US2297256A - Tube control - Google Patents

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Publication number
US2297256A
US2297256A US267189A US26718939A US2297256A US 2297256 A US2297256 A US 2297256A US 267189 A US267189 A US 267189A US 26718939 A US26718939 A US 26718939A US 2297256 A US2297256 A US 2297256A
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Prior art keywords
grid
voltage
current
arc
control
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US267189A
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English (en)
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Schumann Winfried Otto
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Individual
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Individual
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/04—Electrodes; Screens
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/02—Circuits specially adapted for the generation of grid-control or igniter-control voltages for discharge tubes incorporated in static converters
    • H02M1/04—Circuits specially adapted for the generation of grid-control or igniter-control voltages for discharge tubes incorporated in static converters for tubes with grid control

Definitions

  • the present invention relates to vacuum-arc dischargesv (e. g. Hg arcs with natural cathode- Hg cathode-or those with artificial Cathodeglow cathode-) as well as to arc discharges in gases or other metal vapors at low pressures.
  • vacuum-arc dischargesv e. g. Hg arcs with natural cathode- Hg cathode-or those with artificial Cathodeglow cathode-
  • Fig. 2 is a graph illustrating the operation of the arrangement shown in Fig. 1; y
  • Figs 3 to 7 illustrate various embodiments of the present invention.
  • Fig. 1 shows a circuit arrangement and Fig. 2 a diagram for this circuit arrangement.
  • a tube l' which may be filled with mercury and comprises a grid 2 and a resistance R, are connected in the usual manner to the circuit of a .battery E.
  • a source of alternating current may of course be used.
  • 'I'he gridr2 receives an auxiliary voltage Vg. This voltage may be supplied either by a source of direct current, or as shown by way of example, by a. transformer.
  • VB E-JBR, in which JB designates the arc current, so that JB:E RVH i, e. inasmuch as in Fig. 2, the arctension VB is shown as rising from the bottom up, the difference between E and VB (from the horizontal line 4 with E down 'to the VB curve) is proportional to the current JB.
  • the arcvoltage VB at a working voltage E of 110 volts, may be increased up to approximately 50 volts by means of the negative grid voltage, wheretemperature.
  • the arc-current may be controlled continuously and in this zone,V in the case of mercury arcs, the arc-voltage VB growsk continuously from the ignition voltage VBC (initial voltage) up to approximately 50 yolts; this correspondsto the voltage VBK. If one increases the grid voltage still higher, .that is if one exceeds the value VgK, the current decreases very rapidly and suddenly disappears in about a few 10-5 seconds. In other words, the VBV curve would take a continuous course up to point A shown in Fig, 2, while on passing beyond point A,.
  • Themain object ofthe invention is to prevent the current from Vvbreaking off suddenly after reaching point A, while ⁇ maintaining suciently high anode voltages, which according to the embodiment of the invention shown and described lie considerably above the point VBK.
  • this result is obtained in such manner that, after the critical Zone of control voltage (Vga) is reached, in which upon further increases in the control voltage the current would break off, the control action of the grid is again decreased, by means of the influence of the arc current or the arc voltage, so that the current, gradually disappears (curve AB-Fig. 2) with a decrease in the control action (for instance by decreasing grid voltage VgK).
  • the gradual disappearance of the current takes place in accordance with the disappearing grid action, or in other words in the slow manner desired.
  • the control action is xed at any one point on the curve AB, i. e., if it remains constant for a length of time, then the corresponding current JB remains likewise constant for a length of time.
  • any desired current may be adjusted between the full value and zero even for any desired length of time.
  • the electrical eld which accomplishes the conveyance of current between anode and cathode, becomes larger at this place, whereby the additional voltage VB-VBO is created at this place which, in turn, decreases the arc current.
  • the carrier density of the discharge is again decreased which on the other hand, causes an increase in the inuence of the grid upon the arc, whereby a further reduction of the carrier density in the grid apertures is produced together with an increase in the value VB-VBo and simultaneously therewith in the value of the arc voltage.
  • a decrease in the arc current-l is produced again etc.
  • the ultimate reason for this condition may be that, at this stage, the layers of ions around the wires grow extremely rapidly in thickness with increases in the grid Voltage. It might be said that the layers snap closed, thus breaking the current.
