US2806141A

US2806141A - Magnetic electron multiplier switch

Info

Publication number: US2806141A
Application number: US434148A
Authority: US
Inventors: Franklin L Adams
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1954-06-03
Filing date: 1954-06-03
Publication date: 1957-09-10
Anticipated expiration: 1974-09-10

Description

Sept 10, 1957 F. L. ADAMS 2,806,141

MAGNETIC ELECTRON MULTIPLIER SWITCH ATrOP/vgv Sept. 10, 1957 F. ADAMS MAGNETIC ELEcTRoN MULTIPLIER SWITCH 2 Sheets-Sheet 2 Filed June 3, 1954 Y JNVENTOR.

Ff /V/Q L. Agn/15 UnitedStates Patent Oce 2,805,141 Patented Sept.. 10, 1.957

MAGNETIC ELECTRON MULTIPLIER SWITCH Franklin L. Adams, Detroit, Mich., assigner to Bendix Aviation Corporation, Detroit, Mich., a corporation of Delaware Application .lune 3, 1954, Serial No. 434,148

'7 Claims. (Cl. Z50-27) This invention relates to switches and more particularly to high speed electronic switches.

lnrecent years electronic switches have gained importance because of the high switching `speeds that must be provided in the iield of electronics. Although relatively high switching speeds have been attained in certain types of electronic switches, extremely high switching speeds as may be required for certain applications have been lheretofore unattainable. For example, electronic switches presently available cannot be reliably used to provide switching action for electrical signals on the order of megacycles or more.

This invention provides a switch for operating in a simple and reliable manner in response to electrical irnpulses of extremely highfrequency. The invention includes a magnetic electron multiplier in which rst and second series of electrical impulses are applied to first and second grids, respectively, to modulate streams of electrons iiowing through the grids. A third grid positioned at an intermediate point between the iirst and second grids has voltages of opposite polarity applied to it to alternately pass and block the electrons flowing through the first and second grids, In this way, the electrons flowing through the irst and second grids are alternately detected by an electrode positioned to receive the electronsowing through the irst grid during the period that the third grid passes the electrons and to receive the electrons flowing through the second grid during the period that the third grid is at a potential to block the passage of any electrons.

An object of this invention is to provide a switch.

Another object of this invention is to provide an electronic switch.

A further object of this invention is to provide for the use of a magnetic electron multiplier as an electronic switch.

Still another objectis to provide an electronic switch of the above character which is reliable in its operation and is capable of providing switching action at relatively high speeds. f

A still further object is to provide an electronic switch of the above character in which lirst and second electron streams are modulated by lirst and second series of signals, respectively, and are alternately passed and blocked by a grid which is provided with an alternating potential.

Other objects and advantages will become apparent from a detailed description of the invention and from the appended drawings and claims.

" in the drawings: i

`Figure l is a somewhat schematic view partly in block form and partly in perspective illustrating one embodiment ofthe invention.

` Figure 2 is a top plan view of `the electron multiplier shown in Figure 1, illustrating the paths of electron ow upon a biasing of an electrode in the multiplier in a first direction. X

Figure 3 isa top plan view of the electron multiplier 2 shown in Figure l, illustrating the paths of electron flow upon a biasing of an electrode in the multiplier in a second direction.

In one embodiment of the invention a container 10 which may be substantially rectangular in shape, is connected to ground. Disposed within the container 10 at its left end is means for emitting electrons such as a cathode 12. The cathode 12 is positioned to emit electrons towards a grid 14 when the cathode is heated. Positioned at the right end of the container 10 is a cathode 16 which is disposed to emit electrons towards a grid 18 when the cathode is heated.

Disposed to the right of the grid 14 is an electron multiplier generally indicated at 20 which includes

plates

22 and 24 and a plate 26 disposed in opposed relationship to the plate 24. Also included is a plate 28 which faces the plate 26 and is longitudinally displaced in front of the plate 26. The grid 14, the plate 22 and the plate 24 are positioned in laterallycontiguous relationship to one another such that the left extremity of the plate 22 is positioned close to the right extremity of the grid 14 and the left extremity of the plate 24 is positioned close to the right extremity of the plate 22. Each ofthe

plates

22 and 24 are disposed slightly to the rear of the grid 14 and the plate 22, respectively, in a progressively staggered relationship. For example, the grid 14 may be positioned approximately .225 inch in front of the back Wall of the container 10 and the

plates

22 and 24 may be positioned approximately .200 and .175 inch, respectively, from the back wall of the container 10.

