US1628045A - Electronic discharge device - Google Patents

Description

-May 10, 1927. 1,628,045

W. F. HENDRY ELECTRONIC DISCHARGE DEVICE Filed Oct. 8, 1926 Patented May 10, 1927. V

UNITED STATES 1,628,045 PATENT OFFICE.

WILLIAM I. HENDRY, OF OSSINING, NEW YORK, ASSIGNOR TO MAN'HATTAN ELEC- TRIGAL SUPI'LY' GOMYANY, INC,

A CORPORATION OF MASSACHUSETTS.

ELEorEoivIc mscrrAEeE DEVICE.

Application filed. October 8, 1928. Serial No. 140,309.

This invention relates to new and useful improvements in electronic discharge devices, and particularly to rectifiers in which the electrodes are provided within an exhausted or gas-filled envelope.

It is the ob'ect of the present invention to provide a rectifier which is capable of passing current of high voltage and amperage and which has a long life.-

With reference to the drawings, Fig. 1 is a preferred embodiment of the invention illustrated as a half wave rectifier; Fig. 2 shows another manner in which the carbon electrode assembly of Fig. 1 may be constructed; Fig. 8 illustrates the invention as embodied in a full wave rectifier; and Fig. 4 illustrates another embodiment of the invention in a full wave rectifier.

.In the different figures of the drawings corresponding reference characters refer to corresponding elements.

The nature of the invention will be best understood by explaining it in connection with a preferred embodiment thereof illustrated in Fig. 1 of the drawings in vertical cross-section. The rectifier is provided within a glass envelope 11 filled with neon at a pressure of two or three mm. of mercury and comprises a carbon' electrode 2 and a hollow substantially hemispherical aluminum electrode 3. The carbon electrode 2 is fitted within a cavit 4 provided near the upper end of a cylin er 5. The cylinder 5 may be of lava, porcelain orother suitable insulating material and it is longitudinally perforated at 6. An aluminum rod 7 fastened at one end into base 8 of the carbon electrode and at the other end to a leading-in wire 9 passes through the perforation 6. The perforation is enlarged at the lower end of the cylinder 5, as indicated at 10, and accommodates a glass stem 11 which surrounds the rod 7 and the leading-in wire 9.. The base 8 of the carbon electrode substantially fills the cavity 4 of the cylinder and is held therein by means of a mug 12 fitted in an enlar ed cavity 13 in the upper end of the cylin er 5. The ring 12 is of insulating material such as lava, porcelain or the like, or may be of metal if properly insulated from the carbon as shown in Fig. 2 and is held in place by means of a ferrule 14. The carbon point 2 projects through ring 12 above the ferrule 14 and is throughout its circumference spaced from the ring 12. The

'respondinglv high pressure,

ring 12'is undercut at its base, increasing its spacing from the carbon as indicated at 18. The aluminum anode is fastened to an aluminum rod 15 which, together with its leading-in wire 16, is protected by a glass stem 17. The edge of the aluminum electrode extends to a point slightly below the upper end of the cylinder 5.

Fig. 2 shows a modification of the carbon electrode assembly of Fig. 1. This modification is the same as that shown in Fig. 1 except that in place of the insulating ring 12 there is provided a ring of conducting material 21 which is insulated from carbon electrode 2 by means of a washer 20 of nonconducting material such as lava, porcelain or the like. Figs. 3 and 4 are illustrations of full wave rectifiers which comprise two units as shown in Fig. 1, both to"be enclosed in a single envelope and cooperating with one or two aluminum electrodes.

I have found that a rectifier constructed 'in accordance with the present invention is capable. of converting alternating current at very high pressure into direct current at corand operates successfully for 4000 hours ormore. I attribute the high capacity of this rectifier partly to the mounting of the carbon electrode. A theory of operation of this device may be that during that part of the cycle when the carbon is negative, the valve or shut-off action is produced by a screen or shroud of positive particles (ions) which effectually prevents the migration of electrons from the negative (carbon) to the positive (AL) electrode. During this period the (potential drop takes place at a very'short istance from the surface of the carbon point (probably of the same order as the distance through which an electron must fall to produce ionization at the impressed voltage).

It has been found that if the carbon is supportedby an insulating platform or support, then this insulating support is destroyed within a very short time if high potentials are used. Probably the reason for this is that'when the impressed E. M. F is raised to about 550 v., a positive partlcle (ion or sputtered metal particle) coming within the region of large voltage gradient at a small distance from the carbon point, is accelerated to a velocity such that an insulating platform if within this region, even when made of quartz, is destroyed in a few minutes. i v

If, however, the insulating support is protected byan annular cylinder 12 kept away from the carbon point a distance beyond the border line of the positive screen, then no destructive action takes place if the depth of the annular space thus formed, surrounding the carbon point, be such that any positive particles which succeed in entering the space will be drawn into the carbon or stopped by collision with positive partlcles or neon atoms before arriving at the point where the electrode 2 is in contact with the supporting platform 5 or cylinder 12. If the attraction of the carbon electrode and pressure in the envelope is fixed, this should be dependent on two factors, the width of the annular space 19, and the speed of the.

particle.