  • the grid is too effective in this condition and itmust be weakened in its action in order that no snapping-closed of the layers of ions may occur.
  • Such weakening of the grid action may be eirected in various ways.
  • the thickness of the layer of ions round the wires depends on the grid voltage supplied, and
  • any known means may be used for reducing the grid Voltage or increasing the carrier density of the discharge, provided these steps are suiciently dependent upon the arc voltage, the arc current or both.
  • the voltage at the grid may be iniiuenced in such a way that after reaching the critical value Vgn the grid voltage is caused to decrease again, in harmony with the further decrease of the arc current or with the further increase of the arc voltage.
  • Vgn critical value
  • the current either disappears as slowly as desired, or remains constant, 0r that it increases again, when the grid voltage increases again.
  • this may be done for instance by introducing into the grid circuit a voltage or a voltage limitation derived from the arc current or the arc voltage or their timed increase or from them jointly, which prevent Vg, under any circumstances, from passing beyond Vgx so that the layers of ions around the grid wires cannot snap-closed.
  • the grid current generally, is proportional to the arc current in the case of a constant grid voltage
  • the current of the control grid itself may be used for this purpose, if the control circuit is arranged in such a way that, with decreasing grid current, a sufficient lowering of grid voltage is obtained, for instance by means of resistances dependent on the current.
  • part of the source of grid current may be arranged in such a way that its voltage depends to a suiliciently large extent on the grid current.
  • the grid voltage will have to be inuenced by the arc current in two ways, so to speak.
  • control grid may also be iniiuenced by means of the arc voltage or alternately, by using the voltage of a conveniently insulated auxiliary grid i. e., a grid which is connected to the cathode for instance across sufliciently large resistances or inductivities (see Fig. 5).
  • a conveniently insulated auxiliary grid i. e., a grid which is connected to the cathode for instance across sufliciently large resistances or inductivities (see Fig. 5).
  • a conveniently insulated auxiliary grid i. e., a grid which is connected to the cathode for instance across sufliciently large resistances or inductivities (see Fig. 5).
  • a second means of influencing the control grid consists for instance in providing a second grid in the arc. Every control grid has the property of augmenting the carrier density between grid and anode with increasing negative grid voltage, while the carrier density between grid and cathode is influenced comparatively little.
  • the carrier density of the plasma may be adj-usted at will between Ythe two grids by means oi the voltage of the auxiliary grid.
  • the plasma carrier density between the two grids must beV increasedby increasing the negative voltage atthe auxiliary grid-to such an extent during the passage through the critical grid voltage that the layers of ions about the control grid wires cannot snapclosed. This result may be obtained by coupling the two grid voltages in such a manner that, when the critical voltage Vgn'at the controlgrid is reached, the negative voltage at theV auxiliary grid increases sufficiently quickly.
  • the influence of the arc current or of the arc voltage may of course be utilized, as described above. It should be noted that the means for increasing the carrier density of the discharge described above were given merely by way of example.
  • Fig. 2 shows in dotted lines schematically and by way of example the course of a curve after passing through point A up to point D. From this graph it is clear that, when Vgx has been reached and the grid voltage decreases again after point A, the arc voltage VB increases and the current JB decreases gradually.
  • the course of curve A-D depends on the extent to which the grid voltage decreases. If the grid voltage is maintained at a certain value lying below Vgx, one obtains a corresponding constant current value.
  • the entire curve of the grid voltage may also be repeated periodically forward or backward by alternatingly reducing the arc current to zero and then bringing it up to its full value, or Vice Versa. In all these cases breaking off of the current is avoided and the current is continuously controllable within any desired limits.
  • relays known by themselves. These relays, which are influenced by the arc current for instance or by the grid current, or by the arc voltage or by the voltage from an auxiliary grid disposed between anode and control grid and connected for instance through a throttle coil or a resistance with the cathode, lower the grid voltage when passing through VgK. Similarlyy various back couplings employed in the high frequency field may be used but of course, in difierential connection.
