Investigations in the Field of the Ultra-Short Electromagnetic Waves II. The Normal Waves and the Dwarf Waves

Abstract

The results are presented of an investigation of the production of ultra-short undamped electromagnetic waves by using the method of H. Barkhausen and K. Kurz. Method of working diagrams. Normal waves and dwarf waves. A method is developed for the graphic representation of the work of generators of ultra-short waves. This method is based on the construction of special "working diagrams." These diagrams define the location of "regions of oscillations," which show the values of the natural periods of the oscillating circuits and the values of the grid potentials at which oscillations are generated. Vacuum tubes can generate two kinds of ultra-short waves. The first kind have a wave-length approximating that computed by Barkhausen's formula λ^2Eg=da^210^6. Their period is nearly equal to the time required for the electrons to move from the filament to the plate and back (normal waves). The second kind of waves are considerably shorter (dwarf waves). Both kinds of waves satisfy the equation λ^2Eg=const. for points on the working diagram where the plate current (the amplitude of the oscillations) has its maximum value. Complex working diagrams. Dwarf waves of higher orders. Vacuum tubes can have complex working diagrams with a large number of regions of oscillations. In such a case the tube generates different dwarf waves. Their length is two, three and four times shorter than that of the normal waves. Dwarf waves are accordingly divided into waves of the 1st, 2nd, 3rd, etc. orders. The shortest dwarf waves of the 4th order, generated by tubes of the type R5, had a wave-length λ=9.4 cm. The presence of dwarf waves of higher orders shows that vacuum tubes can generate oscillations of a frequency considerably greater than the frequency of the electronic oscillations. Both the normal and dwarf waves belong to the same type of GM-oscillations. Limits were determined within which Barkhausen's formula is applicable. It is shown that the difference in the number of regions of oscillations on the working diagrams depends on the difference in the time required for the electrons to pass in different directions within the tube. The latter depends on the asymmetry in the arrangement of the electrodes. The nature of dwarf waves. Dwarf waves are oscillations of the circuits within the tube or coupled with the tube which are excited in such a manner that during the time τ it takes for the electrons to pass from the filament to the plate and back, the circuits perform two complete oscillations (dwarf waves of the 1st order), three complete oscillations (dwarf waves of the 2nd order) etc. Thus the wave-lengths are equal to: λ0=c0τ (normal waves), λ1=c0τ/2 (dwarf waves of the 1st order), λ2=c0τ/3 (dwarf waves of the 2nd order), λ3=c0τ/4 (dwarf waves of the 3rt order), etc. Dwarf waves 9.5-18.5 cm long originate in oscillating circuits, which are inside the tube. The advantages of dwarf waves of higher orders are shown, owing to the possibility of using lower grid potentials, which leads to a greater steadiness in the operation of the tube.

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