US2138896A

US2138896A - Negative resistance

Info

Publication number: US2138896A
Application number: US98007A
Authority: US
Inventors: Jr Edward H Yonkers
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-08-26
Filing date: 1936-08-26
Publication date: 1938-12-06
Anticipated expiration: 1955-12-06

Description

Dec. 6, 1938..

E. H. YONKERS, JR

NEGATIVE RESISTANCE 3 Sheets-She et l Filed Aug. 26, 1936 Dec. 6,1938. 5 YONKEFRS' JR 2,138,896

NEGATIVE RES I STANCE Filed Aug. 26, 1936 3 Sheets-Sheet 2 Dec. 6, 1938. E. H. YONKERS/JR 2,133,896

NEGATIVE RESISTANCE Filed Aug 26, 1956 3 Sheets-Sheet 3 vmawvvymm l 9AMMA 3i? BY.

l-llllll ulll lllllllllllllll Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE 13 Claims.

My invention relates broadly to negative resistance and more particularly to an improved circuit arrangement for producing negative resistance.

One of the objects of my invention is to provide a circuit arrangement for producing negative resistance by which the value of the negative resist- .ance may be adjusted or controlled over a relatively wide range within the same tube.

Another object of my invention is to provide a negative resistance which may be employed in the generation and amplification of alternating currents, functioning with substantial stability over an adjustable or controllable range of values of negative resistance.

Still another object of my invention is to provide a method of producing negative resistance for permitting adjustment and control of the negative resistance over a wide working range.

A further object of my invention is to provide a construction of negative resistance device including a negative resistance element formed by a multiplicity of alternately arranged plate members disposed between an electron emitting cathode and an anode and connected in an electrical circuit having means for applying a difference of potential across the sets of alternately arranged plate members.

A still further object of my invention is to provide a negative resistance device including an electron emitting cathode and an anode and a negative resistance element disposed therebetween in an evacuated vessel and electrically connected in a negative resistance circuit wherein both accelerating potential and bias potential applied to the negative resistance elementare varied to give a predetermined dynamic characteristic for the device.

Other and further objects of my invention reside in the method of producing negative resistance, structural arrangement and circuit arrangement for the negative resistance device as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which:

Figure 1 is a vertical sectional view of the negative resistance device of my invention; Fig. 2 is a vertical sectional view taken through the negative resistance device of my invention in a position revolved 180 degrees with respect to the position on which the view of Fig. 1 is taken with the plate members constituting the negative resistance element shown in side elevation; Fig. 3 is a horizontal sectional view taken through the negative resistance device of Fig. 1 on line 33 of Fig. 1;

I Fig. 4 is a horizontal sectional view taken through the negative resistance device on line 4-4 of Fig. 1; Fig. 5 is a plan view showing the construction of one of the plate members of the negative resistance element employed in the negative resistance device; Figs. 6. and 7 are theoretical views show- 5 ing the path of movement of electrons from the cathode to the anode and the blocking effect of the plate members constituting the negative resistance element, under difierent conditions of operation of the negative resistance device; Fig. 8 10 is a schematic circuit arrangement of the nega tive resistance device of my invention, employed as a means for generating alternating current where frequency stability is required; Fig. 9 is a schematic circuit arrangement of the negative resistance device employed as a means for generatingalternating current where maximum power output is required or Where extreme low values of negative resistance are required; and Fig. 10

illustrates a family of curves showing the variation in negative resistance which may be obtained with a single tube.

The present invention is directed to improved means for producing negative resistance. In my prior U. S. Patent 2,002,238, granted May 21, 1935, for Negative resistance, I have shown means for producing a negative resistance characteristic wherein the desired inverse current characteristic is obtained through the action of an electrode of peculiar, form upon a constant current electron stream. The value of the negative resistance in this prior device depended largely upon the form or shape of the negative resistance element. In the present invention I employ a modified form of this element which permits convenient control of the value of negative resistance obtained without altering the structure of the device, in other Words, my prior patent discloses means for producing negative resistance of a relatively fixed value for a given tube, whereas in the present invention I provide means for adjusting or controlling values of the negative resistance over a wide range within the same tube.

