US2811669A - Method for directing the electron beam of a binary trochotron periodically - Google Patents

Description

Oct. 29, 1957 s. E. WARRING 2,811,639

METHOD FOR DIRECTING THE ELECTRON BEAM OF A BINARY TROCHOTRON PERIODICALLY Filed July 16, 1953 Fig.1

23 f; 22f; 7'2 21,: .L

Fig.2 a

5- Fig.2b

Fig.2c

-Fi .2d

INVENTOR STlG ERIK WARRING ATTORNEY St i Stig Erik Warring, Hagersten, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application July 16, 1953, Serial No. 368,473 Claims priority, application Sweden July 18, 1952 2 Claims. (Cl. 315-21) This invention relates to a method for directing the electron beam of a binary trochotron periodically.

' The binary trochotron in itself is known earlier. See e. gthe U. S. Patent 2,513,260, particularly Fig. 13 and Fig. 36 and parts of the description pertaining to these figures. 'To be able to explain this invention more fully the structure and mode of operation of the binary trochotron is first briefly described in connection with the enclosed drawing, in which Fig. 1,shows the structure of a. binary trochotron. Figs. 2a, 2b, 2c and 2d show a time diagram in connection with the description of the present invention.

In Fig. l, 1 indicates the envelope of the binary trochotron. 2 is the cathode, the main extension length of which is perpendicular to the plane of the paper. 3 indicates a possible control grid and 4 the anode of the trochotron. 5 is a common electrode, a so-called rail. The contact electrodes of the trochotron (plate electrodes) which in the described embodiment are assumed to be 8, are in the figure indicated with 613. The control electrodes (spades) of the trochotron are in the figure indicated with 1420. They are in groups connected to three points 21, 22 and 23, from which they receive their biases. The group connected to point 21 includes only one spade, 14. The group connected to point 22 consists of two spades, and 16. The group connected to point 23 comprises four spades, 17-20. A magnetic field acts upon the trochotron in a direction parallel with the cathode, i. e. perpendicularly to the plane of the paper. The rail 5 is applied e. g. to zero potential. The anode 4 is applied to a positive potential, e. g. 100 volts. As known the electron beam of' a trochotron will mainly follow an equipotential line. Suppose that the cathode is applied to such a potential that the electron beam will follow the equipotential line for volts. If all spades are connected with the anode so that they obtain the same potential as this, 100 volts, the equipotential line for 50 volts will enter into the box where the plate 13 is, and the electron beam will then hit this plate. If the group of spades connected to the point 23 is connected with the rail 5, whereas the other groups of spades 21 and 22 are connected with the anode, the electron beam will hit the plate 12. If the group of spades connected to point 22 is connected with the rail, whereas the others are connected with the anode, the beam will hit the plate 11. If the groups of spades connected to the points 22 and 23 are connected with the rail whereas the group of spades connected to the point 21 is connected with the anode, the beam will hit the plate 10 et cetera.

This invention relates to a method for a binary trochotron containing a number of groups of control electrodes for directing the electron beam of the trochotron periodically, whereby the electron current of the trochotron may not necessarily be continuous but can very well be pulsed.

This invention is characterized by the fact that for directing the electron beam of the trochotron periodically tes Patent 2,811,659 Patented Oct. 29, 1957 ice to respective contact electrodes the potential of said groups is caused to vary periodically with respective fundamental frequencies according to the formula 2- 'f, where n is the ordinal number for respective group (lnN, where N is the number of groups), whereby the groups may be numbered in an arbitrary sequence, and f is the repetition frequency of the current pulses which are obtained to each separate contact electrode at continuous cathode current.

The invention presents a simple method for producing unmodulated pulses in respective contact electrodes or for distribution of unmodulated or modulated time distributed pulses to respective contact electrodes.

Figs. 2a, b and c show suitable periodical voltage forms intended to be applied to respective groups of control electrodes. The circuit connections for applying the different potentials to the trochotron are apparent from Patent 2,513,260, in particular Figs. 13 and 36 thereof.

