US2226171A - Gas or vapor electric discharge device - Google Patents

Description

Dec. 24, 1940. J. LECORGUI LLEER 2,226,171

GAS OR VAPOR ELECTRIC DISCHARGE DEVICE I Filed June 18, 1938 y INVENTOR C 40 9C0! 0/ 18 1 j 7/ ATTORNEYS Patented Dec. 24, 1940 PATENT OFFICE GAS OR VAPOR ELECTRIC DISCHARGE DEVICE Jean Lecorguillier, Suresnes, France; assignor to Socit Anonyme Pour' les Applications de lE'lectricite et des Gaz Rares, Etablissements Claude-Paz & Silva, Paris,.France Application June 18, 1 93s, Serial No. 214,526 In Switzerland June 22, 1937 8 Claims.

The present invention relates to gas or vapor discharge devices having one or more grids and intended for the conversion of currents or voltages.

For adjusting the ignition point of an are it has been proposed to apply between a grid placed in the discharge path relative to said are and the cathode, an alternating voltage of known waveform and phase-displacement relatively to the main anode-cathode voltage.

This method of control comprises a certain number of disadvantages.

Thus in the particular case of cathode arc relays operating by cathode spot, for example mercury vapor arc relays having a cathode mercury pool or a regeneratable. cathode as described in my application Serial No. 118,986, filed January 4, 1937, the movement of the cathode spot produces such variations in the control characteristic that a steep-fronted wave has to be applied between cathode and grid in order to ensure the exactness of the instant of ignition.

Other disadvantages of this method of grid control result from the fact that its application necessitates the use of a resistance for limiting the grid current. We shall now explain them with reference to Figure l, which illustrates prior art.

This figure shows diagrammatically at l the discharge vessel, at 2 the anode, at 3 the cathode, at 4 the grid, at 5 the source of grid control voltage and at 6 the resistance for limiting the grid current, of an arc relay.

It has been observed that as long as the arc is not ignited, the grid assumes, relatively to the cathode, the potential imposed by the source 5. This is no longer the case when it is immersed in the plasma of the ignited arc. In fact, it is then found that there is produced between the grid and the cathode an electromotive force tending to cause a current to circulate in the grid-cathode direction indicated by the arrow 1.

If the source 5 is a direct-current source and tends to bias the grid negatively, it will be seen that the electromotive force of the grid, to which we have just referred, will itself produce a bias which will diminish the preceding bias. In the absence of the latter, the grid bias depends solely upon the resistance 6, it decreases when this resistance diminishes and in short-circuit it becomes zero. A considerable grid-cathode current may then pass, the value of which depends upon the conditions of construction of the arcrelay vandmay attain 300to 400 milliamperes, this current being proportional to the main arc current.

This fact, which in certain cases does not possess any disadvantage, has a considerable disadvantage in the case where a single device controls the grids of a plurality of arc relays of non- 5 simultaneous operation by means of common resistances inserted in the assemblage. It has, in addition, the disadvantage of giving rise to a considerable consumption of grid control energy, since if the latter is to be small, a rather large 10 value must be given to 6, which is in contradiction to the conditions of de-ionisation necessary for satisfactory operation of the device, the deionisation when the arc is extinguished being more rapid, the lower the grid resistance. 15

According to the invention, the alternating control voltage is applied in a circuit comprising the control grid and an auxiliary electrode which we shall call a probe, placed in contact with the ionised gaseous medium of an ignited arc of 20 the apparatus and having no solid connection with the supply circuit or circuits of the apparatus. The position of the probe in the discharge vessel influences the control characteristic determining the anode voltage as a function of thecritical grid voltage, that is to say, of the limit value of the grid voltage corresponding to the establishment of the discharge current, so as to provide generally a positive contro arc relay, that is to say, a relay not requiring any contin-' uous grid bias superposed on the actual control voltage. Furthermore, its presence permits the grid current limiting resistance to be most often dispensed with.

Due to the-preceding device:

1. The energy which the control source has to supply is considerably reduced. Whereas the power consumption is 3 to 4 watts in the case of Figure 1, with the device according to the invention excellent results are obtained with a zero grid resistance and a control power of 0.1 watt or even less than this.

2. The control characteristics are much more regular than in the device of Figure 1 and the displacement of the cathode spot has very little ac- 45 tion, and consequently:

3. For a large number of applications, a grid control of pure sinusoidal wave form is suitable, which is an important simplification.

For the purpose of illustrating my invention, I 50 have shown several embodiments thereof inthe accompanying drawing, in which:

Figure 2 is a diagrammatic representation of a gaseousarc discharge apparatus according to my invention,

constant or variable Voltage, for example, a bat- Figure 3 is an elevational view of a modification of the apparatus of Figure 1, and

Figure 4 is a similar View of a further modification of the apparatus of Figure 1.

In Figure 2, 8 is a discharge vessel filled with a rare gas such as argon, krypton or xenon or a metallic vapor such as mercury vapor, or with a mixture of rare gases or metallic vapors or with a mixture of one or more rare gases and one or more metallic vapors. 9 is the anode, ID the cathode, I I the grid, l2 the source of control voltage and I3 the probe.