The plate 26 is positioned in front of the plate 24 and is at substantially the same distance from the back wall of the container 10 as is the grid 14, such as .225 inch. The plate 28 is positioned in front of the plate 26. By way of illustration, the plate 28 may be positioned in substantially the same plane as the front wall of the container 10. The plate 28 is connected to ground through a resistance 30 and a detector such as an oscilloscope 32 is connected to the plate 28 to indicate the electrons mpinging upon the plate.

To the left of the grid 18 is provided another electron multiplier generally indicated at 34. The electron multiplier includes plates 36, 38, 40 and 42. The grid 18 and the plates 36 and 38 are positioned in laterally contiguous relationship to one another in the same manner as the grid 14 and the

plates

22 and 24 as previously disclosed except that the plates 36 and 38 are disposed slightly in front of the grid 18 and the plate 36, respectively, in a progressively staggered relationship. For example, the grid 18 may be positioned approximately .225 inch to the rear of the front wall of the container 10 and the plates 36 and 38 may be positioned approximately .200 and .175 inch, respectively, from the front Wall of the container 10.

The plate 40 is positioned behind the plate 38 and is substantially the same distance from the front wall of the container as is the grid 18, such as .225 inch. To the rear of the plate 40 is the grounded plate 42 which may be positioned in substantially the same plane as the back wall of the container 10.

Positioned midway between the `plates 24 and 40 is a grid 44 which may be approximately .200 inch from4 the back wall of the container 10. The grid 44 is connected through a condenser 46 to a voltage source 48 which is adapted to provide an alternating voltage such as a square wave voltage output.

Direct voltages are applied to the

plates

22, 24, 2.6, 36, 38 and 40 to produce a substantially constant electrical iield between the walls of the container 10 and the plates. Since the

plates

22, 24, 26, 36, 38 and 40 are positioned at dilerent distances from the walls of the container 10, different voltages areapplied to the plates to produce a substantially constant electrical iield. The voltages are Y if Y Y Y Y. 2,806,141

,1jr sa. applied to the

plates

22, 24, 26, 36, 38 and 40 from a p l rpower supply 50. Direct voltages are also applied to the grids 14, 18 and 44 from the power supply 50 through resistances 52,154 and 56, respectively.

. The: grid 114; is connected totheoutputoi 'VatsignalY f positioning Lof the pole piecesf62, thefmagnetic flux lines are substantially parallel Vto theplane defined by the endsV of theontainer and the flux lines are disposed in a direction substantially perpendicular "to the electric field provided between the plates Aand the walls of the container.

Wheni the cathode'12 is heated Aelectrons are emitted by the cathode towards theV grid 14. Upon the application of a signal to the grid'14 from the source S8, the number of electrons passed by the grid' 14 are controlled in accordance vwithltle variations in the amplitude of the signal. 'For example, if the signal provided is such that the grid 14 becomes more positive, a proportionately increased numberV of electrons are passed by the grid 14. Similarly, if the signal provided is in a direction to decrease the potential' of the grid 14, a proportionately decreased number oafelectrons are passed by the grid. In this way, the intensity of thefelectron stream passed by the grid 14 is modulated in accordancefwith the variations in the amplitude vof the signals from the source 58.

