Патент USA US2406850код для вставки
Sept'.3,1946. J’, R, HERCE - . ' 2,406,850 ELECTRON DISCHARGE APPARATUS A Filed April 11, 1941 FIG. / I’ ' "I ‘ ' ‘ Y ' 0.6AME Y 74 - OUTPUT > 70 7.5 INVENTOR ‘By J .R. PIERCE ATTORNEY ~' _ 2,406,850 3 4 one, 22, of which the portion l1 of the beam forming electrode is ?tted and to the other, 23, of which there are secured rigid, small diameter wires 24 a?ixed to the cathode shell M. The cylindrical portion l9 of the accelerating anode is provided with a flange 25 extending between a pair of insulating washers 26, the anode being beam by the beam forming electrode I1, l8 and includes a central cylindrical portion 32 integral self-excited and operates to generate oscillations, are accelerated toward the gap between the grid portions 34 and 31 of the electrodes 30 and 3|, respectively, due to the positive potential of the accelerating anode l9. In passing across the gap between the grid portions 34 and 31, the electrons receive a velocity variation and the velocity varied electron stream then passes into secured to the foundation member 2| by an an the space between the electrodes 3| and 38, nular clamping bracket 21 a?lxed to the mem wherein a bunching of the electrons occurs and 10 ber 2|. the velocity variations are converted into density The electron gun, it will be noted, constitutes variations. Because of the negative potential a unitary assembly which is supported from the upon the re?ecting electrode 38, the bunched stem H by a plurality of rigid wires 28 embedded electrons are reversed in direction and again in the stem, and to which wires the foundation cross the gap between the grid portions 34 and member 2| ‘is attached by rigid tie wires 29. 31 of the electrodes 30 and 3 |, respectively, trav Mounted opposite the electron gun and co eling toward the cathode, and deliver energy to axial therewith are a pair of electrodes, desig the resonant cavity. The device, therefore, is nated generally as 30 and 3|, one, 30, of which with an annular disc 33 extending through the 20 which are of extremely low wave-lengths, for example, of the order of a few centimeters, de wall of the enclosing vessel l0 and hermetically pending upon the electrical parameters of the sealed thereto, and includes also a dished reticu system. lated or grid end portion 34. The other elec The electrode 38 is so spaced with respect to trode, 3|, includes a central cylindrical portion 35 integral with an annular disc 36 extending 25 the gap and is operated at such potential that the drift time, that is the total time an electron through and hermetically sealed to the wall of the in the stream is in the space between the elec enclosing vessel I0, and includes also a dished trodes 3| and 38, considering both its motion reticulated or grid end portion 31 conforming to from the gap toward the reflector electrode and and immediately adjacent the grid portion 34 of 30 in the reverse direction, is substantially equal the electrode 30. to (n—%) cycles of the operating frequency, n A dished circular re?ecting electrode 38 is being an integer, so that the returning electrons mounted opposite the electrode 3| and coaxial cross the gap in the proper phase to deliver en therewith and is supported from the stem l2 by a ergy to the resonant cavity. In practice, the res leading-in conductor 39. onant cavity is tuned to the desired operating 35 Associated with the electrodes 30 and 3| and frequency, by adjusting the position of the plung coaxial therewith are a pair of coaxial cylindrical er 43, and the voltage upon the electrode 38 is conductors 40 and 4| which are joined at one then varied until the power output derived from end by an annular metallic spacer 42 and are the output loop 48 is a maximum. slidably engaged intermediate their ends. by an The propriety of the requirement that the drift annular conductor 43 or plunger the position of 40 time for the condition of sustained oscillations which may be adjusted by a drive screw 44 se shall be equal to (n—%) cycles of the operating cured thereto and threaded to the metallic spacer frequency may readily be veri?ed by considering 42. The inner coaxial conductor 40 engages and the history of electrons crossing the gap at var may be secured to the annular disc portion 36 of the electrode 3|. The outer coaxial conductor 4| 45 ious phases of the electric ?eld in the resonant cavity. For convenience, consider an electron is connected to the annular disc portion 33 of the (which will be referred to as the reference elec electrode 30, as by way of metallic annuli 45 tron) that crosses the gap at the instant when clamped to this disc portion and against the con the electric ?eld is changing from the direction ductor 4| by clamping members 46 and 41 which produces electron acceleration to the direc 50 threaded to each other. ' tion which decelerates an electron. The speed The electrodes 30 and 3| together with the co of the reference electron is substantially the same axial conductors 40 and 4| de?ne a resonant upon leaving as upon entering the gap. The elec tron will travel a certain distance, d say, toward by adjusting the position of the plunger 43. Power may be taken from the cavity through a 65 the re?ector before being halted and will reach the gap again after traveling a total distance conductor 48 having a looped inner end as shown equal to 2d. Such electrons as may have crossed and extending through a