US2882399A - Electron switch - Google Patents

Description

April 1959 v w. -c. WILEY 2,882,399

ELECTRON SWITCH Filed Feb. 28 1955 2 Shets-Sheet 1 o 8 8 g Q M a, w E mi} M, Il 6'- w O.

FORMING CIRCUIT I s Q 7 LL A. 5 5 n 3 Q. o (L a INVENTOR.

WILLIAM C. WILEY ATTOR EY April 14, 1959 w. c. WILEY 2,882,399

ELECTRON SWITCH Y I Filed Feb. ,28, 1955 2 Sheets-Sheet 2 WILLIAM WILEY v ATTORNEY Unitd States P t ELECTRON SWITCH William C. Wiley, Detroit, Mich., assignor to Bendix Aviation Corporation, Detroit, Mich., a corporation of Delaware Application February 28, 1955, Serial No. 490,944

3 Claims. (Cl. 25027) This invention relates to a switch and more particularly to an electron switch.

It is often important in electronic apparatus to provide an electron switch for changing the direction of flow of electrons introduced to the switch and for separately receiving the electrons flowing in each direction. With a particular set of conditions, such a switch will operate efiiciently only if substantially all of the electrons introduced to the switch are received at the same place. This requires that the electron flow be completely cut off in all directions except one and that no electrons be lost while travelling in the one direction. Electron switches or switching schemes in present use have not provided the high degree of etficiency which is required for certain applications.

This invention provides a simple and highly efficient electron switch. The switch includes first, second and third electrodes positioned to provide a first region between the first and third electrodes and a second region between the second and third electrodes in contiguous relationship to the first region. By controlling the voltage on only the third electrode, all of the electrons introduced to the switch may be moved through either the first or second regions.

An object of this invention is to provide an electron switch.

Another object of this invention is to provide an electron switch for changing the direction of flow of electrons introduced to the switch.

A further object is to provide a switch of the above character which includes first and second contiguous regions and means for producing a movement of all the electrons through either the first or second regions.

Still another object is to provide a switch of the above character which is simple to construct and is highly efiicient in its operation.

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

In the drawings:

Figure l is a schematic view, partly in block form' and partly in perspective, of a switch constituting one embodiment of this invention.

Figures 2 and 3 are plan views schematically illustrating the operation of the switch shown in Figure 1 under different conditions in the switch.

In one embodiment of the invention, a vacuum tube 8 encloses a source for emitting electrons, such as a cathode 10, positioned to introduce electrons to a gate, generally indicated at 12. The gate 12 includes a pair of substantially parallel plates 14 and 16 disposed to receive at an intermediate position in the region between them the electrons emitted by the cathode 10. The plates 14 and 16 are spaced a relatively small distance apart, such as 1.5 millimeters.

Disposed to the right of the plate 14 in substantially perpendicular relationship to the plate is an electrode 18 and disposed to the left of the plate 16 in substantially perpendicular relationship to the plate is an electrode 20. The electrodes 18 and 20 are in substantial alignment. An electrode 22 is disposed in substantially parallel relationship to the electrodes 18 and 20 to provide a first region between the electrodes 18 and 22 and a second region between the electrodes 20 and 22. The imaginary line 24 in Figure 2 defines the two regions. The electrode 22 may be disposed at a distance, such as 6 millimeters, from the electrodes 18 and 20. An anode 26 is disposed at the end of the first region and an anode 28 is disposed at the end of the second region.

Direct voltages are applied to the cathode IQ. and to the plates 14 and 16 from a power supply 30. For example, 75 volts, 100 volts and --50 volts may be applied to the cathode 10, the plate 14 and the plate 16,'

respectively. Direct voltages are also applied to the electrode 18 and to the electrode 22 through a resistance 32. For example, the electrode 18 may be biased at -180 volts and the electrode 22 may be biased at +20 volts. The electrode 20 is grounded and the anodes 26 and 28 are grounded through resistances 34 and 36, respectively.

The electrode 22 is connected to a pulse forming circuit 38 for applying square wave voltage pulses of negative value to the electrode 22 at desired times. For example, voltage pulses having a magnitude of -220 volts may be applied to the electrode 22. Model 903 of a Double Pulse Generator manufactured by the Berkeley Scientific Instrument Company of Richmond, California may be readily adapted to apply such pulses to the electrode 22 at desired times.

A magnetic field is provided in the region between the plates 14 and 16 and in the regions between the electrode 22 and the electrodes 18 and 20. The magnetic field is produced in a vertical direction substantially parallel to the faces of the plates and the electrodes by a pair of pole pieces 40, one positioned below the electrodes and the other positioned above the electrodes. For example, a magnetic field of 350 Gauss may be provided by the pole pieces.

As previously disclosed the electrons emitted by the cathode 10 are received at an intermediate position in the region between the plates 14 and 16. The electrons are subjected to the combined action of the magnetic field and the electric field provided in the region. This causes the electrons to travel through the region in successively small cycloidal paths illustrated in Figures 2 and 3.

Because of the particular voltages applied to the plates 14 and 16, such as volts and -50 volts, respectively, the electric field provided in the region between the plates is in a direction to keep the gate 12 open so as to provide for the passage of electrons. A change in the direction of the electric field would close the gate 12 since any electrons introduced to the region and 22 and move through the region in successive cycloi dal paths illustrated at 100 in Figure 2. This electron,

movement occurs because of the combined action of the magnetic field and the electric field provided in the first.

region and because of the direction of the magnetic field and the direction of the electric field initially provided in the region. The second region actually repels electrons and prevents their entrance into the region because of the direction of the magnetic field and the direction of the electric field initially provided in the region. For this reason, substantially all of the electrons passed by the gate 12, move through the first region and are received by the anode 26.

