US2310883A - Circuit arrangement with secondary emission electron multipliers - Google Patents

Description

Feb. 9, 1943. K TH M 2,310,883

CIRCUIT ARRANGEMENT WITH SECONDARY .EMISSION ELECTRON MULTIPLIER Filed July 16, 1940 (Moo! 69:0

Sscauo4e Ear/sews PAATE- ATTORNEY Patented Feb. 9, 1943 cmom'r ARRANGEMENT WITH. SEQQNDARY ems sion ELECTRON MULTIPLIERS Kurt Thiim, Berlin-Lichterfelde, Germany; vested in the Alien Property Custodian Application July .16, 1940, Serial No. 345,823 In Germany July 20, 1939 7 Claims.

The invention relates to circuit arrangements for s cond y em ss e eet q m ltip s.

It is an object of the invention to provide a s c ndary mission t o ulti ier ran menthaving a characteristic curve similar to that of arectifier. It is a further object of the invensecondary emission electron multiplier in rectifying circuits without additional circuit elements. The use of a separate rectifier is obviated. Iihe invention can be employed in connection with television transmitting and receiving arrangements, in connection with signal amplifiers, or in connection with arrangements for forming or reforming signals or impulses.

Other aspects of my invention will be apparent or will be specifically pointed out in the description forming a part of this specification, but I do not limit myself to the embodiment of the invention herein described, as various-forms may be adopted within the scope of the claims.

Fig. 1 shows a circuit arrangement according to the invention.

Fig. 2 is a curve representing the current flowing in the circuit of the plate electrode as a function of the primary electron current.

Fig. 3 illustrates a modification of Fig. l wherein a photoelectric cathode is employed.

Fig. 4 illustrates another modification of Fig. 1 wherein separate batteries are used for the output stages of the multiplier.

The circuit of Fig. 1 contains a secondary emission electron multiplier I of thegrid type having a filament 2, a control grid 3, a number of secondary emission electrodes 4 and 5, an anode 6 in form of a grid and a secondary emissive plate electrode 1 arranged behind the anode. The output voltage is taken 01? at resistance .9 while the input is applied to grid 3 and to the cathode circuit. The electrodes of the tube receive their potentials from a potential divider represented by a number of resistances I l. The potential divider is connected between the positive and negative terminal of a source of .anode potential. The resistances are so dimensioned that the grids 4 of the multiplier have potentials dependent upon thecurrent flowing through the multiplier while the grid 5 and the plate electrode '1 are applied to points having potentials which are independent of .the current flowing through the multiplier. The potential divider 'is so dimensioned that the current flowing through theresistance elements 14 is smaller than the maximal output current of the secondary emission electron multiplier. If the maximal currentis flowing in the amplifier the drop of potential along the .resistances [4 is increased so that the potentials of the grids 4 are lowered with respect to gri'dfi. Theconstant potential of the grid 5 and the point in the potential divider to which plate 1 is connected, is derived either from a separate source of potential or as represented in .Fig. '1 by dimensioning the condensers I0 and l l 'for these electrodes large in comparison to the condensers 12 for theremaining electrodes so that these condensers act as chargestorage condensers during the time of the maximal amplitude and can be recharged after the occurrence of the maximal amplitude. In addition to the bleeder current in the potential divider, there is present a current represented by the electrons supplied to the secondary emission electrodes 4,5 and 1. When the'maximal current is flowing in the multiplier, this additional current is of greatest amplitude. If this component is small compared to the bleeder current, it has negligible effect on the voltages of the secondary emission electrodes but if it is large, as is the casein this arrangement at maximal amplitude, it'increases the proportional voltage of the lower voltage secondary emission electrodes and decreases that of the higher volt- .age secondary emission electrodes until the output current remains substantially constant. 'The potential of grid 5 is kept constant by reason of the current in the two sections 14 of thepotential divider next to the grounded terminal of the direct currentsupply being kept constant by'the action of condensers l0 and II whatever may be the current in the output circuit of the multiplier. Condensers l0 and II function as described due to changes which take placein their charges, but these condensers are so'large that the necessary changes in their charges take place without any This arrangement .is particularly useful when the maximal amplitude is of short duration. The condensers 12 have the purpose to avoid undesired backcoupling between the individual grids of the multiplier. They determine furthermore the frequency limit up to which the rectifying effect takes place. It is possible to obtain the efiect that the signals above a certain critical frequency, for example, above 1 MHz are not rectified whereas frequencies below this limit are rectified.

Fig. 4 illustrates a modification of Fig. 1 in which the constant potentials of the grid 5 and the point in the potentia1 divider to which plate I is connected, are derived from' a separate source of potential, such as batteries I6 and ii. The portion of Fig. 4 below the dot and dash line YY is to be substituted for the portion below the dot and dash line Y-Y of Fig. 1. The batteries [6 and I1 are connected in series-aiding relationship and the positive terminal of battery I1 is connected to ground. With this modification, the points [8 and I9 to which the grid ,5 and the plate I are connected respectively are kept at a constant potential with respect to the anode B which is at ground potential.

