US2242888A - Ultra short wave oscillation generator - Google Patents

Description

M y 1941. H. E. HO LLMANN ULTR SHORT WAVE OSCILLATION GENERATOR Filed Jan. 7,, 19:59 2 Shets-Shee t 2 i Ewan/=5 INVENTOR. [25H HOLLMANN ATTORNEY.

Patented May 20, 1941 ULTRA SHORT WAVE OSCILLATION GENERATOR Hans Erich Hollmann, Berlin, Germany, assignor to Telefunken Gesellschaft fur Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application January 7, 1939, Serial No. 249,737 In Germany February 16, 1938 4 Claims. (01. 250-36) The present invention is concerned with an arrangement adapted to produce short wave and ultra short wave electrical oscillations by the aid of an electron pencil or beam which, in electrical or magnetic field of suitable orientation, is twisted into a spiral and which, upon each rotation of the electrons, passes through two or more coupling fields through which it yields the kinetic energy stored therein to an oscillable resonance system.

Before the arrangement of the invention is discussed more fully, at better understanding thereof may be had by reference to the fundamental principles involved in the construction and operation of a magnetic resonance accelerator, known as the cyclotron. Fig. 1 is a circuit sketch of such a known type of 'magnetic resonance accelerator in its most rudimentary form. Fig. 1a is a cross-sectional view of Fig. 1, It should be remembered that the purpose of such an accelerator is to obtain the extremely high accelerations required for atomic conversions of ions and electrons without the use of extremely high accelerator potentials and this is effected by repeatedly imparting to the ions or electrons a periodically recurring acceleration each time by the same, comparatively low potentially. In an arrangement as shown in Fig. 1, this end is accomplished, for instance, in the following fashion: At K, by means of thermionic (incandesced) electrodes, ions or electrons are produced. They are accelerated in ,the fields I and II which are set up between the semi-circular top and bottom electrodes P1 and P1 and top and bottom electrodes P2 and P2 by means of an alternating potential E furnished from a powerful radio frequency generator G, and subject to the simultaneous action of, a constant magnetic field at right angles to the plane of the drawings, they are caused to describe semi-circular paths or orbits. Inasmuch as the time required to travel a unit length of path, owing to the increase in many hundreds of rotations by the particles, ion or electron speeds of several million volts are producible although the alternating potential prevailing across the semicircular plates amounts to only a few tens of thousands of volts.

In the light of a simple energetic consideration,

. it will at once be seen that the aggregate energy contained by multiplication in the accelerated charged particles, which, when these particles come to strike or bombard a collector or gathering electrode, are converted into appreciable heat,

- must be supplied from the radio frequency feed speed upon each passage from one into the other I semi-circular field, is equal, the charged particles reach the accelerator path; that is, the gap between the two semi-circular accelerator fields each time, at an instant when they find again an accelerating phase of the alternating field. Inasmuch as the rate of the charged particles, as a consequence, rises with each passage from one accelerator field to the next, the radius of curvature of their paths will become increasingly greater, so that there results a spiral until the corpuscles emerge from the electric field at a tangent. It is known that in this manner, after potential of generator G. speeds indicated are to be obtained, say, by ions, a supply generator of many kilowatt power is required. It will also be readily seen that the value of the applied radio frequency potential, its frequency, and the intensity of the magnetic field governing the radius of the path or spires must be matched or be in exact harmony to one another in order that, after each semi-circle the desired acceleration may be secured.

The present invention is predicated upon the general rule that conditions could just as well be so chosen that the electrons, prior to their passage from one field to the other, are decelerated rather than accelerated. Thus, the conditions as regards the resonance accelerator before described are inverse; that is, the electrons, if entering into the tube at a high rate of velocity, after passing through each semi-circle, are again and again subjected to a retarding action with the result that they are more and more slowed up. 'Incidentally, each time they fiy through a counteracting field prevailing between the plates, they yield kinetic energy imparted to them upon their entrance by virtue of influence action to the plates. This means that a supply potential impressed, for instance, on the plates will not be deprived of energy, on the contrary, energy will be yielded thereto at the rate or rhythm of the rotations of the electrons. Thus, if the plates P1 and P2 are united with a resonance circuit which is tuned to the period of the electron rotations, the said circuit will be excited to experience natural oscillations, if the voltages and the magnetic field are properly chosen. In other words, the operation of the scheme predicated upon an inversion ofthe basic principle of the resonance accelerator could be represented also in such a way that the-dynamically positive internal resistance of the tube between the plates P1 and P: which constitutes the load of the supply potential of the radio frequency generator G, Fig. 1, and whose dissipation is converted into a multi- In fact, if the voltplicative increase of the speeds of the charged particles, is inverted; that is to say, is changed into a dynamically negative resistance which tends to excite the external circuit with the result that the energy thus put out or delivered is derived from the electron pencil.