When a negative voltage pulse, such as -220 volts, is applied to the electrode 22 from the pulse forming circuit 38, the electric fields in the first and second regions are reversed during the application of the pulse. Whereas, the voltage difierence between the electrodes 18 and 22 was initially 200 and in a direction to attract the electrons into the first region, now the voltage difference between the electrodes 20 and 22 is .200 and in a direction to attract the electrons into the second region, and to produce a movement of the electrons through the region in successive cycloidal paths illustrated at 102 in Figure 3. Furthermore, because of the reversal of the electric field in the first region, electrons are actually repelled by the first region and are prevented from entering the region. Therefore, during the application of the voltage pulse to the electrode 22, substantially all of the electrons passed by the gate 12 move through the second region and are received by the anode 28.

From the above discussion it is clear that the electrodes 18, 20 and 22 form an electron switch for producing a movement of electrons through either the first or second regions.

The switch disclosed above would be especially valuable for use with magnetic electron multipliers. For example, the plates 14 and 16 could be positioned to receive in the region between them the electrons emitted by a particular plate in a multiplier as is disclosed in copending application U.S. Serial No. 479,339 previouly mentioned. The electrode 22 could then be pulsed at timed intervals to receive difierent groups of electrons at difierent anodes in the switch. In this way, electrons produced by different particles that impinge upon the plates of the multiplier can be detected at difiierent anodes and suitable means can be provided for indicating the ratio of the signals produced by the different particles.

The invention disclosed above has several important advantages. The switch is believed to be almost 100% etficient since substantially all of the electrons introduced to the switch are received at the same plate, that is, either the anode 26 or the anode 28. This is true because the electron flow is confined to one direction and because a maintenance of proper voltage relationships in the switch will prevent a loss of any electrons by keeping the electrons from striking the electrodes.

Another important feature of the switch is that the direction of electron flow can be changed by controlling the voltage on only one electrode 22 in the switch. Because of this feature, the voltages applied to the electrodes 18 and 22 may drift moderately and not cause any detrimental unbalance in the operation of the switch. For example, the magnitude of the voltage pulse of 220 volts applied to the electrode 22 may increase or decrease volts and not affect the efficient operation of the switch.

Furthermore, it has been found that the voltages that may be applied to the detectors in the switch are not critical. For example, it has been found that the maintenance of the anodes 26 and 28 at the same potential, such as ground, will not impair the operation of the switch even though the anodes are disposed in the vicinity of electrodes having dilferent voltages applied to them. Because of this feature, it is relatively simple to set up the proper voltage values in the switch.

Since there is always some residual gas in electron switches, ions are formed by the electron flow in the switch. These ions are troublesome because they often reach the anodes in the switch and aifect the accuracy of electron measurements. {In the present invention, any ions formed cannot reach the anodes 26 or 28 to cloud measurements. Instead, the ions are collected by the electrode 18 when the electrons travel in the first region and are collected by the electrode 22 when the electrons travel in the second region. This is another important feature of this invention.

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 limited only by the scope of the appended claims.

What is claimed is:

1. An electron switch, including, a first plate, a second plate spaced from the first plate and disposed in substantially the plane of disposition of thefirst plate, a third plate disposed in substantially parallel relationship to the first and second plates and disposed relative to the plates to provide a first region between the first and third plates and a second region between the second and third plates, means for imposing a magnetic field in the first and second regions, means for introducing electrons through the space between the first and second plates, means for normally biasing the plates relative to one another to produce a movement of the electrons through the first region, means for introducing voltage pulses to the third plate to produce a movement of the electrons through the second region during application of the pulse, and means disposed at the end of the first and second regions to receive the electrons passed through each region.

2. An electron switch, including, a first plate, a second plate disposed in substantial alignment with the first plate and spaced from the first plate, a third plate disposed in substantially parallel relationship to the first and second plates and spaced from the plates, means for providing a magnetic field in the region between the plates, means for introducing electrons through the space between the first and second plates and into the region between the plates, means for biasing the first, second and third plates with different voltages, and means for varying the bias on only the third plate to produce a movement of all the electrons between the first and third plates or between the second and third plates.

3. An electron switch, including, a first plate, a second plate in substantial alignment with the first plate, a third plate parallel to and spaced from the first and second plates, a fourth .plate disposed in a plane perpendicular to the plane of the first and third plates and having two of its edges adjacent to edges of the first and third plates so as to form a U-shaped configuration with the first and third plates, a fifth plate disposed in a plane perpendicular to the plane of the first and second plates and having two of its edges adjacent to edges of the second and third plates so as to form a U-shaped configuration with the second and third plates, means for introducing electrons from between the first and second plates, means for biasing each of the plates with voltages, and means for changing the bias on the third plate between two values so as to cause all of the introduced electrons to move to the fourth plate when that bias is at one value and to cause the electrons to move to the fifth plate when the bias is at the other value.

References Cited in the file of this patent UNITED STATES PATENTS 2,513,260 Alfven et al. June 27, 1 950 2,600,142 Overbeek June 10, 1952 2,639,401 Skellett May 19, 1953 2,710,361 Skellett June 7, 1955 2,726,353 Wallmark Dec. 6, 1955

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