I have found in actual practice that at a neon gas pressure, usually between 2 and 3 mm., if the radial width of the annular space is 1/64, a longitudinal depth of is sufpirically determined.

ficient to withstand an impressed E. M. F. of' 1100 volts. commercial inconvenience of .maintaining such close dimensions, I increased the Width .0 and then found it necessary to increase the depth to A," in order to withstand 1100 volts with ample margin of safety, although a depth showed no signs of distress at approximately 850 volts. Optimum dimensions for any particular purpose may be em- Practice, therefore, seems to prove that a positive particle moving at a speed corresponding to 1100 volts impelling force will, if it approaches within 2- of the negative carbon (as it must to enter the annular space 19), be attracted into contact with it or arrested by other particles before it can travel parallel to its surface. Thus the supporting insulation 5 and the cylindrical shield 12 are assured of permanent protec' tion from heat or bombardment. During the early hours of service a small amount of carbon dust is driven ofi' of the carbon point and possibly to some degree throughout the life of the device, and to insure that the annular space is notfilled with thiswire for said carbon In view, however, of the having therein a filling comprising a rare gas, an electrode within said envelope having an elongated point, a cylinder of insulating material within which said electrode is seated envelope having an elongated point, a cylinder of insulating material within which said electrode is seated with the end of its point projecting, a ring of insulating material surrounding said point and holding said carb'on electrode within said cylinder, said ring being spaced from said point, slightly at its free end and widely at its base, a leading-in electrode, and a second electrode. i

3. In a rectifier, a'sealed glass envelope filled with neon at approximately 2 mm. pressure, a carbon electrode within said envelope having an elongated point and a base, a cylinder of insulating material within which said electrode isseated with the end of its point projecting, a ring of insulating materia'l surrounding a portion of said elongated point and holding said carbon electrode within said cylinder, said ring beingspaced from said point, slightly at its upper edge and widely at its base, a leading-in wire for said carbon electrode passing through said cylinder, and a substantially hemispherical aluminum electrode substantially centered with respect to said carbon electrode.

4. A mounting for an electrode in high potential electrostatic field consisting of an annular cylinder surrounding the electrode but at a distance therefrom slightly greater than the distance through which an electron must fall to produce ionization of surrounding material at impressed voltage whereby an annular space between the electrode and cylinder is defined, the length of said space being increased with an increase of potential.

5. In a gaseous discharge device, an electrode and an insulator, means for restricting the operating area of said electrode comprising an annular cylinder of material surrounding said electrode, with one end of said cylinder terminating at a point adjacent the operating end of said electrode, and spaced therefrom a distance but slightly greater than the distance through which an electron must fall to produce ionization at the impressed voltage, the length of the portion of said cylinder adjacent to said electrode being greater than said distance.

6. In an electric discharge device, an electrode mounting comprising an electrode, an insulating support and an annular cylinder of insulating material surrounding said electrode and spaced a small distance therefrom, the ratio of the width of the said small distance to the length of the annular cylinder being approximately one-eighth, whereby electrical breakdown of the insulating support is prevented.

T. In a high voltage electrical discharge device, an electrode and an insulator adjacent thereto, means for preventing breakdown of said insulator comprising an annular cylinder of insulating material surrounding said electrode and spaced a small distance therefrom, the ratio of the width of the said small distance to the length of the portion of said cylinder adjacent to said electrolde being in the neighborhood of one to ei t.

8. In a gaseous discharge device, an electrode and an insulator, means for preventing electrical breakdown between said electrode and said insulator comprising an annular e linder of material surrounding said electrot e and spaced therefrom a distance but slightly greater than the distance through which an electron must fall to produce ionization at the impressed Volta e.

9. In a high voltage gaseous disc arge device, an envelope filled with a rare gas at low pressure, an insulator, an elongated electrode supported by said insulator and means for preventing electrical breakdown between said electrode and said insulator, comprising an annular cylinder of insulating material surrounding said electrode with one end of the cylinder adjacent to the free end of said electrode, the length of said cylinder being of an inch and the distance between said electrode and said cylinder being 3 2' of an inch.

10. In an electrical discharge device, an electrode and an insulating member perforated to receive said electrode therethrougli to form a space between said electrode and said material, the width of the said space being but slightly greater than the distance through which an electron must fall toproduce ionization at the impressed voltage, and the depth of said space being several times the width thereof.

11. In an electric discharge device having electrodes, an electrode mounting comprising one of said electrodes, and an insulating support, said support having an annular extension which surrounds said electrode and is spaced therefrom a distance but slightly greater than the distance through which an electron must fall to produce ionization at the impressed voltage, the length of the annular extension of said support adjacent to said electrodes being greater than said distance and the angle of the path of the discharge between said electrodes being less than 90.

In testimony whereof, I have signed my name to this specification, this 7th day of October, 1926.

WILLIAM F. HENDRY.

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