Tubes are fundamentally known in the art' which represent further developments of multisplit magnetron tubes andin which an electron pencil enters into a multi-split magnetron system tangentially. For constructional reasons the of the surface of a cylinder shell so that charges 1 were induced in these segments. In line with this effect, the electrode system, like a normal magnetron system, had a length that was comparatively large in comparison with the diameter. In contrast to this prior art, the electrodes of the present invention consist only of lateral or wind plate electrodes, while the oscillation or swim electrodes provided circumferentially of the electrode system in the tube known in the art are dispensed with. This results in considerable advantages, firstly because the electrons are always at the same distance from the oscillation electrodes (the side plates) so that the amplitude of the influenced alternating potentials stays stable and constant during the rotation of the electrons. In the arrangement known in the prior art, the

. electrons receded more and more from the oscillation electrodes in the course of their travel along the spiral path with a resultant deduction of the influence action and thus of the efiiciency. There is this further advantage that such electrons as fail to emerge in the proper phase from the cathode, may be caught or collected by the aid of special constant-potential electrodes mounted at the periphery of the system, whereas such electrons of faulty phase in the older arrangement had a chance to impinge upon and thus bombard the oscillation electrodes. However, because of the heating of the electrodes which is incidentally occasioned, the maximum energy deliverable by these electrodes was diminished. Another particular merit of the electrode arrangement as here disclosed is that, as shown in Fig. 4, a cathode uniformly spread or distributed about the entire circumference and generating a disc ray may be employed. It will be seen that the electrode system here disclosed distinguishes itself even on the outside from the known system in so far as the length is vanishingly small in comparison with the diameter; in other words, that the electronsrevolve inside a narrow plate-shaped space bounded by the oscillating side plates.

A number of arrangements embodying the principles of the invention shall now be described in connection with drawings wherein Fig. 1 illustrates diagrammatically a known type of resonance accelerator; Fig. la is a cross-section of Fig. 1; Figs. 2 to 5, inclusive, illustrate systems in accordance with the invention; and Fig. 4a shows a side section view of Fig. 4.

Fig. 2, in purely schematic form, represents the inversion of a resonance accelerator of the type shown in Fig. 1, according to the invention, for the purpose of wave generation. K is a source of electrons of any desired kind, say an incandesced cathode. Facing the latter and spaced apart therefrom a small distance is an anode diaphragm A impressed with a high potential so that the electrons given off at K are. drawn away therefrom in the form of a filamentary ray or pencil. In line with what has been described previously, the said ray pencil is curved by the aid of a magnetic field at right angles to the plane of the drawing to result in a circular arc. Assuming that at a definite instant a counteracting or opposite field is setup between I and 11, then certain electrons will traverse the slit between I and II at the instant when the potential of P1 and P1 is positive, and that of P2 and Pa negative; these electrons will be retarded and they traverse field II at reduced speed. As a consequence, their path in field II- experiences a. more marked arcuation, with the result that after having traveled through a further semi-.circle, they have come closer to the center of the tube. This process is repeated upon each passage across the slit-field provided the natural period of the alternating potential impressed upon the plates agrees with a full rotation time of the electrons. The consequence is that the path of the electron pencil, because of the ever diminishing ray pencil speed, becomes spirally wound up toward the center inside a homogeneous magnetic field where the electrons are finally collected at their residual speed by the electrode Z and carried (conducted) away.