Because of the action of the electric iield and the magnetic teld in thelregion defined by the walls of Ythe container V10, the electrons passed by the electrode 14 are made to travel in a cycloidal path towards the plate 22 as shown by the broken line'62 in Figure 2 of the drawings. When the electrons impinge upon the plate 22, Vthe plate emits a substantially proportionately increased number of elec-l trons depending upon the number of electrons which are passed by the grid 14 to impinge upon the plate 22; The electrons emitted by the plate 22 follow a cycloidal path to the plate 24 which in'turnemits a Vproportionately increased number of electrons towards the grid yIf the signal applied to the grid 44 from the source 48V is in its Ypositivewcycle at the time the electrons, emitted by the plate 24 reach the grid 44, the electrons pass throughv the Vgrid 44 and, continue to travel in al cycloidal path `until vthey, impinge nuponthe .plate .26. VWhen the electrons Astrike :the plate 26,:theplate emits a proportionately increased numberof'electrons which impinge uponfthe plate 28 for detection by theoscilloscope 32.

If the vsignalrapplied to theV grid.44.from the source 48 is in'its negative cycle, none ofthe electronsV emitted by the plate 24 will pass through the grid 44. 'Instead the electrons will! be` repelled by the grid 44 and will .travel in a Vcycloidal path to the plate 40. VThe electrons which are `then ernittedbyl the plate 4.0 strike .plate 42 andare grounded. V"The electron flow path for this condition is shownby the broken line 64 in Figure 3.:

l The electrons emitted -by ther cathode 16 towards the grid 18 are acted upon in substantially the same manner as disclosed above in relation to the electrons, `emittedby the V,cathode 12 vexcept that Vtheelectrons .are emitted in an opposite direction. The number of electrons passing through'the grid'18 are A,controlledby the variations in the Vamplitude of thesignal applied to the gridfrom the travel in a cycloidal path to the plate 38.n The plate 38 in turn emits a proportionately increased number of electrons which travel towards the grid V44 in a direction opposite to the direction of travel of the electrons emitted by the plate 24.

If the grid 44 is biased in aY positive direction, all of the electrons emitted by the plate 38 are passed by the grid 44 and travel in a cycloidal path towards the plate y4 0. When these electrons strike the plate 40 the plate emits an increased number of electrons which impingeruponV and are grounded by the plate 42. If, however,'the grid 44 is biased ina negative direction, the electrons emitted by the plate 38 are repelled by the grid 44 and travel in a cycloidal path towards the plate 26 as shown by the broken line 68 in Figure 3. When these electrons im- Y pinge upon the plate 26, a proportionately increased number of electrons are emitted by the plate. These electrons impinge upon the Yplate 28and are detected by the oscilloscope 32. Y

When the electrons emitted by the

plates

24 and 38 are passed by the grid 44 during the period that it is biased. in a positive direction as shown in Figure 2, onlythe electrons emitted by the plate 24 reach the plate26 and Y cause the plate 26V to emit a proportionatelyincreased number of electrons for detection by the plate 28. Therefore, while thev grid 44 is biased in its positive direction, the oscilloscope 32 will'provide indications of the'amplitudes of the signals from the source 58 since the intensity of the electron stream passed by the grid 44 4is modulated in accordance with the amplitude of the signals.

When the grid 44 is 'biased in a negative direction as illustrated in' Figure 3, onlythe electrons emitted by the plate 38 reach the plate 26 and cause a proportionately increasedv number of electrons to be emitted by the plate 26 for detection by the plate 28. The oscilloscope 32 then provides indications of the amplitudes of the signals Afrom the source 60 since the electron stream passed bythe grid 18 is modulated in accordance with the amplitude of the signals.

Upon an alternate biasing of the grid 44 because of an alternating signal, from tlie source 48,ithe plate 28 alternately detects the electrons flowing through4 the grid .1.4

Ysource 48.