The voltage forms consist here of square voltages,

whereby the fundamental frequency of the voltage form shown in Fig. 2a is twice as high as the fundamental frequency of the voltage form shown in Fig. 2c. The said voltage forms are each applied to one of the control electrode groups of the trochotron, i. e. to the points 21, 22 and 23. Suppose for instance that the voltage form according to Fig. 2a is applied to point 23, the voltage form according to Fig. 2b to point 22 and the voltage form according to Fig. 2c to point 21. The amplitude of each of said voltage forms and the bias of the control electrode groups are so chosen, that the voltages of the control electrodes vary between the biases of the anode 4 and the rail 5. If the cathode current of the trochotron is supposed to be continuous during the time n, when all control electrodes are positive, the current will pass to the contact electrode 13. During the time t2 when the control electrode group connected to point 23 is negative, whereas the other groups are positive, the current will pass to the contact electrode 12. During the time is the current will pass to the contact electrode 11, during the time t4 to'the contact electrode 10 et cetera. After the end of the time ts when the current has passed to the contact electrode 6, the current will again hit the contact electrode 13 and step from contact electrode to contact electrode in the same manner as before. The electron beam of the trochotron will thus step from contract electrode to contact electrode with a stepping velocity (number of contact electrodes hit per second) corresponding to double the fundamental frequency of the voltage form according to Fig. 2a.

The binary trochotron may, in the described method for directing its electron beam, also be used for distribution of time distributed pulses to respective contact electrodes. The cathode current of the trochotron may for instance be cut off by applying its control rid 3 to a sufliciently negative bias in relation to the cathode 2. To the control grid 2. pulse series consisting of positive pulses is applied, e. g. according to Fig. 2d. These pulses cause that the cathode emits current during their duration time. If the pulses have time positions in relation to the periodical voltage forms according to Fig. 2ad, pulse 24 wiil pass to the contact electrode 13, plus 25 to the contact electrode 12 et cetera. The pulses according to Fig. 2d may be unmodulated or else modulated for instance as regards amplitude, duration or time position or the like. The pulses which are to be distributed may of course be applied as negative pulses to the cathode. They may also be applied as positive pulses to the anode, although the necessary amplitude then of course will be considerably greater.

The voltage form according to Fig. 2a with the highest fundamental frequency may not necessarily be applied to the control electrode group containing most of the coutrol electrodes as has been assumed hitherto. Each of the voltages forms according to Figs. 2a-c may namely be fed to an arbitrary group of control electrodes and the other forms to the other groups of control electrodes in an arbitrary sequence. The only diflerence is that the electron'beam of the trochotron will hit respective contact electrode in another sequence than in the described example. The phase shift between the periodical voltage forms may also be another than what is shown in Figs. Za-c. Yet the voltages forms must pass zero at times when the periodical voltage form with the highest fundamental frequency passes one of its zero passages. A different phase shift within the scope of the indicated condition will only cause the contact electrodes to receive current pulses from the electron beamin another sequence.

The periodical voltage forms fed to respective groups of control electrodes may not necessarily consist of square voltages. Other wave forms may also be used, e. g. sine voltages. Such voltages may very well be used, if for instance the duration of the pulses applied to the control grid is considerably less-than half a period of the periodical voltages form having the highest fundamental frequency.

I claim:

1. The method of periodically directing the electron beam of a binary trochotron including a single acceleration anode, a plurality of contact electrodes and groups of control electrodes interconnected in each group upon respective Ones of said contact electrodes by means of crossing electric and magnetic fields, which comprises applying to said groups potentials periodically varying with the respective fundamental frequencies in accordance with the formula 2"- -f wherein n is the ordinal number for the respective group l n N, wherein N is the number of the groups), the said groups being numbered in arbitrary sequence and f is the repetition frequency of current pulses obtained at each separate contact electrode for a continuous cathode current.

2. In the method of claim 1, the stepof applying to the groups of control electrodes periodical voltage forms passing zero at the times the periodical voltage forms having the highest fundamental frequency passes one of its zero passages.

References Cited in the file of this patent UNITED STATES PATENT? 2,477,008 Rosen July 26,1949 2,513,260 Alfven et al. June 27, 1950 2,522,055 OBrien Sept. 12, 1950 2,533,401 Schramm Dec. 12, 1950 2,616,978 Jonker et al. Nov. 4, 1952 2,620,454 Skellett Dec. 2, 1952 2,623,196 Toulon Dec. 23, 1952 2,666,162 Holloway et al. Jan. 12, 1954

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