What is of particular importance is the fact that it is clearly understood what happens with such electronsas fly through the field in the slit in a faulty phase; in other words, which pass from one semi-circle field to the other at instants when the electric field intensity is in the direction of the ray motion so that the electrons become accelerated in the same way as with the known type of magnetic resonance accelerator described above. These electrons fly along a path indicated by the lines in Fig. 2; in other words, they describe a spiral, as in the known type of 1 resonance accelerator hereinbefore referred to, of growing radius of curvature and they fly out of the controlfield so that, after the first passage through the first split-field, they may be gathered by a collector electrode F. In this manner all electrons of wrong phase are eliminated; otherwise, these particular electrons would compensate those presenting a correct phase in their action, so that only electrons of proper phase, i. e., electrons which have experienced multiplicative retardation remain. The excitation of the external circuit L-'C, in the light of these considerations and of what has been pointed out above is not in need of further explanation; in fact, it is self-explanatory from the law of energies. The collector or gathering electrode F has the shape of a ring closing the uncoupling space to the outside and maintained at a constant potential.

In order that frequencies as high as feasible may be obtained, it is necessary, on the one hand, to use the highest possible radiation speeds, while on the other hand, the electron paths must be abbreviated as far as feasible, i. e., make the tube of the smallest possible dimensions. Another way of accomplishing the same end is to retard the ray several times in the course of one convolution. To this end the semicircular plates P1 and P2, Fig. 2, are replaced by several segment-shaped plates, the latter being alternately connectedwith two ends of the oscillatory circuit to be excited. This results in an arrangement of the kind shown in Fig. 3 which,

in lieu of two semi-circular plates as shown in Fig, 2, contains six segments P1-Ps being insulated from one another so that the ray, in the course of each revolution, is compelled to pass through six such retarding fields. These six segments are alternately combined into two groups P1P3-P5 and P2-P4Pe, the ensuing two groups being united with the ends of the oscillation circuit I-r-C. It will be obvious that the wavelength of this tube is only one-third that shown in Fig. 2, if the geometric dimensions and the same speed of ray are preserved. It will also be understood quite readily that by finer subdivision of the uncoupling field it is readily feasible to obtain extremely short waves. In fact, only the problem associated with the chances of proper adjustment imposes a limitation in this respect.

Inasmuch as it is fundamentally immaterial at what particular point of the circumference of the tube the electron ray is shot into the uncoupling field, the performance of tubes of the invention may be raised by spacing a plurality of electron beam generating systems of the kind illustrated in Figs. 2 and 3 comprising the heated cathode K and the corresponding anode diaphragm A around the periphery and by projecting from these numerous rays or pencils into the tube. All of these would be subject to the described laws; that is to say, electrons of wrong phase thereof would be sorted out, whereas those presenting the proper phase, in other words, energyyielding electrons of each of the beams will be directed along spiral paths towards the center.

Developing the same idea along identical lines,

that is, increasing the number of individual rays I or pencils more and more, the point is eventually reached where discreet rays are entirely dispensed with and where the uncoupling field, around its entire circumference, is surrounded by a source of electrons and an imaging system. A practical embodiment of an arrangement predicated upon this expanded idea of the invention is shown in Fig. 4. .The uncoupling field consists of four segments Pl-P4; of these, pairs placed diametrically opposite are connected and united with the exciting circuit. The said uncoupling field is first surrounded by two anode rings A and A", as shown in Fig. 4a, being at the same potential and having an annular space or gap between them; and they are further surrounded by an annular heating wire K. The latter, in turn, is screened and supported by an annular concentrator electrode Q of semi-circular cross-sectional shape. Instead of a great number of individual rays or pencils, the uncoupling field in this tube is traversed by a disc ray whose electrodes extend from the outside in inward direction and which untwist at the same time spirally.

Fig. 5 finally shows a tube which distinguishes itself from the tube shown in Fig. 4 in that a distinct ray accelerator electrode has been entirely dispensed with, while the segments thereof serve not only as uncoupling electrodes, but at the same time also for the production of an electron lens. For this purpose, the annular cathode K directly surrounds the segments P1 and P2; that is, without interposition of a special anode. As before, the segments are associated with the exciting circuit L-C and they are maintained at cathode potential through this exciting circuit, or else they are slightly biased either negative or positive. The anode proper consists of the metallic cylinder A located in the center which is impressed with a high positive potential.