This feature increases the utility of the device and permits greater convenience and efficiency in the numerous services to which it may be applied, such as the generation or amplification of alternating currents. A further purpose of my present invention is to provide a negative resistance 5() device capable of delivering relatively large amounts of power in the form of alternating current.

Referring more particularly to Fig. 1, I have shown a highly evacuated envelope I which may be of glass or other suitable material formed with the inwardly directed axially aligned pedestal 2 which serves as a supporting means for the electrodes and lead-in wires hereafter described. Extending through and supported by the pedestal 2 I provide the filamentary cathode 3 whose leadin conductors 4 and 5 are connected so as to sup:- ply current for heating the cathode 3 to incandescence. Any suitable means may be employed as a cathode capable of producing a constant current source of electrons. By the expression, constant current source of electrons, I mean a source which delivers a substantially constant electronic current regardless of the difference of potential applied between the source and the other elements of the device over a working range. The filamentary cathode 3 is maintained taut by a suitable spring device 30. introduced between the supporting means and the filament. Regardless of the expansion or contraction of the filamentary cathode 3, the cathode always remains stretched in spaced relation to the associated parts of the device. In the structural embodiment shown in Fig. 1, I provide a negative resistance element 6 consisting of a system of thin annular plates spaced from one another and positioned so that their axes are all coincident with the filamentary cathode 3. The said annular plates are divided into two groups, one group, 6c being rigidly attached to the support rod 8 and the other, 62; to support rod 9. Said support rods are extended through the pedestal 2 and. connected to the terminal conductors l0 and H so that external connection may be made separately to each of the two groups of interleaved annular plates which in combination form the negative resistance electrode. I also provide the cylindrical anode l2 positioned so that it surrounds the previously mentioned elements, with its axis also coincident with the filamentary cathode 3. It is supported from the pedestal 2 by the support rods l3 and I4 with the lead-in wire 15 connected to support wire l3 so that the necessary electrical connection may be made to the anode l2.

In the operation of the device the cathode 3 is heated to incandescence by means of a battery or other current source which is connected to the lead-in wires 4 and 5. The anode I2 is c0nnect ed to a source of positive potential with respect to the cathode so that those electrons which pass between the plates of the negative resistance element are readily carried away.

The negative resistance element, that is the two sets of interleaved annular plates, Ba, and 6b, is, as a whole, operated at positive potentials with respect to the cathode but one set of plates is maintained at a higher potential than-the other set. The value of this biasing potential, that is, the potential difference between the two sets of plates, determines the operating range of as well as the slope of the negative resistance characteristic. For example, referring to Fig. 10 the curves A, B, C, D, E, F, and G represent the variation in total current received by the negative resistance element 6 as the voltage applied to it as a whole is varied and the curves formed by the broken lines A, B, C, D, E, F, and G represent the corresponding changes in the anode current. The curves A and A result when there is no potential difference between the two sets of annular plates. Curves B and B represent the characteristic of the device when the bias potential is 10 volts, 0, C when the bias is 20 volts, and so on to F, F, which results whenthe biasing potential is 50 volts. The curves G and G represent a special case which will be described in a later part of the specification.

It is clear from this family of curves that a Wide variation in the value of negative resistance, as determined by the slope of the falling portion of the curves A, B, C, D, E, F, and G, may be obtained by altering the value of the biasing potential, also that the operating range of the device, that isthe length of the falling portion of the characteristic is also controlled by the value of the bias. It should be understood that the characteristics represented in Fig. 10 were obtained from a single tube of specific electrode dimensions, operating at a definite filament temperature, and that each change in the diameter and spacing of the annular plates which comprise the negative resistance element 6 results in a different family of curves.