and the electrons iiowing through the grid 18. The speed at 'which the Aplate V28 valternately detects the electrons owing through the grids 14 and 18 is dependent upon the frequency of the alternating signal provided by fthe In the manner described above, the apparatus disclosed actsV as an electronic switch to alternately provide indii cations of the amplitudes of the'signals from the sources 58 and 60, `since the electron streams flowing through thev grids 14 and 18 are modulated in accordance with theV signals provided' by the' sources 58Yand 60, respectively. Theafrequency at which the switching action occurs Vis controlled by the frequency'of the signal from the source 48. Ifo provide for the alternate detection of the signals Afromthe sources v58 andl 60 at the proper instant, Vthe frequency ofthe signals-fromv the-source 48' must be the sources 58 and 60. f v Y Forexample, if `the signals from'the sources 58 and 60 recur at the Yrate. of one million times per second, the source 48 maybe adjusted to provide a signal having a one (l) megac'ycle', frequency so that every otherl synchronized to the repetitive rate the signals from signal introduced to the grids 14 and 18.from the sourcesV 58 and, 60, respectively, will bedetected by the plate 28. AIn ,tl1 isway,V .the signals froniftlie source 58 and the source 60 may be' Vviewed side'by side on the screen of` the oscilloscope 32 since the electronsowingtbrough the grids Y14 andv 18 willbe detectedlat diiereiitv The apparatus disclosed above Vhasn several important y advantages. The apparatus( may be used Vtciprovide switchingfaction at extremely high rates,` sueltasV 10 megacycles or more. Furthermore, the apparatus is adaptable for use over a wide range of signals recurring at different rates because the voltage source 48 may be synchronized to the repetitive rate of the signals from the sources 58 and 60. Another advantage is that relatively weak signals may be detected since electron multipliers 20 and 34 will amplify the signals prior to their detection by the plate 28.

Although this invention has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. The invention is, therefore, to be liimtedonly as indicated by the scope of the appended claims.

I claim:

l. In combination, means for providing a flow of electrons in first and second streams, means for controlling the number of electrons flowing in the first and second streams, a grid disposed to pass the electrons in both streams upon a biasing of the grid at a first potential and to block the passage of the electrons in both streams upon a biasing of the grid at a second potential, means for alternately biasing the grid atthe first and second potentials, and a detector disposed relatively to the grid for detecting only the electrons in the first stream upon a passage of the electrons by the grid and for detecting only the electrons in the second stream upon a blocking of the passage of the electrons by the grid.

2. In combination, means for providing a flow of electrons in first and second streams, a first electrode disposed to pass the electrons owing in the rst stream and to control the number of electrons passed by the electrode in accordance with variations in the potential of the electrode, a second electrode disposed to pass the electrons flowing in the second stream and to control the number of electrons passed by the electrode in accordance with variations in the potential of the electrode, a grid disposed between the first and second electrodes to pass the electrons flowing past the first and second electrodes upon a biasing of the grid at a first potential and to block the passage of the electrons upon a biasing of the grid at a second potential, means for alternately biasing the grid at the first and second potentials, and a plate disposed relative to the grid to receive only the electrons flowing in the first stream upon a passage of the electrons by the grid and to receive only the electrons owing in the second stream upon a blocking of the passage of the electrons by the grid.

3. In combination, means for providing a ow of electrons in rst and second streams, a rst grid disposed in the path of electron fiow in the first stream, means for applying a first signal to the first grid to control the number of electrons flowing past the grid in accordance with the variations in the amplitude of the signal, a second grid disposed in the path of electron ow in the second stream, means for applying a second signal to the second grid to control the number of electrons flowing past the grid in accordance with the variations in the amplitude of the signal, a third grid disposed in the path of the electrons flowing past the first and second grids, means for applying a third signal to the third grid for alternately passing and blocking the electrons liowing in the first and second streams, and a plate disposed relative to the third grid to collect the electrons in the first stream upon the passage of the electrons by the third grid and to collect the electrons in the second stream upon the blocking of the passage of electrons by the third grid.

4. An electronic switch, including, means for providing a ow of electrons in first and second streams, means for modulating the intensity of the first electron stream in accordance with variations in the amplitude of a first signal, means for modulating the intensity of the second electron stream in accordance with variations in the amplitude of a second signal, a rst plurality of plates,

one of the plates in the plurality being disposed to receive the electrons flowing in the first stream and to emit an increased number of electrons, the other plates in the plurality being disposed to receive electrons emitted by preceding plates in the plurality and to emit an increased number of electrons, a second plurality of plates disposed in opposed relationship to the rst plurality of plates, one of the plates in the second plurality being disposed to receive the electrons flowing in the second stream and to emit an increased number of electrons, the other plates in the plurality being disposed to receive electrons emitted by preceding plates in the pluralityand to emit an increased number of electrons, a grid disposed to receive, in opposite directions, the electrons emitted by the last plates in the first and second pluralities, means for applying a biasing signal to the grid so that the grid alternately blocks and passes the electrons received, a detector disposed to receive the electrons emitted by the last plate in the rst plurality upon a passage of electrons by the grid and disposed to receive the electrons emitted by the last plate in the second plurality upon a blocking of electrons by the grid, and means connected to the detector to alternately indicate the intensities of the electrons emitted by the last plates n the first and second pluralities.

