explained on the basis of the A-theory. This is not the case for the theory based on Barkhausen's simple characteristic. (B-theory.) The maximum voltage across the arc is very much smaller than required by the B-theory. For the normal Poulsen arc, the extinction voltage is almost as high as the ignition voltage. The most suitable intensity of the magnetic field Ho is proportional to the density of the gas and to the frequency of the oscillations, approximately proportional to the feeding current and increases linearly with the r.f. resistance. The behavior of the arc in fields of different intensities is investigated.