The operation of the device, is similar to that of my former U. S. Patent 2,002,238, granted May 21, 1935, in fact, when the biasing potential represented by curves A and A between the groups of annular plates, 6a and 6b, is zero the operation is identical with the former device. However, when a biasing potential is present the electrons are deflected from their path toward the anode in the direction of those annular plates which are at the more positive potential, thus, increasing the desired effect, which is best described with reference to Figs. 6 and '7 When the electrons are moving slowly due to a relatively low potential on the annular plate system 60., 6b, as a whole, with respect to the cathode 3 all of the electrons emitted from the cathode are precipitated upon the annular plates 60. and 6b by the action of the biasing potential upon the electrons during their passage between the annular plates. This condition is clearly shown in Fig. 6. As the potential of the annular plate system as a whole is increased, the biasing potential remaining at some fixed value, the velocity of the electrons in their passage between the annular plates increases and, hence, the time during which the biasing potential is effective in deflecting their motion toward the surfaces of the plates, becomes less and less and an increasing number of electrons are enabled to pass entirely through the spaces between the plates and, thus, reach the anode l2.

Eventually an upper limit is reached Where a minimum of electrons is received by the electrode 6 and a maximum number reach the anode. This condition is depicted in Fig. '7.

Thus, over the working range of the device and as the potential of element 6 as a whole is increased, the current received by it decreases, providing the desired inverse current characteristic or negative resistance.

The following mathematical analysis of this action yields a theoretical expression for the operating characteristics of the device which closely approximates those determined by experimental methods.

The primary assumption must be made that the rate of electron emission from the cathode is constant over the operating range of potentials applied to electrode 6. Let this emission constant be represented by the symbol A. Now even under the most favorable conditions for the passage of electrons through the openings of element 6 to the anode [2, shown in Fig. 7, a portion of the electron stream is necessarily blocked by the element 6 due to the thickness of the annular plates and support rods which comprise it, thus, causing a portion of the total current, A, to 'fiow in the circuit of electrode 6 at all times. Let this'current be represented by the symbol C which I shall call the blocking constant.

Now since the total current is a constant A the maximum current which can be received by the anode will be A minus C which I will represent by the symbol K, which will hereinafter be referred to as the anode constant.

Now under operating conditions, the current received by electrode 6 will comprise the constant C plus a portion of K. Thus the current i received by electrode 6 may be expressed by the relation i oK-l-C where 5 is a function involving the accelerating potential, (that is, the eifective potential of electrode 6 as a Whole with respect to the cathode), the biasing voltage between the two sets of annular plates 6a and 6b of electrode 6, and the geometrical dimensions of electrode 6. The operating range of the device is obviously limited to those conditions which produce values of between zero and unity.

Now, considering the combined efiects of the accelerating electrostatic field which is parallel to the surfaces of the annular plates of element 6 and the biasing field which is normal to the surfaces of the annular plates of element 6 upon the electron stream in its passage from the cathode toward the anodewe obtain the following expression for the coefficient, qs.

where 1 represents the length of the radial path between the inner and outer edges of the annular plates of element 6.

d represents the spacing between the annular plates of element 6.

E represents the potential of the more positive of the two sets of annular plates of element 6 with respect to the cathode.

e represents the biasing potential between the two sets of annular plates of element 6, e being always in the negative direction with respect to E, so that the accelerating potential, that is, the average potential of element 6 as a whole with respect to the cathode becomes Thus, the expression for the current received by element 6 becomes =dE= n) It is clear from these relations that when the form of the element 6 and the emission rate remain 'constant a family of curves is obtained for various values of e in which the current i varies inversely with the potential E within the working range of the device, similar inform to the curves shown in Fig. 10, when practical values are chosen for the constants K and C.

In the development of this expression I have assumed the emission to be constant for all values of E. However, in practice, it is not possible to obtain this ideal condition, and in the form of the device shown in Fig. 1, I have employed a tungsten filament which, due to the well known phenomenon of saturation, produces a substan tially constant rate of electron emission above a certain critical field strength at the cathode surface. Thus, the lower limit of the useful working range of the device is established by that value of potential which causes a field strength at the cathode just sufiicient to produce saturation.