cylindrical conductor the gap shortly ahead of the reference electron 49 carried by the clamping member 41. cavity which may be tuned to a desired frequency had their speed increased by the action of the During operation of the device, the accelerat ing anode I9 is maintained at a positive poten 60 electric ?eld in the gap and hence penetrated further into the re?ecting ?eld than does the tial with respect to the cathode and the re?ecting reference electron. Traveling a distance equal electrode 38 is maintained at a negative poten to more than 2d, the speedier electrons will tend tial with respect to the cathode. The electrodes to return to the gap at substantially the same 30 and 3| are maintained at the same positive instant as the reference electron. Similarly, such potential with respect to the cathode. In one electrons as may cross the gap shortly after the particular embodiment, operable in the 10 centi reference electron will be slowed down, will pene meter wave-length range, the accelerating anode trate a smaller distance into the re?ecting field, I9 may be operated at the order of 330 volts pos and, traveling a total distance equal to less than itive, the electrodes 30 and 3| may be operated at the order of 250 volts positive, and the re 70 201, will tend to return to the gap at substantially the same instant as those that started earlier. ?eeting electrode 38 may be operated between Thus it will be seen that the reference electron 80 to 100 volts negative or between 22 to 32 volts negative, all with respect to the cathode. The electrons emanating from the cathode l4, I5 are maintained in a substantially parallel may be regarded as the center of an electron group. In order that the group may contribute energy to the electric ?eld to offset the natural damping- in- the.- resonator, the ‘ group should: return to the gap at .an‘instant “when the~electric ?eld is opposed to the motion. of the electrons inthe group and is of ‘maximum intensity. Such 'an instant occurs substantially three-quarters of a , . change > in ,the :output ; obtainable. from the- device, so that ;"the .‘device ais-suitable ‘ for use’ ‘for fre quency modulation jpurposes. For -‘ example, if the devi‘cefwerequsedfor frequency modulation, , an element would-be inserted in the-connection cycle after the reference electron above described ..betweenthe;_ electrode 38’and the potential source ?rst crossed the gap and this and other such itherefor, for varying the potential of the elec instants occur at the times determined‘ by the trode 38 ‘in accordance ‘with the signal 'to be value of (n——1/4) cycles of the operating frequency. modulated. ‘ As a speci?c illustration, such ele Some of the electrons traveling in the reverse mentcould be'the secondary Winding of an out direction, that is from the .space between the .put transformer theprimary winding of which electrodesSl and '38 toward the gap between the was‘in circuit with atransmitter or microphone. grids ~34 and 3?, will be collected by the elec Inasmuch'as the frequency of oscillation is'con trodes 301and 3|. However, a large percentage trollable by ‘the potential‘ of'the‘electrode 38, ‘the of the returning electrons will cross the gap, 15. device disclosed is particularly suitable for use deliver energy to the resonant cavity and pass as'a beatingoscillator’with automatic tuning, in through the grid 34, continuing thereafter toward which case the electrode ‘38 vwould be appropriate the‘electron gun t3. In the vicinity of or within .ly; associated vwith an automatic tuning circuit the gun, such electrons will again have their effective'to maintain‘ the potential of the electrode direction of‘moti'on reversed and be directed back 38 at thevalue requisite ‘for the generation of across the gap. These electrons thus again re oscillations of the desired frequency to thereby maintain-the correctlrelation between the beating versedin direction of ‘motion have substantially random velocities and also are debunched, so that in again crossing the gap they deliver little energy oscillator and‘signal frequencies. ~ High. frequencystability or, stated in another way,v constant frequency ‘operation of the device to the resonant cavity. Effectively they inter 25 mingle with and act similarly to the electrons shown in ‘Fig. 1, maybe realized in one way il ‘emanating from the cathode of the electron gun. lustratedin Fig. v3. ‘In the circuit illustrated‘in It has been found that this re?ection effect and this ?gure, the "oscillator device I0 is associated double reversal of the direction of motion of the ' ‘with a “high‘Q circuit, such as “a ‘resonant cavity electrons is augmented-by the form of the grid 30 de?ned by a cylindrical conductive member ‘ill the vportionstllland 31 and of the electrode 38, that frequency‘ of which “cavity maybe adjusted ac is the dished form thereof, with the inner or curately by a screw ‘H. Mounted adjacent one concavesurface thereof toward the electron gun Wall of the member 10 are a pair of identical recti and that thus shaping these elements reduces ?erelements 12a ‘and 12b which are connected to the magnitude of the current which must be :35 opposite ends of aresistance 13 in turn connected drawn from the cathode to enable the attain ‘across the input terminals of a direct current .mentof a particular output power. The dished ampli?er 14, the mid-point of the resistance 13 form of the electrodes, furthermore, results