5. An electronic switch, including, means for providing a ow of electrons in first and second electron streams, means for modulating the intensity of the electron flow in the first stream in accordance with a first signal, means for modulating the intensity Iof the electron flow in the second stream in accordance with a second signal, a grid disposed to receive, in opposite directions, the electrons flowing in the first and second streams, means for applying to the grid an alternating voltage so that the grid alternately blocks and passes the electrons received, and means disposed to detect the electrons in the first stream upon a passing of electrons by the grid and to detect the electrons in the second stream upon a blocking of the passage yof the electrons by the grid.

6. An electronic switch, including, electrode means, a first plurality of plates disposed in laterally contiguous relationship to one another, the plates being disposed at different distances from the electrode means, means for applying different voltages to the plates in the iirst plurality to provide a substantially uniform field in the region between the electrode means and the plates in the first plurality, a second plurality of plates disposed in laterally contiguous relationship to one another, the plates being disposed at different distances from the electrode means, means for applying different voltages to the plates in the second plurality to provide a substantially uniform field in the region between the electrode means and the second plurality of plates, a first grid disposed in laterally contiguous relationship to a first plate in the first plurality, a second grid disposed in laterally contiguous relationship to a first plate in the second plurality, means disposed to emit a first stream of electrons towards the first grid, means for applying a first signal to the first grid to limit the number of electrons in the first stream passed by the grid in accordance with the variations in the amplitude of the signal, means for applying a second signal to the second grid to limit the number of electrons in the second stream passed by the grid in accordance with the variations in the `amplitude of the signal, means for providing a magnetic field to operate in conjunction with the electrical fields produced between the electrode means and the plates in the rst and second pluralities to produce a cycloidal movement of the electrons passed by the first and second grids, the first plates in the first and second pluralities being disposed to receive the electrons in the first and second streams, respectively, and to emit an increased number of electrons substantially proportionate to the number of electrons received by the plates, the other platesgrin-thefffirst-andisecond-plnralities being Vdisposed to reeive thee1ectronsfemittedebya `preceding plate in the plurality and 5to emita .substantially proportionately increased number `vof e1e`ctrons,.a third Y grid disposed between'itheilast:plates inthe frstand second pluralities and vr'disposedstoreceive;irropposite directions, the electronsgemittedbylthelast plates in both pluralities, means forapplyingathird signal to vthe Vthird grid for biasing the :Ygn'dfto `:alternatelyfpass and Yblock the passage ofr the( electrons.`xfeceived'fbyl the grid, and a detector disposed rlativetofthethirdgrid to-receive the electrons emitted bythev last 1platein the vrst plurality upon a passing of electronsibyfthegrid; andgto receive `the electrons emitted bystllelas'tl plateinsthezsecond plurality upon a blocking ofithepassageofqeleetrons by the grid. Y

V:7.'"In:eombinationga first source for providing a first Y eletronstreaxn, afsecond sorce for providing a second electron.A stream, ta :screen grid of substantially planar Ysidetlie electrons aowingrin thexsecond'ntreamrnieans for 'biasing-Ille l grid at af =rst potential 5to' -provide for thezpassage of theV electrons( in the rst andseeond streams, means forv :biasing theigri'd iat a Iseond potential sto' block Y the; passage of the-electrons 'ini therst; and-secon'destreamsV and means disposed relative to -thefgrid Yto"detectifrznly -2,504,321 G iaeoletto f Apr 18, .1,950

Y Y. l. Y

configuration disposed Vtoleeeive at oeside theuelectrgnsv