It should also be noted that when the biasing potential 6 is zero, the above theoretical relation shows the current i to be a constant for all values of E, whereas, experimentally, an inverse curve results as shown in Fig. 10, curve A. This is due to the fact that the, electrons comprising the stream flowing between the annular plates constitute a space charge equivalent in its action to a small biasing potential which causes the electrons to spread towards the annular plates in the manner described in my former Patent No. 2,002,238, granted May 21, 1935.

The accelerating potential has been considered as being equal to the average potential of the two sets of annular plates comprising electrode 6, that is, one set has the potential E with respect to the cathode and the other, (E-e) thus making the average equivalent to Now for relatively large values of e this condition not substantially parallel to the surfaces of the annular plates comprising element 6, thus increasing the value of the blocking constant C and reducing the efficiency of the device.

This defect is of importance only in the larger power tubes where relatively high values of both e and d are employed to obtain the desired characteristics. In such cases I have overcome this difficulty by increasing the spacing between the cathode and the inner edges of the more positive set of annular plates of electrode 6, so that the potential gradient between the cathode and each set of annular plates comprising element 6 is the same at the upper limit of the operating range of the device, thus imparting an equal acceleration to all electrons leaving the cathode in a direction which is substantially parallel to the surfaces of all the annular plates of element 6 at the upper limit of E, where it is desired that element 6 shall receive a minimum of current.

An important use of my device is as a genertube by limiting the alternating voltage applied to the electrodes, and making for a high degree of frequency stability which is important in many applications.

The operation of the device in this circuit arrangement is as follows: The filament or cathode 3 is heated to incandescence by means of the battery 24. The biasing battery 25 is connected between the two sets of annular plates 6a and 6b which together comp-rise the negative resistance element 6. The battery 25 is connected so that the set of annular plates 5a is negative with respect to the other set 61). The negative resistance element 6 is connected to the inductance 2| at a point 21 such that the portion of the parallel resonant circuit included in the circuit of element 6 presents a load, or effective positive resistance, slightly greater in value than the value of the negative resistance generated in this circuit by virtue of the inverse current characteristic of element 6.

When I refer to negative resistance, I have reference to the slope of the current-voltage relationship, and when this slope is negative, power is delivered to a circuit including the negative resistance, and the smaller the numerical value of the negative resistance, the more power is delivered to the circuit. If the value or" the negative resistance is infinite, it delivers no power to the circuit.

The term negative resistance as used in the specification means the numerical value of the ratio (as d1 which is the reciprocal of the slope of the current voltage curve, it is negative if cLu'rent increases when voltage is decreased, and the steeper the negative slope, the smaller the value of negative resistance, and to maintain oscillation in a parallel resonant circuit, the numerical value of negative resistance must be smaller than the numeri-, cal value of the equivalent parallel resistance of the resonant circuit. In former devices it has not been possible to obtain such long steep negative slopes to current voltage curves, that is, such low numerical values of negative resistance.

The lower end of the parallel resonant circuit is connected to a tap on the battery 26 so' that the element 6 as a whole is maintained at a suitable positive potential with respect to the cathode 3. The anode I2 is maintained at a higher positive potential with respect to the cathode by being connected so as to include the entire battery 26.

Under these conditions oscillations will be generated in the resonant circuit 20 at a frequency determined substantially by the constants of this circuit, because of the well known action of nega-' tive resistance. That is, if the negative resistance device delivers slightly more power to the resonant circuit per cycle than is lost through radia-. tion and heating, oscillations will build up to an equilibrium level and continue as long as the proper conditions are maintained.

Since my device is capable of generating rela tively low values of negative resistance, when it is connected to a parallel resonant circuit of eificient design, that is, one having low losses, the portion of the inductance 2| which is included in the negative resistance circuit may be as low as or percent of the total inductance. Under these conditions the frequency generated by the system is determined by the constants of the resonant circuit alone, capacity and other effects of the negative resistance device which might influence the frequency, being reduced to a minimum; by virtue of the small percentage of the resonant circuit included in the negative resistance circuit.