in being connected to the member 10. _ uniform electron transit times in the region be The resonant cavity of the device It is cou~ tween the electrodes?l and .38. I $40 pled‘to the‘resonant cavity 10 by a coaxial ‘line It’ will be noted that in one sense the device shown and described is a velocity variation device wherein a single resonant cavity isutilized for 15 having aloop end'l?a within the'cavity 10, bothinputand output. The transit timesin the space between ‘the gun and the electrode 30 is .7 45 not critical. Furthermore, it will be appreciated that the device is susceptible of simple operation inasmuch as only one tuning adjustment and one potential adjustment, that of the electrode 38, is necessary‘to effect variation of the oper ating frequency over a fairly wide ‘range. For example, in ‘the speci?c construction shown and described, oscillations over the range of 8 to 13.4 centimeters have been obtained and, operating with a second mode in the cavity, oscillations of .155 5 centimeters wave-length have been obtained. With the resonant cavity tuned to a particular frequency, the oscillator frequency maybevaried' by 20 to 30 megacycles by varying the potential of the electrode .38. It'may be noted also that the coupling con ductor '48 need not have any direct current con nection to the cavity. Hence, the cavity need not be grounded and the :device can be energized from a supply having a negative ground, such, ' for example, as the‘supplyIfor an intermediate frequency ampli?er. Also, it will be appreciated that but relatively low voltages, in comparison with the voltages employed in velocity variation devices of known constructionare necessary upon the electrodes of the device, this being due in .part to'the grid portions 34 and ~37 utilized in the electrodes 39 and 3|. The frequency of oscillation can bevaried over _a fairly wide range with but ‘little resultant 75 the line also connecting the ?rstementioned cav ity-to—two loops ‘16a ‘and 16b in turn connected .to the recti?er ‘elements ‘12a and "12b respec tively. In operation, ‘the accelerating anode I9 and the electrodes ‘"30 ‘and f3! have ‘applied thereto appropriate positive potentialspas by‘battery ‘H, as described heretofore'in connection with Fig. 1, and the- cavity- of the‘device 10 and the potential of the electrode 38,=~supplied‘ by a battery ‘18, are adjusted so that the device oscillates at the desired frequency. The resonant cavity 10 also is ad justed to this frequency. When the discharge device [0 oscillates, energy .is conveyed by the ‘line 15 to the two loops 16a and 151). Also, electromotive fOrceS will be pro .duced in these loops, opposite in phase as applied tothe-recti?er elements 12a and 1219, due to the currents induced in the cavity 10 by the loop 15a. -When the frequency of oscillations produced inthedevice l?is thesame as that to which the cavity 10 is tuned, the voltages produced at the recti?ers 12a and‘TZb by the line 15 directly and by the ~-loop 15a through the cavity 10 will be equal and substantially equal recti?ed voltages will ‘be produced by the recti?er elements. Hence, substantially zero voltage exists across the resistance 13 and no voltage change occurs at the output terminals of the direct current ampli ?er 74. However, ifthe frequency of oscillations gen erated by the device [0 changes from ‘that to which the cavity 10 is tuned, due for example to temperature effects in the discharge deviceor 2,406,850 7 8 ?uctuations in the voltages supplied to the elec trodes thereof, the alternating current voltages appearing across the recti?er elements 12a and 12b will be unequal and consequently the recti ulated portions de?ning a gap, an electron gun opposite one of said electrodes and in alignment with said gap, and a re?ecting electrode oppo site the other of said electrodes and in alignment ?ed voltages will no longer balance so that a di rect current voltage will appear across the in put of the ampli?er 14. Hence, an ampli?ed gun. with said gap, said reticulated portions being dished in the direction away from said electron 2. Electron discharge apparatus in accordance with claim 1 wherein the face of said reflecting electrode toward said gap is dished in the direc tion away from said electron gun. 3. Electron discharge apparatus in accordance quency of oscillations generated by the device with claim 1 wherein said electron gun includes ill will be that to which the cavity 10 is tuned. an accelerating electrode having a reticulated In the electron discharge device illustrated in Fig. 4, the enclosing vessel comprises a metallic 15 portion opposite said one electrode and dished in the opposite direction to the reticulated por cylinder 50 having an internal annular shoulder direct current voltage will be impressed across battery 18, in such direction as to change the potential of the electrode 38 in the manner req uisite to bring it to the value whereby the fre portion 5|, and metallic annular end portions 52 and 53 having sealed thereto insulating mem bers 54 and 55, respectively. Within the vessel are mounted an electron gun l3 and electrodes 31!, 3| and 38 which may be of the same gen tion of said one electrode. 