US2736840A - Device comprising a glow-discharge tube for amplifying voltage pulses, and glow discharge tube for use in such devices - Google Patents

Description

Feb. 28, 1956 I c. H. TOSSWILL 2,736,840

DEVICE COMPRISING A GLOW-DISCHARGE TUBE FOR AMPLIFYING VOLTAGE PULSES, AND GLOW DISCHARGE TUBE FOR USE IN SUCH DEVICES Filed NOV. 1, 1951 INVENTOR Christopher Holy Tosswill United States Patent DEVICE COMPRISING A GLOW-DISCHARGE TUBE FOR AMPLIFYING VOLTAGE PULSES, AND GLOW DISCHARGE TUBE FOR USE IN SUCH DEVICES Christopher Haly Tosswill, Carshalton, England, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application November 1, 1951, Serial No. 254,216

Claims priority, application Great Britain November 3, 1950 4 Claims. (Cl. 315168) This invention relates to a device for amplifying voltage pulses by means of a glow discharge tube in which the voltage pulse is fed to an ignition electrode arranged between anode and cathode and in which a capacitor is connected between cathode and anode and a high resistance is connected in series with the tube.

In addition, the invention relates to a glow discharge tube for use in such a device.

The ignition electrode is generally connected to the anode via a very high resistance and is arranged in a manner such that in the absence of a discharge between anode and cathode it passes a low current which is sufficient for removing ignition delays but not sufficient for starting up the tube. The very high resistance supplies a suitable bias voltage to the ignition electrode so that ignition can be effected with the use of low pulses.

The discharge between anode and cathode struck by the voltage impulse discharges the capacitor. The current pulse through the high resistance for charging the tube is used for indication and if required for further amplifying the voltage pulse. The value of this current is determined by the resistor in view of the requirement that the charging current for the capacitor should be lower than the current at which the discharge through the tube extingnishes (extinction current). It is desirable that the discharge between anode and cathode should be extinguished at a maximum value of the current. The higher this current, the lower may be the resistance. At the same RC-time the capacitor which is connected across the tube can be increased and hence higher current can be obtained with the same number of pulses. However, as an alternative the RC-time may be decreased and the current be left unchanged so that pulses of short sequence can be separated.

In order that it may be possible to amplify even low voltage pulses it is desirable that only low voltage pulses should be required at the ignition electrode for starting up the tube. However, the requirements of high extinction current and low pulses for the ignition are at variance with each other and this has led to the use of two or three glow discharge tubes in parallel in order that nevertheless a sufficient current may be obtained.

The object of the invention is to provide a device having a high ignition sensitivity and a high extinction current.

According to the invention, in a device for amplifying voltage pulses by means of a glow discharge tube in which the voltage pulse is fed to an ignition electrode arranged between anode and cathode and in which a capacitor is connected between anode and cathode and a high resistance is connected in series with the tube, the glow discharge tube comprises between the cathode and the ignition electrode a grid-shaped auxiliary electrode which is connected to the cathode via a high resistance and being arranged at such a distance relative to the cathode that it lies outside the zone of the cathode drop.

2,736,840 Patented Feb. 28, 1956 ICC During ignition the discharge between the ignition electrode and the grid-shaped electrode is initiated, but since the latter is connected to the cathode via a resistor the discharge strikes via the grid across the cathode and on the other hand across the anode. Hence, with decreasing anode voltage, the discharge between the auxiliary electrode and cathode at the same anode current will be extinguished sooner because part of the anode current leaks away via the auxiliary electrode and via the heavy resistor.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing, in which Fig. 1 shows a known circuit arrangement,

Fig. 2 shows a circuit arrangement according to the invention, and

Fig. 3 is a sectional view of a tube for use in a device according to the invention.

Referring to Fig. 1, a tube 1 contains an anode 2, a cathode 3 and and an annular ignition electrode 4. A

resistor 8 of 10 ohms is connected between the anode and the ignition electrode. The cathode is connected to a voltage source of to 200 volts with the interposition of a resistor 5 of the order of 1 megohm via a measuring intrument 6. The pulses to be amplified are fed to the ignition electrode 4. The anode and the cathode have interconnected between them a capacitor 7.

In Fig. 2, the circuit arrangement differs from that in Fig. 1 only in that provision is made of an auxiliary electrode 9 and this auxiliary electrode and the cathode 3 have connected between them a resistor 11 of 1 megohrn.

Referring to Fig. 3, the tube wall and the electrodes are designated by the same reference numerals as in Fig. 1. The cathode 3 and the ignition electrode 4 have arranged between them an electrode 9 which is shaped in the form of a plate in which apertures 10 are drilled. In the case of an anode and cathode diameter of 1 cm. provision may be made for example of 7 apertures, that is to say one at the centre and six evenly distributed about a circle 1 cm. in diameter, all the apertures having a diameter of 1.5 mm.

The circuit arrangement of Fig. 2 operates in a manner such that the potential diiference between the anode and the auxiliary electrode is comparatively low and may be, for example, about 100 volts between the auxiliary electrode and the cathode. In this case, the auxiliary electrode abstracts a current of about 100 a. from the anode current and the cathode current is consequently lower than the anode current by 100 ,ua. Since the extinction is determined by the conditions at the cathode, the discharge is extinguished at a higher total current than if the auxiliary electrode were not present. Since the ignition sensitivity is determined by the arrangement of ignition electrode and auxiliary electrode in relation to one another, it can be chosen to be independent of the adjustment of the extinction current.

What I claim is:

l. A device for amplifying voltage pulses by means of a glow discharge tube in which the voltage pulse is fed to an ignition electrode arranged between anode and cathode and in which a capacitor is connected between anode and cathode and a high resistance is connected in series with the tube, characterised in that the glow discharge tube comprises between the cathode and the ignition electrode a grid-shaped auxiliary electrode which is connected to the cathode via a high resistance and which is spaced apart from the cathode by a distance such that it lies outside the region of the cathode drop.

2. A glow discharge tube for use in a device as claimed in claim 1, characterised in that the cathode and the ignition electrode have arranged between them a grid-shaped auxiliary electrode which lies outside the zone of the cathode drop.

3. Apparatus for amplifying voltage pulses comprising a glow discharge tube having a cathode, an ignition electrode, an anode and a grid-shaped auxiliary electrode which is disposed between said cathode and said ignition electrode and is spaced from said cathode by a distance at which it lies beyond the zone of cathode fall, a capacitor connected between said cathode and said anode, a first resistance having a relatively high value connected between said auxiliary electrode and said cathode, a second resistance having a relatively high value, a source of direct potential having its positive terminal connected to said anode and its negative terminal connected to said cathode through said second resistance, said source having a magnitude to produce a glow discharge in said tube when it is ignited, and means to apply said voltage pulses to be amplified to said ignition electrode.

4. Apparatus, as set forth in claim 3, further including a third resistance connected between said ignition electrode and said anode.

References lit-ed in the file of this patent UNITED STATES PATENTS 2,341,541 Grier Feb. 15, 1944 2,525,808 Litchman Oct. 17, 1950 2,540,035 Rodman Jan. 30, 1951

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