Thus, my device provides an ideal means for generating electrical oscillations where a high degree of frequency stability is required.

Referring now to Fig; 9, in this figure I show a schematic diagram of a circuit in which my device may serve either as an amplifier or as a generator of alternating currents. In this case a relatively high degree of efliciency obtains, and power in the form of pulsating or alternating currents is produced in the anode circuit from which it may be conducted by means of conventional coupling 3! to an antenna or other useful work circuit.

The operation of the device in the circuit shown in Fig. 9 is as follows: The filament 3 is heated to incandescence by means of the battery 24, one set of annular plates 6b is connected to a point 21 on the inductance 2!, the other set of annular plates to is connected to the point higher on the inductance. The bias voltage between Ga and 6b is obtained by means of the resistor 28 which is connected in series with the lead from 6a to the point 38 on the inductance. As has been pointed out some of the electrons emitted from the cathode must always strike the annular plates due to their thickness and this current flowing through the resistance 28 causes the potential of 6a to become lower than that of 62), thus, providing the desired bias. The value of the bias may easily be varied by changing the value of the resistance 28. The condenser 29 is connected in parallel with the resistance 28 to provide a path for the alternating currents which must, flow to the plates Get. It will be understood that a battery as shown in Fig. 8 may be employed in lieu of the resistor 28 and condenser 29.

As before, the lower end of the parallel resonant circuit 20 is connected to a portion of the battery 26 so that the element 6 is maintained at a positive potential with respect to the cathode. The anode I2 is maintained at a higher positive potential with respect to the cathode by being connected so as to include the entire battery 26. The output coupling element 3| is connected in series with the anode lead to provide a convenient means for conveying the power generated in the system to a work circuit such as an antenna.

In the operation of the device under these conditions, the lead connected to the point 21 on the inductance 21 carries the major portion of the inverse current since 6b is the more positive set of annular plates and, hence, the point 21 is chosen soas to obtain the proper matching of positive and negative resistance as described above. The more negative set of annular plates to being connected to a point higher on the inductance 2| receives a higher alternating current potential than 61) when oscillations occur in the resonant circuit 20. The effect of this arrangement is to increase the bias when the variable component of voltage swings below the working voltage, and to decrease the bias correspondingly when the variable component swings above the working voltage. For example, referring again to Fig. 10, if we select a working voltage of E0 and a fixed bias such that the static curve F is produced we obtain a dynamic characteristic designated at G and G when the variable component at the point 21 swings above and below the working voltage E by the amount it.

Thus the more positive set of annular plates 6b will move through a range of potentials (Eo+a sin wt) and the other set 6a will move through a wider range where n represents the coupling ratio between the two

points

27 and 30 on the inductance 2| of Fig. 9. This action is equivalent to progressively increasing the bias potential e as the variable component swings below E0 and progressively decreasing the bias as it swings above Eb, thus producing the steeper inverse current characteristic G, in Fig. 10 and causing the maximum current variations to occur in the anode circuit corresponding to the curve G in Fig. 10. In the development of curve G the coupling ratio of 2 was used, that is, n=2. That is: the variable component of voltage at 21, Fig. 9, is a sin wt; and at 30, it is: 2a sin wt.

The following approximate theoretical expression for this dynamic characteristic G has been derived from the basic current potential relation previously developed.

It will be noted that the curve G in Fig. 10 represents a negative resistance of extremely low value. In actual practice, I have produced negative resistance conditions lower in value than could be produced by previously known negative resistance devices of similar physical and electrical dimensions.

Where it is desired to employ my device as an amplifier rather than as an oscillator, it is only necessary to adjust the resistance 28 of Fig. 9 to a value such that the negative resistance generated is slightly greater than that required to produce oscillations and apply the impulses to be amplified to the point 21 by coupling with the inductance 2|, for example. Where amplification rather than oscillation is desired, it may be advantageous to eliminate the condenser 23 employing only the tapped inductance 2| in the circuit associated with element 6.