It may be mentioned in this connection that the principle underlying the invention is applicable not only to filamentary or slender my pen-- oils, which are here mentioned for the sake of clarity, but also to other forms of rays or pencils, and more particularly fiat rays.

What is claimed is:

1. An ultra short wave oscillation generator comprising an even plurality of electrode structures, greater than two, arranged to substantially enclose an orbital space, connections between alternately located electrode structures, means for producing a substantially uniform magnetic field within said space, means for producing an influx of charged particles'in said space adjacent the periphery thereof with a velocity having a component at right angles to said field and a component parallel to said periphery, whereby said charged particles are caused to circulate in said field with a uniform angular velocity, a resonant circuit having a natural angular frequency higher than the orbital frequency of said electrons and substantially equal to an integral multiple thereof, said resonant circuit having a pair of terminals connected to a pair of adjacent electrodes, whereby the kinetic energy of said influxing particles is intermittently imparted to said resonant circuit as said particles successively pass from a portion of said orbital space enclosed by one of said electrodes to the portion enclosed by the adjacent electrode, and a collector electrode near the periphery of said orbital space and maintained at a suitable polarizing potential relative to the mean potential of said resonant circuit for gathering electrons whose motions are out-of-phase with respect to the circulating electrons.

2. An ultra short wave oscillation generator comprising a plurality of electrode structures arranged to substantially enclose an orbital space, means for producing a substantially uniform magnetic field within said space, means for producing an influx of charged particles in said space adjacent the periphery thereof with a velocity having a component at right angles to said field and a component parallel to said periphery, whereby said charged particles are caused to circulate in said field with a uniform angular velocity, a resonant circuit having a natural angular frequency equal to the orbital frequency of said electrons multiplied by'half the number of said electrode structures, said resonant circuit having a pair of terminals connected-to adjacent electrodes, whereby the I kinetic energy of said influxing particles is intermittently imparted to said resonant circuit as said particles successively pass from a portion of said orbital space enclosed by one of said electrodes to the portion enclosed by the adjacent electrode, and a collector electrode arranged within said orbital space and near said periphery for gathering electrons whose motions are outof-phase with respect to the circulating electrons, said collector electrode being connected to said resonant circuit.

3. An ultra short wave oscillation generator comprising a plurality of electrode structures arranged to substantially enclose an orbital space, means for producing a substantially uniform magnetic field within said space, means for producing an influx of charged particles in said space adjacent the periphery thereof with a velocity having a component at right angles tosaid field and a component parallel to said periphery, whereby said charged particles are caused to circulate in said field with a uniform angl'ilar velocity, a resonant circuit having a natural angular frequency equal to the orbital frequency of said electrons multiplied by half the number of said electrode structures, said resonant circuit having a pair of terminals connected to adjacent electrodes, whereby the kinetic energy of said influxing particles is intermittently imparted to said resonant circuit as said particles successively pass from a portion of said orbital space enclosed by one of said electrodes to the portion enclosed by the adjacent electrode, a collector electrode arranged within said orbital space and near said periphery for gathering electrons whose motions are out-ofphase with respect to the circulating electrons, means for maintaining said collector electrode at a predetermined constant potential, and a collector electrode located at the center of said orbital space for conducting away the circulating electrons-which impinge thereon, and a connection from said last collector electrode to said resonant circuit.

4. An electron oscillator comprising an evacuated envelope, a plurality of electrode structures bounding an orbital space and having adjacently disposed open ends, means for discharging electrons into the space bounded by one of said electrode structures, means for causing said electrons totraverse curved paths of decreasing radii past said electrode structures, a tuned circuit connecting said electrode structures and arranged to subtract energy from said electrons to thereby generate and sustain oscillatory currents in said circuit, a collector electrode arranged within said orbital space near the periphery thereof for gathering electrons whose motions are out-of-phase with respect to the circulating electrons, and a connection between said collector electrode and said tuned circuit.

HAN S ERICH HOILMANN.

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