The arrangement of Fig. 1 has a characteristic curve as shown in Fig. 2 representing the current ip flowing through resistance 9 as a function of the primary electron current Z Kath. reaching the first secondary emission electrode from cathode 2.

' The cathode 2 and the control grid can be replaced by a photoelectric cathode controlled by different quantities of light. This modification is illustrated in Fig. 3. The portion above the dot and dash line XX is to be substituted for the portion above the dot and dash line XX of Fig. 1. The photoelectric cathode i5 is the source of primary electrons which bombard the adjacent secondary emission electrode 5 to produce secondary electrons. The photoelectric cathode [5 may be illuminated in any suitable manner.

The modifications of Figs. 3 and 4 may be used singly or together.

The arrangement of Fig. l is particularly useful for limiting shot signals occurring in the peak amplitude values of the signaling current.

The invention is not limited to the described embodiments. It can be used for rectifying modulated high frequency. The circuit can also be arranged in such a manner that the saturation value of curve l3 in Fig. 2 can be adjusted at will or automatically in dependency of any desired magnitude, for example, as a function of the modulation amplitude.

What I claim is:

l. A circuit arrangement including a secondary emission electron multiplier having a cathode, an anode and a plurality of secondary emissive electrodes, means for controlling the electron current in said multiplier, a source of direct current potential, a potential divider connected across said source, a plurality of said secondary emissive electrodes being connected to points of said potential divider and to ground by way of condensers, the condenser connected to the secondary emission electrode adjacent to said anode being so dimensioned that the potential of this electrode is kept substantially constant when the current through the secondary emission multiplier is increased to its maximal Value for a short period of time less than the time between the occurrences of maximal values of electron emission from the primary cathode to the adjacent secondary emission electrode.

2. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form of a grid located between said cathode and anode,

another secondary emissive electrode in the forni of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from said anode to the positive terminal of said source and to ground, a connection including a resistance from said secondary emissive electrode which is in the form of a plate to the potential tap of said potential divider which is closest to the positive terminal of said source, and a connection from each of said plurality of secondary emissive electrodes, respectively, to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode.

3. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form of a grid located between said cathode and anode, another secondary emissive electrode in the form of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from said anode to the positive terminal of said source and to ground, a connection including a resistance from said secondary emissive electrode which is in the form of a plate to the potentia1 tap of said potential divider which is closest to the positive terminal of said source, a connection from each of said plurality of secondary emissive electrodes, respectively, to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode, and a condenser connected between each tap of said potential divider and ground.

4. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form of a grid located between said cathode and anode, another secondary emissive electrode in the form of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from said anode to the positive terminal of said source and to ground, a connection including a resistance from said secondary emissive electrode which is in the form of a plate to the potential tap of said potential divider which is closest to the positive terminal of said source, a connection from each of said plurality of secondary emissive electrodes, respectively, to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode, a condenser connected between the taps, respectively, of said potential divider to which said secondary emissive electrodes are connected and ground, the condensers which are connected to the taps associated with the two secondary emissive electrodes which are adjacent to said anode being so dimensioned that the potentials of these taps remain substantially constant for all operating conditions.

5. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form of a grid located between said cathode and anode, another secondary emissive electrode in the form of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from the secondary emissive electrode in the form of a grid which is adjacent to said anode to the positive potential of said source, a connection from each of the others, respectively, of said secondary emissive electrodes which are in the form of grids to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode, a second source of direct current potential connected in seriesaiding relationship to said first source and having an intermediate potential tap, a connection from said anode to the positive terminal of said second source and to ground, and a connection from said secondary emissive plate electrode to the intermediate tap of said second source.

6. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form or! a grid located between; said cathode and anode, another secondary emissive electrode in the form of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from the secondary emissive electrode in the form of a grid which is adjacent to said anode to the positive potential of said source, a connection from each of the others, respectively, of said secondary emissive electrodes which are in the form of grids to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode, a second source of direct current potential connected in series-aiding relationship to said first source and having an intermediate potential tap, a connection from said anode to the positive terminal of said second source and to ground, a connection from said secondary emissive plate electrode to the intermediate tap of said second source, and condensers connected between the taps, respectively, of said voltage divider and ground.

'7. A circuit including a secondary emission electron multiplier comprising a primary cathode, an anode in the form of a grid, a plurality of secondary emissive electrodes each in the form of a grid located between said cathode and anode, another secondary emissive electrode in the form of a plate located on the side of said anode opposite to said plurality of secondary emissive electrodes, a source of direct current potential, a voltage divider having a plurality of potential taps connected across said source, a connection from the negative terminal of said source to said primary cathode, a connection from said anode to the positive terminal of said source, a connection including a resistance from said secondary emissive electrode which is in the form of a plate to the potential tap of said potential divider which is closest to the positive terminal of said source, and a connection from each of said plurality of secondary emissive electrodes, respectively, to potential taps on said potential divider of increasing positive potential starting with the electrode closest to said primary cathode.

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