It will be understood that the oscillatory systems of my invention function through the action of negative resistance and do not depend I have found the method of operation, construction and arrangement of the negative resistance of my invention highly practical. I realize that modifications and changes may be made in the construction and arrangement of parts of the device and the circuit in which the device is connected, and I accordingly intend no limitations upon my invention other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. The method of producing negative resistance which includes the projection of a constant current electron stream, and the maintenance of a substantially constant transverse electrostatic field and of a longitudinal electrostatic field subject to variation, the transverse component of current in the electron stream being inversely variable with the strength of the longitudinal electrostatic field.

2. The method of producing negative resistance which includes the projection of a constant current electron stream, the maintenance of a longitudinal and of a transverse electrostatic field for affecting the electrons in the electron stream, and the variation of the strength of the longitudinal electrostatic field for varying the velocity of electrons in the stream and permitting the transverse electrostatic field to influence the electrons in correspondingly varying degree.

3. A negative resistance device, comprising an evacuated vessel, an electron emitting cathode and an anode therein, a negative resistance element disposed between said electron emitting cathode and said anode and comprising a multiplicity of spaced parallel disposed plates, means including said cathode for producing a constant flow of electrons from the cathode toward said anode in a direction parallel to said plates, means for applying an accelerating potential to said element as a whole, said accelerating potential being subject to variation for varying the velocity of electronsfiowlng from said cathode to said plate, and means for establishing substantially constant electrostatic deflecting fields between said plates normal-to the path of said electrons, whereby the portion of the electron stream received by the negative resistance element varies inversely with the said accelerating potential applied thereto as a whole.

4. A negative resistance device, comprising an evacuated envelope, an electron emitting cathode, means including said cathode for producing -a constant current electron stream, an anode interposed in the path of said stream, means for maintaining said anode at a positive potential with respect to said cathode, and a negative resistance element disposed between said anode and said cathode, means for maintaining said element at a less positive potential than said anode with respect to said cathode for producing an electrostatic accelerating field in the direction of said electron stream, said element comprising a plurality of parallel spacially related plates forming a geometrical figure whose lateral extension as compared with the spacial relation of the plate members is such that electrostatic lines of force between said plates and said cathode, and between said plates and said anode, extend only partly into the space between the plates comprising the negative resistance element, and. wherein no lines of electrostatic force extend between the plates from said. cathode to said anode, the potential of said element with respect to said cathode being subject to variation for varymg the velocity of electrons passing between said plates to said anode, and means for establishing a substantially constant difference of potential between consecutive plates of the negative resistance element for producing a constant electrostatic deflecting field normal to the direction of said electron stream whereby the quantity of electrons received by the said negative resistance element from said cathode varies inversely with electron emitting cathode, means including said cathode for producing'a constant current electron stream, an anode, and a negative resistance element disposed therebetween means for maintaining said anode at a positive potential with respect to the said cathode, and the said negative resistance element comprising a plurality of spaced parallel plates so oriented as to oiTer a minimum of obstruction to the rectilinear passage of electrons from said cathode to said anode, said negative resistance element being connected to two diiferent sources of potential, a variable primary potential from a first of said sources adapted to maintain the element as a whole positive with respect to said cathode, and a substantially constant secondary potential from the other of said sources adapted to maintain a difierence of potential between consecutive plates of said negative resistance element, said element having an inverse current characteristic over a useful working range with respect to the primary voltage applied to it substantially of the form wherein E=the variable primary or accelerating potential of the negative resistance element with respect to said cathode; e=the constant secondary potential whose electrostatic field is normal to that of the accelerating potential E; Z=length of the path between the plates; d=distance between the plates; K=the constant representing the maximum current which may be received by the anode; and C=blocking constant depending upon obstruction to electrons ofiered by the plates of said negative resistance element.