In the case where the device considered comprises one or more metal members or parts in contact with the ionised medium of the discharge vessel and forming part of the latter or disposed in its interior, for example if the device is a tube having a metal vessel or a metal anode arm, it is obviously possible to employ as a probe, at least one of said members or parts. It is also possible to employ in a device according to the invention at least one of said members or parts conveniently selected and more especially the anode arm relative to the anode associated with the control grid, as a supplementary grid.

By means of such a supplementary grid biased for example relatively to the cathode or a second probe, a variable slope of the characteristic anode voltagecritical control grid voltage, may be ob tained; if the supplementary grid is then biased by means of a variable source of current, any desired form of control characteristic of the main grid is obtained.

Such an improveddevice is shown by Way of example in Figure 3. At I4 is shown the discharge vessel, at I the anode, at 16 the cathode (here selected of the regeneratable type according to the U. S. Patent No. 2,041,595), at I! the main control grid, at IS the source of control voltage, for example, an alternator placed between the grid I1 and the probe Hi, the latter situated, as is to be preferred, near the outlet orifice of the arm, at 20 the metal anode arm biased relatively to the cathode by the resistance 2| and the source of tery or alternator 22, and'at 23 the maintenance electrode or electrodes 24 is the supply source for the anodic alternating current.

It may be advantageous to apply the control voltage in the circuit of agrid distinct from the .above mentioned control or main grid, this new grid surrounding the probe and-being biased for example relatively to the cathode or a second probe, it being thereby possible to obtain a control of the main grid by means of an exceedingly low power.

Such a form of construction is illustrated in Figure 4 Where the parts already shown in Figure 3 correspond to the same reference numbers as in this last figure. According to this embodiment of the invention, the grid 25 surrounding the probe I9 is connected to the cathode through the source of control voltage [8.

What I claim is:

1. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid and an auxiliary electrode each within said container, means for producing periodically an electrical field between said cathode and anode, said auxiliary electrode being arranged in the medium intended to be ionized by the dis charge between the cathode and the anode and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode, and periodic-voltage-supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments.

2. In a gaseous discharge device for operation underarc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid and an auxiliary electrode, each within said container, means for producing periodically an electrical field between said cathode and anode, said auxiliary electrode being arranged in the medium intended to be ionized by the discharge between the cathode and the anode, laterally relative to the discharge path so as not toexert any action on the discharge current flow,

and having no solid connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode, and periodic-voltage-supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments. v3. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a grid and an auxiliary electrode, each within said container, means for producing periodically an electric field between said cathode and anode, said auxiliary electrode being arranged in .a medium intended to be ionized by the discharge between the cathode and the anode and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode, periodic-voltage-supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments, a second grid in said container and means for applying a voltage between said second grid and the cathode to de form the starting characteristic of the device.

4. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid and an auxiliary electrode, each within said container, means forproducing periodically an electric field between said cathode and an: ode, said auxiliary electrode being arranged in the medium intended to be ionized by the discharge between the cathode and the anode laterally relative to the discharge path so as not to exert any action on the discharge current flow,

and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode, periodic-voltage-supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments, a second grid in said container and means for supplying a'voltage between said second grid and-the cathode to deformthe starting characteristic of thedevice.

5. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron-emitting cathode, an anode, a control grid and an auxiliary electrode, each within said container, means for producing periodically an electric field between said cathode and anode, said auxiliary electrode being arranged in the medium intended to be ionized by the discharge between the cathode and the anode, and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to saidauxiliary electrode, periodicvoltage-supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments, an anode shield surrounding said anode, and means for applying a voltage between said second grid and the cathode, to deform the starting characteristic of the device.

6. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid and an auxiliary electrode, each within said container, means for producing periodically an electric field between said cathode and anode, said auxiliary electrode being arranged in the medium intended to be ionized by the discharge between the cathode and the anode, laterally relative to the discharge path so as not to exert any action on the discharge current flow and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode, periodiccurrent-voltage supplying means interposed in said conductor for providing a voltage that attains a starting value at predetermined moments, an anode shield surromiding said anode, and means for applying a voltage between said second grid and the cathode to deform the starting characteristic of the device.

'7. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid, an auxiliary electrode and a second grid surrounding said auxiliary electrode, each within said container, means for producing periodically an electric field between said cathode and anode, said auxiliary electrode being arranged in the medium intended to be ionized by the discharge between thecathode and the anode, and having no solid electrical connection with the said means, an electrical conductor connecting said control grid to said auxiliary electrode and periodic voltage supplying means interposed between said second grid and the cathode for providing a periodic voltage that attains a starting value at predetermined moments, whereby a periodic potential is impressed on said auxiliary electrode, which causes a periodic voltage to be applied between the control grid and said auxiliary electrode.

8. In a gaseous discharge device for operation under arc-like discharge conditions, a container, an electron emitting cathode, an anode, a control grid, an auxiliary electrode and a second grid surrounding said auxiliary electrode, being so arranged in the medium intended to be ionized by the discharge between the cathode and the anode, laterally relative to the discharge path so as not to exert any action on the discharge current flow, and having no solid electrical connection within the said means, an electrical conductor connecting said control grid to said auxiliary electrode and periodic voltage supplying means interposed between said second grid and the cathode for providing a periodic voltage that attains a starting value at predetermined moments, 1

whereby a periodic potential is impressed on said auxiliary electrode, which causes a periodic voltage to be applied between the control grid and said auxiliary electrode.

JEAN LECORGUILLIER.

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