US1863702A - Gaseous conduction method and apparatus - Google Patents

Description

June 21, 1932. c. cs. SMITH I GASEOUS CONDUCTION METHOD AND APPARATUS Filed April 12', 1926 n/fiwenzow amrz saaimwb WQAMWJ/ Patented June 21, 1932 UNITED STATES PATENT OFFICE CHARLES G. SMITH, OF MEDFORD, MASSACHUSETTS, ASSIGNOR TO RAYTHEON INQ, OF CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS GASEOUS CONDUCTION MET HOD AND APPARATUS Application filed April 12,

In prior application Serial No. 7 6,7 94 filed December 21, 1925, is described a gaseous conduction device having means for produclng a highfrequency electrodeless ring discharge, thereby to reduce the voltage drop by ionizing the gas between cathode and anode. According to this invention improved results are obtained by producing a high-frequency discharge between electrode surfaces, one or both of which may be auxiliary electrodes other than the main electrodes of the device.

The period of the high-fre uency discharge should be substantially con ned to the time required for an electron to travel between said The liberation of electrons at the electrode surfaces introduces complicated phenomena involving factors of mobility,

mean free path, work function, etc. which ordinarily produce the so-called cathode drop, but by employing hi h frequencies according to this invention a. g. 10 per second) the cathode drop effect is substantially eliminated, presumably because the excursions of the ositive ions are small (during each half-cySe) in com 'arison to the mean free path of the ions. y virtue of the ionization produced by the high-frequency dish charge, preferably close to the cathode surface, the cathode-anode dischar e may be caused to assume arc characteristics without heating the cathode to temperatures ordinarily employed to produce an are by thermiomc emission, probably for the reason that the number of positive ions falling at any instant u on the electrode is sufiicient to account in arge measure for the currents flowing between cathode and anode. Conseuently large current can be passed through t e gaseous medium between the main electrodes with small applied voltages. The effect may be enhanced by confining the region surrounding the active surface of the cathode to restrict radiation, as by making the cathode hollow and producing the highgequency discharge inside the hollow cath- For the purpose of illustrating the genus of the invention, reference may be had to the drawing in which Figure 1 is a view of one embodiment of the invention; Figure 2 is a 1926. Serial No. 101,284.

re-entrant stem S of the housing H.- The gas contained in the housing is preferably one which is readily ionizedand therefore for illustration a drop of mercury is shown at M to supply mercury vapor at a suitable I pressure. If desired, other gases may be employed in the various embodiments of the present invention, such as caesium, etc., as disclosed in my prior applications.

In operation, the high-frequency discharge is produced between the plates K by means of high-frequency potential difference trans mitted through the transformer T. The resulting high-frequency current, which may ave a magnitude of the order of one-tenth ampere or more, ionizesthe gas or vapor between the electrodes K, as evidenced by a glow in the space between these electrodes, and as a result of this ionization in-the region of the cathode surfaces the main discharge between the cathode surfaces and the anode A may be produced with a comparatively low potential drop between the anode and cathode surfaces.

The embodiment shown in Fig. 2 is sim ilar to that shown in Fig. 1 and corresponding parts are correspondingly designated.

However, the cathode is in the form of a hol-.

low box K which is approximately spherical.

This box has a discharge opening D opposite the anode, and at the bottom it has two cylindrical protuberances fitting over the insulat} ing sleeves I. The high-frequenc transformer T is connected to two rods and R spaced from each other within the hollow 1-; cathode, instead of vbeing connected toth cathode surfaces as in Fig. 1. When a highfrequency discharge is produced between the rods R and R the gas within the hollow cathode is ionized, thereby practically eliminating the cathode drop at the interior surface of the cathode, the main discharge passing between the interior surface of the oathode and the anode through the opening D by virtue of the high state of ionization inside the cathode. By confining the radiation generated inside the hollow cathode, the state of ionization may be enhanced and maintained with less loss of energy. Inasmuch as the ionized region is surrounded by the cathode K the latter serves to confine the radiation and the conservation of radiation may be still further effected in various ways as disclosed in my prior applications. For example, the loss of radiation through the cathode K may be greatly reduced by making the inside surface of the cathode brightly reflecting. As in the case of the embodiment shown in Fig. 1, the form shown in Fig. 2 may employ any suitable gas at the pressure best suited to the particular use for which the device is intended.

Obviously the invention may be applied in ways differing widely from the two embodiments chosen for the pur ose of illustration, and the claims are there ore intended to be merely illustrated and not limited by the figures.

I claim:

1. The method of producing a gaseous discharge having arc characteristics between a cathode and an anode in a sealed vessel filled with gas at substantial pressure, which comprises maintaining in the gaseous body adjacent said cathode an auxiliary high frequency discharge of the order of one-tenth of an ampere and of a frequency of the order of 100,000 cycles per second or more to ionize the gas adjacent the cathode and to impart to the discharge to the anode the character of an arc.

2. The method of producing a low voltage gaseous discharge between a cathode aggregate comprising a pair of spaced electrodes and an anode in a discharge device having a sealed vessel filled with gas at substantial pressure, which comprises maintaining between said spaced electrodes an independent high frequency discharge having a period confined to the time required for an electron to travel between said spaced electrodes.

3. A unidirectional gaseous: conduction device comprising a sealed vessel containing a gas filling of substantial pressure, an anode a cathode aggregate having an extended cathode surface, said cathode ag egate having associated therewith a pair 0 spaced electrodes, means for maintaining between said pair of spaced electrodes a big}:) frequency space current ionizing the tween said electrodes to a degree at w 'ch a discharge having arc characteristics is produced between said anode and said cathode aggrecathode and an an gate, said cathode aggregate including means I constituting an enclosure around the gas adjacent the cathode surface between said spaced electrodes to conserve the energy and the ionization of the gas adjacent to, the cathode surface.

4. A unidirectional gaseous conduction decharacteristics is maintained between said I cathode and said anode.

5. A unidirectional gaseous conduction device comprising a sealed vessel containing a gas filling of substantial pressure, an anode, a cathode aggregate comprising a pair of spaced electrodes, and means for maintaining between said pair of spaced electrodes, a igh frequency space current ionizing the gas etween said electrodes to a degree at which a discharge having are characteristics is produced between said anode and said cathode aggregate, the period of said high frequency space current being not larger than approximately the time necessary for an electron to travel under the applied voltage hetween the high frequency discharge surfaces.

6. A unidirectionlal space current device com risin an enve 0 containing a gas, a

p g 05: spaced from each other within said envelo means adjacent said cathode .enclosing a jacent the surface of said cathode a body of ionizable gas adapted to sustain a gaseous discharge, a pair of spaced electrodes disposed in the enclosed space, and high uency inducing means connected to said pair of spaced-electrodes for producing in the enclosed gas a high frequency discharge ionizing said gas to provide electric carriers for maintainin a discharge between said cathode .and sai anode having are characteristics.

Signed by me at Boston, Massachusetts,-

this 8th day of A ril 1926.

. LES G. SMITH.

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