6. In a high frequency oscillatory system a negative resistance device comprising an evacuated vessel including an electron emitting cathode for supplying a constant current of electrons, an anode, and a negative resistance element disposed therebetween, said negative resistance element including sets of plate members, one set of said plate members being alternately interposed in spacial relation between the other set of said plate members, means for establishing a difference of potential between consecutive plate members, a source of voltage connected between said cathode and anode, and a resonant circuit connected between said negative resistance element and an intermediate point on said source of voltage.

'7. In a high frequency oscillatory system, a negative resistance device comprising an evacuated vessel including an electron emitting cathode for supplying a constant current of electrons, an anode, and a negative resistance element disposed therebetween, said negative resistance element including sets of plate members, one set of said plate members being alternately interposed in spacial relation between the other set of said plate members, means for establishing a difference of potential between consecutive plate members, a source of potential connected between said cathode and anode, a resonant circuit including an inductance element, a connection from one side of said resonant circuit to an intermediate point on said source of potential, and a connection from said negative resistance element to a tap on said inductance, the location of said tap on said inductance being selected so that the effective positive resistance presented by the resonant circuit is substantially balanced by the negative resistance provided by said device.

8. In a high frequency oscillatory system, a negative resistance device comprising an evacuated vessel including an electron emitting cathode for supplying a constant current of electrons, an anode, and a negative resistance element disposed therebetween and comprising interleaved sets of plate members, means for establishing a difference of potential between the respective sets of plate members, a source of voltage connected between said cathode and anode, a resonant circuit including inductance, capacity and resistance elements, taps on said inductance individually connected with the respective sets of said plate members, the tap of higher dynamic potential being connected with the set of lower static potential, and a connection between said resonant circuit and an intermediate point on said source of voltage.

9. In a high frequency oscillatory system, a negative resistance device comprising an evacuated vessel including an electron emitting cathode for supplying a constant current of electrons, an anode, and a negative resistance element disposed therebetween and comprising interleaved sets of plate members, a source of voltage connected between said cathode and anode, a resonant circuit including inductance, capacity and resistance elements, a connection between a tap on said inductance and one of said sets of plate members, a connection between a tap of higher oscillatory potential on said inductance and the other of said sets of plate members, whereby different values of said inductance are included in the connections to said sets of plate members, means included in the second said connection for deriving a bias potential for the respective set of plate members relative to the other of said sets, and a connection between said resonant circuit and an intermediate point on said voltage source.

10. A negative resistance device including a cathode structure for producing a constant current electron stream, an anode structure interposed in the path of said stream, a negative resistance element, means including said element for producing a variable electrostatic accelerating field in the direction of said stream, and means also including said element for producing a constant electrostatic deflecting field normal to the direction of said electron stream.

11. The method of producing negative resistance as set forth in claim 2 and including further the progressive increasing in strength of the transverse electrostatic field as the strength of the longitudinal electrostatic field decreases, and vice versa, for producing negative resistance of increased value.

12. In a negative resistance device as set forth in claim 10, an arrangement for accentuating the negative resistance characteristic of the negative resistance element comprising in combination with the means for producing a variable accelerating field, means for varying the deflecting field inversely and in proportion to the variation of the accelerating field.

13. A negative resistance electron tube device comprising a cathode structure, means including said cathode structure for producing a constant current electron stream, an anode structure interposed in the path of said stream, a negative resistance element comprising a pair of plate members disposed parallel with respect to the electron stream in said device, means for applying an operating potential to said element as a whole with respect to said cathode structure, means for applying a bias voltage between the plate members comprising said element, and means for subjecting the operating potential applied to said element as a whole to variations for thereby affecting the velocity of electrons in said electron stream, the number of electrons received by said element being in inverse relation to the velocity of the electrons in the stream, as determinedby the potential of said element as a Whole, and in direct relation to the biasing voltage between said plate members, Within the working range of the device.

EDWARD H. YONKERS, JR.