4. Electron discharge apparatus comprising a pair of coaxial electrodes having juxtaposed grid portions de?ning a. gap, an electron gun op posite one of said electrodes and coaxial there with, and a reflecting electrode opposite the other of said electrodes and in alignment with said gap, said grid portions being concavo-convex and uni eral construction as the corresponding elements in the device shown in Fig. 1 and described here inabove. The annular disc portion 33 of the elec formly spaced with the concave surface thereof trode 30 is seated against one end of the inter toward said electron gun, and the surface of said nal annular portion 5| of the enclosing vessel and re?ecting electrode toward said other electrode has bearing thereagainst a cylindrica1 metallic being concave and uniformly spaced from the spacer 56 against which there is seated in turn grid portion of said other electrode. the annular disc 36 of the electrode 3|. The 5. Electron discharge apparatus comprising an 30 electrodes 30 and 3| and the spacer 56 are ?t enclosing vessel having a cylindrical metallic por ted slidably within the cylinder 50 and may be tion provided with an internal annular shoulder, clamped in position by a cylindrical sleeve 51 ?t an electrode having an annular portion seated on ted within the metal cylinder 50. said shoulder and having a central electron per In this construction, the resonant cavity is en tirely within the enclosing vessel, being de?ned 35 meable portion, a second electrode having an outer annular portion and a central electron per by the electrodes 30 and 3|, the spacer 56 and meable portion in juxtaposition to said ?rst elec the portions of the cylinder 50 between the discs tron permeable portion, a cylindrical metallic 33 and 36. Energy may be taken from the cav spacer member engaging said annular portions ity through the conductor 59 which extends, of said electrodes and bounding therewith a res through an eyelet 58 secured to the cylinder 5!] onant cavity, an electron gun opposite one of said and is hermetically sealed to the eyelet by a glass electron permeable portions, an auxiliary elec or other insulating bead. The cavity may be trode opposite the other of said electron perme tuned through a coaxial line 60 of adjustable ef able portions, said annular portions and said fective length in shunt with the cavity, the in spacer member being slidably ?tted Within said ner conductor of the coaxial line being con-‘ metallic portion of said vessel, and means secur nected to the disc 33 and the outer conductor of ing said portions and spacer member against said the coaxial line contacting and being secured to shoulder. the metal cylinder 50. 6. Electron discharge apparatus in accordance The device illustrated in Fig. 4 may be operated in the same manner as the device shown in Figs; 50 with claim 5 comprising a variable coaxial line coupled to said cavity. 1 and 2 as described heretofore. '7. Electron discharge apparatus comprising an enclosing vessel having a cylindrical metallic por tion, a pair of electrodes within said vessel and de?ning a resonant cavity with a section of said metallic portion, said electrodes having inner re ticulated portions in juxtaposition and de?ning a gap and having also outer portions conduc tively connected to said metallic portion, an elec sulation in other constructions are avoided as are also extraneous capacities of such insulators. 60 tron gun opposite one of said electrodes, and a re?ecting electrode opposite the other of said Also, it will be noted that this construction en A particular feature of the construction illus trated in Fig. 4 resides in the fact that the cav ity does not include any joints so that power losses due to contact resistance losses in such joints or to radiation losses through gaps therein are avoided. Furthermore, the cavity is free from insulating material so that losses due to in ables the very accurate alignment and spacing of the electrodes so that the construction of de electrodes, said reticulated portions being con cavo-convex and having the concavo face thereof toward said electron gun. vices for operation at very high frequencies, at 8. Electron discharge apparatus in accordance which accurate alignment and spacing of the 65 with claim '7 wherein the surface of said re?ect electrodes is very important, is facilitated. ing electrode opposite said other electrode is co Although speci?c embodiments of the inven axial with and-curved in the same direction as tion have been shown and described, it will be the reticulated portion of said other electrode. understood that they are but illustrative and that 9. Electron discharge apparatus comprising a various modi?cations may be made therein with 70 pair of electrodes having juxtaposed grid por out departing from the scope and spirit of this tions de?ning a gap, means cooperatively asso invention as de?ned in the appended claims. ciated with said electrodes de?ning a resonant What is claimed is : cavity therewith, an electron gun including a 1. Electron discharge apparatus comprising a pair of spaced electrodes having juxtaposed retic 75 cathode opposite one of said grid portions, a re 2,406,860‘ ?eeting electrode opposite the other of said grid portions, said grid portions‘ being dished and having the inner faces thereof toward said elec tron gun, re?ecting electrode having a dished surface facing the grid portion to which it is opposite, means for maintaining said pair of elec 10 trodes at a positive potential with respect to said cathode, and means for maintaining said re?ect ing electrode at a high negative potential relative to said cathode. ' JOHN R. PIERCE.