  • Fig. 3 shows for instance a control arrangement for avoiding excessively high voltages
  • a condenser C takes care of the return path of the grid voltage.
  • ca pacity C
  • an ohm resistance may be used.
  • the resistances r1 and r2 serve for proper adjustment.
  • Fig. 4 dillers from that of Fig. 3 merely in that the reduction of the grid action is effected not capacitively, but directly.
  • the process in itself is the same, that is on reaching VgK the growth of the anode voltage is transmitted directly to the grid circuit so that areduction of the negative grid voltage is produced.
  • auxiliary grid 3 disposed between control grid 2 and the anode.
  • This auxiliary grid 3 is connected to the cathode over point K and the resstances r1 and r2.
  • the two grids 2 and 3 are connected jointly over resistance r2 with the cathode.
  • the Voltage of the auxiliary grid 3 increases in the same proportion as the voltage of the anode and acts across resistancerz so that a reduction of the grid action of control grid 2 is produce
  • the point K may be connected to the anode, as shown in Fig. 6. In that case, the arc voltage, which increases during a decrease of the current, reacts upon the control grid 2 and reduces the negative voltage of the same as against the cathode.
  • Fig. 7 shows a modified arrangement in which, by use of an auxiliary grid, the nature of the plasma is altered in such a way that on reaching Vgx the control action of the control grid is reduced.
  • auxiliary grid designated by numeral 4
  • Auxiliary grid 4 is connected to a device 5 which is connected in the known manner (for instance amplier, transformer, compensation circuit etc.) in such a Way that the voltage of the auxiliary grid 4 becomes more negative as against the cathode in the breaking 01T zone.
  • the control action is obtained in dependence upon the anode voltage, across a resistance r3. as well as in dependence upon the anode current, across resistance r4.
  • the device 5 must comprise a means, known in itself, for reversing the direction of these actions.
  • Method of controlling and extending the field of control over the arc current in a system comprising an arc discharge tube provided with anode, cathode and control grid, and electricity supplying means for said anode, cathode and grid, which method comprises applying a voltage to thearc discharge tube to form an arc between anode and cathode, applying a voltage to said grid having a negative value as against the discharge plasma, and increasing said grid voltage, whereby the arc discharge voltage is proportionally increased, and continuing to increase said grid voltage until the critical point in the arc voltage is reached, being the point immediately after which the arc current breaks off, and passing through said critical point with a constant grid voltage; thereafter decreasing said grid voltage as slowly asdesired and to the desired degree, whereby the arc current may be slowly decreased or maintained at any desired point beyond said critical point, sudden breaking off of the arc current after the critical point being thus prevented.
  • Method of controlling and extending the iield of control over the arc current in a system comprising an arc discharge tube provided with anode, cathode and control grid, and electricity supplying means for said anode, cathode and grid, which method comprises applying a voltage to the arc discharge tube to form an arc, imparting a negative voltage to said grid as against the discharge plasma, and increasing this Voltage diierential between the grid and the plasma, whereby the arc discharge voltage is proportionally increased, and continuing to increase the said differential between grid and plasma until the critical point in the arc voltage is reached, being the point immediately following which the arc current breaks off, and passing through said criticalpont with a constant grid voltage; thereafter decreasing said diierential between grid and plasma as slowly as desired and to the desired degree, whereby the arc current may be slowly decreased or maintained at any desired point beyond said critical point, sudden breaking oi of the arc current after the critical point being thus prevented.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Electron Sources, Ion Sources (AREA)
US267189A 1938-04-11 1939-04-10 Tube control Expired - Lifetime US2297256A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE540126X 1938-04-11

Publications (1)

Publication Number Publication Date
US2297256A true US2297256A (en) 1942-09-29

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Family Applications (1)

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US267189A Expired - Lifetime US2297256A (en) 1938-04-11 1939-04-10 Tube control

Country Status (4)

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US (1) US2297256A (xx)
FR (1) FR852848A (xx)
GB (1) GB540126A (xx)
NL (1) NL58115C (xx)

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Publication number Publication date
GB540126A (en) 1941-10-07
NL58115C (xx)
FR852848A (fr) 1940-03-04

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